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Experimental direct solar steam generation power plant opens in Spain

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April 4, 2011

An experimental new direct solar steam generation power plant generates electricity by usi...

An experimental new direct solar steam generation power plant generates electricity by using the Sun's rays to heat water and create steam

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When most of us think of sunlight being used to generate power, we likely picture photovoltaic cells. Concentrated solar power plants however, use lenses or mirrors to heat fluid – such as synthetic oil – which in turn is used to generate high-pressure steam to drive a conventional turbine. A new experimental solar steam generation power plant that opened last week in southern Spain is aiming to improve on the efficiency of existing systems by using water as the direct working fluid and incorporating novel methods for storing the energy, so it can be dispensed even on cloudy days or at night.

The pilot plant is located in the municipality of Carboneras, and is the result of a collaboration between the German Aerospace Center (Deutsches Zentrum für Luft- und Raumfahrt, or DLR) and Spanish utility company Endesa. It was officially put into use on March 31st.

The water in the receiver tubes is kept at a pressure of up to 120 bar (1740 psi), which results in the creation of superheated 500C (932F) steam. That higher temperature allows the whole process to work more efficiently, bringing down the cost of solar thermal power generation and making it a more viable option.

Heat gathered by the plant can be stored in both sensible and latent forms, for use in creating energy when the sun isn't brightly shining. In the sensible heat system, heat from the steam is absorbed by a concrete storage system, so it can later be released to create more steam and drive the turbine. In the latent heat system, the steam is used to heat salt, which absorbs energy when it reaches a temperature of 305C (581F) and changes from a solid to a liquid state. When the salt cools back down below 305 degrees and reverts to its solid form, that energy is released.

The Carboneras plant's latent heat storage system

The Carboneras plant now boasts the world's largest high-temperature latent heat storage facility.

"The advantage of such a system is its capacity to store large amounts of energy in a small volume and with a minimal temperature change," said Doerte Laing, Thermal Energy Storage Research Area Manager at the DLR Institute of Technical Thermodynamics. "The energy in the system can be transferred and absorbed very efficiently by phase transition at a constant temperature."

Researchers plan to keep the plant in use until the end of the year. They will be validating the direct solar steam generation process itself, the storage methods, and the flexible pipe connections that are necessary for the mirror and receiver tube assembly to pivot as it tracks the Sun.

About the Author
Ben Coxworth An experienced freelance writer, videographer and television producer, Ben's interest in all forms of innovation is particularly fanatical when it comes to human-powered transportation, film-making gear, environmentally-friendly technologies and anything that's designed to go underwater. He lives in Edmonton, Alberta, where he spends a lot of time going over the handlebars of his mountain bike, hanging out in off-leash parks, and wishing the Pacific Ocean wasn't so far away.   All articles by Ben Coxworth
2 Comments

What kind of output are they hoping for? Or what do they need to achieve to equal `viability'?

Earl Leonard
5th April, 2011 @ 09:23 pm PDT

Can the superheated material be shipped around to local power plants, by ship or rail? Youn could have smaller generators and long distance transmission lines, and set up the heat factories elsewhere, like the sahara or where land is idle

Paucus
12th July, 2012 @ 04:52 am PDT
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