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Cool Earth Solar: pursuing a viable alternative to fossil fuels

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October 25, 2008

The Cool Earth concentrator design

The Cool Earth concentrator design

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October 25, 2008 There is no doubt that mankind stands at a pivotal point in our history in relation to our consumption of global resources and the resultant impact on the planet on which we live. By far the biggest concern is our ever-growing appetite for energy to power the lifestyles we have grown not only accustomed to, but also dependent upon. Solar is one answer with great potential, but economics and the amount of power it can produce in comparison to fossil fuel power stations has held it back so far. Now new approaches like Cool Earth’s collectors are becoming advanced enough to effectively tackle these problems with technology that relies on inexpensive and free materials, is scalable, able to compete economically with fossil fuel power plants and is capable of delivering not just megawatts, but gigawatts of clean power.

The 2008 EIA International Energy Outlook Report stated that in 2005 electric power plants produced 17,320 terawatt-hours (TWh) worldwide - in 2030, the world is projected to need about 33,264 TWh, or nearly double that amount. Clearly, the finite resources of coal, oil and natural gas are not going to be enough to meet these needs - the experiences over the past few years in relation to oil production and prices are proof enough of that. Such economic concerns do not even take into account the rapidly accelerating effects of global warming caused by the burning of these fossil fuels.

Although technological breakthroughs seem to be made every other day in the areas of solar power, it takes time for new technology to be developed and made real-world ready. The other major concern is that even though many large-scale solar plants are being built around the world, they are still well behind fossil fuel burning plants when it comes to energy output. There are plans underway to build 100 MW and 500 MW plants in Nevada and California respectively within the next four years and Australia also has plans for a large scale solar concentrator station with a 154 MW facility powering more than 45,000 homes. But, when you consider that the average coal plant has an output of anywhere from 1000-5000 MW and the average nuclear plant from 600-1200MW, it is easy to see why solar is still discounted as a viable alternative.

Now California based company Cool Earth believes it has overcome these problems with its concentrated photovoltaic (CPV) technology. While most existing photovoltaic (PV) systems take the form of flat panels, such as those found on rooftops in the form of solar hot water heaters, or boxes-with-lenses and require large amounts of heavy, expensive materials, Cool Earth’s patented CPV technology instead uses inflated solar concentrators. These concentrators are shaped like balloons and are primarily made of PET (polyethylene terephthalate) polyester film and air - a design approach that Cool Earth says radically reduces material requirements as well as plant deployment costs and time.

Each 8-foot-diameter concentrator consists of a transparent upper hemisphere and a reflective lower hemisphere. When inflated with air, the concentrator naturally forms a shape that focuses or concentrates sunlight onto a PV cell placed at the focal point. This means fewer cells are needed to produce a lot more electricity. In fact, a single cell in one of Cool Earth’s concentrators generates about 300 to 400 times the electricity of a cell without a concentrator. The inflated structure is naturally strong and aerodynamically stable, able to withstand winds of 125 miles per hour. The transparent upper surface of the concentrator also has the added benefit of protecting the PV cell and mirrored surface from the environment, including rain and snow, as well as insects and dirt.

Each concentrator has additional structural components: a small steel strut and a harness. The steel strut, tethered in place, holds the cell at the focal point inside the concentrator and provides a conduit for a small water loop that cools the cell – this is in contrast to the large, material-intensive heat spreaders and sinks used by most other CPV companies. Completing the structure is a lightweight, flexible steel band, which forms a harness around the circumference of the concentrator and is used to hold and point the concentrator.

The patented support system used to keep the concentrators in place is based on the architectural principles of tensegrity, whereby structures stabilize their shapes by continuous tension or "tensional integrity" rather than by continuous compression. Since this method negates the need to design to protect against buckling, which only occurs in compression, the amount of steel used in the structure can be reduced by 60 times and, since there are no concrete forms or footings, and no bulldozing, animals can graze and take shelter beneath the arrays. All in all Cool Earth say that the resulting system of wood posts and steel cables uses a minimum amount of material, has a small footprint, and causes the least disruption to the natural environment of any solar power plant.

Cool Earth claims that one solar power plant, using Cool Earth's technology, covering 150 miles by 150 miles, would generate enough power to meet all the electrical needs of the United States through 2030. Before ateempting anything near that size Cool Earth is building a small prototype solar plant near its Livermore headquarters and will launch its first commercial-grade plant this winter to prove it can scale its technology. The plant will only produce 1.4 MW, but they plan to launch a full size 10 to 30 MW plant by next summer. While initially the projects will be in California and the South West US, Cool Earth want to expand overseas.

“To address the global energy problem, we’ve got to scale bigtime worldwide,” says Cool Earth Solar CEO Rob Lamkin. For those of you already making plans to throw a few concentrators on the roof, think again. The system can only be installed on the ground and, once it is fully certified, the plans are to make it available for commercial and industrial use.

While rooftop solar panels and individual efforts of energy conservation are an important part of fighting global warming, it is the governments of the world, and in particular the developed world, that must commit to cleaner, greener energy sources – not just in words, but also in action – to ensure that the planet has a future. The amount of sunlight that hits the Earth's surface in one hour is enough to power the entire world for a year and at the moment the world is harnessing barely a fraction of that potential power.

Technologies such as that developed by Cool Earth can hopefully provide a real alternative to mankind’s dependence on fossil fuels and convince governments, particularly in developed countries, that solar is a technology whose time has come. To point the finger at developing nations and say, “but they aren’t doing anything”, is simply counter-productive. Developing nations need to take the initiative and provide an example to the rest of the world. Although the initial monetary costs may be higher than simply continuing on with fossil fuels, the cost to mankind in terms of lost food production caused by changing weather patterns and myriad unforeseen consequences could be much, much higher.

For further info visit Cool Earth Solar.

Darren Quick

About the Author
Darren Quick Darren's love of technology started in primary school with a Nintendo Game & Watch Donkey Kong (still functioning) and a Commodore VIC 20 computer (not still functioning). In high school he upgraded to a 286 PC, and he's been following Moore's law ever since. This love of technology continued through a number of university courses and crappy jobs until 2008, when his interests found a home at Gizmag.   All articles by Darren Quick
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