Issue Date: January 15, 2007
I would like to correct a commonly held misconception that was perpetuated in the article "Solar Revolution" regarding the cost of solar energy (C&EN, Nov. 20, 2006, page 25). The article asserts that "Solar energy is ... one of the most expensive sources of energy." If the statement had been restricted to photovoltaic solar energy, then it would have been correct; however, this claim is not generally true.
Fortunately for the planet, there is a less well known solar technology called concentrating solar power (CSP) that is cost-effective today. CSP generates electrical power from steam that is produced by focusing mirrors.
Large CSP plants were deployed in the Mojave Desert two decades ago and have been supplying the California market with over 350 MW ever since. More recently, CSP plants are going on-line in Arizona, Nevada, and Spain, and purchase power agreements have recently been signed with California electrical utilities for several thousand megawatts. CSP plants are typically built with about six hours of thermal storage so they can deliver power just when it is most valuable to the utility-from midday until the early evening-at a competitive cost of around $0.10/kWh. An assessment by the National Renewable Energy Laboratory showed that the solar resource for CSP is sufficient to supply the entire national electricity demand several times over.
As James Hansen of NASA and many other climate scientists tell us, we only have about a decade to make major reductions in greenhouse gas emissions or we risk pushing the planet into one of several global-warming positive feedback loops. Since electricity generation is our greatest single source of carbon dioxide emissions, we must rapidly phase out coal-fired plants and deploy noncarbon electricity-generating technologies like wind and CSP to avoid global disaster.
We have the technology available today to put the planet on a sustainable power pathway. We need only the willpower and leadership to carry out the transition.
J. Thomas McKinnon
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