Southern Nevada alone is set to house 63 utility-scale solar projects, depending on the Bureau of Land Management’s acceptance of proposed land leases. The vast majority of these projects are concentrated solar thermal power plants, which produce clean energy but require large amounts of water to function. While the Nevadan desert (as well as California and Arizona) may be ideal in terms of solar intensity, the severe lack of water is a whole other issue, an issue that is raising a lot of eyebrows as the BLM attempts to sort it all out. Photo Credit: Dominic’s pics So the essential problem is this: President Obama is mandating an increase in renewable energy production. North American deserts are prime candidates for solar power, yet they come with a serious lack of water. Solar thermal power plants require large amounts to create the steam that spins the turbines and to cool the steam as it is condensed back into water in cooling towers (called a wet-cooled system). Most of the fresh water used up by these plants is lost in these cooling towers where waste heat is evaporated into the air. The National Parks Service has also come out against proposed desert solar thermal plants. In an interagency memo released by Public Employees for Environmental Responsibility (PEER), NPS Pacific Regional Director Jon Jarvis raised concerns about the number of large scale solar projects awaiting approval in Nevada. He noted that:
“The NPS asserts that it is not in the public interest for BLM to approve plans of development for water-cooled solar energy projects in the arid basins of southern Nevada, some of which are already over-appropriated, where there may be no reasonable expectation of acquiring new water rights in some basins, and where transference of existing points of diversion may be heavily constrained for some basins.”
Molten salts are used in some cases that can be heated to higher temperatures without losing efficiency, thus reducing the amount of water necessary for cooling. Another option is air-cooling, but with this system you sacrifice efficiency and increase building costs. So in the meantime, CSP plants—long favored by the federal government—are using, or want to use, large amounts of water. According to Basin and Range Watch, a solar parabolic trough plant uses 760 to 920 gallons of water per megawatt hour.
All this water comes from local sources and communities, which are already struggling for water—in Nevada and throughout the Southwest. Combine this issue of water usage with the vast amounts of desert land and wildlife affected by solar farms, and the environmental argument against big solar plants grows. Nevada’s proposed solar power plants remain on hold as the BLM works out an environmental impact assessment.
Photo Credit: Al lanni
Once again this issue brings into focus the need for distributed generation, rooftop solar installations. Southern California especially is chock full of available rooftop space for photovoltaic solar systems, which are already on existing transmission lines, require no water, and enjoy the same sunlight that remote deserts enjoy. The problem with this is, quite frankly, that it puts more power into the hands of the consumer. A corporation cannot own the sun (yet) but it can own the equipment that collects the sun’s energy and then sell that energy to you for a price. Distributed generation takes the corporation out of the equation to a large extent—not good news for Big Solar but potentially great news for homeowners and local solar installers. With all due respect to the solar industry (and much is due), considering water and land issues, plus the vast solar potential resting right over our heads, a note of caution from the BLM is quite welcome.