Ch. 16
3. What are four ways to save energy and money in transportation? Summarize the development of more energy-efficient vehicles. Explain the importance of developing better batteries and list some advances in this area. What are fuel cells and what are their advantages? What are some technologies applied by green architecture? Explain benefits of living roofs. List four ways to improve energy efficiency in new buildings and eight ways to improve energy efficiency in existing buildings. List six ways in which you can save energy where you live. Give three reasons why we waste so much energy.List five advantages of relying more on a variety of renewable energy sources and list three factors that are holding back such a transition.
One way is to use cogeneration, which involves using a b=combined heat and power system. For example, the steam used for generating electricity in a CHP system can be captured and used again to heat the power plant or other nearby buildings, rather than released into the environment as waste heat. The energy efficiency of these systems is 75-90%. Denmark leads the world by getting 52% of its electricity from CHP systems, compared to just 8% in the United States. Industries could also use more energy-efficient electric motors. Typical inefficient motors use one-fourth of the electricity produced in the United States and 65% of the electricity used in U.S. industry. Most of these motors run only at full speed with their output throttled to match the task--somewhat like keeping one foot on the gas pedal of a car and the other on the brake pedal to control its speed. They can be replaced with more energy-efficient variable-speed motors, which run at the minimum rate needed for each job. Recycling materials such as steel and other metals is a third way for industry to save energy and money. For example, producing steel from recycled scrap iron uses 75% less high=quality energy than does producing steel from virgin iron ore and emits 40% less CO2. A fourth way is to use more energy-efficient lighting. Yet another way to save energy would be to redesign the software and cooling systems in government and private electronic data processing systems. This could be done with available technology. One reason why many consumers buy large and energy-inefficient motor vehicles is that they do not realize that gasoline costs them much more than the price they pay at the pump. The hidden costs not included in the price include government subsidies and tax breaks for oil companies, car manufactures, and road builders; costs of pollution control and cleanup; time waste idling in traffic jams; and higher medical bills and health insurance premiums resulting from illnesses caused by air and water pollution. One way to include more of these hidden costs in the market price is through gasoline taxes, which are widely used in Europe but are politically unpopular in the United States. Some analysts call of increasing U.S. gasoline taxes and reducing payroll and income taxes to balance such increases, thereby relieving consumers of any additional financial burden. Another way for governments to encourage higher energy efficiency in transportation is to give consumers significant tax breaks or other economic incentives to encourage them to bu more fuel-efficient vehicles. Energy expert Amory Lovins has proposed a fee-bate program in which buyers of fuel-inefficient vehicles would pay a high fee, and the resulting revenues would be given to buyers of fuel-efficient vehicles as rebates. Other ways to save energy and money in transportation include building and expanding mass transit systems within cities, constructing high-speed rail lines between cities, and carrying more freight by rail instead of in heavy trucks. Another approach is to encourage bicycle use by building bike lanes along highways and on city streets. The University of New England in Maine offers free, high-quality bikes to new students who agree to eave their cars at home. Also, many companies are saving money by using Internet conferencing as an alternative to flying their employees to meetings.
8. What is the key concept for this section? What is geothermal energy and what are three sources of such energy? What are the major advantages and disadvantages of using geothermal energy as a source of heat and to produce electricity?
Geothermal energy has great potential for supplying many areas with heat and electricity, and has a generally low environmental impact, but the sites where it can be produced economically are limited. Geothermal energy is heat stored in soil, underground, rocks, and fluids in the earth's mantle. One way to capture geothermal energy is by using a geothermal heat pump system. It can heat and cool a house by exploiting the temperature difference, almost anywhere in the world, between the earth's surface and underground at depth of 3-6 meters, where the temperature typically is 10-20 C year-round. In winter, a closed loop of buried pipes circulates a fluid, which extracts heat from the ground and carries it to a heat pump, which transfers the heat to a home's heat distribution system. In summer, this system works in reverse, removing heat from a home's interior and storing it in the ground. We can also tap into deeper, more concentrated hydrothermal reservoirs of geothermal energy. This is done by drilling wells into the reservoirs to extract their dry steam, wet seam, or hot water, which are then used to heat homes and buildings, provide hot water, grow vegetables in green houses, raise fish in aquaculture ponds, and spin turbines to produce electricity.
9. What is the key concept for this section? What are the major advantages and disadvantages of using hydrogen as a fuel to use in producing electricity and powering vehicles.
