Investing in the world’s largest solar power tower plant

We’ve invested $168 million in an thrilling new solar energy power plant being urbanized by BrightSource Energy in the Mojave Desert in California. Brightsource’s Ivanpah Solar Electric Generating System (ISEGS) will produce 392 gross MW of clean, solar energy. That’s the equal of taking more than 90,000 cars off the road over the lifetime of the plant, projected to be more than 25 years. The investment makes business sense and will help make certain that one of the world’s largest solar energy projects is completed.

We need smart capital to change our energy sector and build a clean energy future. This is our largest investment to date, and we’ve now invested over $250 million in the clean energy sector. We’re eager about Ivanpah because our investment will help organize a compelling solar energy technology that provides reliable clean energy, with the potential to considerably reduce costs on future projects.

Power towers, which have been productively demonstrated in the U.S. and abroad at smaller scale, are based on a relatively simple idea. The technology works by using a field of mirrors, called heliostats, to think the sun’s rays onto a solar receiver on top of a tower. The solar receiver generates steam, which then spins a traditional turbine and generator to make electricity. Power towers are very competent because all those mirrors focus a marvelous amount of solar energy onto a small area to produce steam at high pressure and temperature (up to 1000 degrees F). Think about burning a tuft of grass with a magnifying glass, only multiplied by thousands (or the original application: Archimedes’ heat ray that supposedly used mirrors to burn enemy ships!).

Several large solar projects are in the works in the sunny Southwest (and around the globe), but Ivanpah will be the first solar power tower system of this scale. The Ivanpah Power Tower will be about 450 feet tall and will use 173,000 heliostats, each with two mirrors. The project is being constructed by Bechtel, a major engineering firm. Construction began in October 2010, and is predictable to finish in 2013.

The Ivanpah scheme will also be financed by NRG and with clean energy technology loan guarantees provided by the U.S. Department of Energy. We hope that investing in Ivanpah spurs sustained development and deployment of this promising technology while hopeful other companies to make similar investments in renewable energy.