JAN 19

Solar power towers have proven to be a fairly efficient way of converting solar energy into electricity. In a solar power tower, energy from a large array of mirrors focused onto a tower that captures the heat in some way, and then converts that heat to electricity using a boiler and turbine. It's a great system, but building that heat-resistant tower and pumping all of those fluids up and down can be pretty expensive.

Which is why researchers at the Masdar Institute, the Tokyo Institute of Technology and Cosmo Oil are working together on "beam down" solar. Instead of having the heat-capturing system up on that big tower, a second set of mirrors directs the light back down at the ground where it can be captured by a system that doesn't have to be suspended many stories in the air.

It's certainly cheaper than a traditional solar power tower. The bad news is that the extra set of mirrors lowers the efficiency of the system by about 20%. If that can be made up for with reduced capital costs, however, they could be in business. In the end, creating cheap ways of capturing solar energy is probably going to be more important than creating efficient ways.

Of course, the project is still in the early phases...they haven't even hooked it up to a boiler yet. But the initial prototype seems promising.

Via GreenTechMedia

Comments (5)

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written by Jess @ Openly Balanced, January 19, 2010

Does the possibility of a ground heat-capturing system make it technologically feasible to construct them on top of existing structures? If so, it seems like that could make another big difference in capital costs.

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It seems a bit more practical than conventional methods but...
written by Karl, January 21, 2010

Why wouldn't a lens of some sort work to focus the light to a specific area on the ground? Not a conventional glass lens but perhaps some kind of composite could work. Adjusting for the angle of the sun may pose problem but there has to be a way to engineer around that, and it seems like it would be as cost effective as a massive amount of mirrors...

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With a little work might this work with desalinization, simultaneously?
written by Me, January 27, 2010

Might waste heat (post generator) might be enough to heat the water through stages of distillation which go back upward, building potential energy for distribution down and away?
I'm eager to learn more about this and the structural stability.

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written by rattle, February 07, 2010

Rather than use huge arrays of mirror to reflect the light up as this article discusses, why don't they use a single huge lens, like a magnifying glass or fresnel lens that would concentrate the sunlight DOWN onto the tank of fluid? The lense could be computer guided to keep the light focused throughout the day. It seems this would reduce the land space needed by the mirrors on the ground and could possibly give the same concentration of engergy.

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The other side
written by Brian, February 16, 2010

Well, if elevating the receiver is expensive, and adding another set of mirrors is too lossy, what about elevating the primary mirrors?

You could use a natural or man-made slope (picture an amphitheater) and put the collector on the flat part at the bottom. There are some parts of the southwest where the cliffs are near vertical!

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