Hydrogen is a clean energy source as long as it is not produced with the use of fossil fuels, but it has a negative net energy yield. Widespread use of hydrogen as a fuel would eliminate most of the outdoor air pollution that comes from motor vehicles and coal-burning power plants. There are three challenges in turning the vision of hydrogen as a fuel into reality. First, there is hardly any hydrogen gas in the earth's atmosphere, so it must be produced from hydrogen, which is chemically cocked up in water and in organic compounds such as methane and gasoline. In other words, H2 must be produced by using other forms of energy, and therefore has a negative net energy yield. Second, fuel cells are the best way to use H2 to produce electricity, but current versions of fuel cells are expensive. However, progress in the development of nanotechnology could lead to less expensive and more energy efficient fuel cells. Third, whether or not a hydrogen-based energy system produces less outdoor air pollution and CO2 than a fossil fuel system depends on how the H2 is produced. If renewable energy sources such as wind farms and solar-cell power plants were used to make H2, these CO2 emissions would be sharply reduced.
2. What are the two key concepts for this section? What is energy efficiency? Explain why we can think of energy efficiency as an energy resource. What percentage of the energy used in the United States is unnecessarily wasted? List five widely used energy inefficient technologies. What are the major advantages of reducing energy waste? List four ways to save energy and money in industry. What is cogeneration? How can electric utility companies help people reduce their energy waste? What is a smart grid and why is it important? What are the hidden costs of using gasoline?
Improvements in energy efficiency could save at least a third of the energy used int he world and up to 43% of the energy used in the United States. We have a variety of technologies for sharply increasing the energy efficiency of industrial operations, motor vehicles, appliances, and buildings. Energy efficiency is a measure of how much useful work we can get from each unit of energy we use. Improving energy efficiency means using less energy to provide the same amount of work in the forms of light, heat, transportation, and other benefits. This amounts to a largely untapped source of energy that is abundant, clean, cheap, and readily available. Huge data centers, filled with racks of electronic servers that process information flowing on the Internet, use only about 10% of the electrical energy they pull off of the grid. The other 90% ends up as low-quality heat that flows into the environment. Most of these centers run 24 hours a day at their maximum capacities regardless of the demand .They also require large amounts of energy for cooling and for providing hundreds to thousands of backup batteries. The internal combustion engine that propels most motor vehicles wastes about 80% of the high-quality energy in its fuel. In other words, only about 20% of the money that people spend on gasoline gets put to good use. A nuclear power plant, which produces electricity, wastes about 75% of the high-quality energy in its nuclear fuel and probably closer to 82% when we include the additional energy used in the nuclear fuel cycle. A coal-fired power plant wastes about 65% of the energy that is released by burning cal to produce electricity, and probably 75-80% if we include the energy used in dig up the coal and transport it to the plant, and to transport and store the ash by-product. By improving energy efficiency, we can gain numerous economic and environmental benefits. To most energy analysts, it is the quickest, cleanest, and usually the cheapest way to provide more energy, reduce pollution and environmental degradation, and slow projected climate change.
4. What is the key concept for this section? Distinguish between a passive solar heating system and an active solar heating system and discuss the major advantages and disadvantages of using such systems for heating buildings. What are three ways to cool houses naturally? What are solar thermal systems, how are they used, and what are the major advantages and disadvantages of using the,? What is a solar cell and what are the major advantages of using such devices to produce electricity?
