Chapter 20 & 21: Energy Alternatives

Advantages of Nuclear Reactors

-Cleaner energy than fossil fuels (no air pollution from stack emissions) -Less health risks -Less uranium needs to be mined -Safer for workers

Closed vs. Open Cycle Approach to Ocean Thermal Energy Conversion

-Closed Cycle Approach= pipes warm surface water to a facility to evaporate chemicals, such as ammonia, that boil at low temperatures -Open Cycle Approach= evaporates warm surface water in a vacuum and uses the steam to spin turbines

What are the environmental consequences of hydropower?

-Damming rivers destroys wildlife habitat -Natural flooding of rivers is disrupted: Natural riparian habitat is flooded upstream of the dam, and deprived of water downstream of the dam. -Sediments get trapped in reservoir: Suppression of flooding prevents river floodplains from receiving nutrient-rich sediment from the river. -Causes thermal pollution -Disturbs biodiversity -Social and economic impacts

What are some policies that will support renewable energy?

-Feed-in tariffs -Goals or mandates set by governments that a minimum percentage of power comes from renewable sources. -Government investment in research and development. -Lending programs to renewable energy start-up businesses. -Tax credits and rebates to individuals and businesses who produce or buy renewable energy.

What are the primary limitations of ocean energy sources?

-Few designs for machinery to harness wave energy have been tested for commercial use -Transmitting electricity to shore is expensive

Disadvantages of Geothermal Energy

-Geothermally heated water can release a small amount of dissolved gases, including carbon dioxide, methane, ammonia, and hydrogen sulfide -Can be depleted if plants use heated water faster than it can be recharged -The Earth's crust shifts naturally over time, so areas that produce hot groundwater may not always do so.

Advantages of Solar Energy

-Inexhaustible energy sources -Solar technologies like PV cells use no fuel, are quiet and safe, with little maintenance -Local control of power -Provides many new green jobs -Does not emit greenhouse gases and other pollutants -Little maintenance required

Disadvantages of Wind Power

-Intermittent resource (we have no control over when it will occur) -Wind varies from place to place -Local residents often oppose them (not in my backyard) -Pose a threat to birds and bats

What the advantages of hydropower?

-It is a completely renewable source of energy. -Hydropower is efficient, with an EROI ratio of more than 80:1, higher than any other modern energy source. -No carbon dioxide or other pollutants are emitted.

Advantages of Hydrogen Fuel

-It is the most abundant element in the universe, so we will not run out. -No air pollution -Energy Efficient

What are the greatest limitations associated with hydrogen fuel cells?

-Lack of infrastructure to make use of it -Leakage of hydrogen from its production and transport -Use could potentially deplete stratospheric ozone and increase the atmospheric lifetime of the greenhouse gas methane

Advantages of Biodiesel

-Less vehicle emissions -Nearly identical fuel economy -Cost effective -Nontoxic and biodegradable -Can be sourced from food waste

Disadvantages of Solar Energy

-Not all regions are equally sunny -Intermittent resource -Up front high cost/ high initial investment

Advantages of Wind Power

-Produces no emissions -Efficient in its energy returned on investment (EROI): they produce 20 more times of energy than they consume -Use less water -Can be used on many scales -Farmers and ranchers can lease their land for wind development -Only requires maintenance costs (no ongoing fuel costs) -Creates many job opportunities

Advantages of New Renewable Energy Sources

-Reduction in air pollution. -Reduction in greenhouse gas emissions that drive global climate change. -Diversification of an economy's energy mix.

Benefits of Geothermal Energy

-Releases less gases than fossil fuels -Renewable

Describe the structure and function of a typical fission reactor. What is the fuel?

-Structure= Reactor core is housed within a reactor vessel; and the vessel, steam generator, and associated plumbing loops are often protected within a containment building. -Function= converts the energy within an atom's nucleus to usable thermal energy by splitting apart atomic nuclei

Disadvantages of Nuclear Reactors

-Uranium containing minerals are uncommon -Nonrenewable energy source (uranium ore is finite) -A lot is disposed as radioactive waste -Potential for an accident at the plant -Another concern is that radioactive material could be stolen from plants and used in terrorist attacks -Building plants is enormously expensive

What are the ocean energy sources?

-Wave Energy -Tidal energy -Ocean Thermal Energy Conversion (OTEC)

What are the top 3 sources of energy in the world? Of these, what is used for most electricity production in the world?

1. Oil (31.1%) 2. Coal (28.9%) 3. Natural Gas (21.4%) Coal is used for most electricity production in the world.

Photovoltaic Solar Energy

A device designed to collect sunlight and directly convert it to electrical energy. When light strikes one of a pair of metal plates in the cell, this causes the release of electrons, which are attracted by electrostatic forces to the opposing plate. The flow of electrons from one plate to the other creates an electrical current. The basis of PV solar technology.

