The Uncertain Future of Large Scale Solar Thermal Power Plants

(3BL Media/Justmeans) - Last week, I wrote about my visit to the Shams-1 hybrid thermal solar-natural gas plant in Abu Dhabi. This 100MW plant, which combines concentrated solar power (CSP) with natural gas, is capable of generating power around the clock. The plant’s technical support manager, Abdulazoz Al Obaidli, said that it was unclear whether more plants like this one would be built, seeing as how new solar photovoltaic plants were challenging this technology on both price and efficiency. Improvements could also be realized with this approach, but it’s unclear, especially given the long lead times for building a plant like this, what the comparison will be down the road.

While CSP plants are basically steam plants with mirrors, photovoltaics are semi-conductors which have a tendency to follow something called Moore’s Law that has seen performance doubling and costs dropping at regular intervals like clockwork. And though we tend to think of PV in terms of small rooftop installations, there are, in fact 19 PV plants of 100MW or more, the largest being the Topaz Solar Farm in San Luis Obispo, CA, which weighs in at 550MW.

While the matter is far from settled, there are a number of other challenges facing CSP, sometimes called solar thermal plants, which use the heat of the sun to produce steam, unlike photovoltaics that convert sunlight directly in electricity. The CSP plants, given the thermal mass of fluids in the system, do produce more stable power and are thus better suited to baseline applications.

Shape of Things to Come? Huge Concentrating Solar Plant Opens in Mojave Desert.

They say that enough sunshine falls on the Earth in one hour, to meet the demands of the whole planet for a year. But how much area is needed to collect what we need? If we divide the area of the earth (196 million square miles) by the number of hours in a year (8,760), we end up with around 22,500 square miles, a little less than the size of West Virginia.

 The massive Ivanpah concentrating solar thermal power—also called concentrating solar power (CSP)—plant stretches out over five square miles, the largest of its kind in the world, has opened in the Mojave Desert, at a site 45 miles southwest of Las Vegas. The plant, which consists of 350,000 tiltable tracking mirrors, each the size of a garage door, can produce 392 megawatts, enough power to run 140,000 homes. The mirrors are focused on three towers, forty stories tall, each containing a boiler. The steam produced from the concentrated sunlight then drives a turbine-generator, much like the steam from a coal-fired plant would. The three-tower system is more space-efficient than a single tower, requiring 25% less land. The plant is also unique in that it uses far less water than other similar plants. The $2.2 billion complex is jointly owned by NRG Energy, Google, and Oakland-based BrightSource Energy. The plant will sell power to PG&E Corp. and Edison International under a 25-year contract.

Throughout its history, response to the project has teetered on the line between the desire for clean, renewable energy, and the desire to preserve open land. In 2012, the government stepped in to designate 17 "solar energy zones" in areas identified as being less wildlife-sensitive and having fewer natural resources. The zones include about 450 square miles in six states—California, Nevada, Arizona, Utah, Colorado and New Mexico.

Despite these precautions, government documents show that dozens of dead birds from sparrows to hawks have been found on the site, some of them with melted feathers. The suspected causes of death include collisions with mirrors and scorching. In November alone, 11 dead birds were found, including two with singed feathers. This was enough for the ever-skeptical Wall Street Journal to refer to the plant as a “$2.2 billion bird-scorching project.”

The bird problem is potentially serious enough to forestall a similar project near the Joshua Tree National Park because of the impact it might have on golden eagles and other protected species.

While the successful commissioning of the plant certainly bodes well for the future of solar energy in America, the question of whether we will be seeing lots more plants like this one is a little harder to answer. Besides the bird issue, which is currently undergoing further study, there is another issue that could effect more decision makers: cost.

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