Xcel Explores Potential of Concentrated Solar

Xcel Explores Potential of Concentrated Solar
by Allen Best
09.17.09 - 05:18 pm
Unique Experiment Launched East of Grand JunctionDENVER – Any economic booster’s promotion kit for Colorado cheerily announces the state’s 300 days of sunshine per year.In reality, old sol lounges at some places more than others, and a map posted on the National Renewable Energy Laboratory website shows the sunshine intensity for the West. In comparison to the painful-looking road rash of California’s Mojave Desert, the San Luis Valley in Colorado looks like a bad bruise. Still, it’s the sunniest swath of Colorado. Pockets near Grand Junction, Fairplay and the Four Corners also look bruised, at best.But seen in another light, those bruises look like gold. Some of the world’s best minds have concluded that solar energy remains the most promising of the renewable sources for a long-term energy foundation.In this transformation, Colorado could become a major player. Nate Lewis, a professor of chemistry at the California Institute of Technology, has calculated that an area of southeastern Colorado and adjoining areas of New Mexico, Oklahoma and Texas could by itself convert enough solar energy into electricity to meet the nation’s existing needs.As this was the setting for the Dust Bowl in the 1930s, this suggests a rags-to-riches story as the nation pushes to decarbonize its economy.Xcel Energy, Colorado’s largest electrical supplier, has already created an eight-megawatt farm of photovoltaic panels near Alamosa in the San Luis Valley.Now, a less familiar type of technology called concentrated solar power is being deployed east of Grand Junction at the Cameo coal-fired power plant, where Abenoga Solar is partnering with Xcel Energy to erect parabolic mirrors on 6.4 acres. The mirrors will redirect the sun’s rays to a central unit, where fluid will be heated to produce steam and hence generate electricity.This is just a tiny step. Cameo, among the smallest of Xcel’s power plants in Colorado, generates 77 megawatts of electricity by burning coal. This new solar unit will add just 1 megawatt.This is the first concentrated solar plant in Colorado, although it’s likely not the last. Xcel has proposed to state regulators adding 280 megawatts of concentrated solar and other cutting-edge technology, including geothermal, to its portfolio, along with 700 megawatts of energy from wind and photovoltaic sources. The company currently produces 54 percent of its electricity by burning coal.The basic technology of concentrated solar has been around for decades. Installations in the Mojave Desert altogether can produce 350 megawatts of electricity. Huge up-front costs have held it back. But now, with coal and natural gas more expensive than 20 years ago, concentrated solar is starting to shine.“It’s a proven technology,” says Chuck Kutscher, one of NREL’s leading researchers in concentrated solar at its campus in Golden. He points to a new 64-megawatt plant near Las Vegas, a 259-megawatt plant being built to supply Phoenix, and proposals –- backed up by cash down-payments -– that could theoretically yield 97,000 megawatts of solar power, most of it from installations in the Mojave Desert.Kutscher points out that energy captured by concentrated solar can be retained for six hours through the medium of molten salt.. Batteries can store electricity produced by photovoltaic panels, but at much higher costs.“It produces power in a way that utility folks are familiar with,” says Kutscher.Costs remain higher than coal or even natural gas. The new plant in Arizona, for example, will produce electricity at an estimated cost of 14 to 15 cents per kilowatt-hour. That’s wholesale. In Colorado, the retail cost of electricity runs about 10 cents a kwh.But while sunshine can be expected to cost the same for decades, natural gas has been subject to wild price swings. A year ago it was selling for more than $13 per million British thermal units; in early September the price was $2.35 at the Opal Hub in Wyoming.Xcel plans to close Cameo, an old coal-fired plant, next year. Before it does, however, this provides an opportunity to kick the tires of this idea of integrating solar with coal for possible application elsewhere. It is the first such attempt in the world.If successful, more electricity can be generated without expanding the carbon footprint, says Randy Larson, senior project manager for Xcel.“Colorado is not the prime location for solar, but it has some very good locations,” says Larson. “Grand Junction is pretty good. Pueblo is good, although not as good as the Mojave.”Leslie Glustrom, director of an activist group called Clean Energy Action, says Xcel has changed its mind about the value of concentrated solar since 2007. “All told, we have a lot to be grateful for,” says Glustrom, who sued Xcel in an effort to block the utility’s construction of a 750-megawatt coal-fired plant called Commanche III, which will go on line later this year at Pueblo.Carol Tombari, author of Power of the People: America’s Electrical Choices, calls concentrated solar a sleeper. She notes significant venture capital has been invested in concentrated solar. “Yes, venture capital sometimes makes mistakes. But on the order of magnitude that has been invested in this, I’d say it’s going to succeed.” How it succeeds still remains in doubt. In theory, solar from Colorado could be used to light Los Angeles. Already, LA gets power from the Pacific Northwest, 1,000 miles away. But the cost of building this new transmission remains a major challenge, both financially and, to an extent, environmentally. The journey to this El Dorado of sunshine-based wealth still has plenty of shadows, says Kelly Murphy, who organizes conferences about energy topics. Even California, with an earlier timeline for increasing its renewable energy portfolio, has struggled to connect metropolitan markets with the energy available in the sun-soaked Mojave Desert, he says.Many energy analysts see concentrated solar being part of a much bigger mix of renewables that together are stronger than the sum of their parts.Hank Price, who manages the engineering for Abenoga Solar in Colorado, sees need for a diverse set of renewable resources. “If you were really thinking, you would throw in hydroelectric, wind and perhaps geothermal, and you could have a nice renewable mix,” he says. The intermittency of wind and other renewables makes them difficult to integrate to create steady so-called base-load generation.
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