Hydrogen Fuel Cells

A device that can store and transport energy to produce electricity, much as a battery can. A hydrogen fuel cell generates electricity by the input of hydrogen fuel and oxygen, producing only water as a waste product.

Nuclear Reactors

A facility within a nuclear power plant that initiates and controls the process of nuclear fission to generate electricity. Inside nuclear reactors, a substance called a moderator (usually water or graphite) will slow down neutrons emitted by fission enough that they will impact other atoms, creating a fission chain reaction. If uncontrolled, the fission chain reaction can become a runaway process of positive feedback, creating the explosive power of a nuclear bomb. Control rods made of a neutron-absorbing substance can be inserted or removed from the reactor to control the rate of the reaction. Heat from fission is absorbed by water, which is converted to steam that spins a large metal turbine. Containment buildings prevent leaks of radioactivity.

Wind Turbine

A mechanical assembly that converts the wind's kinetic energy, or energy of motion, into electrical energy. The wind turns the blades of the rotor, which rotates the machinery inside a compartment called a nacelle, which sits atop a tower. Inside the nacelle, a gearbox converts the rotational speed of the blades, which can be up to 20 revolutions per minute or more, into much higher speeds. This provides adequate motion for the generator to produce electricity.

Electrolysis

A process in which electrical current is passed through a compound to release ions. Electrolysis offers one way to produce hydrogen for use as fuel: Electrical current is passed through water, splitting the water molecules into hydrogen and oxygen atoms.

Feed-in Tariff

A program of public policy intended to promote renewable energy investment, whereby utilities are mandated to purchase electricity from homeowners or businesses that generate power from renewable energy sources and feed it into the electrical grid. Under such a system, utilities must pay guaranteed premium prices for this power under long-term contract

Radioisotopes

A radioactive isotope that emits subatomic particles and high-energy radiation as it "decays" into progressively lighter isotopes until becoming a stable isotope.

Pumped Storage

A technique used to generate hydroelectric power, in which water is pumped from a lower reservoir to a higher reservoir when power demand is weak and prices are low. When demand is strong and prices are high, water is allowed to flow downhill through a turbine, generating electricity.

Thin-Film Solar Cells

A variation of PV technology where the photovoltaic materials are compressed into ultra-thin sheets that are less efficient, but can be produced and installed more cheaply.

Passive Solar Energy

An approach in which buildings are designed and building materials are chosen to maximize direct absorption of sunlight in winter and to keep the interior cool in the summer. Planting vegetation can provide a temperature buffer and thermal mass materials that absorb, store, and release heat slowly are used to build the roof, walls, and floor.

Active Solar Energy

An approach in which technological devices are used to focus, move, or store solar energy. Ex: Flat plate solar collectors are dark-colored, heat-absorbing metal plates mounted in flat glass-covered boxes that absorb solar heat from the roof and transfer it to hot water tanks inside the building.

Ocean Thermal Energy Conversion (OTEC)

An energy source (not yet commercially used) that involves harnessing the solar radiation absorbed by tropical ocean water by strategically manipulating the movement of warm surface water and cold deep water.

How do hydrogen fuel cells work?

Atoms of hydrogen are split into protons and electrons. The protons, or hydrogen ions, pass through a proton exchange membrane. The electrons, meanwhile, move from a negative electrode to a positive one via an external circuit, creating a current and generating electricity. The protons and electrons then combine with oxygen to form water molecules.

Co-Firing

Biomass can be combusted directly to generate electricity, or mixed with coal in a process called co-firing.

Why is biomass considered "carbon neutral"?

Burning biomass emits a lot of carbon, but this is balanced by the fact that photosynthesis had pulled this same amount of carbon from the atmosphere to create the biomass just years, months, or weeks before.

Tidal Energy

Coastal areas with large differences in height between high and low tide can be used to harness tidal energy. Tidal energy is Energy harnessed by erecting a dam across the outlet of a tidal basin. Water flowing with the incoming or outgoing tide through sluices in the dam turns turbines to generate electricity.

Concentrated Solar Power

Concentrated solar power (CSP) intensifies solar energy by gathering it from a wide area and focusing it on a single point. Ex: Solar cookers are portable ovens that use reflectors to focus sunlight and cook food.

What is the controversy over the production and use of ethanol?

Controversial because it takes up a great deal of land and growing corn for ethanol requires substantial inputs of fossil fuel energy. Growing corn to produce ethanol intensifies pesticide use, fertilizer use, freshwater depletion, energy use, and other impacts of industrialized agriculture. Significant land is also required; to replace all the automotive fuel used in the United States with ethanol from corn, the nation would need to expand its corn acreage by more than four times.

