Solar-thermal: a better way to use sun’s heat

There are two primary ways to generate electricity from solar power, photovoltaic panels and solar-thermal plants which focus the sun’s heat to generate steam that turns a generator.
Solar-thermal plants can be large enough to replace a coal or gas-powered plant. BrightSource Energy, a California company, will soon begin constructing the first in a series of plants that will collectively supply more than 2.6 gigawatts of electricity, enough to serve about 1.8 million homes.
The June 6-12 issue of The Economist includes a photograph of a solar power tower plant in the Mojave Desert which shows hundreds of mirrors focusing rays of concentrated sunbeams on a water-filled glass tower.
Solar-thermal power is less expensive than photovoltaic power and is becoming even more economical as the science progresses. Its advantages are that the heat generated can be stored in heavy liquids so that power can be generated when the sun isn’t shining. Hybrid plants use natural gas part of the time and the sun’s energy when it is available.
Solar-thermal plants run best when it is hottest and the demand for electricity is greatest.
According to New Energy Finance, about 12 gigawatts of solar-thermal power capacity is now being planned worldwide — an enormous expansion, considering that only 500 megawatts of capacity has been built to date.
The potential is boundless. Mark Methos of America’s National Renewable Energy Laboratory said solar-thermal power could in theory generate 11,000 gigawatts in America’s Southwest alone. “That is about 10 times America’s entire existing power generation capacity,” the Economist reported.
There are disadvantages. The plants require millions of gallons of water to be turned into steam and to use for cooling, a challenge in the desert areas where the plants are most efficient. They must also be connected to transmission lines, which are expensive to build and are most readily available in populated areas rather than sparsely settled deserts. The plants are expensive to build and capital for them is hard to find without significant government subsidies.
Despite these negatives, the outlook for solar-thermal is bullish. Those in the industry expect a massive upsurge in the immediate future. The plants, of course, only emit carbon dioxide when the turbines must be powered by natural gas. If a significant percentage of America’s electricity needs could be met by the sun’s power, the U.S. would do more than its share to reduce global warming.
A reliable source of non-polluting electricity would also make plug-in automobilies a real alternative to the internal combustion engine and greatly reduce the need to import oil within a decade or so.

RENEWABLE energy has moved out of the impossible dream realm. Solar power, wind power, geothermal power, tidal power and power from biomass are all available to us. The technology to use these sources has been developed. It only needs refinement and economy of scale to make renewable power available to every part of the world at an affordable cost. We no longer must depend on the ever-dwindling supply of carbon-based fuels which science has proved to be a threat to our future.
The sooner the United States and the other rich nations decide to devote the resources needed to accomplish the shift, the sooner the world be will released from its dangerous dependence on oil and coal.

— Emerson Lynn, jr.