Unit 10 Test

Know regarding sea level rise: What accounts for most of the expected sea level rise?

About two-thirds of the increase will result from expansion of water as it warms.

What is the correlation between CO2 and temperature over the past 400,000 yrs?

As CO2 increases, temperature increases.

What is geo-engineering? What are some drawbacks?

Carbon capture and storage (CCS) is one proposed geoengineering scheme for helping us to slow global warming and the resulting climate change. Most scientists oppose using such large-scale solutions, because the long-term effects of such projects on the earth's energy flow, chemical cycling processes, and vital biodiversity are unknown. However, in recent years, some scientists have become discouraged by the glacially slow response of governments to what they see as the global emergency of climate change with its projected serious harmful effects. Some of these scientists are suggesting that we at least look at the possible implications and costs of using large-scale geo-engineering schemes as a last resort, if humanity fails to deal with the world's climate change emergency soon enough. For example, some scientists have suggested using balloons, large jet planes, or giant cannons to inject sulfate particles into the stratosphere where they might reflect some of the incoming sunlight into space and thus cool the troposphere. It is thought that the effect would be similar to the cooling effect that lasted about 15 months after the 1991 volcanic eruption of Mt. Pinatubo. Huge amounts of SO2 would have to be injected into the stratosphere about every 2 years. Other scientists reject this idea as being too risky because of our limited knowledge about possible unknown effects. In addition, such a scheme could accelerate ozone depletion by boosting levels of ozonedestroying chlorine in the stratosphere; it could also increase acid rain in the troposphere. This short-term technological fix would also allow CO2 levels in the lower atmosphere to continue rising, which would increase the acidity of the oceans, thereby decreasing their ability to absorb CO2 and disrupting ocean life. This could then accelerate global warming and climate change. Some scientists would deal with this problem by building a global network of thousands of chemical plants that would remove hydrochloric acid from seawater to reduce ocean acidity. But this also could have unpredictable and possibly harmful ecological effects. Scientist James Lovelock has suggested that we anchor huge vertical pipes in the sea as part of a system that would allow wave motion to pump nutrientrich water up from the deep ocean to fertilize algae on the ocean surface. He contends that the resulting algal blooms would remove CO2 from the atmosphere and emit dimethyl sulfide, which would contribute to the formation of low clouds that would reflect sunlight. Another scheme is to tow 8,000 ice-making barges to the Arctic each year to re-ice the Arctic Sea. And another is to wrap large areas of glaciers with insulating blankets to slow down their melting and to help preserve ski resort businesses. The major problem with these techno fixes is that if they ever fail while we continue adding CO2 to the atmosphere, the rebound effects could be calamitous. Geo-engineering schemes all depend on complex machinery running constantly and flawlessly, and essentially forever, mostly to pump something from one place to another in the environment. Once the machines break down, natural processes would overwhelm such a system, and atmospheric temperatures would soar at a rapid rate and accelerate climate change. Critics of large-scale geo-engineering schemes argue for slowing climate change by using prevention approaches, such as improving energy efficiency, replacing fossil fuels with already available renewable energy resources, and drastically reducing tropical deforestation. They say this makes more sense than gambling on large-scale, costly changes to the global environment that could have unknown and potentially long-lasting harmful effects.

What is a wind farm? Why are some countries planning on building offshore wind farms?

Electricity and specific tasks. Wind, rotates propellers, and powers generators. Utilize turbines (electrical energy generated by kinetic energy moving a turbine which then works a generator). Can be installed on an individual building/property. Advantages are that it is cleaner and renewable compared to fossil fuels and other sources. Renewable, no pollutants, ocean, efficient technology, prevent hurricane damage, and cost efficient. Cost low once gets going. Fossil fuels used in building. Offshore wind farms have a higher potential for power generation due to faster and more constant winds, also providing energy at a more stable rate. There are no visual or noise pollution disadvantages as those caused by onshore wind farms.

What is Yucca Mountain? What are some advantages & disadvantages to using it?

In 1985, the DOE announced plans to build a repository for underground storage of high-level radioactive wastes from commercial nuclear reactors. The proposed site is on federal land in the Yucca Mountain desert region, 160 kilometers (100 miles) northwest of Las Vegas, Nevada. The projected cost of this facility (financed jointly by nuclear power companies and taxpayers) is at least $58 billion and may reach $100 billion. The projected opening date is 2017 but it will probably be 2020 or later because of scientific problems with the site, a number of legal battles, and insufficient federal funding. The idea is to encapsulate the radioactive material in a synthetic material called zircon, seal it in steel canisters, and store the canisters in underground tunnels that are supposed to be unaffected by earthquakes or a rising water table for at least 10,000 years. However, the site is located in the third most seismically active region in the United States. And a 2007 study by Ian Farman and other scientists indicated that the zircon coatings may degrade faster than originally projected. Critics charge that the selection of the Yucca Mountain site has been based more on political convenience than on scientific suitability. Some scientists argue that the site should never be allowed to open, mostly because rock fractures and tiny cracks may allow water to leak into the site and eventually corrode the waste storage casks. According to a 2004 review panel, any rain that percolates into the mountain could carry radioactive wastes leaking from corroded containers into groundwater, irrigation systems, and drinking-water wells and contaminate them for thousand of years. In 1998, Jerry Szymanski, formerly the DOE's top geologist at Yucca Mountain and now an outspoken opponent of the site, said that if water flooded the site it could cause an explosion so large that "Chernobyl would be small potatoes." In 2002, the U.S. National Academy of Sciences, in collaboration with Harvard University and University of Tokyo scientists, urged the U.S. government to slow down and rethink its nuclear waste storage process. These scientists contend that storing spent fuel rods in dry-storage casks in well-protected buildings at nuclear plant sites, or at several other larger interim storage sites, is an adequate solution for at least 100 years, in terms of safety and national security. This would buy time to carry out more research on this complex problem and to evaluate other sites and storage methods. Opponents also contend that the Yucca Mountain waste site should not be opened because it could decrease national security. The plan calls for wastes to be shipped by truck or rail cars to the Nevada site. This would require about 19,600 shipments of wastes from nuclear power plants across much of the country for an estimated 38 years before the site is filled. At the end of this period, the amount of newly collected radioactive waste stored at nuclear power plant sites would be about enough to fill another such repository. Critics contend that it would be much more difficult to protect such a large number of shipments from terrorist attacks than to provide more secure ways to store such wastes at nuclear power plant sites or other centralized sites. The U.S. government is over 10 years behind in providing a repository for radioactive wastes from commercial power plants. Because of contracts it signed with owners of nuclear reactors in the 1980s, taxpayers must now reimburse plant owners for the costs of storing spent fuel rods at 122 plant sites in 39 states. If the Yucca Mountain site opens by 2017, these little-known government expenses will cost taxpayers about $7 billion and about $11 billion if the opening of the repository is delayed until 2020. Such subsidies plus the estimated $58 billion that the government has spent on developing the Yucca Mountain site add to the already high cost of the nuclear fuel cycle. Despite rising costs and serious objections from scientists and citizens, in 2002, the U.S. Congress approved Yucca Mountain as the official site for storing the country's commercial nuclear wastes.

What are the three grades of coal? How are they transformed from one grade to the next?

It exists in several grades depending on the depth of burial (pressures) and temperatures that it formed under (Peat is not technically considered coal, but can be used as biomass fuel). Lignite is the lowest grade of coal. Bituminous coal has been subjected to moderate amounts of pressure and is the most abundant in the US. It has higher amounts of impurities than other forms of coal. The highest grade of coal is Anthracite, which is classified as a metamorphic rock (heat content refers to how easily burned).

What do the following parts of a nuclear plant do? Containment shell

Like a coal-burning power plant - the fuel source is just different. A containment shell with thick, steel-reinforced, concrete walls surrounds the reactor core. It is designed to keep radioactive materials from escaping into the environment, in case there is an internal explosion or a melting of the core within the reactor. It also protects the core from some external threats such as tornadoes and impacts from airplane crashes.

From previous units: LD-50 & be able to relate it to radiation

One approach is to determine the lethal dose—the amount needed to kill an animal. A chemical's median lethal dose (LD50) is the dose that can kill 50% of the animals (usually rats and mice) in a test population within an 18-day period. The purpose of a bioassay is to determine the LD-50 of a substance

Know regarding sea level rise: Why melting sea ice is less of a concern than melting land ice

Some good news is that because sea ice floats, it does not contribute to a rising sea level when it melts. The Arctic's contribution to a rising sea level will come from land-based ice that melts and runs into the sea faster than new ice forms. This is especially true of Greenland.

What is biomass? What is biofuel? biodiesel? ethanol? What is the main difference in the composition of biodiesel vs ethanol?

The dry weight of all organic matter contained in its organisms. Burning biomass has not net CO2 emissions only if it is replenished with new plant growth faster than it is used. In a food chain or web, chemical energy stored in biomass is transferred from one trophic level to another. Mass of living organic material. Biofuel is any fuel that is derived from biomass—that is, plant or algae material or animal waste. Since such feedstock material can be replenished readily, biofuel is considered to be a source of renewable energy, unlike fossil fuels such as petroleum, coal, and natural gas. Biodiesel is used for gas for cars and combustion engines, transportation, biogas for cooking, electricity, and petroleum-based diesel fuel and gasoline substitute. Use diesel combustion engines. Can be used in motor vehicles. Algae is substitute and corn for petroleum and biofuels. Indirect solar energy because it is combustible organic compounds made from photosynthesis. Oil part. Ethanol, on the other hand, uses sugars. Soy is another source. Involves burning things. It burns cleaner than fossil fuels. Reduced CO and CO2 emissions (still produces CO2), high net energy yield, reduced hydrocarbon emissions, better gas mileage, renewable. Takes a lot of land to produce, and it is more expensive and inefficient. Increased NOx emissions/smog, higher environmental cost, low net energy yield for soybean crops, loss of biodiversity, and difficulty for engines in cold weather. Expensive process, not widely consumed, requires huge areas of land and some crops have low yield, runoff, increased greenhouse gas emissions, threat to biodiversity. Ethanol is used for motor vehicles, corn-based ethanol is used in blends with gasoline to reduce air pollution, ethanol can be used as a replacement for gasoline. Currently, this method of energy generation works by growing corn. However, growing and extracting corn is very energy-intensive because fossil fuels are used to make fertilizer and pesticides that help to grow the corn and are also needed to ferment corn sugar. Moreover, only the corn seeds are used for ethanol and the rest is thrown away. However, if we use a different part of corn or a different plant to obtain cellulosic biomass, it can be better. The process begins with microorganisms. The microbes tear the cellulose apart, releasing sugar compounds locked within. In fermentation tanks, another microbial species turns that sugar into ethanol. The long-term goal is to combine genetic material from the two species into a single microbe that can make ethanol from cellulose in one efficient step. Turning two steps into one step is such a big deal because it would be revolutionary from an economic point of view. The carbon dioxide is captured at the source, compressed for transport, and then injected deep into rock formations at carefully selected, safe locations where it is stored permanently. Ethanol has to be taken from plants such as corn or bagasse, whose residue is fermented, and distilled to produce ethanol. This ethanol is burned and acts as a sort of fuel, similar to gasoline. Ethanol = distilled corn; used as a biofuel; alternatives are expensive, but ecologically friendly. Compares to fossil fuels and other energy sources by depending on which plants you use and the method of creating the ethanol. For Brazil, where they use sugarcane to produce ethanol, ethanol yields 8 times the amount of energy taken to produce it (the most efficient form of ethanol) while gasoline takes 4.1. Whereas in the United States where they use corn ethanol, it only produces 1.1-1.5 net energy which isn't very efficient compared to fossil fuels. Corn is very space and resource intensive, 1 bushel of corn = 3 gallons of fuel. US needs 130 billion gallons of fuel, so would need the entire country to convert completely to biofuel made from corn. Ethanol produces twenty-five percent fewer greenhouse emissions. Currently, fossil fuels are used to make fertilizer and pesticides to help corn grow and are also needed to ferment corn sugar. However, if cellulosic ethanol can be manufactured without burning fossil fuel, such as by using switchgrass, net carbon emissions can essentially be zero. Advantages and disadvantages are, depending on the way ethanol is harvested, a major advantage of using this energy source is that it produces twenty five percent fewer greenhouse emissions. Additionally, flex-fuel vehicles that can burn ethanol and gasoline do not cost much more than conventional cars. Moreover, it has a lot of potential because it is great motor fuel, it is just a matter of how inexpensive we can make it and how much of it we can make. Ethanol's potential can be fulfilled by using other parts of corn and other plants such as switchgrass (which can be grown on land without nitrogen fertilizers) and turning the two steps used to produce ethanol from ground-up corn stalks into one. Finally, we have the land to grow enough biomass to replace at least a quarter of the gas we now consume with cellulosic ethanol. Also, ethanol could replace gasoline altogether if cars were more efficient. And, so long as less fossil fuels are used in the process and there is a decreased amount of deforestation to plant more crops to produce ethanol, it could be considered a renewable resource. However, there are some major disadvantages of using this energy source as well. For example, it is not that great for the environment. It is very energy-intensive to grow corn and extract energy from it. This is because fossil fuels are used to make fertilizer and pesticides to help corn grow and are also needed to ferment corn sugar. Some critics claim it takes more energy to make ethanol than we get out of ethanol. While others caution that we can never grow enough corn to meet demands. It is also more expensive and can make food made from the crop more expensive (e.g. corn goods). Also, harvesting of corn and conversion to ethanol to use as biofuel emits nearly the same amount of carbon dioxide as its external bioproducts. Finally, it may cause a loss of biodiversity through deforestation to grow more crops to build crop plantations and it takes land away from solar panels that could produce more energy. Involves burning things and can be used in motor vehicles. Produces CO2.

