New Solar Power Plants Might Impact Water Supplies

Compared to traditional sources of energy--such as nuclear, coal, petroleum, natural gas or large-scale hydro--most clean sources of power currently being championed in the U.S. are much better from a water standpoint. Well-known exceptions include corn-based ethanol and soy-based biodiesel, but now certain types of solar power are also attracting criticism for their impacts on water resources.

River Network's Saving Water, Saving Energy program has been promoting clean energy sources, including solar and wind power, that reduce greenhouse gas emissions and minimize adverse impacts on our water resources. But energy production is complicated and there are many different types of solar power production. According to an article from the New York Times, some forms of solar can significantly increase water demands which can be a problem when you consider many of the most suitable locations for solar power are in arid regions:

A National Park Service official has warned the Bureau of Land Management that approving dozens of solar power plants in southern Nevada could dramatically impact water supplies across the arid region.

An estimated 63 large-scale solar projects are proposed for BLM lands in the region, and the plants are expected to use a large amount of groundwater to cool and wash solar panels, according to the Feb. 5 memorandum sent by Jon Jarvis, director of the Park Service's Pacific West Region, to BLM's associate state director in Nevada.
...
"In cases where plans of development have been submitted, the vast majority of these projects propose to use utility-scale, concentrating solar power technologies" that "can be expected to consume larger amounts of water" for cooling than other technologies, Jarvis wrote.

"In arid settings, the increased water demand from concentrating solar energy systems employing water-cooled technology could strain limited water resources already under development pressure from urbanization, irrigation expansion, commercial interests and mining," he wrote.

Now before you jump up and start opposing solar power because of its water impacts, keep in mind that not all solar is created equal. The technology mentioned in this article is called concentrated solar thermal, which is basically a power plant that consists of a vast array of mirrors that redirect the suns energy to heat a tower of water or troughs of synthetic oil. The heated water or oil then drive a turbine to create electricity.

When most of us think of solar power we tend to think of photovoltaic (PV) solar, which consists of photovoltaic cells that directly convert the suns energy into electricity without the added step of heating water to drive a turbine. Luckily, PV solar is still a great technology in terms of water impacts. While significant amounts of water are used in the production of PV solar cells, virtually no water is required during the operation of PV solar panels. The problem is, PV solar is still considered too costly to be used for large-scale power production.

The controversy around the proposed solar projects is a good illustration of just how complex our energy choices are. On the one hand, we need to reduce carbon emissions to combat global warming but on the other hand, we cannot forget about the unintended consequences of our new energy choices, namely the water impacts. In many cases the carbon benefits may outweigh the freshwater costs of a renewable energy project. In other cases the water impacts will be too great and it will take an engaged river and watershed community to make sure everyone is aware of how high those costs will be.