Passive and active solar heating systems can heat water and buildings effectively, and the costs of using direct sunlight to produce high-temperature heat and electricity are coming down. Homes and buildings can get all or most of their heat through a passive solar heating system. Such a system absorbs and stores heat from the sun directly within a well insulated structure. Water tanks and walls and floors made of concrete, adobe, brick, or stone can store much of the collected solar energy as heat and release it slowly throughout the day and night. An active solar heating system captures energy from the sun by pumping a heat-absorbing fluid through special collectors, usually mounted on a roof or on special racks to face the sun, Some of the collected heat can be used directly. The rest can be stored in a large insulated container filled with gravel, water, clay, or a heat-absorbing chemical and used as needed. Rooftop active solar collectors are also used to heat water in many homes and apartment buildings. Direct solar energy actually works against us when we want to keep a building cool, but we can sue indirect solar energy to help cool buildings. Block the high summer sun with shade trees, broad overhanging eaves, window awnings, or shades. In warm climates, use a light-colored roof to reflect as much as 90% of the sun's heat, or use a green roof. Use geothermal heat pumps for cooling. One of the problems with direct solar energy is that it is dispersed. Solar thermal systems, also known as concentrated solar power, use different methods to collect and concentrate solar energy in order to boil water and produce steam for generating electricity. These systems are used mostly in desert areas with ample sunlight. One such system uses troughs of curved collectors that concentrate solar energy and use it to heat synthetic oil in a pipe that runs through the center of each trough. This concentrated heat-as high as 400 C- is used to boil water and produce steam that powers a turbine that drives a generator to produce electricity. Another system uses an array of computer-controlled mirrors to track the sun and focus its energy on a central power tower to provide enough heat to boil water that is used to produce electricity. The heat produced by either of these systems can also be used to melt a certain kind of salt stored in a large insulated container. The heat stored in this molten salt system can be released as needed to produce electricity at night or on cloudy days.
7. What are the two key concepts for this section? What is biomass and what are the major advantages and disadvantages of using wood to provide heat and electricity? What are the major advantages and disadvantages of using biodiesel and ethanol to power motor vehicles? Explain how algae and bacteria can be used to produce fuels nearly identical to gasoline and diesel fuel.
Solid biomass is a renewable resource for much of the world's population, but burning it faster than it is replenished produces a net gain in atmospheric greenhouse gases. We can use liquid biofuels derived from biomass to lessen our dependence on oil-based fuels, but creating biofuel plantations can degrade soil and biodiversity, increase greenhouse gas emissions, and lead to higher food prices. Biomass consists of plant materials that we can burn directly as a solid fuel or convert into gaseous or liquid biofuels. Biomass is another indirect form of solar energy because it consists of combustible organic compounds in plant matter produced mainly by photosynthesis. Solid biomass is burned mostly for heating and cooking, but also for industrial processes and for generating electricity. In agricultural areas, crop residues and animal manure are collected and burned. Wood is a renewable resource only if it is not harvested faster than it is replenished. One way to deal with this problem is to plant fast-growing trees, shrubs, or perennial grasses in biomass plantations. But repeated cycles of growing and harvesting these plantations can deplete the soil of key nutrients. Also the clearing of forests and grasslands for such plantations destroys or degrades biodiversity.And some plantation tree species such as European polar and American mesquite are invasive species that can spread from plantations and take over nearby areas. Liquid biofuels such as ethanol and biodiesel are being increasingly used to fuel motor vehicles. The biggest producers of liquid biofuels are, in order, the United States, Brazil, the European Union, and China. Biofuels have three major advantages over gasoline and diesel fuel produced from oil. First, biofuel crops can be grown throughout much of the world, and thus they can help countries to reduce their dependence on imported oil. Second, if these crops are not used faster than they are replenished by new plant growth, there is no net increase in CO2 emissions, unless existing grasslands or forests are cleared to plant biofuel crops. Third, biofuels are easy to store and transport through existing fuel networks and can be used in motor vehicles at little or no additional cost.
1. Describe the potential for using renewable energy from the wind to produce most of the electricity used in the United States.
Unlike nonrenewable fossil fuels, wind power is widely distributed and inexhaustible. The cost of producing electricity from wind is much lower than that of producing it by using the nuclear fuel cycle and roughly equal to the cost of producing electricity by burning coal. When we include the harmful environmental and health costs, producing electricity from wind is cheaper than producing it from coal. Using wind power also greatly reduces our emissions of climate-changing carbon dioxide into the atmosphere. Wind power proponents call for a crash program to develop land-based and offshore wind farms in the United States. Over time , this would help reduce dependence on coal, which, when burned,produces air pollutants that kill at least 24000 Americans a year and adds huge amounts of CO2 to the atmosphere, Greatly expanding the US wind turbine industry would also create much-needed new jobs and boosts the American economy.
10. What is the key concept for this section? List eight questions that policy makers should ask about each source of energy. List three general conclusions that energy experts have come to in considering possible energy futures. List five major strategies suggested by such experts for making the transition to a more sustainable energy future. Explain three strategies that governments can use to encourage or discourage the use of an energy resource. What are this chapter's three big ideas? Explain how we would be applying the six principles of sustainability by improving energy efficiency and shifting to renewable energy resources.
