chapter 13Review
In this chapter, we have examined the role of conservation as well as increased energy efficiency in reducing the demand for energy. We have described the different categories of renewable energy and examined the two most prominent renewable energy sources: biomass and energy from flowing and standing water. Biomass energy contains modern carbon and can be obtained from wood, charcoal, and animal wastes. Energy can be harnessed from both standing water and free flowing water, typically to generate electricity. Solar energy can be harnessed both passively and actively. The most prominent active collection of solar energy comes from photovoltaic cells that convert sunlight into electricity. Wind energy is harnessed directly and a wind turbine is very similar to the turbines used to generate electricity from fossil fuels. Geothermal energy from Earth can be used in specific locations. Hydrogen is a fuel that has much promise but is not likely to be used widely anytime soon. Each renewable energy resource has its advantages and disadvantages and these can be considered from both environmental and economic perspectives.
Energy conservation Tiered rate system Peak demand Passive solar design Thermal mass Potentially renewable Nondepletable Renewable Biofuel Modern carbon Fossil carbon Carbon neutral Net removal Ethanol Biodiesel Flex-fuel vehicle Hydroelectricity Run-of-the-river Water impoundment Tidal energy Siltation Active solar energy Photovoltaic solar cell Wind energy Wind turbine Geothermal energy Ground source heat pump Fuel cell Electrolysis Smart grid | Liquid fuel created from processed or refined biomass. A diesel substitute produced by extracting and chemically altering oil from plants. Hydroelectricity generation in which water is retained behind a low dam or no dam. An energy source that cannot be used up. Heat energy that comes from the natural radioactive decay of elements deep within Earth. The application of an electric current to water molecules to split them into hydrogen and oxygen. An electrical-chemical device that converts fuel, such as hydrogen, into an electrical current. In energy management, an energy source that is either potentially renewable or nondepletable. A system of capturing energy from sunlight and converting it directly into electricity. A technology that transfers heat from the ground to a building. An activity that does not change atmospheric CO2 concentrations. Electricity generated by the kinetic energy of moving water. A turbine that converts wind energy into electricity. The storage of water in a reservoir behind a dam. Finding and implementing ways to use less energy. A property of a building material that allows it to maintain heat or cold. Construction designed to take advantage of solar radiation without active technology. A billing system used by some electric companies in which customers pay higher rates as their use goes up. A vehicle that runs on either gasoline or a gasoline/ethanol mixture. The accumulation of sediments, primarily silt, on the bottom of a reservoir. Energy captured from sunlight with advanced technologies. Energy that comes from the movement of water driven by the gravitational pull of the Moon. The process of removing more than is replaced by growth, typically used when referring to carbon. An efficient, self-regulating electricity distribution network that accepts any source of electricity and distributes it automatically to end users. Energy generated from the kinetic energy of moving air. An energy source that can be regenerated indefinitely as long as it is not overharvested. Carbon in biomass that was recently in the atmosphere. Carbon in fossil fuels. The greatest quantity of energy used at any one time. Alcohol made by converting starches and sugars from plant material into alcohol and CO2. |
Module 37 Conservation, Efficiency, and Renewable Energy
Describe strategies to conserve energy and increase energy efficiency.
Turning down the thermostat and driving fewer miles are examples of steps individuals can take to conserve energy. Buying appliances that use less energy and switching to compact fluorescent light bulbs are examples of steps individuals can take to increase energy efficiency. Buildings that are carefully designed for energy efficiency can save both energy resources and money. Reducing the demand for energy can be an equally effective or a more effective means of achieving energy sustainability than developing additional sources of energy.
Explain differences among the various renewable energy resources.
Renewable energy resources include nondepletable energy resources, such as the Sun, wind, and moving water, and potentially renewable energy resources, such as biomass. Potentially renewable energy resources will be available to us as long as we use them sustainably.
Module 38 Biomass and Water
Describe the various forms of biomass.
Biomass is one of the most common sources of energy in the developing world, but biomass energy is also used in developed countries. In theory, biomass energy is carbon neutral; that is, the carbon produced by combustion of biomass should not add to atmospheric carbon concentrations because it comes from modern, rather than fossil, carbon sources. Wood is a potentially renewable resource because, if harvests are managed correctly, it can be a continuous source of biomass energy. Ethanol and biodiesel have the potential to supply large amounts of renewable energy, but growing and processing these fuels makes demands on land and energy resources.
Explain how energy is harnessed from water.
Most hydroelectric systems use the energy of water impounded behind a dam to generate electricity. Run-
Module 39 Solar, Wind, Geothermal, and Hydrogen
List the different forms of solar energy and their application.
Passive solar energy takes advantage of relatively inexpensive strategies such as the direction windows are facing in a building. Active solar technologies use technology to obtain heat or electrical energy from the Sun and have high initial costs but can potentially supply relatively large amounts of energy. Active solar applications can be small, such as those that fit on a rooftop or in a field, or they can be extremely large, on an industrial scale.
Describe how wind energy is harnessed and its contemporary uses.
Wind turbines can be located on land or in the near-
Discuss the methods of harnessing the internal energy from Earth.
Geothermal energy from underground can heat buildings directly or can generate electricity. However, geothermal power plants must be located in places where geothermal energy is accessible.
Explain the advantages and disadvantages of energy from hydrogen.
The only waste product from a hydrogen fuel cell is water, but obtaining hydrogen gas for use in fuel cells is an energy-
Module 40 Our Energy Future
Discuss the environmental and economic options we must assess in planning our energy future.
Although many scenarios have been predicted for the world’s energy future, conserving energy, increasing energy efficiency, relying on renewable energy sources to a greater extent, and improving energy distribution and storage through new technologies will all be necessary to achieve energy sustainability. Despite these clearly stated goals, fossil fuel consumption continues and it does not appear that its use will decrease any time soon.
Consider the challenges of a renewable energy strategy.
Improving the electrical grid in the United States is vital if we are to increase reliance on renewable forms of electricity. However, because the grid is so widespread, expanding and maintaining its geographic spread and electrical capacity are expensive. Even with an expanded grid, there are numerous obstacles to increasing renewable electricity generation. The high economic cost—