Prospects For Solar Thermal Power

A  new solar thermal electric power installation in Boulder City Nevada uses arrays of mirrors to concentrate sun light to drive electric power generation. The cost of electricity for this plant is estimated at 15-20 cents per kilowatt-hour (kwh).

Many states, including California, are imposing mandates for renewable energy. All of that is reviving interest in solar thermal plants.

The power they produce is still relatively expensive. Industry experts say the plant here produces power at a cost per kilowatt- hour of 15 to 20 cents. With a little more experience and some economies of scale, that could fall to about 10 cents, according to a recent report by Emerging Energy Research, a consulting firm in Cambridge, Mass. Newly built coal-fired plants are expected to produce power at about 7 cents per kilowatt-hour or more if carbon is taxed.

That is at least double what cheaper sources of electricity cost in the United States. Can the costs really go down substantially with a bigger market?

While solar thermal still costs more than wind power predictable daylight hours and the ability to store the heat allows solar thermal to provide a more reliable power source.

According to the U.S. Department of Energy, wind power costs about 8 cents per kilowatt, while solar thermal power costs 13 to 17 cents. But power from wind farms fluctuates with every gust and lull; solar thermal plants, on the other hand, capture solar energy as heat, which is much easier to store than electricity. Utilities can dispatch this stored solar energy when they need it--whether or not the sun happens to be shining.

Solar thermal doesn't have to be able to provide electric power 24 hours per day to be useful. If its cost could drop in half then solar thermal would greatly reduce the use of coal and natural gas and allow limited fossil fuels to last longer and pollute less..

One solar thermal facility in Nevada is claimed to use 400 acres for enough electricity to power 14,000 homes.

Acciona's plant, which began operation last year, produces 64 megawatts of electricity for the utility company Nevada Power, enough to light up 14,000 homes. The company's Spanish competitor Abengoa just announced a plan to build a 280-megawatt solar thermal plant outside Phoenix, which would be the largest such project in the world.

All you need is a lot of sun, a lot of space and a lot of mirrors — and NS1 has all of the above. 182,000 parabolic mirrors are spread over 400 acres of flat desert, creating a glistening sea of glass visible from miles away.

That's 35 homes worth of electric power per acre of land. Mind you, this is an area of the United States that gets above average amounts of sunlight. But this result suggests that use of solar thermal to power all homes would not use an inordinate amount of land - at least not in countries with lower population densities.

Solar thermal looks cheaper than solar photovoltaics and the heat from solar thermal can be stored to stretch into evening hours. But solar photovoltaics might have better prospects for lower cost reductions and it lends itself more easily to decentralized use and smaller installations on homes and other buildings.

By Randall Parker at 2008 March 06