Renewable Energy

New Type of Solar Holds Promise

By Derrill Holly | ECT Staff Writer Published: October 25th, 2012

Could concentrated solar energy earn a place in the renewable energy portfolios of some electric cooperatives?

This concentrated solar power system is deployed near Almeria, Spain. (Photo By: AORA Solar)

This concentrated solar power system is deployed near Almeria, Spain. (Photo By: AORA Solar)

At least one solar developer believes the technology could be economically viable, if coupled with small-scale generation, powered by virtually any additional heat source.

Co-op researchers and others in the utility industry are being approached about utility-grade use of the technology, which is already in use in two countries, and under consideration for development in several others.

“The footprint for a concentrated solar energy array is about one-third the size of a photovoltaic array offering similar capacity,” said Javier Munỡz Durãn, AORA Solar’s technical director. The company, based in Spain, is trying to determine interest in 100-kilowatt hybrid solar-fossil generation systems.

Representatives of the Cooperative Research Network viewed a presentation by AORA officials at NRECA’s Arlington, Va., headquarters Oct. 19.

While the costs of any initial units built in the United States remain to be determined, company officials hope volume will eventually lead to deployment costs comparable to other concentrated solar projects.

The use of heated air as the generation source instead of molten salt or steam is a different approach to concentrated solar power.  An array of automated parabolic mirrors focus energy onto an elevated receiver to heat air in a chamber to 950 degrees Celsius [1,742 Fahrenheit].

“We look forward to seeing some demonstrations of this technology so co-op engineers can visit and ‘kick the tires’,” said Doug Danley, a CRN contract engineer who viewed the presentation.

The turbine-generator can also be powered with an external heat source, including natural gas, diesel or biogas from a landfill or biodigester. As temperatures drop and sunlight declines, a supplemental fuel source takes over.

When intake temperatures rise above 35 degrees Celsius (95 degrees Fahrenheit) a misting spray of water consuming less than 44 gallons per megawatt hour of produced electricity cools components. Limited water usage could be particularly appealing in the arid Southwest where water can be a sensitive issue.

Systems are already deployed in Israel and Spain and officials are now hoping to develop small commercial sites in the United States, where weather, topography and other factors are favorable.

The National Renewable Energy Laboratory has determined that parts of seven southwestern states from Texas to California are “the most economically suitable lands available for deploying of large-scale concentrating solar power plants.”

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