This has been the summer– and is now the autumn — of solar love here in the Southwest.
Last week we reported on the announcement by Tucson Electric Power Company (TEP) that they plan to build a 25-MW PV solar power plant outside of Tucson. That’s nearly twice the size of the largest existing PV plant in the US today.
Now comes news about another potential milestone on the solar highway. If Phoenix city officials agree to a plan recommended by a local group, the leading-edge solar thermal technology known as the SunCatcher™ may be deployed for the first time in industrial scale, right here in the Valley of the Sun.
We’ve written about the SunCatcher™ here before — back in July when Sandia National Laboratories and Stirling Energy Systems unveiled this breakthrough system. The SunCatcher™ uses giant mirrors made from polished steel to concentrate solar energy. That focused energy drives a hydrogen engine which, in turn, produces electricity.
Each SunCatcher™ dish is 38 feet wide by 40 feet high. Tessera Solar, based in Houston, plans to use 7,000 of them, enough to generate 175 MW of electricity. That’s seven times more power than the record-setting PV installation outside of Tucson will produce.
Harnessing solar power holds great promise for fighting global warming, but there are potential downsides to solar thermal power plants (as Barry Commoner reminds us: There is no such thing as a free lunch). One of the most serious problems associated with solar thermal is water use. The most efficient place to site a solar thermal plant is where it’s hot and clear for the longest periods. That’s here — in the desert. Unfortunately, most concentrating solar power (CSP) technologies use large amounts of water for cooling purposes.
The SunCatcher™ doesn’t need a coolant. The only time it needs water is when the mirrors are dusty and have to be washed off. That said, I don’t want to minimize the very real questions that remain about exactly how much water will be needed even for this H2O-sipping technology. The Las Vegas Sun had an excellent article recently about the surprising amount of water needed to clean PV panels in the desert. Water usage will have to be looked at very carefully even with the SunCatcher™. The Sonoran desert is hot and dry. Even now, in late September, as I write this it’s 104°F (40ºC).
Another potential problem has to do with the effects of a new power plant on the wildlife here.
People who are unfamiliar with the Sonoran desert tend to think of it as barren. Parts of it are. But most of the land here is crammed with life — plants, including cactus and trees, mammals such as javelina (a wild cousin of the pig), lizards, snakes (you don’t have to like them, just respect the role they play in the desert ecosystem), and more varieties of birds than I recall ever seeing when I lived in Iowa for many years.
The key is to site power plants on land that has already been “disturbed” (read: ruined). The Tessera project would be built next to a large county landfill. I think that qualifies as disturbed.
We’ll be putting up a video soon, showing the SunCatchers™ in action. True, the action is pretty slow-paced. Nothing like coal power generation, with its mining and leaking toxic tailing ponds, or blasting mountaintops to smithereens to get at the coal, and huge furnaces, giant turbines and clouds of soot streaming out the stacks. These enormous dishes sit, basking in the brilliant desert sunlight. Their small motors don’t even make much noise.
But, perhaps its time we found a better source of thrills and spills than power generation. We’ve seen that movie far too many times as it is.