Friday, April 22, 2016

Bright times ahead for concentrated solar power

The Crescent Dunes solar power plant in the Nevada desert, as well as being visually stunning (see the pictures on the Time Magazine website, and scroll through them using the arrows just below the first picture), uses some revolutionary new technology, and circumvents a major drawback of solar power.
While most solar power generation uses photovoltaic technology to produce power from the panels themselves, Crescent Dunes uses over 10,000 billboard-sized mirrors (heliostats), covering an area of nearly 3km diameter, to reflect the sun's rays onto a 200m tall central tower, where the concentrated sunlight heats up salt to temperatures of over 560°C. The molten salt is capable of retaining these high heat levels for long periods, with a heat loss of less than ½°C per day, thus turning it into a kind of thermal battery. This stored heat can then be used to power traditional steam turbines to produce electricity whenever power is needed by the grid, such as during periods of peak demand, even at night.
The plant is capable of producing over 500,000 megawatt-hours of electricity per year, enough to power 75,000 homes, all with zero carbon emissions. Nevada electricity utility NV Energy has a 25-year contract to purchase all the electricity produced by the plant.
Crescent Dunes' developer, SolarReserve, now has three of these concentrated solar power projects - the other two are in Copiapó, Chile, and in Postmasburg, South Africa - and as the price of electricity from traditional sources continue to rise, as is predicted, this relatively new technology will become increasingly cost-efficient. While millions are being invested in battery technology to store renewable energy in the form of electricity, SolarReserve's molten salt storage technology uses a relatively cheap and plentiful medium. The company is also hoping that, as its model begins to enjoy more widespread deployment, costs will fall substantially, much as has been seen in the photovoltaic market.

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