eSolar

(3/5/2009) - The basic technology behind geothermal, solar, and wind energy production is well developed.  Wind and geothermal energy is already cost-competitive with new natural gas and sometimes coal plants (depending on circumstances).  Though solar energy isn’t quite there yet, several new developments are showing promise.  As I wrote about in December, a company called Cool Earth Solar is developing technology that they say will make solar PV cost-competitive with natural gas and possibly coal. 

Now a company named eSolar is proposing to do the same for solar thermal as Cool Earth Solar (CES) says they will do for PV.  Briefly, a solar thermal plant generates electricity by using the sun’s energy to boil water into steam, which then drives a standard turbine.  Several different designs are used to create electricity this way.  Nevada’s Solar One consists of rows of parabolic mirrors that focuses the sun’s light on pipes filled with circulating mineral oil heat transfer fluid.  The fluid transfers the heat to water, which boils and creates steam, etc. 

Another popular solar thermal design uses thousands of heliostats – flat mirrors that track the movement of the sun – to reflect light onto a center tower.  Department of Energy’s Solar Project has demonstrated the viability of this concept.  Instead of immediately heating water, the Solar Project has experimented using molten salts to store heat so that the plant can continue to make electricity when the sun goes away.