Steve Years jogged my memory about solar thermal over the weekend with his blog entry about a 64MW facility coming online in Nevada this year.

Solar Thermal Plant operations illustration


As you can see from the illustration above, this is a binary power system where heat is transferred to a working liquid that carries heat to water which is then vaporized into steam and cycled through a turbine sent to a condenser for cooling and then it starts the cycle again. Since the sun only shines so much, there is a natural gas boiler that takes over at night and when weather conditions aren’t appropriate to enable a steady flow of energy to consumers.

Map of appropriate solar-thermal regions of the globe


Not only are solar thermal systems ready for primetime, they’ve been working for some time. The largest operator is Florida Power and Light who operates the largest plant, the 310MW Solar Electric Generation Systems (SEGS) is a set of 7 array plants in the Mojave Desert in California. Obviously this isn’t a 100% renewable system, but it is a step in the right direction combining natural gas with sunlight to do the heavy lifting during peak consumption.

The costs of solar thermal systems are still relatively high, around $3.9M per MW in the Nevada Solar One 64MW project. The technology is competitive with “clean coal” technologies, though it’s still a far cry from the $0.75M per MW for natural gas fired generation. But it’s a great step forward from photovoltaic systems that still cost somewhere north of $8M per MW.

One has to wonder if the solar thermal folks should be talking to the binary geothermal bunch and the chemistry already completed allowing power to be generated from 75 degree centigrade resources, that has to be more cost effective than the 400 degree centigrade solar thermal design specificiation.

This entry was posted on Monday, March 19th, 2007 at 7:48 am and is filed under Solar.