We can make the transition to a more sustainable energy future by greatly improving energy efficiency, using a mix of renewable energy resources, and including the environmental and health costs of energy resources in their market prices. How much of the energy resource is likely to be available in the near future and in the long term? What is the estimated net energy yield for the resource? What are the estimated costs for developing, phasing in, and using the resource? What kinds of government research and development subsidies and tax breaks will be needed to help develop the resource? How vulnerable is the resource to terrorism? How will extracting, transporting, and using the resource likely affect the environment, the earth's climate, and human health? Does use of the resource produce hazardous, toxic, or radioactive substances hat we must safely store for very long periods of time? In considering possible energy futures, scientist and energy experts who have evaluated energy alternatives have come to three general conclusions. First, during this century there will likely be a gradual shift from large, centralized macropower systems to smaller, decentralized micropower systems such as wind turbines, house hold solar-cell panels, rooftop solar water heaters, and small natural gas motor vehicles to hybrid and plug-in electric cars. The second general conclusion of experts about the future of energy use is that a combination of improved energy efficiency and carefully regulated use of natural gas will be the best way to make the transition to using mostly renewable energy resources during this century.The third general conclusion is that because fosssil fuesls are still abundant and artificially cheap, we will continue to use them in large quantities.
5. What is the key concept for this section? Define hydro power and summarize the potential for expanding it. What are the major advantages and disadvantages of using hydropower? What is the potential for using tides and waves to produce electricity.
We can use water flowing over dams, tidal flows, and ocean waves to generate electricity, but environmental concerns and limited availability of suitable sites may limit the use of these energy resources. Hydropower is any technology that uses the kinetic energy of flowing and falling water to produce electricity. It is an indirect form of solar energy because it depends on heat from the sun evaporating water, which is deposited as rain or snow at higher elevations where it can flow to lower elevations in rivers as part of the earth's solarpowered water cycle. The most common approach to harnessing hydropower is to build a high dam across a large river to create a reservoir. However, some analyst expect that use of large scale hydropower plants will fall slowly over the next several decades as many existing reservoirs fill with silt and become useless faster than new systems are built. Also, there is growing concern over emissions of methane, a potent greenhouse gas, from the decomposition of submerged vegetation in hydropower plant reservoirs, especially in warm climates. In addition, if atmospheric temperatures continue to rise and change the world's climate as projected, many mountain glaciers will melt. Several of these melting glaciers are the m=primary sources of water for some hydropower plants, so the electrical outputs of these plants are likely to drop. The use of microhydropower generators may become an increasingly important way to produce electricity.
6. What is the key concept for this section? What are the advantages of using taller wind turbines? Summarize the global potential for wind power. What are the major advantages and disadvantages of using wind to produce electricity?
When we include the environmental costs of using energy resources in their market prices, wind power is the least expensive and least polluting way to produce electricity. Unlike fossil fuels, wind is abundant, widely distributed, and inexhaustible. A wind farm can be built within 9 to 12 months, can be expanded as needed, and has a small land footprint. Although wind farms can cover large areas of land, the turbines occupy only about 1% of the land, which can be used for other purposes such as growing crops or raising cattle. Wind farms do not need water for cooling, unlike coal, natural gas, and nuclear power plants. Also, home owners and neighborhoods can use a small, quiet wind turbines that operate at low speed to produce electricity. In addition, wind power has a high net energy yield. The DOE and the Worldwatch Institute estimate that, if we were to apply the full-cost pricing principle of sustainability by including the harmful environmental and health costs of various energy resources in comparative cost estimates, wind energy would be the cheapest way to produce electricity. Like any energy source, wind power has some drawbacks. For example, areas with the greatest wind power potential are often sparsely populated and located far from cites. Thus, to take advantage of the potential for electricity from wind energy, the United States and other countries will have to invest in upgrading and expanding their outdated electrical grids, converting them to smart grid systems. However, even if we continue to rely on coal-fired and nuclear power plants, such an upgrade and expansion will still have to take place. Many of the new lines could be run along state-owned interstate highway corridors to avoid legal conflicts and further degradation of natural areas. Another problem is that winds can die down and thus require a backup source of power, such as natural gas, for generating electricity. However, analysts calculate that a large number of wind farms in different areas connected to a smart electrical grid could take up the slack when winds die down in any one areas and thus could make wind power a very stable source of electricity.