Know what happened at Chernobyl & Three Mile Island

Three Mile Island (America's worst commercial nuclear power plant accident): -On March 29, 1979, one of the two reactors at the Three Mile Island (TMI) nuclear plant near Harrisburg, Pennsylvania, lost its coolant water because of a series of mechanical failures and human operator errors. This led to the most serious commercial nuclear power plant accident in U.S. history. With the loss of coolant, the reactor's intensely radioactive core became partially uncovered and about half of it melted and fell to the bottom of the reactor. Had there been a complete core meltdown, large amounts of dangerous radioactivity would have been released into the surrounding countryside. Fortunately, the containment building kept most of the radioactivity released from the partially exposed core from escaping, and there were no immediate human casualties. However, unknown amounts of radioactivity had escaped into the atmosphere. About 50,000 people were evacuated, and another 50,000 fled the area on their own. Various studies have shown no increase in cancer rates from radiation released by the accident, but there is controversy over this issue because of insufficient data. Partial cleanup of the damaged TMI reactor, along with lawsuits and payment of damage claims, have cost $1.2 billion—almost twice the reactor's $700 million construction cost. Without significant government subsidies, loan guarantees, and accident insurance guarantees, banks and other lending institutions have shown little interest in financing new U.S. nuclear power plants, because the TMI accident showed that utility companies could lose more than $1 billion in equipment and cleanup costs, even without any established harmful effects on public health. In raising public fears about the safety of nuclear power, the TMI accident led to improved safety regulations for U.S. nuclear plants and improved emergency and evacuation plans. Nuclear power proponents point out that there have been no notable U.S. accidents since TMI. And since 1991, the U.S. reactor fleet has operated at about 90% capacity, up from about 60% in the early 1980s. Chernobyl (the world's worst nuclear power plant accident): -Chernobyl is known around the globe as the site of the world's most serious nuclear power plant accident. On April 26, 1986, a series of explosions in one of the reactors in a nuclear power plant in Ukraine (then part of the Soviet Union) blew the massive roof off a reactor building. The reactor partially melted down (Figure 15-20) and its graphite moderator caught fire and burned for 10 days, releasing more than 100 times the amount of radiation generated by the atomic bombs dropped by the United States on the Japanese cities of Hiroshima and Nagasaki at the end of World War II. The initial explosion and the prolonged fires released a huge radioactive cloud that spread over much of Belarus, Russia, Ukraine, and Europe and eventually encircled the planet. In 2008, after 22 years, areas of the Ukraine and northern Europe are still dangerously contaminated with radioactive materials as a result of the accident. According to U.N. studies, the Chernobyl disaster was caused by poor reactor design (not used in the United States or in most other parts of the world) and by human error, and it had serious consequences. By 2005, 56 people had died prematurely from exposure to radiation released by the accident. The World Health Organization projects that eventually, this number will grow to 9,000. But the Russian Academy of Medical Sciences estimated the eventual death toll at 212,000. Because of secrecy and sparse reliable data, we will never know the real death toll. After Chernobyl, some 350,000 people had to abandon their homes because of contamination by radioactive fallout. In addition to fear about long-term health effects such as cancers, many of these victims continue to suffer from stress and depression. In parts of Ukraine, people still cannot drink the water or eat locally produced fruits, vegetables, fish, meat, or milk. In contaminated areas, the frequency of birth defects and mental retardation in newborns has increased. There are also higher incidences of thyroid cancer, leukemia, and immune system abnormalities in children exposed to radioactive fallout. Thyroid cancers are so common that the resulting surgical scars at the base of the neck are known as the "Chernobyl necklace." Chernobyl taught us a hard lesson: A major nuclear accident anywhere has effects that reverberate throughout much of the world. One more major nuclear power accident anywhere in the world could have a devastating impact on the future of nuclear power. Japan, an earthquake-prone country that gets 39% of its electricity from nuclear power, has come close to having such an accident. The country has suffered a string of nuclear accidents and cover-ups of such accidents. In 2007, a powerful earthquake in northern Japan caused severe damage to the world's largest nuclear plant (largest in terms of power output) and caused it to be shut down for at least a year. Despite the risks, Japan plans to replace 20 of its 55 aging nuclear reactors between 2010 and 2030.

How do clouds, aerosols and soot particles factor into climate? Will they counteract or amplify climate change?

A major unknown in global climate models is the effect that changes in the global distribution of clouds might have on the temperature of the atmosphere. Warmer temperatures increase evaporation of surface water and create more clouds. Depending on their content and reflectivity, these additional clouds could have two effects. An increase in thick and continuous light-colored clouds at low altitudes could decrease surface warming by reflecting more sunlight back into space. But an increase in thin and discontinuous cirrus clouds at high altitudes could warm the lower atmosphere. In addition, infrared satellite images indicate that the wispy condensation trails (contrails) left behind by jet planes might have a greater impact on atmospheric temperatures than scientists once thought. Although air travel is responsible for less than 2% of global greenhouse gas emissions, NASA scientists found that jet contrails expand and turn into large cirrus clouds that tend to release heat into the upper troposphere. If these preliminary results are confirmed, emissions from jet planes could be responsible for as much as half of the warming of the lower atmosphere in the northern hemisphere. Air travel is increasing rapidly and there is no technological fix for this problem unless hydrogen is phased in as a fuel for planes. Much more research is needed to evaluate the effects of clouds on global warming and climate change. Aerosols (suspended microscopic droplets and solid particles) of various air pollutants are released or formed in the troposphere by volcanic eruptions and human activities. They can either warm or cool the air and hinder or enhance cloud formation depending on factors such as their size and reflectivity. Most aerosols, such as light-colored sulfate particles produced by fossil fuel combustion, tend to reflect incoming sunlight and cool the lower atmosphere. Sulfate particles also cool the lower atmosphere by serving as condensation nuclei that form cooling clouds. Scientists estimate that sulfate particles played a roll in slowing global warming between 1880 and 1970. However, a 2008 study by atmospheric scientist V. Ramanathan and his colleagues found that the black carbon particulate matter emitted into the air by diesel exhaust, burning forests and grasslands, and cooking with solid fuels (such as coal, wood, charcoal, and cow dung) has a warming effect on the atmosphere four times greater than was estimated earlier. Climate scientists do not expect aerosol and soot pollutants to counteract or enhance projected global warming and the resulting climate change very much in the next 50 years for two reasons. First, aerosols and soot fall back to the earth or are washed out of the lower atmosphere within weeks or months, whereas CO2 remains in the lower atmosphere for about 120 years. Second, aerosol and soot inputs into the lower atmosphere are being reduced because of their harmful impacts on plants and human health—especially in developed countries. According to the IPCC, the fall in sulfate concentrations in most developed countries since 1970 has played a role in the warming of the atmosphere, especially since 1990. This trend will allow further increased global warming as sulphate concentrations continue to drop because of improved air pollution regulations.

What is carbon capture and storage (CCS)? What are the problems with it?

A third output approach is carbon capture and storage (CCS). It involves removing CO2 from the smokestacks of coal-burning power and industrial plants and then storing it somewhere. CO2 gas could be pumped deep underground into coal beds and abandoned oil and gas fields. Or the gas could be liquefied and injected into thick sediments under the sea floor. Analysts point to several problems with this approach. One is that power plants using CCS are much more expensive to build and operate than conventional coal-burning plants and thus would sharply raise the price of electricity for consumers. Without strict government regulation of CO2 emissions, carbon taxes to bring coal prices in line with environmental costs, or generous subsidies and tax breaks, coal-burning utilities and industries have no incentive to build such plants. According to the U.S. Department of Energy, the current costs of CCS systems will have to be reduced by a factor of ten before these systems will be widely used. A second problem is that CCS is an unproven technology that would remove only part (perhaps 25-35%) of the CO2 from smokestack emissions. No plants using CCS exist, and building and testing them could take 20-30 years and huge amounts of money with no guaranteed successes. A third problem is that this process requires large inputs of energy, which could increase CO2 emissions and cancel out some of the gains made from collecting and storing some of the CO2. A fourth problem is that CCS promotes the continued use of coal, which should probably be phased out. Coal companies talk about a future based on greatly increased use of clean coal technologies, such as coal-tosynfuels. But even with successful CCS and cleaner coal technologies, coal is by far the world's dirtiest fuel to dig up and burn. And if coal's harmful environmental costs were included in its price, burning coal would be a very costly way to produce electricity compared to most other alternatives. It is not surprising that coal companies are pushing for a shift to CCS coal-fired plants to be funded with the help of generous taxpayer subsidies and tax breaks. Indeed, without CCS, the conventional coal industry probably will not survive in the long term. And because converting coal to synfuels produces twice as much CO2 per volume of fuel as burning gasoline, CCS also helps to make the coal-to-synfuels industry more feasible. This helps to assure a future for the coal industry, which will ensure continued increasing CO2 emissions. A fifth problem is that providing huge government subsidies and taxbreaks for developing and testing CCS technology would divert or reduce the huge subsidies and taxbreaks needed for the rapid development of solar, wind, geothermal, and other forms of renewable energy that reduce rather than attempt to deal with CO2 emissions. A sixth very serious potential problem with CCS is that essentially no leaks are allowed. In effect, the stored CO2 would have to remain sealed from the atmosphere forever. Any large-scale leaks due to earthquakes, other geological events, or wars, as well as any number of smaller continuous leaks from storage sites around the world, could dramatically increase global warming and the resulting climate change in a very short time. According to a 2007 estimate by environmental scientist Peter Montague, if 25% of the carbon in the world's estimated remaining fossil fuels were sequestered, any leakage greater than 0.16% of the total amount stored per year could eventually result in runaway global warming and climate change. And if 75% of the world's estimated remaining carbon in fossil fuels were sequestered, it would take a leakage of only 0.05% of the amount stored per year to lead to the same result. Montague contends that we cannot bury several trillion tons of CO2 in the ground or under the sea with complete confidence that leaks totaling 0.05% of the total amount stored per year will not occur at any time in the future. According to the precautionary principle, we should not rely on a technology that commits us to an essentially irreversible threat. Reliance on nuclear power commits human societies to fail-safe storage of dangerous radioactive wastes for up to 240,000 years. But Montague points out that relying on CCS to store much of the CO2 we produce commits human societies to fail-safe storage of the CO2 forever. To coal companies, CCS is the wave of the future that will help to keep them in business. To scientists like Peter Montague, CCS is an extremely risky output solution to a serious problem that can be dealt with by using a variety of cheaper, quicker, and safer input approaches. To these scientists, when we face a problem such as CO2 coming out of a smokestack or exhaust pipe, the most important question to ask is not what do we do with it, but how do we avoid producing the CO2 in the first place?

