Solar farms that sip desert water



Concentrating Solar Power (CSP) gets a bad rap from desert dwellers. First, there’s the concern over disturbing some of our wildest areas to build sprawling solar farms. Many object to how the giant sites can ruin their view of the desert.

But the biggest concern is over what these lands possess in minute amounts.

“Water usage is becoming the larger issue,” a lawyer for one solar power company told a reporter in April.

Depending on the design, CSP can use up to 750,000 gallons of water for each GWh of electrical production (roughly the same as a comparable coal or nuclear power plant).

That’s one reason for the buzz created by a CSP system that was recently unveiled at the Sandia National Laboratories in Albuquerque, New Mexico. The SunCatcher™ is a game changer.

The modular unit uses zero gallons of water for cooling, and only a small amount for washing dust from its highly polished mirrors.

Each unit consists of 40 polished steel mirrors formed into a parabolic dish to concentrate solar energy. That energy powers a Stirling hydrogen engine which results in electrical generation. Not only does this design sip water, it is also the most efficient solar technology for producing electricity (pdf). In 2008, an earlier version of the Suncatcher™ set a record of 31.25 percent net efficiency.

Water Usage and Electrical Generation

Renaissance solar dish

Renaissance solar dish

Although CSP has recently received a lot of negative attention for using large amounts of water, the problem is not limited to solar farms.

“Dominated by coal and gas fired steam generating plants,” writes Gary Deason, deputy director of the Center for Sustainable Environments at Northern Arizona University, “electrical generation in the Intermountain West consumes over 650 million gallons of water per day…”

That’s enough to meet the water usage of the entire state of Colorado. And that’s with virtually no water being used currently for large-scale CSP farms. CSP facilities in Europe rely on a design that is water intensive. That’s controversial enough across the pond. But to many in the American Southwest, which is defined largely by its lack of water, the plan to locate water hogs to generate electricity seems downright absurd.

Water law expert Robert Glennon recently wrote a controversial piece on this topic for the Washington Post. It was titled, “Is Solar Power Dead in the Water?”

The new SunCatcher™ has another factor going for it: jobs. Many of which will come from the downsized auto industry. The large steel mirrors (and many other parts) will be produced by the auto industry.

As Stirling Energy Systems CEO, Steve Cowen recently explained, “By utilizing the automotive supply chain to manufacture the SunCatcher™, we’re leveraging the talents of an industry that has refined high-volume production through an assembly line process. More than 90 percent of the SunCatcher™ components will be manufactured in North America.”

Preparations are underway to begin building a demonstration facility in the Arizona desert in September. Sixty of the new dishes will have a capacity of 1.5 MW. In the next few years, Stirling and its sister company, Tessera, have plans to increase their total capacity to 1.6 GW, from 65,000 SunCatcher™ units.

That’s not a huge amount of electricity, perhaps. It points, however, to an ever brighter future for zero emission, clean and renewable energy — that does not deplete other critical resources such as water.

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