Chapter 16: Energy: Some Basics

Transcription

1 Chapter 16: Energy: Some Basics

2 Energy Crisis in Ancient Greece and Rome Greeks and Romans used wood to heat there homes. As local supplies ran out had to bring it in from farther away. Eventually both societies learned to build houses south facing Allows sun to heat house in winter Sustainable In Rome laws pasted to protect a person s right to solar energy.

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4 Energy Today and Tomorrow Energy situation facing the US today is similar to that faced by Greeks and Romans. Use of wood peaked 1880s Coal use peaked 1920 Reaching the peak of oil and gas use The decisions we make today will affect energy use for generations.

5 Energy Basics To understand energy it is easiest to begin with the idea of force We have all exerted force by pushing or pulling The strength of force can be measured by how much it accelerates an object Think of pushing a car uphill

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7 Energy Basics In physicists terms Exerting force over a distance moved is work Work is the product of a force times a distance Energy is the ability to do work When the car is higher on the hill the potential energy of the car has increased Energy can be converted from one kind to another The total energy conserved First law of thermodynamics

8 Energy Basics Energy quality The ability of the energy to do work The higher quality of the energy, the more easily it can be converted to work. Second law of thermodynamics Energy always tends to go from a more usable (higher-quality) form to a less usable (lowerquality) form. When you use energy, you lower its quality.

9 Energy Efficiency Two fundamental types of energy efficiencies are derived from the first and second laws of thermodynamics: the first-law efficiency and the second-law efficiency. First-law efficiency deals with the amount of energy without any consideration of the quality or availability of the energy.

10 Energy Efficiency Second-law efficiency refers to how well matched the energy end use is with the quality of the energy source. Low values indicate where improvements in energy technology and planning may save significant amounts of high-quality energy.

11 Energy Efficiencies Electricity generating plants have nearly the same first-law and second-law efficiencies. Generating plants are examples of heat engines. Produces work from heat. Most of the electricity generated in the world today comes from heat engines Use nuclear fuel, coal, gas, or other fuels.

12 Fossil Fuels and Alternative Energy Sources 90% of the energy consumed in the US comes from fossil fuels Petroleum, natural gas, and coal. They are essentially nonrenewable. Other sources of energy Include geothermal, nuclear, hydropower, and solar Referred to as alternative energy sources. Solar and wind, are not depleted by consumption and are known as renewable energy.

13 Energy Consumption in the US Today US dependent on the three major fossil fuels coal; natural gas; and petroleum. From 1950 to late-1970s, energy consumption increased tremendously From 30 exajoules to 80 exajoules. Since about 1980, energy consumption has increased by only about 20 exajoules. Suggests that policies to improve energy conservation through efficiency improvements have been at least partially successful.

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16 Energy Consumption in the US Today Energy losses are associated with the production of electricity and transportation. Most occur through the use of heat engines Looking at the generalized energy flow of the US for a particular year We imported considerably more oil than we produced Consumption distributed in three sectors: residential/commercial, industrial, and transportation. We remain dangerously vulnerable to changing world conditions affecting the production of oil.

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19 Energy Conservation, Increased Efficiency and Cogeneration Conservation of energy Simply getting by with less demand for energy. Increased energy efficiency Involves designing equipment to yield more energy output from a given amount of input energy (first-law efficiency)

20 Energy Conservation, Increased Efficiency and Cogeneration Cogeneration Processes designed to capture and use waste heat rather than release it as a thermal pollution. can increase the overall efficiency of a typical power plant from 33% to as much as 75%

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22 Building Design A spectrum of possibilities exists for increasing energy efficiency and conservation in residential buildings. Design and construct homes that minimize the energy consumption Design buildings to take advantage of passive solar potential For older homes:insulation, caulking, weather stripping, installation of window coverings, storm windows, and regular maintenance.

23 Industrial Energy Industrial production of goods continues to grow significantly. U.S. industry consumes about one-third of the energy produced. More industries are using co-generation and more energy-efficient machinery.

24 Automobile design Early 1970s, the average US automobile got 14 mpg. By 1996, the average was 28 mpg for highway driving. In 2004 many vehicles sold were SUVs and light trucks with fuel consumption of mpg. SUVs declined in 2006.