Know how burning fossil fuels interferes with the carbon cycle

Fossil fuels are a carbon sink in the carbon cycle, basically a natural way of sequestering carbon out of the atmosphere for millions of years. This is why it is such a big deal to burn them—we are re-introducing carbon molecules that have not been a part of the atmosphere in millions of years.

What relative wavelength is the light entering the atmosphere from the sun? Leaving the atmosphere?

-Visible light (shorter wavelength) -Infrared (longer wavelength)

Be able to give advantages and disadvantages of each of the following energy sources: Ethanol

Advantages and disadvantages are, depending on the way ethanol is harvested, a major advantage of using this energy source is that it produces twenty five percent fewer greenhouse emissions. Additionally, flex-fuel vehicles that can burn ethanol and gasoline do not cost much more than conventional cars. Moreover, it has a lot of potential because it is great motor fuel, it is just a matter of how inexpensive we can make it and how much of it we can make. Ethanol's potential can be fulfilled by using other parts of corn and other plants such as switchgrass (which can be grown on land without nitrogen fertilizers) and turning the two steps used to produce ethanol from ground-up corn stalks into one. Finally, we have the land to grow enough biomass to replace at least a quarter of the gas we now consume with cellulosic ethanol. Also, ethanol could replace gasoline altogether if cars were more efficient. And, so long as less fossil fuels are used in the process and there is a decreased amount of deforestation to plant more crops to produce ethanol, it could be considered a renewable resource. However, there are some major disadvantages of using this energy source as well. For example, it is not that great for the environment. It is very energy-intensive to grow corn and extract energy from it. This is because fossil fuels are used to make fertilizer and pesticides to help corn grow and are also needed to ferment corn sugar. Some critics claim it takes more energy to make ethanol than we get out of ethanol. While others caution that we can never grow enough corn to meet demands. It is also more expensive and can make food made from the crop more expensive (e.g. corn goods). Also, harvesting of corn and conversion to ethanol to use as biofuel emits nearly the same amount of carbon dioxide as its external bioproducts. Finally, it may cause a loss of biodiversity through deforestation to grow more crops to build crop plantations and it takes land away from solar panels that could produce more energy.

Be able to give advantages and disadvantages of each of the following energy sources: Hydrogen

Advantages are compared to fossil fuels, renewable resource, emits no CO2 but low levels of CO2 (in pulling off molecules and putting into fuel form) (if CO2 produced during manufacturing and installation is included), and safer to use. More efficient, reduces pollution, health benefits, and safer to store. Disadvantages are more expensive, will always have a negative net energy yield, and production can be harmful. Moreover, cost (expensive in beginning but saves a lot in the long run), new policies, and fossil fuels can be used in electrolysis.

Be able to give advantages and disadvantages of each of the following energy sources: Geothermal

Advantages are that it is the key to more sustainable future. According to the EPA, after super-insulation, a well designed geothermal heat pump system is the most energy-efficient, reliable, environmentally clean, and cost-effective way to heat or cool a space. It produces no air pollutants and emits no CO2. Installation costs are recouped after 3-5 years, and then such systems save their owners money. Scientists estimate that using just 1% of the heat stored in the uppermost 5 kilometers (8 miles) of the earth's crust would provide 250 times more energy than that stored in all the earth's oil and natural gas reserves. Currently, about 40 countries (most of them in the developing world) extract enough energy from hydrothermal reservoirs to produce about 1% of the world's electricity, enough to meet the needs of 60 million people and equal to the electrical output of all 104 nuclear power plants in the United States. Disadvantages are that Geothermal energy has two main problems. One is that the current cost of tapping large-scale hydrothermal reservoirs is too high for all but the most concentrated and accessible sources, although new drilling and extraction technologies may bring these costs down. The other is that some dry- or wet-steam geothermal reservoirs could be depleted if their heat is removed faster than natural processes can renew it. Recirculating the water back into the underground reservoirs for reheating could slow such depletion. Using geothermal energy generally has a much lower environmental impact than using fossil fuel energy. At concentrated and accessible hydrothermal sites, electricity can be produced at a low cost compared to other alternatives. On average, a geothermal power plant produces no CO2, but about one-sixth as much CO2 as a power plant burning natural gas emits, and one tenth the amount emitted by a coal-burning power plant if CO2 produced during manufacturing and installation is included. Geothermal power plants utilize turbines (electrical energy generated by kinetic energy moving a turbine which then works a generator).

Be able to give advantages and disadvantages of each of the following energy sources: Hydropower (from dams)

Advantages are that there is less pollution, more energy produced, and is renewable compared to fossil fuels. Do not have to rely internationally. Flood control and water supply. Produces lots of energy because we have a lot of water. Disadvantages are that it is really expensive, unpredictable, and disrupts ecosystems.

Know the following units and be able to solve problems using them: BTUs

British thermal unit. 252 cal = 1,055 J. Unit of energy. Used by water heaters, furnaces, air conditioners. To solve for energy, multiply power by time. If energy is the volume of the water in a stream, power is the speed of water. (Review energy practice problems)

Know the main greenhouse gases

CO2, CH4, N2O, H2O, etc.

How does coal form?

Coal is formed from decay of plant material (sometimes you can see leaves & stems in the coal).

How much solar energy reaching Earth is Absorbed by the surface?

Earth's planetary albedo is about 0.31. That means that about a third of the solar energy that gets to Earth is reflected out to space and about two thirds is absorbed.

Where does most domestic oil come from? (2 locations)

Domestic oil primarily comes from two places 1. Gulf of Mexico, site of Deepwater Horizon spill in 2010 (immense damage to region's biodiversity) 2. Alaska's North Slope, oil transported across Alaska in the Trans-Alaska pipeline (see photo) and then brought by tanker to lower 48

What gas is primarily in natural gas?

Natural gas is a mixture of gases, but is primarily composed of methane (CH4).

Know some ways that individuals can reduce their carbon footprints

Refer to lecture: climate change updates

From previous units: Know the second law of thermodynamics & be able to relate it to these chapters

The Second Law of Thermodynamics states that entropy (disorder) always increases in a closed system. Another way to say this is that energy always goes from more useful to a less useful form when it changes from one form to another. This means that we cannot recycle useful energy. The Second Law explains why perpetual motion machines are impossible.

What is the most common type of nuclear reactor? What fuel does it use?

The most common reactors are called light-water reactors. The fuel for a reactor is made from uranium ore mined from the earth's crust. Mined uranium ore must be enriched to increase the concentration of its fissionable uranium-235 from the normal 0.7% to about 3%. Enriched uranium-235 is processed into small pellets of uranium dioxide. Each pellet, about the size of an eraser on a pencil, contains the energy equivalent of about a ton of coal.

What are solar (photovoltaic) cells?

Used for the production of energy. Comes from solar towers or panels. Convert sunlight into electrical energy. When the sunlight hits these panels, they create an electrical field converting energy to power homes. Lots of mirrors that concentrate rays. Very similar to power plants. Series of cells electrons can flow through.

Know the following units and be able to solve problems using them: Kilowatt-hours/ megawatt-hours (know conversion)

Units of energy. To solve for energy, multiply power by time. If energy is the volume of the water in a stream, power is the speed of water. 1 kilowatt (kW) = 1000 W (house). 1 megawatt (MW) = 1000kW = 1 million W (city). Used in electricity. (Review energy practice problems)

Know the following units and be able to solve problems using them: Watts/ Kilowatts/ megawatts (know conversion)

Watts are a unit of power (rate of energy flow - energy per unit of time). 1 Watt is 1 joule/second. To solve for power, divide energy by time. If energy is the volume of the water in a stream, power is the speed of water. 1 kilowatt (kW) = 1000 W (house). 1 megawatt (MW) = 1000kW = 1 million W (city). (Review energy practice problems)

What is a half-life? How does it relate to nuclear energy? Know how to solve half-life problems

• Original amount: fraction=1 • After one half-life: fraction=1/2 • After two half-lives: fraction=1/4 Every half life problem will ask one of the following: • time elapsed or time per half life (HL) • Fraction • Sample Size • Number of half-lives Can solve with formulas or by making a table -Formulas • (1/2)^n=fraction remaining •Time elapsed/n=time/HL • n=number of half-lives -Make a table -Review nuclear practice problems

How are hydrothermal reservoirs of geothermal energy used to provide energy in geothermal power plants?

(For more info: https://www.energy.gov/eere/geothermal/how-geothermal-power-plant-works-simple) We have also learned to tap into deeper, more concentrated hydrothermal reservoirs of geothermal energy, as Iceland has done for decades. Wells are drilled into these reservoirs to extract their dry steam, wet steam, or hot water, which are used to heat buildings, provide hot water, grow vegetables in greenhouses, raise fish in aquaculture ponds, and spin turbines to produce electricity. Cool water left over can be pumped back into the reservoirs to be reheated.

Be able to explain why biodiesel/ ethanol are not great alternatives to fossil fuels. What is a geothermal heat pump?

(This article gives a good overview: https://www.nytimes.com/2015/01/29/science/new-report-urges-western-governments-to-reconsider-reliance-on-biofuels.html?_r=0) Biodiesel takes a lot of land to produce, and it is more expensive and inefficient. Increased NOx emissions/smog, higher environmental cost not, low net energy yield for soybean crops, loss of biodiversity, and difficulty for engines in cold weather. Expensive process, not widely consumed, require huge areas of land and some crops have low yield, runoff, increased greenhouse gas emissions, threat to biodiversity. There are some major disadvantages of using ethanol. For example, it is not that great for the environment. It is very energy-intensive to grow corn and extract energy from it. This is because fossil fuels are used to make fertilizer and pesticides to help corn grow and are also needed to ferment corn sugar. Some critics claim it takes more energy to make ethanol than we get out of ethanol. While others caution that we can never grow enough corn to meet demands. It is also more expensive and can make food made from the crop more expensive (e.g. corn goods). Also, harvesting of corn and conversion to ethanol to use as biofuel emits nearly the same amount of carbon dioxide as its external bioproducts. Finally, it may cause a loss of biodiversity through deforestation to grow more crops to build crop plantations and it takes land away from solar panels that could produce more energy. (For more info: http://energy.gov/energysaver/geothermal-heat-pumps) Geothermal heat pumps naturally cool or heat a home using underground-surface temperature differences. Below approximately 10 ft under the ground surface, the temperature stays around 50-60 degrees F. Heating and cooling buildings and to produce electricity. Can be installed on an individual building/property. Used in/involve power plants. Exploiting the temperature differences between the earth's surface and underground, almost anywhere in the world at a depth of 3-6 meters. In winter, a close loop of buried pipes circulates a fluid (usually water or an antifreeze solution), which extracts heat from the ground and carries it to a heat pump, which transfers the heat to a home's heat distribution system (usually a blower and air ducts). In summer, this system works in reverse, removing heat from a home's interior and storing it in the ground. These systems can also be modified to provide hot water. Key to more sustainable future. According to the EPA, after super-insulation, a well designed geothermal heat pump system is the most energy-efficient, reliable, environmentally clean, and cost-effective way to heat or cool a space. It produces no air pollutants and emits no CO2. Installation costs are recouped after 3-5 years, and then such systems save their owners money. Scientists estimate that using just 1% of the heat stored in the uppermost 5 kilometers (8 miles) of the earth's crust would provide 250 times more energy than that stored in all the earth's oil and natural gas reserves. Currently, about 40 countries (most of them in the developing world) extract enough energy from hydrothermal reservoirs to produce about 1% of the world's electricity, enough to meet the needs of 60 million people and equal to the electrical output of all 104 nuclear power plants in the United States. Geothermal energy has two main problems. One is that the current cost of tapping large-scale hydrothermal reservoirs is too high for all but the most concentrated and accessible sources, although new drilling and extraction technologies may bring these costs down. The other is that some dry- or wet-steam geothermal reservoirs could be depleted if their heat is removed faster than natural processes can renew it. Recirculating the water back into the underground reservoirs for reheating could slow such depletion.

How will reducing population and poverty help slow climate change?

