Cool Earth Solar makes power with 'balloons'

Cool Earth Solar has raised at least $21 million (£11 million) to further develop a solar generator that you could mistake for a shiny kiddie pool. The Livermore, California-based company uses a radical technique called concentrated solar photovoltaics, in which light is magnified onto solar cells to maximise electricity output.

Cool Earth Solar plans to manufacture plastic balloons that will be suspended on metal and wire structures. These round balloons reflect light onto a solar cell to generate electricity.

Because its design uses relatively cheap and readily available components, these solar concentrators can generate electricity at a cost comparable to that of natural-gas plants. The inflated solar collectors can withstand 100 mile-per-hour wind.

The setup can also be unfurled globally, rather than only in places with available funding for expensive energy projects. The company says it's negotiating with utilities to sell electricity from its solar farms.

Although most people envision rooftop panels when they think of solar electricity, many new solar technologies are being developed for power plants. Utilities in some US states, notably California, need to comply with renewable-energy mandates. And certain regions, such as the desert in America's southwest and parts of Spain, are well-suited for solar-thermal power plants.

Concentrating solar photovoltaic arrays are also being tried for industrial-scale solar power, but unlike Cool Earth Solar's balloons, these use sophisticated mounting systems and expensive solar cells. We like the balloon effect.

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