Page 610 - Environment: The Science Behind the Stories

and testing of over 3000 PV systems, providing a boost to while both sides have filed complaints with the World Trade
fledgling companies in the solar industry. But later, as oil Organization in an escalating global trade dispute.
prices declined, so did government support for solar power. Despite volatility in the industry as firms try to deal with
Largely because of the lack of investment, solar energy swings in national policies, global production of PV cells con-
contributes just 0.22%—22 parts in 10,000—of the U.S. energy tinues to rise sharply, while prices fall (see Figure 21.10). At the
supply, and just 0.1% of U.S. electricity generation. Even in Ger- same time, efficiencies are increasing, making each unit more
many, which gets more of its energy from solar than any other powerful. Use of solar technology should continue to expand as
nation, the percentage is only 5%. However, solar energy use has prices fall, technologies improve, and governments enact eco-
grown by 30% each year worldwide in the past four decades, a nomic incentives to spur investment.
growth rate second only to that of wind power. Solar energy is
proving especially attractive in developing countries, many of
which are rich in sun but poor in infrastructure, and where hun- Solar energy offers many benefits
dreds of millions of people still live without electricity.
PV technology is the fastest-growing power generation The fact that the sun will continue burning for another 4–5 bil-
technology today, having recently doubled every two years lion years makes it practically inexhaustible as an energy source
(Figure 21.10). China leads the world in yearly production of PV for human civilization. Moreover, the amount of solar energy
cells, followed by Germany and Japan. Germany leads the world reaching Earth should be enough to power our civilization once
in installation of PV technology, and German rooftops host over we develop technology adequate to harness it. These advantages
one-third of all PV cells in the world. Germany’s investment of solar energy are clear, but the technologies themselves also
began in 1998 when Hermann Scheer spearheaded a “100,000 provide benefits. PV cells and other solar technologies use no
Rooftops” program to install PV panels atop 100,000 German fuel, are quiet and safe, contain no moving parts, require little
roofs. The popular program ended up easily surpassing this goal, maintenance, and do not require a turbine or generator to create
and today over 1.2 million German rooftops have PV systems. electricity. An average unit can produce energy for 20–30 years.
The United States ranks fifth in production of PV cells, Solar systems also allow for local, decentralized control
and U.S. firms account for only 4% of the industry. Recent over power. Homes, businesses, and isolated communities can
federal tax credits and state-level initiatives may help the use solar power to produce electricity without being near a
United States recover the leadership it lost to other nations in power plant or connected to a grid. This is especially helpful
this technology, but China is moving faster and is dominat- in developing nations, where solar cookers (see Figure 21.8a)
ing the market. In fact, the Chinese government’s support of enable families to cook food without gathering fuelwood. This
its solar industry has led to so much production that supply lessens people’s daily workload and helps reduce deforestation.
has outstripped global demand in recent years. Highly subsi- In refugee camps, solar cookers are helping to relieve social
dized Chinese firms are selling solar products abroad at low and environmental stress. The low cost of solar cookers—many
prices (often at a loss), driving American and European solar can be built locally for $2–10 each—has made them accessible
manufacturers out of business. In response, the United States in many impoverished areas. In developed nations, most PV
and European nations have slapped tariffs on Chinese imports, systems are connected to the regional electric grid. As a result,
homeowners with PV systems can sell their excess solar energy
to their local utility through feed-in tariffs or net metering.
The development and deployment of solar systems are
producing many new green-collar jobs. Currently, among
14 100
major energy sources, PV technology employs the most peo-
90
Average module price (dollars per watt) 10 Price Production 70 Global solar power capacity (gigawatts) reduction of greenhouse gas emissions and other air pollut- CHAPTER 21 • N E w R ENE wA bl E E NER gy AlTERN AT iv E s
ple per unit energy output, resulting in over 800,000 jobs
12
worldwide (see Figure 21.4).
80
A major advantage of solar power over fossil fuels is its
ants (see Figure 21.3). The manufacture of photovoltaic cells
60
8
does currently require fossil fuel use, but once up and running,
50
a PV system produces no emissions. Consumers can access
6
online calculators offered by the U.S. Department of Energy
40
and the U.S. Environmental Protection Agency to estimate the
30
4
tem. At the time of this writing, these calculators estimated
20
that installing a 5-kilowatt PV system in a home in Fort Worth,
2
10 economic and environmental effects of installing a PV sys-
Texas, to provide over half of its annual power needs would
0 0 save the homeowners $681 per year on energy bills and would
1995 1997 1999 2001 2003 2005 2007 2009 2011 prevent over 5 tons of carbon dioxide emissions per year—as
Year much CO as results from burning 570 gallons of gasoline.
2
Figure 21.10 Global production of PV cells has been growing Even in overcast Seattle, Washington, a 5-kilowatt system pro-
exponentially, and prices have fallen rapidly. Data from REN21, ducing half a home’s energy needs can save $310 per year and
2013. Renewables 2013: Global status report. REN21, UNEP, Paris; and U.S. prevent over 3.5 tons of CO emissions (equal to 390 gallons
2
Department of Energy, EERE, 2011. 2010 Solar technologies market report. of gas). 609

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