25 Automobile design Today, some hybrid (gasoline-electric) vehicles exceeds 90 mpg on the highway and 60 mpg in the city. Improvement has several causes: Increased efficiency and resulting conservation of fuel Cars that are smaller, w/ engines constructed of lighter materials Combination of a fuel-burning engine with an electric motor

26 Values, Choices, and Energy Conservation Ways of modifying behavior to conserve energy include the following: Ride a bike, walk, or take a bus or train to work. Using carpools to travel to and from work or school Purchasing a hybrid car (gasoline-electric) Turning off lights when leaving rooms Taking shorter showers (conserves hot water) Putting on a sweater and turning down the thermostat

27 Values, Choices, and Energy Conservation Using energy-efficient compact florescent lightbulbs Purchasing energy-efficient appliances Sealing drafts in buildings with weather stripping and caulk Better insulating your home Washing clothes in cold water whenever possible Purchasing local foods to reduce energy in transport Using powerstrips and turning them off when not in use

28 Energy Policy U.S. energy policy during the past halfcentury has not moved us closer to energy self-sufficiency. We import more oil than ever. In the late 1990s, the US spent $2 billion per year on R and D for energy. By comparison, $45 billion per year went to R and D for the military.

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30 Energy Policy Act of 2005 Some of the provisions are as follows. 1. Promotes conventional energy sources 2. Promotes nuclear power 3. Encourages alternative energy 4. Promotes conservation measures 5. Promotes research 6. Provides for energy infrastructure

31 Hard Path vs. Soft Path Hard path involves finding greater amounts of fossil fuels and building larger power plants. Continuing the past emphasis on quantity of energy used. Requires no new thinking; no realignment of political, economic, or social conditions; and little anticipation of coming reductions oil.

32 Hard Path vs. Soft Path According to hard-path proponents, we should 1. Let the energy industry develop the available energy resources 2. Let industry, free from government regulations, provide a steady supply of energy with less total environmental damage.

33 Hard Path vs. Soft Path The second road of energy policy is called the soft path. It involves energy alternatives that emphasize:

34 Hard Path vs. Soft Path They rely heavily on renewable energy resources, such as sunlight, wind, and biomass. They are diverse and are tailored for maximum effectiveness under specific circumstances. They are flexible, accessible, and understandable to many people. They are matched in energy quality, geographic distribution, and scale to end-use needs.

35 Energy for Tomorrow Future changes in population densities as well as intensive conservation measures will probably change existing patterns of energy use. To stabilize the climate in terms of global warming, use of energy from fossil fuels would need to be cut by about 50%. Reductions in energy use need not be associated w/ lower quality of life.

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37 Energy for Tomorrow What is needed is increased conservation and more efficient use of energy: More energy-efficient land-use planning that maximizes the accessibility of services and minimizes the need for transportation. Agricultural practices and personal choices that emphasize 1. Eating more locally grown foods 2. Eating more vegetables, beans, and grains. Industrial guidelines for factories that promote energy conservation and minimize production of waste.

38 Integrated, Sustainable Energy Management Integrated energy management recognizes that no single energy source can provide all the energy required. Range of options that vary from region to region will have to be employed. The mix of technologies and sources of energy will involve both fossil fuels and alternative, renewable sources.

39 Integrated, Sustainable Energy Management A basic goal is to move toward sustainable energy development, implemented at the local level. Would have the following characteristics: It would provide reliable sources of energy. It would not cause destruction or serious harm to our global, regional, or local environments. It would help ensure that future generations inherit a quality environment with a fair share of the Earth s resources.

40 Integrated, Sustainable Energy Management A good energy plan is part of an aggressive environmental policy with the goal of producing a quality environment for future generations. A good plan should do the following: Provide for sustainable energy development. Provide for aggressive energy efficiency and conservation.

41 Integrated, Sustainable Energy Management Provide for the diversity and integration of energy sources. Provide for a balance between economic health and environmental quality. Use second-law efficiencies as an energy policy tool.

42 Integrated, Sustainable Energy Management The global pattern of ever-increasing energy consumption led by the US cannot be sustained w/o a new energy paradigm Includes changes in human values rather than a breakthrough in technology. Choosing to own fuel-efficient automobiles and living in more energy-efficient homes are consistent with a sustainable energy system.