The effectiveness of these strategies would be enhanced by reducing population, which would decrease the number of fossil fuel consumers and CO2 emitters. It would also help to reduce poverty, which would decrease the need of the poor to clear more land for crops and fuelwood. The three input strategies and the population control strategy follow the four scientific principles of sustainability.

What is the Keystone XL pipeline? What are some of the pros and cons to building it?

In the fall of 2012, the US released an environmental impact statement on a proposed pipeline to bring oil from the tar sands in Alberta, Canada to refineries in Texas, called the Keystone XL. This pipeline would supplement already existing pipelines bringing this oil into the US and could reduce our dependence on foreign oil. Some concerns about the pipeline are that spills would be damaging to surrounding ecosystems and that there is no guarantee that oil transported in the pipeline would be sold in the US (it could be exported).

Approximately how efficient are coal and nuclear plants?

It is approximately 30% efficient. This provides 40% of the world's electricity, mostly in China, US, & India (US gets 50% of its energy from coal).

How are oil & natural gas formed? What type of rock are they stored in?

Also called crude oil or petroleum, oil is formed from plankton settling to the bottom of a sea and accumulating in an oxygen-free environment. Overtime they are buried by layers of sediment and compressed. If the proper geological features are present, the oil can accumulate in a "trap" within the layers of sedimentary rock. Oil will be held in the pores in the rock and must be pumped out. Natural gas forms with oil and is found floating on oil reservoirs, but can't be used unless a pipeline has been built. If there is no pipeline it is often seen as a nuisance and burned off to get access to the oil. Natural gas is a mixture of gases, but is primarily composed of methane (CH4). A lot of natural gas is trapped in rock (shale).

How does hydropower work? How can energy be obtained from tides/ waves?

1. Tidal streams 2. Tidal barrages 3. Tidal lagoons Used for homes and businesses. Dams are pretty common and we get lots of energy from them. Must be located on coastlines. Utilize turbines (electrical energy generated by kinetic energy moving a turbine which then works a generator).

What is hydraulic fracturing (fracking)? Why did it become more popular in the last decade?

A lot of natural gas is trapped in rock (shale) and so must be extracted using a process called hydraulic fracturing, or fracking. Fracking involves a gas company drilling a well thousands of feet deep so it is well below groundwater. Then, freshwater mixed with a variety of chemicals (acid, slickwater, and disinfectant) (to make the water flow more smoothly) and sand/clay are injected into the well to create immense pressure. The pressure of the fluid inside the well causes the shale around the well to crack. The grains of sand in the fluid get stuck in the cracks, holding them open to allow gas or oil to flow out of the shale into the well. This process became popular only recently. In 2005 the US Energy Policy Act exempted oil and gas companies from some requirements of the Safe Drinking Water Act. It was only because of this exemption that fracking operations were allowed to inject fracking fluid into the ground.

What do we do with old nuclear power plants?

A nuclear power plant eventually comes to the end of its useful life, mostly because of corrosion and radiation damage to its metal parts. Because it contains intensely radioactive materials, it cannot simply be abandoned. Instead, it must be decommissioned, or retired—the last step in the nuclear power fuel cycle. Scientists have proposed three ways to do this. One strategy is to dismantle the plant after it closes and store its large volume of highly radioactive materials in a high-level nuclear waste storage facility, which no country has built so far. A second approach is to install a physical barrier around the plant and set up full-time security for 30-100 years, until the plant can be dismantled after its radioactivity has reached safer but still quite dangerous levels. A third option is to enclose the entire plant in a tomb that must last and be monitored for several thousand years. Such a tomb was built around the Chernobyl reactor that exploded, but after a few years, it began crumbling and leaking radioactive wastes. It is being rebuilt at great cost.

What are some advantages of using natural gas compared to other fossil fuels? What are some disadvantages?

Although it releases CO2, natural gas is often considered a more environmentally friendly fuel source than other fossil fuels for the following reasons: • It has a higher net energy yield (50%) • It releases less CO2 per unit of energy than coal and oil • It is cleaner burning and so produces fewer primary air pollutants • It produces electricity more efficiently than coal • Power plants are also cheaper to build & maintain than coal & nuclear plants • Ample supplies remain. Some energy analysts think it could be a "bridge fuel" to help transition society off of fossil fuels

Know how climate change would affect the following: Particularly vulnerable species and ecosystems

According to the 2007 IPCC report, changes in climate resulting from global warming are now affecting physical and biological systems on every continent and are altering ecosystem services in some areas. According to the 2007 IPCC study, approximately 30% of the land-based plant and animal species assessed so far could disappear if the average global temperature change exceeds 1.5-2.5 C° (2.7-4.5 F°). This percentage could grow to 70% if the temperature change exceeds 3.5 C° (6.3 F°). The hardest hit will be plant and animal species in colder climates, such as the polar bear in the Arctic and penguins in Antarctica; species at higher elevations; plant and animal species with limited ranges, such as some amphibians; and those with limited tolerance for temperature change. The ecosystems most likely to suffer disruption and species loss from climate change are coral reefs, polar seas, coastal wetlands, high-elevation mountaintops, and alpine and arctic tundra. Some types of forests unable to migrate fast enough to keep up with climate shifts will decline, and others, such as oak-pine and oak-hickory forests in the United States, may expand northward. Mostly because of drier conditions, forest fires may increase in some areas such as the southeastern and western United States. This would severely degrade some forest ecosystems, add more CO2 to the atmosphere, reduce total CO2 uptake by plants, and accelerate global warming and climate change through still another positive feedback loop. A warmer climate can also greatly increase populations of insects and fungi that damage trees. In the Canadian province of British Columbia, for example, warmer winters have led to surges in mountain pine beetle populations that have infected huge areas of lodgepole pine forests, which are now dying. Pine beetles have also damaged about 60% of the lodgepole pines in the U.S. state of Colorado, which has been experiencing warmer winters. In Yellowstone Park in the United States, global warming has increased beetle infestations of white bark pine trees that grow at high altitudes. This threatens the park's grizzly bears, which feed on white bark pine seeds.

Know how climate change would affect the following: Human health

According to the IPCC and a 2006 study by U.S National Center for Atmospheric Research, heat waves in some areas will be hotter, more frequent and longer. This will increase the number of deaths and illnesses, especially among older people, those with poor health, and the urban poor who cannot afford air conditioning. During the summer of 2003, a major heat wave killed about 52,000 people in Europe (an estimate based on a detailed analysis in 2006 by the Earth Policy Institute)—almost two-thirds of them in Italy and France. On the other hand, in a warmer world, fewer people will die from cold weather. However, a 2007 study by Mercedes Medin-Ramon and his colleagues suggests that increased numbers of heat-related deaths will be greater than the projected drop in cold-related deaths in a warmer world. A warmer, CO2-rich world will be a great place for rapidly multiplying insects, microbes, toxic molds, and fungi that make us sick, and for plants that produce allergenic pollens. Longer and more intense pollen seasons will mean more itchy eyes, runny noses, and asthma attacks. Insect pests and weeds will likely multiply, spread, and reduce crop yields. In a warmer world, microbes that cause tropical infectious diseases such as dengue fever, yellow fever, and malaria are likely to expand their ranges and their prevalence, if mosquitoes that carry them spread to temperate and higher elevation areas that are getting warmer. And while more frequent prolonged droughts would sharply reduce populations of mosquitoes, populations of their predators, such as dragonflies and damselflies would also decline. In addition, hunger and malnutrition will increase in areas where agricultural production drops. Higher atmospheric temperatures will also increase some forms of air pollution. The greatest effect will be to speed up the rate of the chemical reactions that produce ozone and other harmful chemicals in photochemical smog in urban areas. Increasing illness, hunger, flooding, and drought will likely lead to forced migrations of tens of millions of people. Environmental scientist Norman Myers says that climate change during this century could produce at least 150 million, and perhaps 250 million, environmental refugees. The higher estimate would be equal to about four-fifths of the current U.S. population. A 2005 WHO study estimates that each year, climate change already contributes to the premature deaths of more than 150,000 people—an average of 410 people a day—and that this number could double by 2030. Most of these deaths are the result of increases in malaria, diarrhea, malnutrition, and floods that can be traced to climate change. In addition, the WHO estimates that climate change causes 5 million sicknesses each year. By the end of this century, the annual death toll from climate change could be in the millions.

Know how climate change would affect the following: Changes in precipitation & water availability

According to the IPCC, global warming will increase the incidence of extreme weather such as heat waves and droughts in some areas, which could kill large numbers of people, reduce crop production, and expand deserts. At the same time, because a warmer atmosphere can hold more moisture, other areas will experience increased flooding (especially flash floods) from heavy and prolonged precipitation.

Know regarding sea level rise: Consequences (projected by the IPCC)

According to the IPCC, the projected rise in sea levels during this century (excluding the additional effects of storm surges) could cause the following essentially irreversible effects: • Degradation or destruction of at least one third of the world's coastal estuaries, wetlands, and coral reefs. • Disruption of many of the world's coastal fisheries. • Flooding of low-lying barrier islands and erosion and retreat of gently sloping coastlines (especially on the U.S. Eastern and Gulf Coasts). U.S. states that would loose the most land to flooding are Louisiana, Florida, North Carolina, Texas, and South Carolina. • Flooding of agricultural lowlands and deltas in coastal areas where much of the world's rice is grown. • Contamination of freshwater coastal aquifers with saltwater and brackish water and decreased supplies of groundwater currently used for irrigation, drinking, and cooling power plants in such areas. • Submergence of low-lying islands in the Pacific Ocean, the Caribbean Sea, and the Indian Ocean, which are home to 1 of every 20 of the world's people. • Flooding of coastal areas, including some of the world's largest cities, and displacement of at least 100 million people, especially in China, India, Bangladesh, Vietnam, Indonesia, Japan, Egypt, the United States, Thailand, and the Philippines. A 2007 study by the Organization for Economic Cooperation and Development (OECD) estimated that, by 2070, coastal flooding from a sea level rise of 0.5 meter (1.6 feet) would affect 150 million people and cause property and other damages of $35 trillion (roughly equal to the current global world product). The United States would suffer the highest estimated monetary loss—over

What are some ways of adapting to climate change?

According to the latest global climate models, the world needs to make a 50-85% cut in emissions of greenhouse gases by 2050 to stabilize concentrations of these gases in the atmosphere and prevent the planet from heating up more than 2C° (3.6F°). This will be necessary in order to prevent rapid climate changes and the resulting projected harmful effects. However, because of the difficulty of making such large reductions, many analysts believe that, while we work to slash emissions, we should also begin to prepare for the projected harmful effects of essentially irreversible climate change. Some analysts and religious leaders call for the world's richer nations to increase technological and monetary aid to poorer regions at risk from climate change in order to help them deal with the changes. Emphasis could be on developing genetically engineered crops that could thrive in a warmer world and constructing flood defenses in low-lying coastal areas of countries such as India, Indonesia, and Bangladesh, which may experience more severe flooding due to global warming. Relief organizations, including the International Red Cross and Oxfam are turning their attention to projects such as expanding mangrove forests as buffers against storm surges, building shelters on high ground, and planting trees on slopes to help prevent landslides. Sea wall design and construction will be a major growth industry. And low-lying countries such as Bangladesh are trying to figure out what to do with millions of environmental refuges who would be displaced by rising sea levels. Some cities plan to establish cooling centers to shelter residents during increasingly intense heat waves. Some U.S. cities, including New York City and Seattle, Washington, have developed adaptation plans, as have some states, including California, Alaska, Maryland, Washington, and Oregon. Alaska has plans to relocate coastal villages at risk from rising sea levels and storm surges. California is beefing up its forest firefighting capabilities and is proposing desalination plants to help relieve projected water shortages, which will worsen as mountain glaciers melt. And some coastal communities require that new houses and other new buildings be built high enough off of the ground to survive projected higher storm surges; others are prohibiting new construction in especially vulnerable areas. Some people fear that emphasizing these adaptation approaches will distract us from the more urgent need to reduce greenhouse gas emissions. However, to some analysts, projected climate change is already such a serious threat that we have no alternative but to implement both prevention and adaptation strategies, and we have no time to lose.

