Is Solar Power Dead in the Water?
By Robert Glennon
Sunday, June 7, 2009
Congress's rush to embrace solar power is having
some unintended consequences. It will turn over a large chunk of federal
land to private energy companies, and it may involve withdrawing
billions of gallons of water from sensitive desert habitat.
By 2015, Congress wants the Interior and Energy
Departments to place, on federal land, renewable energy projects that
can generate at least 10,000 megawatts of electricity. The Energy Policy Act of 2005 has set
off a frantic land grab as solar and wind energy companies rush to
obtain permits for projects in Arizona, California, Colorado, Nevada,
New Mexico and Utah.
As of mid-March, the Bureau of Land Management had
received 158 applications for permits for solar power plants, covering
more than one million acres of land -- an area larger than Rhode Island.
Most of the proposed plants are located near the border of Arizona,
California and Nevada. This area of the Mojave Desert seems perfect for
solar power; it's hot and flat and vast. What the Mojave Desert doesn't
have is water.
Most people think of solar power as the flat panels
on a neighbor's roof that are used to heat water. This photovoltaic
system directly converts the sun's waves into electricity. But so far,
it's not commercially feasible. The power is costly and there's no juice
at night, but utilities want cheap power 24/7. On the plus side,
photovoltaic solar uses almost no water.
In contrast, most large solar power projects use a
system called concentrating solar power, or CSP, that heats a fluid that
boils water to turn a turbine. CSP, just like any thermal power plant,
produces waste heat as a byproduct. In most cases, cooling towers
release the heat to the atmosphere through evaporation, a process that
uses gobs of water. In fact, CSP
uses four times as much water as a natural gas plant and twice as much
as a coal or nuclear plant.
It is possible to use an air-cooled system, but CSP
plants in the Mojave Desert face an obvious problem: It's hot outside,
which makes air cooling inefficient. According to a 2007 DOE report, dry-cooled CSP plants take
more space, cost almost 10 percent more to build and generate 5 percent
less electricity. Given that solar power is competing with low-cost
natural gas and coal-fired plants, power companies would naturally
prefer to use wet-cooling systems.
To date, only a few CSP plants have been permitted
on federal land, but that will change soon. The Obama administration is
now evaluating the impact of solar power development, a process that may
be completed next year. The National Park Service, which is concerned
about the impact of wet-cooled plants on endangered species in southern
Nevada, wants the federal government to deny permits for water-cooled
plants. Air-cooling would cut the water use by 80 to 90 percent.
The Park Service is right. As the process moves
forward, the administration should insist that CSP plants embrace
air-cooling. There is no reason to permit hundreds of new groundwater
wells to be drilled in the Mojave Desert. It doesn't have the water.
If solar companies want to use wet-cooling towers,
they can purchase land and water rights from the private sector. Over
the last year, Arizona Public Service Company, the state's largest
electric utility, has partnered with solar power companies to build two
large-scale CSP projects on private land. The land, more than six square
miles, has been used to grow alfalfa and cotton. These wet-cooled plants
will use less water than the farms are already using.
This reallocation of water -- from farming to power
generation -- offers a lesson for the country as a whole. As the United
States confronts inevitable water shortages, we need to insist that
power companies, developers and others who need water offset the impact
of their new uses by persuading existing water customers to use less.
That's a lot smarter than trying to squeeze water from the stones of the
Robert Glennon is the author of "Unquenchable:
America's Water Crisis and What to Do About It."