General Motors has taken a number of significant steps to make their vehicles greener, and they are doing similar things with their manufacturing plants, as well. This week, the company has made two announcements about using rooftop solar arrays to power its manufacturing facilities.
The Detroit–Hamtramck plant, which produces the Chevy Volt, will be having a 516 kilowatt solar array installed on six acres of land on the south side of the plant as part of a cooperative venture with the local electrical utility company, DTE. Using power from the solar array is expected to save GM $15,000 per year.
Researchers at Wake Forest University have developed a new type of polymer solar-thermal device that combines photovoltaics with a system that captures the Sun‘s infrared radiation to generate heating. By taking advantage of both heat and light, researchers say the device could deliver up to 40 percent savings on the cost of heating, as well as helping reduce power bills by producing electricity.
The hybrid cell is designed with an integrated array of clear tubes, five millimeters (approx 1/4 inch) in diameter. Lying flat, visible sunlight shines into the clear tube which is filled with an oil blended with a proprietary dye, heating the oil which then flows into a heat pump to transfer the warmth inside a home.
Electrical current is produced via a polymer photovoltaic sprayed onto the back of the tubes.
The result is a solar-thermal device with an impressive 30 percent conversion efficiency.
In comparison to flat solar cells, the tube design also has the advantage of being able to capture light at oblique angles, so it can accumulate power for a much longer stretch in the day and be more readily integrated into building materials – it could be produced to resemble a roofing tile for example.
The research team aims to produce a 3 foot square solar thermal cell over the coming months, a key step in bringing the technology closer to market.
“It’s a systems approach to making your home ultra-efficient because the device collects both solar energy and heat,” said David Carroll, Ph.D., director of the Center for Nanotechnology and Molecular Materials at Wake Forest University. “Our solar-thermal device takes better advantage of the broad range of power delivered from the sun each day.”
Mechanical engineers at Arizona State University are experimenting with graphite as a cheap way of augmenting the efficiency of solar thermal systems by improving the heat-absorbing properties of liquid used for generating steam.
“We estimate that this could mean up to $3.5 million dollars per year more revenue for a 100-megawatt solar power plant,” said Robert Taylor, a graduate student in mechanical engineering at Arizona State University.
The team from Arizona State University turned their attention to the solar thermal collectors, an essential part of a solar thermal power system, also known as concentrating solar power systems. The collectors focus sunlight to heat liquid that makes steam which drives a turbine to generate power.
“The big limitation of PV panels is that they can use only a fraction of the sunlight that hits them, and the rest just turns into heat, which actually hurts the performance of the panels,” said Mr. Taylor. In contrast, solar thermal collects and uses the heat which would be lost by PV.