Chapter 13 Review

chapter 13Review

Key Terms

Learning Objectives Revisited

• 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.

• 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.

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• Explain how energy is harnessed from water.

  Most hydroelectric systems use the energy of water impounded behind a dam to generate electricity. Run-of-the-river hydroelectric systems impound little or no water and have fewer environmental impacts, although they often produce less electricity.

• 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-offshore environment. Frequently, a number of wind turbines are grouped together in wind farms. Wind is the most rapidly growing source of renewable electricity. It is a clean, nondepletable energy resource, but objections to wind farms are increasing because of aesthetics, sound, and hazards the turbines pose to birds and bats.

• 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-intensive process. If hydrogen could be obtained using renewable energy sources, it could become a truly renewable source of energy.

• 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—at least initially—for renewable forms of electricity is a challenge. Also, the difficulty and economic cost of storing electricity have no easy solutions at present.