Ex-United Technologies Rocket Scientists To Build 150 MW Solar Heliostat in Sonoran Desert

SolarReserve ; a California start-up spin-out from United Technologies' Rocketdyne has filed an application with the CPUC to build a 150-megawatt heliostat solar farm with seven hours of after-sunset energy stored in molten salt.

By Susan Kraemer
November 4, 2009

SolarReserve; a California start-up spin-out from United Technologies' Rocketdyne has filed an application with the CPUC to build a 150-megawatt heliostat solar farm with seven hours of after-sunset energy stored in molten salt. These are the rocket scientists responsible for our solar-powered space exploration.

Theirs would be the first heliostat type of solar array to produce grid power in California. Abengoa has several in Spain, and plans one in Arizona. United Technologies has licensed the original technology to the new company SolarReserve and its wholly owned subsidiary Rice Solar Energy, LLC, (RSE).

The start-up has years of solid research behind it. The Rocketdyne scientists developed the solar salt technology they will use in the Rice Solar Energy Project, and they proved that it worked back in the 90's in a 10 MW demo.

Here's how their heliostat mirror solar works:

1. Nearly 18,000 billboard-sized sized mirrors will be arranged on 12-foot posts in a circle to aim concentrated beams of sunlight at a salt-filled receiver at the top of a 538 foot tower.

2. The molten salt gets hotter and hotter all day as the sun beats down (up to 1,050 degrees) and then when it's needed, that heat can be released to generate electricity the old fashioned way, by flowing through a steam-generating system driving a turbine at the bottom of the tower.

3. As the mixture loses heat it is recirculated back up to the top to get fired up again by the suns heat reflected off the heliostat mirror sytem, and round and round it goes, all 4.4 million gallons of molten salt.

The salt is a mixture of simple sodium nitrate and potassium nitrate and will be mixed onsite as received directly from mines in solid crystallized form and used without additives. When melted it looks like water.

Any utility-scale solar plant needs to bypass NIMBY opposition, whether that is genuinely heartfelt or merely the fossil-funded kind of "environmentalist" opposition. Unfortunately the Heartland Institute (of "500 scientists who deny climate change" fame)  is preying on the uninformed with complete falsehoods about how much water solar power uses.

In reality, even wet-cooled solar thermal, utility-scale solar's piggiest water hog, uses only 1/60th of the water that nuclear can use and one 1/50th as much as a coal plant can; according to the (pdf) Report to Congress on Concentrating Solar Power Commercial Application Study: Reducing Water Consumption of Concentrating Solar Power Electricity Generation.

But to bypass these real or trumped-up impediments to clean energy SolarReserve will build their heliostat solar array on private land and will air-cool it. Dry cooling uses only about 10% of the relatively miniscule amount of water that wet cooled solar thermal uses.

United Technologies will guarantee the output for investors. SolarReserve got $140 million in investment in September last year.