Cool Earth Solar has one of those radical green-tech ideas that may actually make a real commercial impact.
In the next two weeks, the company plans to start testing a prototype solar plant built around rows of reflective balloons hung on poles. The solar balloons, which are eight feet in diameter, look something like a tube for sledding or laying around the pool, but each one can generate 1 kilowatt of electricity.
An early version of Cool Earth Solar's solar concentrator without the 'receiver' that holds the solar cell.
(Credit: Cool Earth Solar)It's a design that combines cheap building materials, notably plastics, with expensive high-efficiency solar cells. Light goes through the side of the balloon facing the sun, is reflected on an aluminum coating on the bottom, and is concentrated onto solar cells in a "receiver."
The method can concentrate light between 300 and 400 times. To keep heat under control, the balloons have an automated water-cooling system.
The test installation for Cool Earth Solar, which was founded in 2006, will be small--on the order of a few dozen suspended balloons, according to a company representative. That's so that the company can make changes to the second version of its concentrating solar balloon.
Following that test system, which will generate about 100 or 200 kilowatts of electricity when done, the company intends to start building a 1.5-megawatt commercial solar power plant this winter, said CEO Rob Lamkin. One and half megawatts is enough power to supply about 400 or 500 U.S. homes. That installation, expected to be constructed in Tracy, Calif., will sell electricity to a utility.
Following that, Cool Earth Solar hopes to ramp up quickly, Lamkin said. It is planning another test facility, sized at 10 megawatts, for next summer, he said.
Unlike the rest
Cool Earth Solar's design is nothing like most concentrating photovoltaic (CPV) systems, which concentrate sunlight onto solar cells to make electricity.
Typically, concentrating solar devices use lenses and mirrors to direct and focus light to squeeze more electricity from high-end cells. The lenses, as well as the mounting and cooling systems, add significantly to the cost.
Cool Earth Solar's device, too, concentrates light onto expensive solar cells. But using materials like aluminum-coated plastic--the same sort of thing you'd find in a Power Bar wrapper--means the company can make electricity at $1 per watt, a few dollars per watt cheaper than other companies, Lamkin said.
Early version of Cool Earth Solar's concentrators mounted on poles.
(Credit: Cool Earth Solar)He said that Cool Earth Solar will be able to sell electricity to utilities at the low end of what solar power plant providers project, which is in the range of 10 cents to 14 cents per kilowatt-hour.
Equally significant to cost is the flexibility that the balloons allow in terms of location.
Concentrating photovoltaic systems demand the right sun conditions, making them suitable only for certain areas like the southwest United States. That has set off a race among solar technology companies to find and get approvals for appropriate land. But Lamkin said that Cool Earth Solar is looking at a far broader set of possible locations where land is not as much in demand.
"It turns out, land is not an issue for us," he said. "What's exciting is because we are modular, we don't need to find super flat land in the lower Mojave desert. We're happy to be in farm land in rural California that no other solar companies are going after."
Cool Earth Solar raised $21 million in funding earlier this year. Lamkin said the company doesn't intend to raise more money in the coming year.
Cool Earth Solar on Thursday said it has raised at least $21 million to further develop a solar generator that you could mistake for a shiny kiddie pool.
The Livermore, Calif.-based company said the Series A round, from undisclosed investors, could be augmented by other investors in 60 days.
A ballon that makes electricty.
(Credit: Cool Earth Solar)Cool Earth Solar has taken a radical approach to building a solar-power plant using a technique called concentrated solar photovoltaics, in which light is magnified onto solar cells to maximize electricity output.
It plans to manufacture plastic balloons, which 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 plastic solar collectors are mounted.
(Credit: Cool Earth Solar)Our goal from the very start was to find a clean-energy generation solution that could address the global scale of the carbon problem. We discarded everything that couldn't scale, relied on rare components, or had some other critical bottleneck. Ultimately, we developed a novel technology which radically reduces the amount of material in our system and balances labor and capital costs.
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 states, notably California, need to comply with renewable-energy mandates. And certain regions, such as the Southwest U.S. desert 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, these use sophisticated mounting systems that track the sun and expensive solar cells.
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