Thursday, July 2, 2015

Solar energy farms in dessert regions-A novel strategy to co-generate bio-fuel

Solar energy is one of the most researched areas of renewable sources of power and in the last one decade lots of investments have been made in erecting solar panels in all countries, especially tropical ones with maximum exposure to sun light. China to day stands tall among all developing countries and even outpaces many wealthy countries in making cheap solar panels and producing huge quantum of power through them. In India also the present government, after waking up to the real potential of solar energy has substantially enhanced its target to produce solar power across the country. Though cost wise solar power may not be in a position to out-prize conventional energy from fossil fuels, hydroelectric or coal, progressive lowering of prizes of solar panels is bringing it almost on par with them. If scientists from an American University are to be taken seriously, millions of hectares of desert land that sprawl across all the continents, are right candidates for setting up giant sized "solar farms" that can generate solar power plus bio-energy materials which can be very attractive to potential investors. Here is a take on this exciting development which deserves attention by the authorities in India.

"Solar farms that would "co-locate" carefully selected crop plants between rows of photovoltaic panels might produce an energy "win-win" yield of electricity and biofuel, researchers at Stanford University say. Computer models suggest the solution is ideal for sunny and arid regions in the U.S. Southwest, they say. "Co-located solar-biofuel systems could be a novel strategy for generating two forms of energy from uncultivable lands: electricity from solar infrastructure and easily transportable liquid fuel from biofuel cultivation," Stanford postdoctoral researcher Sujith Ravisays. Ravi and environmental Earth system science professors David Lobell and Chris Field are conducting the research at the university's Stanford Woods Institute for the Environment. Solar farms create electricity out of sunlight, but a supply of water is needed to wash dust from the solar panels to make sure they run at maximum efficiency. To minimize the spread and buildup of dust, the ground around the photovoltaic panels is also kept moist with water. Desert-tolerant plants planted between and underneath the panels could use the excess water running off the panels, and as they grow could anchor the soil, cutting down on the problem of dust. Such a system could allow solar farms to operate with reduced water needs, Ravi says. "It could be a win-win situation," he says. "Water is already limited in many areas and could be a major constraint in the future. This approach could allow us to produce energy and agriculture with the same water." Not just any crop would be appropriate, the researchers acknowledge, and food crops in particular are not well-suited to arid desert regions. However, there is perfect candidate crop well-suited to the inhospitable environment, they say: Agave. The prickly plant, known to most people as the source of tequila, thrives on poor soil and high temperatures in its native North and South America. Tequila aside, they say, it can be a source for liquid ethanol, which as a bio fuel can be blended with gasoline or operate as a sole source of power for ethanol vehicles. For that purpose it's even better than many food crops already being used as biofuel stock, Ravi says. "Unlike corn or other grains, most of the agave plant can be converted to ethanol," he says".

Though the scientists have excited the whole world with their computer generated model studies, it is not known whether any experimental solar farms is working any where presently. Agave is a fructose rich plant used extensively in South America to produce the alcoholic beverage Tequila and this has amply demonstrated its ability to produce ethanol which is the most commonly accepted bio fuel in the world to day. What is to be proven is whether Agave plant can grow with high productivity in all deserts in the world. Setting up solar plants in desert also needs some water for keeping the panel surface free of dust for maximum photo voltaic efficiency and despite the computer simulation offering some hope for future co-generating solar farms, imponderable ground conditions will have to be assessed before such farms become a reality.


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