Be able to give advantages and disadvantages of each of the following energy sources: Solar Thermal systems/ Concentrated solar power

Advantages are that is uses less energy than traditional methods. Uses renewable energy from the sun for power = no fossil fuels or greenhouse gases. Provides power to lots of people even at night (previously only fossil fuels). Disadvantages are that it is awkward and more expensive to use. Natural gas winning race for cheap power.

Be able to give advantages and disadvantages of each of the following energy sources: Biodiesel

Advantages are that it burns cleaner than fossil fuels. Reduced CO and CO2 emissions (still produces CO2), high net energy yield, reduced hydrocarbon emissions, better gas mileage, renewable. Disadvantages are that it takes a lot of land to produce, and it is more expensive and inefficient. Increased NOx emissions/smog, higher environmental cost, low net energy yield for soybean crops, loss of biodiversity, and difficulty for engines in cold weather. Moreover, it is an expensive process, not widely consumed, require huge areas of land and some crops have low yield, runoff, increased greenhouse gas emissions, threat to biodiversity.

Be able to give advantages and disadvantages of each of the following energy sources: Wind power

Advantages are that it is cleaner and renewable compared to fossil fuels and other sources. Renewable, no pollutants/generating electricity with the turbines emits no air pollution, ocean, efficient technology, prevent hurricane damage, and cost efficient. Cost low once gets going. Fossil fuels used in building. Disadvantages are that they can harm/kill birds and bats, lots of space, unreliable, the manufacture of turbines emits CO2, they can generate noise pollution, and strong winds are isolated (steady winds are intermittent). Zero emission, proximity of protected birds, and environmental disruption.

Be able to give advantages and disadvantages of each of the following energy sources: Photovoltaic (solar) cells

Advantages are that it is environmentally friendly compared to fossil fuels, although some small emissions. High net energy yield, low environmental impact, easily exempt or moved, last 20-40 years. Low environmental impact, low air pollution, and very cheap. Disadvantages are that nearby trees can shade solar panels, low efficiency, relies on electricity storage system or backup.

What activities have increased CO2, CH4 and N2O in the troposphere?

Agriculture, deforestation, and burning of fossil fuels

Know how the following positive feedback mechanisms accelerate climate change: hurricanes (refer to the example of Katrina & Rita in 2005)

An example of such increasing hurricane intensity was Hurricane Katrina, which occurred in 2005, a year when Atlantic water temperatures were especially warm. With an 8.5-meter-(28-foot-) high storm surge, Katrina caused massive damage and flooding in New Orleans, Louisiana (USA) and the surrounding area and killed more than 1,500 people. The 2005 hurricane season was the most active on record. Satellite imaging revealed that wind and longterm exposure to water from hurricanes Katrina and Rita in 2005 killed or severely damaged more trees in Mississippi and Louisiana than any recorded forestry disaster in U.S. history. This contributed to global warming, according to a 2007 study by Jeffrey Q. Chambers and his colleagues. They found that the estimated loss of over 320 million big trees sharply reduced the amount of CO2 removed from the atmosphere. In addition, the researchers estimated that as the dead and damaged trees decayed, they emitted CO2 equal to the total amount that all forest trees in the United States absorb in a year.

What are Milankovitch cycles? How do they relate to climate?

Another longterm driver of changes in Earth's climate are the Milankovitch Cycles, which are natural changes in the Earth's orbit around the sun and axial tilt. The three different cycles are precession, eccentricity, and obliquity. Precession is like the "wobble" when a top spins and means that the earth's axis slowly changes where it points in the sky. This changes when each hemisphere experiences summer and winter. If a hemisphere experiences winter when it is farthest from the sun, it may have cooler overall temperatures Obliquity is a change in the angle of the tilt of the Earth's axis. (It is currently tilted at 23.5 degrees). This affects the difference between summer and winter in a given hemisphere. Eccentricity is the change in the shape of the earth's orbit, making it more or less oval shaped. All three cycles are caused by the gravitational pull of the moon, sun and other planets in the solar system. In general, they affect the difference between summer temperatures and winter temperatures in a hemisphere and result in ice ages. When a hemisphere has consistently cooler summers, that can mean that less ice melts in the summer, causing the beginning of an ice age. Whereas if a hemisphere were to have consistently warmer winters, less ice will form, which may cause an ice age to end. These changes can trigger changes in carbon dioxide which will amplify the effect of the cycles on Earth's climate.

Where in the world can geothermal heat pumps be installed? Where can geothermal power plants be installed? Why?

Geothermal heat pumps can be installed on an individual building/property. Almost anywhere in the world. Geothermal wells that supply geothermal power plants are drilled to depths of approximately, for a horizontal loop you only need to dig between 6 - 8 feet deep and for a vertical loop you need to drill between 250 and 300 feet deep.

What are the CAFE standards? How do these standards compare to those of other countries?

Between 1973 and 1985, average fuel efficiency for new vehicles sold in the United States rose sharply because of government-mandated corporate average fuel economy (CAFE ) standards. However, since 1985, the average fuel efficiency for new vehicles sold in the United States decreased to about 9 kilometers per liter (kpl) (21 miles per gallon (mpg)). This was mostly because there was no increase in the CAFE standards until 2008, and because mileage standards for popular trucks and SUVs are not as high as those for cars. Fuel economy standards in Europe, Japan, China, and Canada are much higher than those in the United States. A 2008 law raised CAFE standards in the United States to 15 kpl (35 mpg) to be attained by 2020. This will still put U.S. fuel efficiency standards much lower than those of the other countries.

Know how the following positive feedback mechanisms accelerate climate change: melting of glaciers

Climate models predict that global warming will be the most severe in the world's polar regions, the Arctic and Antarctica. Light colored ice and snow in the polar regions help to cool the earth by reflecting incoming solar energy. The melting of such ice and snow exposes much darker land and sea, which absorb more solar energy. This will likely cause polar regions to warm faster than lower latitudes, which will further accelerate global warming and the resulting climate change, which in turn will melt more sea ice, which will raise atmospheric temperatures more, and faster, in a runaway positive feedback loop.

What are some advantages & disadvantages to getting energy from coal?

Coal is plentiful (especially in US- "the Saudi Arabia of coal") however it has a number of disadvantages. Coal is very polluting (industrial smog). It contains carbon dioxide (CO2), which contributes to climate change (Coal burning accounts for ¼ of world's CO2 emissions). Coal exhaust also contains NOx which can lead to photochemical smog and acid rain. N2O is also a greenhouse gas. Sulfur dioxide (SO2), which causes acid rain, also is emitted from coal plants. Additionally there are particulates (soot, fly ash), which can lead to industrial smog, Mercury (Hg), a neurotoxin, and other trace radioactive materials. Mining coal is destructive and leads to loss of habitat, as well as air and water pollution. Coal is mostly obtained through strip mining and mountaintop removal.

Understand the differences in environmental impact when ethanol is derived from different sources (sugar cane vs corn)

Currently, this method of energy generation works by growing corn. However, growing and extracting corn is very energy-intensive because fossil fuels are used to make fertilizer and pesticides that help to grow the corn and are also needed to ferment corn sugar. Moreover, only the corn seeds are used for ethanol and the rest is thrown away. However, if we use a different part of corn or a different plant to obtain cellulosic biomass, it can be better. For Brazil, where they use sugarcane to produce ethanol, ethanol yields 8 times the amount of energy taken to produce it while gasoline takes 4.1. Whereas in the United States where they use corn ethanol, it only produces 1.1-1.5 net energy which isn't very efficient compared to fossil fuels. Corn is very space and resource intensive, 1 bushel of corn = 3 gallons of fuel. To cover, US needs of 130 billion gallons of fuel, so would need the entire country to convert completely to biofuel made from corn. Ethanol produces twenty-five percent fewer greenhouse emissions. Currently, fossil fuels are used to make fertilizer and pesticides to help corn grow and are also needed to ferment corn sugar. However, if cellulosic ethanol can be manufactured without burning fossil fuel, such as by using switchgrass, net carbon emissions can essentially be zero.

How much solar energy reaching Earth is Reflected & scattered into space?

Earth's planetary albedo is about 0.31. That means that about a third of the solar energy that gets to Earth is reflected out to space and about two thirds is absorbed.

What fuel source is used most in developed countries?

In the US we use mostly fossil fuels (85%). Developed countries depend heavily on oil.

Know how climate change would affect the following: Agricultural productivity

Farming, probably more than any other human activity, depends on a stable climate. Thus, farmers will face dramatic changes due to shifting climates and a faster hydrologic cycle, if global warming continues as projected. Agricultural productivity may increase in some areas and decrease in others. According to the 2007 IPCC report, crop productivity is projected to increase slightly at middle to high latitudes if global temperatures rise by 1-3 C° (1.8-5.4 F°), but productivity would likely decrease at higher temperatures. Models project that moderately warmer temperatures and increased precipitation at northern latitudes may lead to a northward shift of some agricultural production to parts of midwestern Canada, Russia, and Ukraine. But overall food production could decrease because of unsuitable soils in these northern regions. There could be a 10-15% drop in rainfall in the United States and several other parts of the world. But as long as the temperature does not rise by more than 3 C° (5.4 F°), scientists hope that new genetically modified varieties of key food crops could tolerate this drier climate. Climate change models predict a decline in agricultural productivity in tropical and subtropical regions, especially in Southeast Asia and Central America, where many of the world's poorest people live. In addition, flooding of river deltas due to rising sea levels could reduce crop and fish production in these productive agricultural lands and nearby coastal aquaculture ponds. Food production could also decrease in farm regions dependent on rivers fed by snowmelt and glacier melt; arid and semiarid areas where prolonged drought will increase; and humid areas in southeastern Asia that are vulnerable to changes in monsoon patterns, which could bring more devastating storms and heavier flooding. According to the IPCC, for a time, food will be plentiful because of the longer growing season in northern regions. But by 2050, the IPCC warns that some 200- 600 million of the world's poorest and most vulnerable people could face starvation and malnutrition from the effects of climate change.

What incentives do people have in Japan and Europe to conserve fuel?

Gasoline prices are much higher in Japan and most European nations, because their governments have set higher fuel-efficiency standards and imposed high gasoline taxes to encourage greatly improved fuel efficiency.

Give two ways that governments can do to help slow climate change.

Governments can use four major methods to promote the solutions. One is to strictly regulate carbon dioxide and methane as pollutants. Second, governments could phase in carbon taxes on each unit of CO2 or CH4 emitted by fossil fuel use, or they could levy energy taxes on each unit of fossil fuel that is burned. Decreasing taxes on income, wages, and profits to offset such taxes could help make such a strategy more politically acceptable. In other words, tax pollution, not payrolls and profits. Some European countries are phasing in such a tax shift. A related approach is to place a cap on total humangenerated CO2 and CH4 emissions in a country or region, issue permits to emit these pollutants, and then let polluters trade their permits in the marketplace. This cap-and-trade approach has a political advantage over taxes, but it would be difficult to manage because there are so many emitters of greenhouse gases, including industries, power plants, motor vehicles, buildings, and homes. And according to a 2008 study by Goldman Sachs, one of the world's largest investment banks, a cap-and-trade strategy is an important way to cut CO2 emissions, but by itself would not be enough to achieve the desired drop in such emissions. Environmental economists argue that, regardless of whether governments use taxes or a cap-and-trade system, the most important goal is to get all emitters to pay the full environmental and social costs of their carbon emissions. The resulting higher costs for fossil fuels would spur innovation in finding ways to reduce carbon emissions, improve energy efficiency, and phase in noncarbon renewable energy alternatives. A third strategy is to level the economic playing field by greatly increasing government subsidies to businesses and individuals to encourage their use of energy-efficiency technologies, carbon-free renewable energy sources, and more sustainable agriculture. This would also include phasing out or sharply reducing subsidies and tax breaks that encourage use of fossil fuels and nuclear power, unsustainable agriculture, and clearing of forests. In other words, we could shift from environmentally-degrading to environmentally-sustaining subsidies and tax breaks. A fourth strategy would focus on technology transfer. Governments of developed countries could help to fund the transfer of the latest green technologies to developing countries so that they could bypass older, energywasting and polluting technologies. Helping poorer countries to deal with the harmful effects of climate change would make sense, because these are the countries that will suffer the most from these effects, which have been caused mostly by developed countries. Increasing the current tax on each international currency transaction by a quarter of a penny could finance this technology transfer, which would then generate wealth for developing countries and help to stimulate a more environmentally sustainable global economy.

