Monday, October 5, 2009

Solar Power At Night!

One of the, often sited, drawbacks of solar energy is that it does not produce power at night. A new solar plant in the Arizona desert is about to change that.

It is named "Starwood Solar One" and it will be located 75 miles west of Phoenix in the Harquahala Valley.

When complete in 2013, the 290 MW solar thermal power plant will cover 1900 acres of desert and be the largest dispatchable solar power plant in the world. A "dispatchable" plant is one that can be tapped for electricity whenever needed, such as peak demand periods day or night.

'How is that possible?', you might ask.

Mirrored troughs concentrate the sun to heat liquids, that are piped into giant insulated tanks of molten salt. The tanks are heated to over 700 degrees Fahrenheit. With an insulated thermal mass this large, the tanks can maintain their temperature for weeks with very little degradation. This means that they can be used to generate steam and drive turbines whenever needed, day or night and even during cloudy weather.

Simple temperature monitors can be used to estimate production capacity currently stored in the tanks. This makes the plant output highly predictable and dependable; something photovoltaic and wind cannot do currently. It would take weeks of "solar drought" in Arizona before the plant would not be able to produce at full capacity.

It will produce enough power for ~73,000 customers. The construction will also create 7700 jobs and have a price tag of $2.7B. With no ongoing fuel costs, it will pay for itself and then some; all while not polluting and no miners need to die and no mountain tops need to be removed to feed it.


This type of solar thermal energy as well as geothermal energy are demand-response sources that can be used to supply the base load. This also allows them to adjust to the fluctuations that wind and photovoltaic can produce. Together these can make a complementary portfolio of renewable energy production.

UPDATE: Despite all the contracts signed in May, on October 1st, this project was, sadly, canceled. I hope Starwood can find someplace more dedicated to renewable energy to build.

Links:
Huffington Post
Green Energy News
EcoGeek

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