[p2p-research] Environmental issues around solar energy plants

[Michel Bauwens]

http://www.inthesetimes.com/article/4756/when_renewable_is_not_sustainable/

The solar energy industry is similarly benefiting from federal legislation
that paid no attention to water and land availability. In 2005, Congress
enacted the Energy Policy Act, giving the Departments of Energy and Interior
the mandate to establish renewable energy projects on federal land, which
will generate more than 10,000 megawatts of electricity.

The obvious place to locate solar projects is in the desert Southwest, where
the sun shines year-round. As of June 2009, solar power companies had filed
applications for more than 150 permits for solar power plants on federal
land in Arizona, California and Nevada, mostly land owned by the Bureau of
Land Management (BLM), an agency of the Department of the Interior.
Assembling a sufficient number of solar panels or mirrors for a power plant
requires a large tract of land. The permits being evaluated by BLM involve
more than one million acres of land, an area larger than the state of Rhode
Island.

BLM has begun preparation of an Environmental Impact Statement (EIS). To
date, the bureau hasn’t announced what kind of leases or permits it will
grant corporations for the use of federal land. Clearly, there must be
long-term arrangements if the plants are to be commercially viable. The net
effect will be to turn over exclusive use of federal land to for-profit
corporations.

More troublesome is the potential water use of these companies. If solar
power is generated by photovoltaic cells, it uses almost no water. The cells
directly convert the sun’s rays into electricity. Such systems are becoming
more common in home applications, but still remain rare for commercial-scale
power plants. They are extremely costly and the power is not constant, as it
is generated only during the day when the sun shines. Utilities greatly
prefer cheap 24/7 power.

For commercial power plants, solar companies use a technology known as
“concentrating solar thermal” (CST). The sun heats a fluid that boils water.
The steam spins a turbine that generates electricity. All thermal power
plants produce waste heat as a byproduct and use cooling towers to release
the waste heat to the ambient atmosphere—usually by the evaporation of
water. Apart from the first step that uses the sun’s heat, CST is an
old-fashioned thermal power plant that consumes vast quantities of water.

That’s not a problem for a plant located in Michigan, but 150 solar plants
located in the Mojave Desert create a major water problem. Desert wildlife,
including endangered species, depend heavily on rare seeps and springs that
would likely dry up because of large-scale groundwater pumping.

It is feasible to air-cool CST plants but, again, the desert climate poses a
problem. It’s hot outside, which makes dispersing the waste heat using hot
desert air very inefficient. The solar companies prefer to use wet-cooled
plants, because they cost almost 10 percent less to build and generate five
percent more power than do air-cooled plants.

The National Park Service and many environmental organizations are beginning
to realize that the water demands of ethanol and solar power are
problematic. The Park Service has urged the Departments of Energy and the
Interior to deny permits for water-cooled plants. Air cooling would reduce
water consumption by as much as 90 percent. As the EIS process moves
forward, these departments should give preference to plants that use
air-cooling. The last thing we need are hundreds of commercial-scale
groundwater wells drilled on water-scarce federal land.
Congress must integrate its energy and water policies. This is critical as
global warming begins to reduce flows in western rivers, which translates
directly into a loss of energy produced by hydroelectric facilities at
federal dams. Replacing this lost energy without using fossil-fuel plants
will be a real challenge.

-- 
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