What is the LEED program?

Green building certification standards now exist in 21 countries, spurred by the World Green Building Council, established in 1999. Since 2001, the U.S. Green Building Council's Leadership in Energy and Environmental Design (LEED) program has accredited more than 25,000 building professionals in energy and environmental design. It has established guidelines, and it awards its much-coveted silver, gold, and platinum standard certifications to buildings meeting certain standards. One platinum standard building is China's Ministry of Science and Technology in Beijing. Its surrounding area is paved with porous bricks made of fly ash left over from burning coal. These bricks allow water to flow through them and to help replenish the city's aquifer. Solar cells made in China provide about 10% of the building's electricity, and it has a solar hot water heating system also made in China. A soil substitute used in its energy-saving roof garden is 75% lighter and holds three to four times more water per cubic meter than dirt can hold. The use of concrete building blocks filled with insulating foam also saves energy. This is an impressive showcase building, but China lags far behind other countries in energy-efficient building design. Nevertheless, within 20 years, China expects to be the world's leader in this area and to sell its innovative designs and materials in the global marketplace.

What do we currently do with high-level radioactive waste? How long does spent nuclear fuel need to be stored safely? What are some pros & cons to recycling spent fuel?

High-level radioactive waste (nuclear): remains radioactive/dangerous for long periods of time. Low-level radioactive waste: remains radioactive/dangerous for short periods of time. Half-life of isotope (differs in number of neutrons) involved differs. Each part of the nuclear power fuel cycle produces radioactive wastes. High-level radioactive wastes, which consist mainly of spent fuel rods and assemblies from commercial nuclear power plants and assorted wastes from the production of nuclear weapons, must be stored safely for 10,000-240,000 years depending on the radioactive isotopes present. For example, wastes containing highly toxic and fissionable plutonium-239 (which can also be used to make nuclear weapons) must be stored for about 240,000 years before decaying to safe levels. And according to a Nevada state agency report, 10 years after being removed from a reactor, an unshielded spent-fuel assembly would still emit enough radiation to kill a person standing 1 meter (39 inches) away in less than 3 minutes. Most scientists and engineers agree in principle that deep burial is the safest and cheapest way to store high-level radioactive waste. However, after almost 60 years of research and evaluation, no country has built such a repository. And some scientists contend that it is not possible to show that any method will work for 10,000-240,000 years. U.S. scientists are working on a process involving the recycling of some wastes, which might reduce the amount of radioactive waste produced by conventional reactors by 40%. Critics say that the recycled fuel would contain as much as 90% plutonium (compared to 1% in conventional spent fuel), which would make it attractive to terrorists for making nuclear weapons. However, advocates say the recycling process would make it difficult to extract the plutonium for use in a bomb. For decades, researchers have been looking—without success—for ways to change harmful radioactive isotopes into less harmful isotopes. Even if a method were developed, costs would probably be extremely high, and the resulting toxic materials and low-level (but very long-lived) radioactive wastes would still require a safe disposal method. After almost 60 years of effort, no country has come up with a scientifically and politically acceptable way to store high-level radioactive wastes safely for tens of thousands of years. An important and often ignored fact about using nuclear power to produce electricity is that, even if all the nuclear power plants in the world were shut down tomorrow, we would still have to deal with all the intensely radioactive wastes they have produced, some of which will have to be isolated safely for 240,000 years. No other existing or abandoned technology has subjected the world to such long-term health risks.

Know how climate change would affect the following: Air pollution

Higher atmospheric temperatures will also increase some forms of air pollution. The greatest effect will be to speed up the rate of the chemical reactions that produce ozone and other harmful chemicals in photochemical smog in urban areas

What is the IPCC? Make sure you know what they do (not just what the letters stand for)

In 1988, the United Nations and the World Meteorological Organization established the Intergovernmental Panel on Climate Change (IPCC) to document past climate changes and project future changes. The IPCC network includes more than 2,500 climate experts from more than 130 countries. Its 2007 report was based on more than 29,000 sets of data, much of it collected since 2002. In this report, the IPCC listed a number of findings indicating that it is very likely (a 90-99% probability) that the lower atmosphere is getting warmer and that human activities are responsible for most of the recent temperature increase and will be responsible for most of the larger increase projected for this century. In 2007, former U.S. Vice President Al Gore shared the Nobel Peace Prize with the IPCC for alerting the world to the reality and dangers of global warming and its effects on the world's climate. In his acceptance speech he said, " . . . the Earth has a fever. And the fever is rising. . . . We are what is wrong, and we must make it right."

Know the basic idea of the Kyoto Protocol and its pros & cons

In December 1997, more than 2,200 delegates from 161 nations met in Kyoto, Japan, to negotiate a treaty to slow climate change. The first phase of the resulting Kyoto Protocol went into effect in February 2005 with 174 of the world's 194 countries (but not the United States) ratifying the agreement by mid-2008. It requires 36 participating developed countries to cut their emissions of CO2, CH4, and N2O to an average of at least 5.2% below their 1990 levels by 2012. Developing countries were excluded from having to reduce greenhouse gas emissions in this first phase, because such reductions would curb their economic growth. In 2005, countries began negotiating a second phase that is supposed to go into effect after 2012. The protocol also allows trading of greenhouse gas emissions among participating countries. For example, a country or business that reduces its CO2 emissions or plants trees receives a certain number of credits. It can use these credits to avoid having to reduce its emissions in other areas, or it can bank them for future use or sell them to other countries or businesses. In 2005, the European Union instituted such a cap-and-trade system for carbon emissions. However, in 2007, critics pointed out that the system was not working well because the caps were set too high and thus have been encouraging greenhouse gas emissions. Environmental economists warn that the success of any cap-and-trade emissions system depends on setting caps low enough to increase the value of the tradable allowances and periodically reducing the caps to encourage further innovation in reducing emissions. They also advise that such a system by itself will not achieve the desired reductions in greenhouse gas emissions. Some analysts praise the Kyoto agreement as a small but important step in attempting to slow projected global warming. They hope that rapidly developing nations such as China, Brazil, India, and Indonesia will agree to reduce their greenhouse gases in the second phase of the protocol. Others see the agreement as a weak and slow response to an urgent global problem. In 2001, President George W. Bush withdrew the United States from participation in the Kyoto Protocol, arguing that it would harm the U.S. economy. He also objected to the agreement because it did not require emissions reductions by rapidly developing countries such as China, India, Brazil, and Indonesia, which were producing large and increasing emissions of greenhouse gases. Most analysts, and 59% of Americans responding to a 2007 poll, believe that the United States, which has the world's highest overall and per capita CO2 emissions, should use its influence to improve the treaty rather than to weaken and abandon it.

What is a conservation easement (see carbon footprint activity)?

In a conservation easement, a landowner voluntarily agrees to sell or donate certain rights associated with his or her property - often the right to subdivide or develop - and a private organization or public agency agrees to hold the right to enforce the landowner's promise not to exercise those rights.

What is the greenhouse effect? How does it warm the earth?

Less than half of the incoming sunlight (visible light) heats the ground. The rest is reflected away by bright white clouds or ice or gets absorbed by the atmosphere. The sunlight that makes it to the ground warms the Earth's surface. The warm ground and oceans give off infrared (IR) (heat) radiation, which we feel as heat. That IR radiation or heat moves back up through the atmosphere. Most of it is trapped (absorbed) by greenhouse gases (such as CO2, CH4, N2O, and H2O), preventing them from leaving as fast as them arrived. After a while, the IR radiation is re-radiated in all directions and leaks back out into space. For the most part, the energy coming to Earth as sunlight equals the energy leaving as IR. If it doesn't, Earth heats up or cools down. Recently the energy budget has not been balanced. As we add greenhouse gases to the atmosphere, they trap more heat close to the planet and Earth warms.

How much solar energy reaching Earth is Absorbed by the clouds and atmosphere?

Less than half of the incoming sunlight heats the ground. The rest is reflected away by bright white clouds or ice or gets absorbed by the atmosphere.

What do the following parts of a nuclear plant do? Coolant

Like a coal-burning power plant - the fuel source is just different. A coolant, usually water, circulates through the reactor's core to remove heat, which keeps fuel rods and other materials from melting and releasing massive amounts of radioactivity into the environment. An LWR includes an emergency core cooling system as a backup to help prevent such meltdowns.

What do the following parts of a nuclear plant do? Turbines

Like a coal-burning power plant - the fuel source is just different. A nuclear power plant is a highly complex and costly system designed to perform a relatively simple task: to boil water to produce steam that spins a turbine and generates electricity.

What do the following parts of a nuclear plant do? Fuel rods

Like a coal-burning power plant - the fuel source is just different. Large numbers of the pellets are packed into closed pipes called fuel rods, which are then grouped together in fuel assemblies, to be placed in the core of a reactor.

What do the following parts of a nuclear plant do? Control rods

Like a coal-burning power plant - the fuel source is just different. To control the reaction, devices called control rods are moved in and out of the reactor core to absorb neutrons, thereby regulating the rate of fission and amount of power produced.

What is the difference between passive and active solar heating? How can buildings be cooled naturally?

Makes houses more energy efficient. Passive solar technologies use design features to capture and distribute the sun's heat. The sun heats house based on specific angle of sun. Can be installed on an individual building/property. There are two ways to harness solar energy. Passive systems are structures whose design, placement, or materials optimize the use of heat or light directly from the sun. Active systems have devices to convert the sun's energy into a more usable form, such as hot water or electricity.

How do coal plants work?

Making energy from coal is basically an inefficient way of boiling water to produce steam to turn turbines to produce electricity.

What affects albedo? How does it affect temperature?

Many different things cover the Earth such as soil, rocks, water, forests, snow, and sand. Materials like these have different ways of dealing with the solar energy that gets to our planet. Dark colored surfaces, like ocean and forests, reflect very little of the solar energy that gets to them. Light colored parts of the planet surface, like snow and ice, reflect almost all of the solar energy that gets to them. The amount of energy reflected by a surface is called albedo. Albedo is measured on a scale from zero to one (or sometimes as a percent).-Very dark colors have an albedo close to zero (or close to 0%).-Very light colors have an albedo close to one (or close to 100%). Because much of the land surface and oceans are dark in color, they have a low albedo. They absorb a large amount of the solar energy/light waves that gets to them, reflecting only a small fraction of it. Forests have low albedo, near 0.15. Snow and ice, on the other hand, are very light in color. They have very high albedo, as high as 0.8 or 0.9, and reflect most of the solar energy that gets to them, absorbing very little. The albedo of all these different surfaces combined is called the planetary albedo. Earth's planetary albedo is about 0.31. That means that about a third of the solar energy that gets to Earth is reflected out to space and about two thirds is absorbed. The Moon's albedo is 0.07, meaning that only 7% of the energy that gets to it is reflected. If Earth's climate is colder and there is more snow and ice on the planet, more solar radiation is reflected back out to space and the climate gets even cooler. On the other hand, when warming causes snow and ice to melt, darker colored Earth surface and ocean are exposed and less solar energy is reflected out to space causing even more warming. This is known as the ice-albedo feedback. Clouds have an important effect on albedo too. They have a high albedo and reflect a large amount of solar energy out to space. Different types of clouds reflect different amounts of solar energy. If there were no clouds, Earth's average albedo would drop by half.

How can sunlight be used to produce high-temperature heat and electricity (aka concentrated solar power)?

Mirrors point towards boiler towers causing them to create steam and power a turbine. At night, tanks of salt heated during day work at night to turn turbines. Transmission lines. Reflect light to big tower and concentrate to salt.

What are some drawbacks to using hydrogen as an energy source? How could it become a viable energy source in the future?

More expensive, will always have a negative net energy yield, and production can be harmful. Cost (expensive in beginning but saves a lot in the long run), new policies, and fossil fuels can be used in electrolysis. Before you can use hydrogen as an energy source, you must get it into its pure form by separating it from other elements.

What is ANWR? What is the controversy surrounding this region?

