A Bright Idea In Solar Energy

How do you save solar energy for a rainy day? Scientists at Israel's Weizmann Institute of Science in Rehovot are building an experimental solar energy system that produces a storable fuel, but avoids burning it, and thus stays pollution-free. Professor Israel Dostrovsky, founder of Weizmann's solar research program, believes that this so-called heat-pipe approach will prove "the key to large-scale use of solar energy."

Weizmann's pilot plant has 64 giant, computer-controlled mirrors that focus sunlight on a methane-filled tank atop a tower. As the methane absorbs the sun's concentrated heat, it breaks down into hydrogen and carbon monoxide. This hazardous mixture, called synthesis gas, can be stored or piped to distant customers. Then, a chemical reaction converts the gas back into methane, liberating enough heat to produce steam, which can be used to generate electricity. Meanwhile, the reconstituted methane will be piped back to the solar plant, therefore allowing the cycle to be repeated in an endless loop. The $1 million pilot plant will undergo three years of testing. If it works, the next steps will be a small prototype, then a commercial plant.