Solar technology could offset natural gas use

By Erin Voegele | January 12, 2009
Colorado-based Abengoa Solar Inc., a subsidiary of Spain-based Abengoa S.A., recently announced that its solar thermal technology is available to biofuels producers, offsetting the use of natural gas at production facilities.

Abengoa Solar's technology uses a parabolic mirror to focus the sun's direct beam radiation onto a receiver tube, said Sales Manager Peter Thompson. "The receiver is a pipe that absorbs the sun's energy, heating the transfer fluid inside," he said. "The heat transfer fluid is pumped throughout the solar field, gathering solar thermal heat energy. The heat energy is then circulated through a heat exchanger, providing either hot water for a boiler feedwater system or in some cases steam using a steam generator." Depending on the temperature required, the heat transfer fluid may consist of water, water and glycol, or specialized oil.

Thompson said the technology is best suited for areas where clear, sunny days are common, such as in the Southwest. "As most renewable energy systems go, a supplemental source of energy is required when the sun is not available," he said. The system is typically partnered with a boiler system to offset the use of natural gas, he added.

Not only does the technology offset natural gas costs, but it also reduces greenhouse gas emissions, Thompson pointed out. Due to its design, the technology requires less equipment to produce the same amount of power when compared with flat plate designs. According to Abengoa, solar thermal systems are eligible for a 30 percent federal investment tax credit and accelerated depreciation. In states with renewable energy portfolios, rates of return may be even more attractive.

"The use of solar energy, in contrast to natural gas, provides a measure of energy price stability," Thompson said. "Environmentally, the use of solar energy at a biofuels plant will greatly increase its net energy gain and will answer a major criticism leveled against the industry."