The Arctic National Wildlife Refuge in Northern Alaska is thought to contain oil reserves. Many politicians are advocating exploratory drilling in the coastal plain in this region. Many people argue that ANWR is small compared to the state of Alaska so it will not produce much damage to drill there. However, it is actually the size of South Carolina. Another argument for drilling in ANWR is that it will reduce our dependence on foreign oil. However, it is estimated to provide enough oil for 2 years at most-less if demand continues to rise (see graph). There is a misconception that ANWR is an arctic wasteland; ANWR is composed of fragile tundra habitat, which is home to many species, and is a key nesting ground for millions of migratory birds. Additionally, tundra has a low resilience and thus takes a long time to recover from ecological disturbances. Nevertheless, drilling in ANWR would boost Alaska's economy. Also, holds cultural significance for indigenous Alaskans and could disrupt permafrost, causing it to melt and release methane.

What is nuclear fusion? Why don't we use it for energy?

Nuclear fusion is a nuclear change in which two isotopes of light elements, such as hydrogen, are forced together at extremely high temperatures until they fuse to form a heavier nucleus, releasing energy in the process. Scientists hope that controlled nuclear fusion will provide an almost limitless source of high-temperature heat and electricity. Research has focused on the D-T nuclear fusion reaction, in which two isotopes of hydrogen—deuterium (D) and tritium (T)—fuse at about 100 million degrees. With nuclear fusion, there would be no risk of meltdown or release of large amounts of radioactive materials from a terrorist attack, and little risk of additional proliferation of nuclear weapons, because bomb-grade materials are not required for fusion energy. Fusion power might also be used to destroy toxic wastes, supply electricity for ordinary use, and decompose water to produce hydrogen fuel, which holds promise as an energy source. This sounds great. So what is holding up fusion energy? In the United States, after more than 50 years of research and a $25 billion investment of mostly government funds, controlled nuclear fusion is still in the laboratory stage. None of the approaches tested so far has produced more energy than it uses. In 2006, the United States, China, Russia, Japan, South Korea, and the European Union agreed to spend at least $12.8 billion in a joint effort to build a large-scale experimental nuclear fusion reactor by 2040 and to see if it can produce a net energy yield. If everything goes well, after 34 years, the plant is supposed to produce enough electricity to run the air conditioners in a small city for a few minutes. This helps to explain why many energy experts do not expect nuclear fusion to be a significant energy source until 2100, if then. Indeed, some skeptics joke that "nuclear fusion is the power of the future and always will be."

Know why many experts think that nuclear energy cannot significantly reduce global warming.

Nuclear power advocates also contend that increased use of nuclear power will reduce the threat of global warming by greatly reducing or eliminating emissions of CO2. Scientists point out that this argument is only partially correct. Nuclear plants themselves do not emit CO2, but the nuclear fuel cycle does—a fact rarely reported in media stories about nuclear power. Such emissions are presumably much less than those produced by burning coal or natural gas to generate the same amount of electricity and about the same as those emitted by the entire process of producing and operating solar cells and offshore wind farms. However, according to a 2004 study by German scientists, considering the entire nuclear fuel cycle, CO2 emissions per kilowatt-hour of electricity are much higher than the numbers in Figure 15-14 indicate. In a 2003 study "The Future of Nuclear Power," MIT researchers concluded that some 1,000 to 1,500 new reactors (compared to the 439 that exist today) would have to be built worldwide by 2025 in order to put a serious dent in projected global warming. Those plants would require a new large repository every few years to store the resulting amount of highly radioactive nuclear waste. Building and operating this many new plants would also hasten the depletion of high-grade uranium ores, and mining, processing, and transporting these ores releases CO2. Shifting to low-grade ores to meet increased fuel demands would increase the carbon footprint of the nuclear fuel cycle. In 2007, a leading think tank, the Oxford Research Group, said that in order to play an effective role in slowing global warming, a new nuclear reactor would have to be built somewhere in the world every week for the next 70 years—an impossibility for logistical and economic reasons. And physicist Brice C. Smith estimates that even if this were possible, because of the retirement of old reactors, the proportion of electricity coming from nuclear power would increase only slightly from its current 16% to 20%. Analysts contend that cutting energy waste and increasing the use of renewable energy resources to produce electricity are much better and faster ways to reduce CO2 emissions.

What is the nuclear fuel cycle? Know the steps & how it contributes to CO2 emissions

Nuclear power plants, each with one or more reactors, are only one part of the nuclear fuel cycle. This cycle includes the mining of uranium, processing and enriching the uranium to make fuel, using it in a reactor, and safely storing the resulting highly radioactive wastes until their radioactivity falls to safe levels. The final step in the cycle occurs when, after 15-60 years, a reactor comes to the end of its useful life and must be retired, or decommissioned. It cannot simply be shut down and abandoned, because its structure contains large quantities of intensely radioactive materials that must be kept out of the environment for many thousands of years. Each step in the nuclear fuel cycle adds to the cost of nuclear power and reduces its net energy yield. Overall, the current nuclear fuel cycle is extremely inefficient, using or wasting an amount of energy equivalent to about 92% of the energy content of its nuclear fuel. In evaluating the safety, economic feasibility, and overall environmental impact of nuclear power, energy experts and economists caution us to look at the entire fuel cycle, not just the nuclear plant.

What are petrochemicals? Know some examples and how they are extracted from petroleum

Oil is refined using distillation into a number of products, called petrochemicals (see diagram). This process is based on differences in boiling points.

Know the three types of fossil fuels

Oil, natural gas & coal are all considered fossil fuels. They are byproducts of the decomposition of living organisms, specifically anaerobic decomposition of organisms (decomposition without oxygen) that lived millions of years ago.

Know how the following positive feedback mechanisms accelerate climate change: melting of permafrost

The amount of carbon locked up as methane in permafrost soils is 50-60 times the amount emitted as carbon dioxide from burning fossil fuels each year. If the permafrost in soil and lake bottoms in parts of the rapidly warming Arctic melts, significant amounts of methane (CH4) and carbon dioxide (CO2) will be released into the atmosphere, and this will accelerate global warming and the resulting climate change. According to the 2004 Arctic Climate Impact Assessment, 10-20% of the Arctic's current permafrost might thaw during this century, decreasing the total area of arctic tundra. The resulting increase in emissions of CH4 and CO2 would cause more warming, which would in turn melt more permafrost and cause still more warming and climate change in yet another positive feedback loop.

What is albedo?

The amount of energy reflected by a surface is called albedo.

Know the sources of data that scientists can use to get information about past climate/ past CO2 levels

Past temperature changes are estimated by analysis of radioisotopes in rocks and fossils; plankton and radioisotopes in ocean sediments; tiny bubbles of ancient air found in ice cores from glaciers; temperature measurements taken at different depths from boreholes drilled deep into the earth's surface; pollen from the bottoms of lakes and bogs; tree rings; historical records; insects, pollen, and minerals in different layers of bat dung deposited in caves over thousands of years; and temperature measurements taken regularly since 1861. Such measurements have limitations, but they show general changes in temperature, which in turn can affect the earth's climate.

What is meant by a carbon sink/ carbon reservoir?

Places that hold nutrients for extended amounts of time. Carbon sinks: soil, forests, the atmosphere, and fossil fuels.

Know how the following positive feedback mechanisms accelerate climate change: conditions created by prolonged drought

Recall that drought occurs when evaporation from increased temperatures greatly exceeds precipitation for a prolonged period. According to a 2005 study by Aiguo Dai and his colleagues, between 1979 and 2002, the area of the earth's land (excluding Antarctica) experiencing severe drought increased from about 15% to 30%—a total area about the size of Asia. Prolonged drought over several decades is caused by a combination of natural changes and cycles in the earth's climate system and human activities such as widespread deforestation and increased greenhouse gas emissions. According to the 2007 IPCC report, these human influences are very likely to increase throughout this century. As this browning of the land increases, in the affected areas, there will be less moisture in the soil; stream flows and available surface water will decline; net primary productivity will fall; growth of trees and other plants will slow, which will reduce CO2 removal from the atmosphere and intensify global warming; forest and grassland fires will increase, which will add CO2 to the atmosphere; water tables will fall with more evaporation and irrigation; some lakes and seas will shrink or disappear; more rivers will fail to reach the sea; 1-3 billion people will face a severe shortage of water; biodiversity will decrease; and the area of dry climate biomes, such as savannas, chaparral, and deserts, will increase. In other words, some of the effects of prolonged drought over several decades create conditions that, through positive feedback, accelerate global warming and climate change and lead to even more drought.

How could recycling save energy in industry?

Recycling materials such as steel and other metals is a third way for industry to save energy and money. Producing steel from recycled scrap iron in an electric arc furnace uses 75% less energy than producing steel from virgin iron ore. Switching three-fourths of the world's steel production to such furnaces would cut energy use in the global steel industry by almost 40% and sharply reduce its CO2 emissions. Similarly, if all of the world's energy-intensive cement producers used today's most energy-efficient dry kiln process, the global cement industry could cut its energy use by 42% and greatly reduce its CO2 emissions.

Know how climate change would affect the following: Aquatic organisms that build shells/ skeletons (know the chemical equations!)

Refer to ocean acidification lecture.

How do we know a hotter sun is not responsible for climate change?

Solar output has been named as a cause of global climate change. This is being heavily evaluated for the 5th IPCC report, which will come out in 2014. The data show that since about 1950, we have been in a less- active period for the sun, and solar irradiance has actually decreased slightly, nevertheless, our temperature has continued to go up. (see graph to right). This would indicate that increasing solar irradiance is not the cause of the current warming trend. The second graph (left) of data from Livermore National Laboratory shows that since 1980, solar irradiance has been almost constant (with a slight decrease), which does not explain the increased warming trend at Earth's surface. Another indication that changes in solar irradiance could not be the cause of global climate change is the pattern of temperature change in the upper atmosphere. With more solar irradiance, we would expect to see all layers of the atmosphere increase in temperature. However, if we look at data for temperatures of the troposphere compared to the stratosphere since 1958, the data show that the stratosphere is actually cooling, while the troposphere continues to warm (shown below). Layers higher in the atmosphere (the mesosphere and thermosphere), also show a cooling trend similar to that of the stratosphere. These trends in the upper atmosphere are exactly what was predicted by climate models if the tropospheric warming was primarily cause by greenhouse gases. Since the greenhouse gases are trapping more heat in the troposphere, the heat is not radiating through the upper layers of the atmosphere, warming them, on its way to space. Without this heat, the upper layers are cooling down, while the troposphere heats up.

What is cogeneration?

Some companies save energy and money by using cogeneration, or combined heat and power (CHP), systems. In such a system, two useful forms of energy (such as steam and electricity) are produced from the same fuel source. For example, the steam produced in generating electricity in a CHP system can be used to heat the plant or other nearby buildings, rather than released into the environment and wasted. The energy efficiency of these systems is as high as 80% (compared to 30-40% for coal-fired boilers and nuclear power plants), and they emit one-third as much CO2 per unit of energy produced as do conventional coal-fired boilers. Cogeneration has been widely used in Europe for years and its use in the United States and in China is growing.

What is OPEC? Why are they a powerful organization? How much of the world's oil do they control?

The oil industry is the largest business in the world, so controlling oil reserves is a huge source of economic & political power. Saudi Arabia has the largest portion of oil reserves (25%). Canada is second with 15% (though not an OPEC member). Together, all OPEC countries control 60% of the world's oil. OPEC is very secretive so no one actually knows the real amount of the world's oil reserves. Stanford researchers estimate that about 75% of the world's reserves are owned by government run (not private) companies, giving these governments a huge influence.

What are tar sands & oil shales? How does their net energy yield compare to conventional sources of oil?

There are two other ways for us to extract oil, but both have relatively low net energy yields. Oil Shales are shale (mudstone) that contain high levels of hydrocarbons. They are found in the western US. The oil is extracted by crushing the rocks and heating them. This also requires lots of energy & water (net energy is even lower than that of tar sands!) Tar Sands (see photo) are sands that contains bitumen (thick sticky oil). They are not very concentrated and must be extracted by strip mining. This process requires lots of energy & water as well. Most of these tar sands are located in Canada. (This is the reason why Canada's reserves are 15% of world total). The net energy yield of tar sands is lower than the net energy for traditional oil. Additionally, because so much energy is used in extracting the oil, tar sands produce more CO2 per unit burned than conventional oil.

