As the United States searches for sources of alternative energy and a means to reduce its production of greenhouse gas (GHG) emissions, solar power plants have emerged as a leading candidate to address both of these problems. While these plants do indeed provide an additional means of producting energy that could potentially reduce the amount of GHG that are emitted into the atmosphere by up to 2.7 billion tons per year, a new battle regarding the use of solar energy is emerging.
Because the most profitable concentrating solar power systems require significant amounts of water to cool the system and to produce steam, concerns about the depletion of water resources in the vicinity of these plants is growing. This is especially true in the Southwest where the majority of these plants would be located (there have been over 150 solar applications submitted for projects in Nevada, California, and Arizona alone).
In the Armagosa Valley in southern Nevada, concerns over falling water tables and the well being of wildlife populations have driven the backlash against the influx of solar plants. A proposal by the Spanish company Solar Millenium, which would sprawl over a whopping 4,000 acres, has been stymied by activists working to protect rare wildlife, such as the Devil’s Hole pupfish, which would be severely impacted by drawdowns in the water table. Similar battles are being waged in California and Arizona.
While there will continue to be serious questions raised about the environmental impacts of large-scale solar projects, which can encroach upon vast tracts of wildlife habitat, require extensive construction of transmission lines over long distances, and may release harmful chemicals, the controversy between water resources and solar power may be an unnecessary one.
While most of the currently proposed steam-turbine plants are water intensive operations, not all solar power generation is. For example, air cooled solar power plants would reduce water-usage by up to 97% compared to steam powered plants. Developers argue, however, that the dry systems cost 5 percent to 10 percent more to build and may reduce energy production by as much as 20% during the hottest times of year. From the water resource perspective, this is a trade off that would be well-worth taking.
Additionally, photovoltaic (PV) systems are another option that require a significantly smaller amount of water than concentrating solar power systems, as water is needed only to clean the panels to ensure maximum insolation. Breakthroughs in ultraefficient PV technology now make PV more cost effective and competitive with traditional concentrating solar power. More recent discoveries in the field offer further evidence that even greater improvements in solar efficiency, which may revolutionize the industry, are not too far beyond the horizon.
Such findings may have the potential diffuse the clash between clean energy enthusiasts and those concerned about water resources, but only if there are incentives and legislation that will ensure that the most water efficient solar power generation is used. We can only hope that the “Fast Track” initiatives proposed by Secretary of the Interior Ken Salazar to expand solar energy production in the Southwest will make water use efficiency a priority.