Solar-Thermal Energy Could Reduce Coal Plant’s Carbon Footprint

FEBRUARY 12, 2009

Using solar-thermal technology at coal-fired power stations could turn out to be the cheapest way to simultaneously expand solar energy use and reduce coal plants' carbon footprint. Or at least that's what the Electric Power Research Institute (EPRI) is hoping to find out with a nine-month study, Technologyreview.comreports.

The nonprofit organization recently launched a $640,000 study to understand the scale of the opportunity and the engineering challenges involved with making the two technologies work together. The study will examine the potential use of solar-thermal technology at two coal-fired power stations in New Mexico and North Carolina.

Last month, five electric utilities in the U.S. and Canada joined EPRI to host studies of the impacts of retrofitting carbon capture technology to existing coal-fired power plants.

The idea is not entirely new: about six new and existing natural-gas power stations are being designed or adapted to incorporate solar-thermal technology.  However, the overall efficiency of retrofitted hybrid solar-gas plants is still limited – when the sun goes down, a gas steam turbine that has been modified to accommodate waste heat plus solar heat will suffer an efficiency penalty from running at partial load.

However, for the hybrid technology to work, power plants will need a combination of strong sun and flat, open ground to host a solar thermal collector field. Moreover, governments need to put a firm price on carbon emissions from coal to justify trading cheap coal for more costly solar-thermal energy.

In January, EPRI noted that energy efficiency programs in the U.S. could realistically reduce the rate of growth for electricity consumption by 22 percent over the next two decades - if key barriers can be addressed.