Tiny experimental plants built in the 1980s in California ran into problems when energy prices dropped.

But as oil, natural gas and electricity costs soar, companies are racing to build commercial solar thermal plants that are the size of conventional power plants.

"Now the industry starts again," said Burghard von Westerholt, head of thermal solar for private German specialty glass company SCHOTT.

Mandatory caps and potential limits on emissions of greenhouse gases from fossil fuels have also promoted the new technology, industry officials said.

Utah-based International Automated Systems Inc. on Thursday signed an agreement to install a $150 million, 100-megawatt power plant for Solar Renewable Energy in Nevada.

And North Carolina based-Solargenix, in which Spanish building and services company Acciona SA is buying a 55 percent stake, will break ground over the weekend on a 64 MW, $100 million solar thermal plant called Nevada Solar One. The company said it will be the first US commercial solar thermal plant, coming on line in 2007.

TINY, BUT GROWING

Currently, all the types of solar energy provide only about 1 percent of US power. One hurdle is price. Solar thermal at present costs about 12 to 15 cents per kilowatt hour, Westerholt said, compared with natural gas power which costs 10 cents per KWH.

But as production grows, solar companies expect costs to slip to 8 cents per KHW in five years.

SCHOTT will provide components for at least one 50 MW plant per year in the US Southwest deserts every year until 2010, said Westerholt.

He said the region's intense sun and growing population make it ideal. SCHOTT plans to open a manufacturing center in the United States that would provide 100 jobs, he said.

And solar thermal is growing globally.

A white paper produced by environmental group Greenpeace, the International Energy Agency's SolarPACES, and the European Solar Thermal Industry Association, claims that by 2040 solar power could satisfy more than 5 percent of the world's electricity demand. The best places for it are Australia, the United States, Spain, the Middle East and North Africa, which could export power from the sun to Europe on high-tech power lines, the report said.

Westerholt said SCHOTT will provide parts for 500 MW of solar thermal in Spain by 2010.

Fred Mayes, an alternative energy expert at the US Energy Information Administration, said that solar thermal is pricey compared with wind energy and fuel from biomass. But it does have advantages, he said. Power from the desert sun is more reliable than wind power during the day - the time of peak prices. And unlike biomass fuels, it emits no greenhouse gases.

Rhone Resch, president of the Washington, D.C.-based Solar Energy Industries Association, said the technology is ideal for power in the US West where supply is tight and prices are high. "(Utilities) are negligent to their ratepayers if they are not considering building a concentrating solar plant in the next five years."