What is similar and what is different about burning coal and solar heating?

Answer 1

"It might not please many environmentalists, but a major energy company is adding solar-thermal power to a coal plant and says this could be the cost-effective way to produce energy while lowering CO2 emissions. Abengoa Solar and Xcel Energy, Colorado's largest electrical utility, have begun modifying the coal plant, which is based near Grand Junction, Colorado. Under the design, parabolic troughs will be used to preheat water that will be fed into the coal plant's boilers, where coal is burned to turn the water into steam. Cost savings comes from using existing turbines and generators and from operating at higher efficiencies, since the turbines and generators in solar-thermal plants are normally optimized to run at the lower temperatures generated by parabolic mirrors."