From Search to Sunshine: Google Ponders Move Into Solar Thermal Energy

Last Updated Mar 1, 2010 2:11 AM EST

Google has a lot of side projects. Besides being a search and advertising giant, the company has its fingers in just about every computing technology. But this one is odd even for Google: a couple years from now, the company could be manufacturing mirrors for the solar industry.

Bill Weihl, Google's green energy czar, first floated the idea of making mirrors at a talk last September. Mirrors aren't involved in solar panels, the solar technology that most people are familiar with. But they are heavily used in solar thermal tech, in which reflected sunlight boils water to drive turbines.

At the time, nobody was certain how seriously to take Weihl -- would Google really step outside of computing to try its hand at materials technology? Last Friday, Reuters reported that Google has done exactly that, producing an initial prototype that could be ready for the mass market, according to Weihl, in one to three years.

There's a reason for Google's interest. The company's philanthropic arm,, has investments in two solar thermal companies, BrightSource Energy and eSolar. At the moment, the two are the most prominent solar thermal companies in the United States. Brightsource recently won a $1.37 billion government loan guarantee for a solar thermal plant, while eSolar is planing a $2 billion plant in China, among others.

Weihl also told Reuters that Google could potentially cut the cost of mirrors for solar thermal in half. That's a big deal. In solar thermal, the sprawling fields of mirrors cost more than any other component. The cheapest solar thermal tech is still about a third more expensive than wind or coal-powered electricity; cutting the price of mirrors in half could make it nearly cost-competitive.

There's always a speculative element to this sort of announcement, and critics will be quick to point out that plenty of scientists have tried their hand at making cheaper mirrored surfaces. That includes solar thermal companies. Ausra, for instance, spent some of its early venture funding on a highly automated mirror manufacturing plant in Nevada.

Google seems to be approaching the problem from another direction, with Weihl telling Reuters that the company has been using "unusual materials" for the mirror and substrate. That may mean no metal and no glass, which are the two priciest elements of most mirrors.

Most of the big solar thermal startups seem to use a fairly standard metal-based mirror. But there are companiess that claim to offer cheap, flexible mirrored surfaces (3M did a lot of research on mirrored film in the 1980s and sells some today), as well as a couple of small startups that say they have special in-house tech.

Cool Earth Solar is one example. Their cheap Mylar solar device looks a bit like a blown-up balloon with one side clear, and the opposite interior side mirrored to reflect light onto a solar cell -- think of the shiny inside of a bag of potato chips. The tiny solar thermal startup GlassPoint, which I recently talked to, also says it has ultra-cheap mirrors.

[Image credit: Alex Lang / flickr]