Solar Tower
There are two ways to harness energy from the sun. One is through photovoltaic panels, which transform sunlight directly to electricity. But — news flash — the sunlight also produces heat, which can be concentrated using mirrors to produce steam, which then drives electric turbines. It's this second form — called solar thermal or concentrated solar power — that has the most potential for utility-scale power generation. In fact, there are already solar thermal plants operating in the deserts of Nevada and California, using low rows of curved mirrors to concentrate sunlight.
But Bill Gross at eSolar thinks that he can improve on that fairly basic technology. Instead of rows of mirrors, eSolar uses vertical mirrored towers of that perfectly concentrate sunlight on a ground target. Using sophisticated software that Gross helped write himself — he was an Internet entrepreneur before breaking into alternative power — the mirrors perfectly track the sun as it crosses the sky, maximizing the amount of electricity that can be produced. The result is a relatively compact but power utility-scale plant that gets the most out of that free source of energy called the sun.