Biodiesel

Diesel fuel produced by mixing vegetable oil, used cooking grease, or animal fat with small amounts of ethanol or methanol (wood alcohol) in the presence of a chemical catalyst.

New Renewable Energy Sources

Energy from the sun, wind, geothermal heat, and ocean water are "new renewables" because: -They are just beginning to be used on a wide scale. -They are harnessed using technologies still in a rapid phase of development. -They will likely play much larger roles in the future.

Bioenergy (Biomass Energy)

Energy harnessed from plant and animal matter, including wood from trees, charcoal from burned wood, and combustible animal waste products, such as cattle manure. Fossil fuels are not considered bioenergy sources because their organic matter has not been part of living organisms for millions of years and has undergone considerable chemical alteration since that time. In principle, bioenergy is renewable and releases no net carbon dioxide into the atmosphere.

Wave Energy

Energy harnessed from the kinetic motion of ocean waves. Many designs for machinery to harness wave energy have been invented, but few have been adequately tested. Ex: snake-like energy converter, which floats up and down with the waves.

Cellulosic Ethanol

Ethanol produced from the cellulose in plant tissues by treating it with enzymes. Techniques for producing cellulosic ethanol are under development because of the desire to make ethanol from low-value crop waste (residues such as corn stalks and husks), rather than from the sugars of high-value crops. Cellulose is found in all plant material and has no food value.

What country produces the largest % of its electricity from nuclear power?

France

Biofuels

Fuel produced from biomass sources and used primarily to power automobiles. Examples include ethanol and biodiesel.

How do geothermal power plants generate electricity?

Geothermal power plants generate electricity using naturally heated water from underground.

Where is geothermal energy potential greatest in the US?

Geothermal resources in the US are greatest in the Western states

Summarize the Case Study on Germany

Germany harnesses the most solar power per person in the world, using 6% of its electricity from solar power. Germany has a feed-in-tarriff system, meaning that utilities have to buy electricity from anyone on the grid who can produce it from renewable sources. Germany is also the world leader in wind power. It is 3rd in the world in using power from biomass, 3rd in solar water heating, 3rd in electrical power capacity from renewable sources, and second in renewable energy generated per person. Germany gets 28% of its energy from renewable sources. This was all prompted by the Renewable Energy Sources Act of 2000, which assigned a payment rate according to market considerations for every renewable energy source. Germany is gradually lowering its tariffs, until a goal of about 52 gigawatts of capacity is reached. Germany's system of tariffs and government subsidies of renewable energy technology has served as a model for more than 70 other countries, who are implementing similar systems.

Would a geothermal power plant or a ground source heat pump more likely be found in Darien?

Ground source heat pumps are more likely found in Darien because the soil is cooler than the air in the summer and warmer than air in winter.

Ground Source Heat Pump

Harnesses geothermal energy from near-surface sources of earth and water to heat and cool buildings. Soil absorbs and releases heat more slowly than air, so several inches below the surface, temperatures are nearly constant year-round. Ground-source heat pumps take advantage of this by transferring heat from the ground into buildings during the winter, and back into the ground during the summer. Ground-source heat pumps are highly energy-efficient, as heat is being moved from place-to-place instead of being produced from outside inputs.

Biomass

In energy, organic material derived from living or recently living organisms, containing chemical energy that originated with photosynthesis.

Where in the world is the most nuclear energy produced?

In the US

Fukushima Daiichi

Japanese nuclear power plant severely damaged by the tsunami associated with the March 2011 Tohoku earthquake that rocked Japan. Most radiation drifted over the ocean away from population centers, but the event was history's second most serious nuclear accident. 18,000 people were killed and thousands of buildings were destroyed.

What regions of the US have the greatest wind potential?

Mountaneous regions, areas of the Great Plains, along the coasts, Texas. Offshore sites can also be ideal for wind farms, because the wind speed is greater and the air is less turbulent.

Where does nuclear energy come from?

Nuclear energy comes from processed and enriched uranium

Conventional Alternatives

Nuclear power, hydropower, and biomass energy (bioenergy) are considered "conventional alternatives" to fossil fuels because they are already well-established and in wide use. These have less impact than fossil fuels, but more impact than "new renewable" alternatives like solar, wind, geothermal, and ocean power. Conventional alternatives provide much of our electricity.

Biopower

Power attained by combusting biomass sources to generate electricity. Waste products from logging, sawmills, pulp mills, and paper mills can be used as a source for biopower. Biopower is cleaner, contributes less to climate change, and is generally more sustainable than burning fossil fuels.

Green-Collar Jobs

Shifting to renewable energy creates new employment opportunities in the design, installation, and maintenance of the changing energy infrastructure.

Has nuclear power increased or decreased in recent years?

