“If we talk about geothermal or wind, all these other sources of renewable energy are limited in their quantity,” Eicke Weber, director of the Fraunhofer Institute for Solar Energy Systems, in Freiburg, Germany, told me last fall. “The total power needs of the humans on Earth is approximately 16 terawatts,” he said. (A terawatt is a trillion watts.) “In the year 2020 it is expected to grow to 20 terawatts. The sunshine on the solid part of the Earth is 120,000 terawatts. From this perspective, energy from the sun is virtually unlimited.”
There are two main ways to harness it. The first is to produce steam, either with parabolic troughs like the ones in Nevada or with a field of flat, computer-guided mirrors, called heliostats, that focus sunlight on a receiver on top of an enormous “power tower.” The second way is to convert sunlight directly into electricity with photovoltaic (PV) panels made of semiconductors such as silicon.
“I always say the United States addresses the idealists, those who want to save the planet—the Birkenstock crowd. In Germany the law addresses anyone who wants to get 8 percent return on his investment for 20 years.”
Via – Rajesh Jain.