What are the differences between plug-in hybrids and conventional hybrid cars?

There is growing interest in developing superefficient and ultralight cars that could eventually get 34-128 kpl (80- 300 mpg). One of these vehicles is the energy-efficient, gasoline-electric hybrid car, invented by Ferdinand Porsche in 1900 and improved with modern technology by Japanese automobile companies such as Toyota and Honda. It has a small traditional gasoline-powered motor and an electric motor used to provide the energy needed for acceleration and hill climbing. The most efficient models of these cars get up to 20 kpl (46 mpg) on the highway and emit about 65% less CO2 per kilometer driven than a comparable conventional car emits. The next step in the evolution of more energy-efficient motor vehicles will probably be the plug-in hybrid electric vehicle—a hybrid with a second and more powerful battery that can be plugged into a standard outlet and recharged. By running primarily on electricity, they could easily get the equivalent of at least 43 kpl (100 mpg) for ordinary driving and up to 430 kpl (1,000 mpg), if used only for trips of less than 64 kilometers (40 miles). Manufacturers hope to have a variety of plug-in hybrids available by 2010, and some analysts project that they could dominate the motor vehicle market by 2020. The key is to develop a battery that will have enough range and be strong, safe, reliable, and affordable enough to use in a mass auto market. Replacing the current U.S. vehicle fleet with highly efficient plug-in hybrid vehicles over 2 decades, would cut U.S. oil consumption by 70-90%, eliminate the need for oil imports, save consumers money, and reduce CO2 emissions by 27%, according to a 2006 Department of Energy study. If the batteries in this national car fleet were recharged mostly with electricity generated by wind, solar energy, hydropower, and geothermal energy instead of by coal-burning power plants, U.S. emissions of CO2 would drop by 80-90%, which would greatly help to slow global warming and projected climate change.

What strategies can governments use to facilitate a shift toward sustainable energy sources? (Thinks about what has been done in CA)

To most analysts, economics, politics, and consumer education hold the key to making a shift to a more sustainable energy future. It will require maintaining consistent and sustained energy policies at the local, state, and national levels so that businesses can make long-range plans. Governments can use three strategies to help stimulate or dampen the short-term and longterm use of particular energy resources. First, they can keep the prices of selected energy resources artificially low to encourage use of those resources. They do this by providing research and development (R&D) subsidies and tax breaks to encourage the development of those resources, and by enacting regulations to favor them. For decades, this approach has been employed to stimulate the development and use of fossil fuels and nuclear power in the United States and in most other developed countries. The U.S. oil industry received almost half of the $600 billion in R&D subsidies provided by taxpayers between 1950 and 2003, according to the U.S. Department of Energy and the Congressional Budget Office. And in 2007, the Department of Energy allocated $159 million for solar energy R&D. At the same time, it allocated nearly double this amount, $303 million, for nuclear energy R&D and $427 million for coal R&D. For decades, this sort of policy has created an uneven economic playing field that encourages energy waste and rapid depletion of nonrenewable energy resources, while it discourages improvements in energy efficiency and the development of renewable energy resources. To many energy analysts, one of the most important steps governments can take to level the economic playing field is to phase out the $250-300 billion in annual subsidies now provided worldwide for fossil fuels and nuclear energy—both mature industries that could be left to stand on their own, economically. These analysts call for greatly increasing subsidies for developing renewable energy and energy-efficiency technologies. If this had been done beginning in 1980, they say, the world probably could have greatly increased its energy sustainability, sharply decreased its dependence on imported oil, avoided two wars in the Middle East, and be well on the way to slowing global warming and projected climate change. The second major strategy that governments can use is to keep energy prices artificially high for selected resources to discourage their use. They can do this by eliminating existing tax breaks and other subsidies that favor use of the targeted resource, and by enacting restrictive regulations or taxes on its use. Canada, in 2007 introduced rebates for hybrid vehicles, a tax on gas-guzzlers, and subsidies for development of renewable fuels. China is also taxing gas-guzzlers and raising energy-efficiency requirements for homes and office buildings. Such measures can increase government revenues, encourage improvements in energy efficiency, reduce dependence on imported energy, and decrease use of energy resources that have limited supplies. To make such changes acceptable to the public, analysts suggest that governments can offset energy taxes by reducing income and payroll taxes and providing an energy safety net for low-income users. Third, governments can emphasize consumer education. Even if governments offer generous financial incentives for energy efficiency and renewable energy use, people will not make such investments if they are uninformed—or misinformed—about the availability, advantages, disadvantages, and relative costs of energy resources. For example, cloudy Germany has more solar water heaters and solar cell panels than sunny France and Spain, mostly because the German government has made the public aware of the environmental benefits of these technologies. It has also provided consumers with substantial economic incentives for using them. The good news is that we have the technology, creativity, and wealth to make the transition to a more sustainable energy future within your lifetime, as the state of California is proving. Making this transition depends primarily on education and politics—on how well individuals understand ecological and environmental problems, and on how they vote and then influence their elected officials. People can also vote with their pocketbooks by refusing to buy inefficient and environmentally harmful products and by letting company executives know about their choices. The U.S. state of California has a population of 37 million people and is the world' sixth largest economy. It uses less energy per person than any other U.S. state. While overall per capita energy use in the United States has grown by half since 1974, California's energy use per person has stayed about even. The state has accomplished this through a mix of state regulations and high electricity prices, and at the same time it has kept its economy growing. Because California promotes the use of cleaner, renewable sources of power, state residents pay close to the highest rates for electricity anywhere in the United States. This helps reduce energy waste and encourages the use of energy-efficient devices. In the long run, because of increased efficiency, it also saves people money. While the average American uses 12,000 kilowatt-hours (kWh) of electricity in a year, the average California resident uses less than 7,000 kWh. That translates to about $800 in savings for the average Californian, even with the state's high electricity prices. And while U.S. per capita CO2 emissions stayed about the same between1974 and 2004, such emissions in California fell by 30%. Actions taken by the state of California to reduce energy waste include establishing the nation's first and strictest building standards for energy efficiency, setting stringent appliance efficiency standards, and giving rebates for purchases of solar energy equipment. The state has also created a strategy called decoupling, in which utility profits were disconnected from the amount of electricity sold, and instead, are now tied into the amount of energy conserved.

What are climate stabilization wedges? Know some examples of wedges

U.S. scientists Robert Socolow and Stephen Pacala at Princeton University have outlined a plan for holding 2057 CO2 levels to those in 2007 in order to help us avoid harmful effects. They have identified 15 different strategies, which they call climate stabilization wedges. Phasing in each wedge would reduce CO2 emissions by roughly the same amount during the coming 50-year period. They estimate that getting CO2 emissions to 2007 levels by 2057, and holding them there would require implementing any 8 of the 15 wedges during the next 5 decades or phasing in amounts of all 15 wedges sufficient to be the equivalent of implementing 8 wedges. Socolow and Pacala have turned their proposals into a role-playing wedges game that is being adapted and used in some schools. A 2007 study by the American Solar Energy Association showed how implementing just the energy efficiency and renewable energy wedge strategies alone could lead to a 60-80% reduction in greenhouse gas emissions by 2050. Refer to wedges game and wedges game conclusion.

What are the three types of radiation? Which is the most penetrating?

Vary in penetrating power.

What is net energy (net energy yield)? Why is it a more accurate way to compare fuel sources?

We can make this determination based on net energy (amount of energy gained minus the amount expended to gain it/use it). For example, to determine the net energy for coal you have to take into amount the energy spent to mine it and process it. This is based on the 2nd law of thermodynamics which says that when energy changes forms, it will always become lower quality (example-energy being lost as heat). As a result, energy is also lost in the process of transporting it from the point of generation to the point of use. Net energy varies based on fuel source, but also what the fuel is being used for. Additionally, net energy can change with time. As we deplete natural gas and oil reserves, for example, it will take more energy to obtain them, so the net energy ratio drops. With that in mind, we're going to focus on fossil fuels and the ways that we expend energy to obtain them.

How can we make new and existing buildings more efficient?

We can realize huge savings in energy by designing and building for energy efficiency and retrofitting existing buildings to make them more energy efficient. In fact, a 2007 U.N. study concluded that better architecture and energy savings in buildings could save 30-40% of the energy used globally. For example, orienting a building so it can get more of its heat from the sun can save up to 20% of heating costs and as much as 75% when the building is well insulated and airtight—a simple application of the solar energy principle of sustainability. The 13-story Georgia Power Company building in the U.S. city of Atlanta, Georgia, uses 60% less energy than conventional office buildings of the same size use. The largest surface of the building faces south to capture solar energy. Each floor extends out over the one below it. This blocks out the higher summer sun to reduce air conditioning costs but allows the lower winter sun to help light and heat each floor during the day. In the building's offices, energy-efficient compact fluorescent lights focus on work areas instead of illuminating entire rooms. Such green buildings have been used widely in Europe for almost 2 decades, especially in Germany and the Netherlands, and are beginning to catch on in the United States. Green architecture, based on energy-efficient and money-saving designs, makes use of natural lighting, passive solar heating, geothermal heat pumps for heating and cooling, cogeneration, solar hot water heaters, solar cells, fuel cells, natural ventilation, recycled building materials, energy-efficient appliances and lighting, motion sensors for lighting, rainwater collection, recycled waste water, waterless urinals, composting toilets, and nontoxic paints, glues, and building materials. Some green designs also include living roofs, or green roofs, covered with soil and vegetation. They have been used for decades in Europe and are becoming more common in the United States. Another important element of energy-efficient design is superinsulation. A house can be so heavily insulated and airtight that heat from direct sunlight, appliances, and human bodies can warm it with little or no need for a backup heating system, even in extremely cold climates. An air-to-air heat exchanger prevents buildup of indoor air pollution. The building cost for such a house is typically 5% more than that for a conventional house of the same size. The extra cost is paid back by energy savings within about 5 years, and the homeowner can save $50,000-100,000 over a 40-year period. Superinsulated houses in Sweden use 90% less energy for heating and cooling than typical American homes of the same size use. Since the mid-1980s, there has been growing interest in straw bale houses. The walls of these superinsulated houses are made by stacking compacted bales of low-cost straw (a renewable resource) and then covering the bales on the outside and inside with plaster or adobe.

Know some possible solutions to the problems resulting from the use of coal as a fuel

Wet scrubbers & electrostatic precipitators can be used to reduce the amount of pollution leaving a power plant's smoke stacks. Norway & Sweden have taxed per unit of CO2 produced (since 1991) to reduce the use of coal. Researchers are working on finding energy substitutes, like renewables. German scientists have learned how to make steel without burning coal (previously, steel could only be made this way). Synthetic natural gas (syngas) is often touted as a less polluting alternative to coal, however it is less efficient, produces more CO2 than coal, and has a low net energy yield.

Know some advantages and disadvantages of fracking.

When done properly this is an effective method for increasing the production of natural gas containing rock and has provided jobs and overall economic growth in many American communities in recent years. However, if the drill rig or well cap are faulty, the fracking fluid can leak into groundwater, contaminating it. There have also been cases where the methane gas itself contaminates groundwater when it leaks out near the top of the well. Once the fluid has been used, wastewater must be disposed of, which is done in pits on the surface. These pits can also contaminate groundwater and surface water sources. Fracking requires millions of gallons of fresh water to be pumped into the wells to achieve the necessary pressure in the well, so water usage is also a concern with this method. Additionally, air pollution is associated with fracking operations since there is a large amount of machinery required, which burn large amounts of fossil fuels. Also, earthquakes.

How much energy is wasted unnecessarily in the US? What are some ways that it is wasted?

You may be surprised to learn that 84% of all commercial energy used in the United States is wasted. About 41% of this energy is wasted unavoidably because of the degradation of energy quality imposed by the second law of thermodynamics. The other 43% is wasted unnecessarily, mostly due to the inefficiency of incandescent lights, furnaces, industrial motors, coal and nuclear power plants, most motor vehicles, and other devices. Another reason is that many people live and work in leaky, poorly insulated, badly designed buildings.