Solar thermal power cuts a fascinating contrast with solar photovoltaics and wind turbines — today’s leading renewable energy technologies — besting one on price and the other on quality. Little surprise then that it is being selected for power plants equal in output to large wind farms and ten-times the size of the largest photovoltaic installations.
Whereas photovoltaics employ semiconductors to directly convert sunlight into electricity, solar thermal power stations convert sunlight into heat to generate steam and drive a turbine. This roundabout is, ironically, a huge money-saver. The mirrors, pipes, pumps and steam turbines that form a solar thermal plant cost less than half than an equivalently powerful array of photovoltaics.
Solar thermal cannot similarly challenge wind turbines on cost (at least not at present). But solar thermal plants can store some of the energy they capture and, as a result, produce a much steadier and more reliable supply of electricity than the famously variable wind turbine.
So why then did we hear so much about solar photovoltaics over the past decade and sol little of solar thermal? Because the latter is inherently utility-scale technology, whereas photovoltaic panels provide value one rooftop at a time. Fred Morse, a solar thermal pioneer and currently senior advisor to renewable energy developer Abengoa Solar, likens it to a bakery operating through the depression. “If you had a bakery and you sold cookies or big wedding cakes, during hard times you could sell a lot of cookies,” says Morse. “PV has little niche markets and it could grow and grow and as the price came down it expanded those markets to where it is today.”
These days, thanks to state and (albeit on-again-off-again) federal incentives and record fuel prices, solar power is back to wedding cakes.
For more, check out “Solar without the Panels”