CitiesGoGreen - February 2009 - (Page 13) Solar Balloons Could Power the Earth Utilities may soon be getting megawatts from solar balloon installations. Using small amounts of inexpensive materials, and suitable for a wide variety of locations, they could scale quickly and become a major energy source. he 20-pound balloon, eight feet across, shines in the sun. The balloon’s transparent top allows light to enter, where it is reflected from the aluminum-coated, highly reflective lower part and concentrated on one point. This puts all the light energy on a water-cooled photovoltaic cell, held in place by a steel arm. Interior air pressure is continuously monitored and adjusted to maintain the perfect shape to concentrate the reflected light on the collector. by Sam McNeil Because the light is so concentrated, the PV cell generates 300-400 times more electricity than it would in a one-sun environment. Each balloon generates one kW. Two or three could power a home, and the United States could be powered by an installation 150 miles by 150 miles, supplying all its electrical needs through 2030, according to the developer, Cool Earth Solar. The balloons, suspended in a web of wooden posts and steel cables 10-20 feet above the ground, pivot in two dimensions, following the sun for maximum results. The pole-based installation minimizes site preparation as well as ecological disruption. It also means the balloons can be installed in many more locations than conventional solar collection systems, including rolling hills or even in working agricultural lands such as vineyards. The skin of the balloons is the tough but inexpensive and recyclable plastic film used to bag potato chips and other snacks. The bottom half is aluminum coated: one T soda can contains enough material for 725 balloons. Each balloon is able to support a person’s weight and withstand 125 mph winds. The other components of the system are also readily available: wooden poles, steel cables, and stamped metal parts. Altogether the material used is a small fraction of what other solar photovoltaic systems require. The balloons must be replaced every year or two, but take only 15 minutes to install in the patented “tensegrity” suspension system, making maintenance low cost. The result is a solar concentrator 400 times cheaper than competitive systems. “Our major structural element is air, which so far is free,” says Cool Earth Solar CEO Rob Lamkin, “ and the sun isn’t taxed either.” Founder Eric Cummings believes the generating system’s installed cost at scale will be a dollar a watt, less than natural gas but still more than coal, a target for the future. Even aside from improvements in Cool Earth’s technology or production costs, a cap and trade system on carbon dioxide emissions could raise the cost of coal-fired electricity, leveling the playing field. Installations can be near existing power lines, minimizing the need for new grid infrastructure, another costly part of the equation. A prototype facility of 100-200 balloons producing 100-250 kW is under construction near the company’s headquarters in Livermore, CA. The intent of the experiment is to test and adapt the technology for industrial production. Then comes a 10-30 MW commercialsized plant in 2009. Cleantechnica.com quotes Lamkin as saying, “Initially, we’ll be doing projects in California and the Southwest, but we do want to expand overseas. To address the global energy problem, we’ve got to scale bigtime worldwide.” Cool Earth estimates new plants will take six months to construct. The plan is for the company to build and operate the facilities, giving utilities a clean, renewable energy supply which can scale to need. Eventually the company also intends to offer commercial systems and to build systems in rural off-grid areas, bringing power to the poorest. v Sam McNeil is a freelance environmental convergence journalist based out of Seattle, moving to Tunisia to study Arabic and the growing Sahara Desert. 13 February/March 2009 http://peswiki.com/index.php/Directory:Cool_Earth_Solar http://citiesgogreen.com/issues/february-2009/current-features/solar-balloons-could-power-the-earth http://citiesgogreen.com/issues/february-2009/current-features/solar-balloons-could-power-the-earth http://www.Cleantechnica.com http://cleantechnica.com/2008/09/30/cool-earth-solar-constructing-first-solar-balloon-prototype-plant/ http://www.coolearthsolar.com/ http://www.CitiesGoGreen.com
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