Since the late 1980s, nuclear power's growth has slowed, with an increase of only 2.5% per year worldwide. Public anxiety from Chernobyl and Fukushima has made utilities less willing to invest in nuclear power.

Chenobyl

Site of a nuclear power plant in Ukraine (then part of the Soviet Union), where in 1986 an explosion caused the most severe nuclear reactor accident the world has yet seen. Radiation escaped for 10 days. It killed 31 people directly and sickened or caused cancer in thousands more.

Which form of renewable energy has experienced the most rapid growth in recent years?

Solar: PV technology is the fastest growing power source today, having recently doubled every two years.

Biogas

Source of electricity from biomass from the anaerobic bacterial breakdown of waste in landfills, which produces methane that can be captured and sold as fuel. A biogas plant in the Swedish city of Kristianstad takes in forestry waste, crop waste, garbage, and food waste, and uses it to generate biogas. The biogas is used to generate electricity and to heat homes.

What is the central case study on Sweden?

Sweden's 1980 referendum phased out their country's nuclear power program, shutting down all nuclear plants by 2010. This was difficult as Sweden had turned to nuclear power to reduce the use of coal, oil, and natural gas. The nation cut its fossil fuel use in half since the 1970s. They did this by using nuclear energy. Hydroelectric power also was supplying most of the country's electricity. Sweden then boosted bioenergy and wind by applying a carbon tax to fossil fuels and by subsidizing renewable energy through a certificate program in which producers and users of fossil fuel electricity were mandated to buy certificates from producers and users of renewable electricity. Sweden now gets half of its energy from renewable sources. They are aiming to ultimately completely get rid of fossil fuels.

Storage Hydropower Technique

Technique used to generate hydroelectric power, in which large amounts of water are impounded in a reservoir behind a concrete dam and then passed through the dam to turn turbines that generate electricity.

Three Mile Island

The Three Mile Island accident occurred in 1979, in reactor number 2 of Three Mile Island Nuclear Generating Station Pennsylvania, near Harrisburg. It was the most significant accident in U.S. commercial nuclear power plant history. Three Mile Island experienced an accident due to human error and mechanical failure that led to draining of water from the reactor vessel. This caused a meltdown, where the fuel rods melted and began releasing high amounts of radiation. Three Mile Island was considered a near-miss, because the fuel rods did not completely meltdown, and the radiation was contained.

How does the US energy usage compare to the rest of the world's?

The US does not use as much coal as the rest of the world but does use more oil and natural gas as well as nuclear.

Meltdown

The accidental melting of the uranium fuel rods inside the core of a nuclear reactor, causing the release of radiation.

Ethanol

The alcohol in beer, wine, and liquor, produced as a biofuel by fermenting biomass, generally from carbohydrate-rich crops such as corn or sugarcane.

Half-Life

The amount of time it takes for one-half the atoms of a radioisotope to emit radiation and decay. Different radioisotopes have different half-lives, ranging from fractions of a second to billions of years.

Nuclear Fusion

The conversion of the energy within an atom's nucleus to usable thermal energy by forcing together the small nuclei of lightweight elements under extremely high temperature and pressure. Developing a commercially viable method of nuclear fusion remains an elusive goal.

Nuclear Fission

The conversion of the energy within an atom's nucleus to usable thermal energy by splitting apart atomic nuclei.

Nuclear Energy

The energy that holds together protons and neutrons within the nucleus of an atom. Several processes, each of which involves transforming isotopes of one element into isotopes of other elements, can convert nuclear energy into thermal energy, which is then used to generate electricity.

Hydroelectric (Hydropower)

The generation of electricity using the kinetic energy of moving water.

How is radioactive waste handled?

The half-lives of the leftover radioisotopes from fission reactors is upward of hundreds of millions of years. Radioactive waste must be placed in unusually stable and secure locations where radioactivity will not harm future generations. Currently, nuclear waste from power generation is being held in temporary storage at nuclear power plants. Spent fuel rods are kept in pools of water to keep them cool and reduce radiation.

Run-of-River

The run-of-river technique diverts a portion of the river's flow through a pipe or channel, passing it through a powerhouse, and returning it to the river. Run-of-river approaches eliminate much of the environmental impact of large dams, but does not generate as much power. This does not disturb the flow of the river.

Geothermal Energy

Thermal energy that arises from beneath Earth's surface, ultimately from the radioactive decay of elements amid high pressures deep underground. Can be used to generate electrical power in power plants, for direct heating via piped water, or in ground-source heat pumps.

Where in the world is biomass energy heavily relied upon? What are its impacts?

Used in rural regions of developing nations by burning fuelwood to heat their homes, cooking, and lighting. This can lead to deforestation, soil erosion, and desertification.

Parabolic Trough Approach

Uses curved mirrors to focus sunlight onto synthetic oil in pipes, which is then used to heat water into steam, which then drives turbines.