Page 624 - Environment: The Science Behind the Stories

Conclusion use fuel cells to produce electricity when and where it is
needed, helping to create a nonpolluting and renewable
Rising concern over air pollution, global climate change, transportation sector.
health impacts, and security risks resulting from our Renewable energy sources have been held back by lim-
dependence on fossil fuels—as well as concerns over sup- ited funding for research and development and by competition
plies of oil and natural gas—have convinced many people with established nonrenewable fuels whose market prices do
that we need to shift to renewable energy sources that pol- not cover external costs. Despite these obstacles, renewable
lute far less and that will not run out. Renewable sources technologies have progressed far enough to offer hope that
with promise for sustaining our civilization far into the we can shift from fossil fuels to renewable energy. To what
future without greatly degrading our environment include degree we can also limit environmental impact will depend
solar energy, wind power, geothermal energy, and ocean on how soon, how quickly, and how carefully we make the
energy sources. Moreover, by using electricity from renew- transition—and to what extent we put efficiency and conser-
able sources to produce hydrogen fuel, we may be able to vation measures into place.

Reviewing objectives

you should now be able to: • Solar energy is perpetually renewable, creates no emis-
sions, and enables decentralized power. (p. 609)
Outline the major sources of renewable energy, • Solar radiation varies in intensity from place to place and
summarize their benefits, and assess their potential time to time, and harnessing solar energy remains expen-
for growth sive. (pp. 610–612)
• The “new renewable” energy sources include solar,
wind, geothermal, and ocean energy sources. They are Describe wind power and how we harness it, and
not truly “new,” but rather are in a stage of rapid devel- evaluate its benefits and drawbacks
opment. (p. 600)
• Energy from wind is harnessed using wind turbines
• The new renewables currently provide far less energy and mounted on towers. (pp. 612–613)
electricity than we obtain from fossil fuels or other conven-
tional energy sources. (pp. 600–601) • Turbines are often erected in arrays at wind farms located
on land or offshore, in locations with optimal wind condi-
• Use of new renewables is growing quickly, and this growth tions. (pp. 613–615)
is expected to continue as people seek to move away from
fossil fuels. (pp. 600–601) • Wind power is one of today’s fastest-growing energy
sources. (p. 613)
• Relative to fossil fuels, the new renewables alleviate air
pollution, reduce greenhouse gas emissions, and can self- • Wind energy is renewable, turbine operation creates no
renew. They can diversify a society’s energy mix and bring emissions, wind farms can generate economic benefits, and
income and jobs to communities. (pp. 601–602) the cost of wind power is competitive with that of electric-
ity from fossil fuels. (p. 614)
• Government subsidies have long favored nonrenewable
energy, but investment and public policies such as feed- • Wind is an intermittent resource and is adequate only in
in tariffs can speed our transition to renewable sources. some locations. Turbines kill some birds and bats, and
(pp. 602–603) wind farms often face opposition from local residents. CHAPTER 21 • N E w R ENE wA bl E E NER gy AlTERN AT iv E s
(pp. 611, 614–616)

Describe solar energy and the ways it is harnessed,
and evaluate its advantages and disadvantages Describe geothermal energy and the ways we
make use of it, and assess its advantages and
• Energy from the sun’s radiation can be harnessed using disadvantages
passive methods or by active methods involving powered • Thermal energy from radioactive decay in Earth’s core rises
technology. (p. 606)
toward the surface and heats groundwater. This energy may
• Solar technologies include flat plate collectors for heating be harnessed by geothermal power plants and used to directly
water and air, mirrors to concentrate solar rays, and photo- heat water and air and to generate electricity. (pp. 616–617)
voltaic (PV) cells to generate electricity. (pp. 606–608)
• Geothermal energy can be efficient, clean, and renewable.
• PV solar is today’s fastest-growing energy source. (p. 609) However, naturally heated water occurs near the surface
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