IBM announced its involvement in a collaboration to develop an affordable photovoltaic system capable of concentrating solar radiation 2,000 times and converting 80 percent of the incoming radiation into useful energy.
The effort to develop a High Concentration Photovoltaic Thermal (HCPVT) system is funded by a three-year, $2.4 million grant from the Swiss Commission for Technology and Innovation awarded to scientists at IBM Research; Airlight Energy, a supplier of solar power technology; ETH Zurich’s Professorship of Renewable Energy Carriers and Interstate University of Applied Sciences Buchs NTB (Institute for Micro- and Nanotechnology MNT). The HCPVT system can provide desalinated water and cool air in sunny, remote locations where they are often in short supply.
IBM made its announcement on April 22, Earth Day. Based on a study by the European Solar Thermal Electricity Association and Greenpeace International, technically, it would only take 2 percent of the solar energy from the Sahara Desert to supply the world's electricity needs. Unfortunately, current solar technologies on the market today are too expensive and slow to produce, require rare Earth minerals and lack the efficiency to make such massive installations practical, IBM said.
“The prototype High Concentration Photovoltaic Thermal (HCPVT) system is unique in that it is highly efficient at harnessing the sun's radiation using affordable materials, like cement,” Christopher Sciacca, communications manager at IBM Research – Zurich, told eWEEK. “This will reduce the cost by 3 times when compared with similar systems. If we are successful we can change the conversation about the cost of fossil vs. solar because the levelized cost of energy will be less than 10 cents per kilowatt hour (KWh). For comparison, feed in tariffs for electrical energy in Germany are currently still larger than 25 cents per KWh and production cost at coal power stations are around 5-10 cents per KWh.”
The prototype HCPVT system uses a large parabolic dish, made from a multitude of mirror facets, which are attached to a sun-tracking system. The tracking system positions the dish at the best angle to capture the sun's rays, which then reflect off the mirrors onto several microchannel-liquid cooled receivers with triple junction photovoltaic chips--each 1x1 centimeter chip can convert 200-250 watts, on average, over a typical eight hour day in a sunny region.
The entire receiver combines hundreds of chips and provides 25 kilowatts of electrical power. The photovoltaic chips are mounted on micro-structured layers that pipe liquid coolants within a few tens of micrometers off the chip to absorb the heat and draw it away 10 times more effective than with passive air cooling.
The coolant maintains the chips almost at the same temperature for a solar concentration of 2,000 times and can keep them at safe temperatures up to a solar concentration of 5,000 times, IBM said.
The direct cooling solution with very small pumping power is inspired by the hierarchical branched blood supply system of the human body and has been already tested by IBM scientists in high performance computers, including Aquasar. An initial demonstrator of the multi-chip receiver was developed in a previous collaboration between IBM and the Egypt Nanotechnology Research Center.
“For the past several years scientists in Zurich have been focused on using hot water to cool supercomputers and we have successfully demonstrated this with Aquasar and SuperMUC, which was in June 2012 the fastest supercomputer in Europe,” Sciacca said. “In a collaboration with the Egypt Nanotechnology Research Center this same concept was developed to also cool chips used in a solar concentrator. This is a significant achievement in that we can harness the solar radiation of the sun 2000x. In fact, our calculations support it up to 5,000 times.”
"We plan to use triple-junction photovoltaic cells on a micro-channel cooled module which can directly convert more than 30 percent of collected solar radiation into electrical energy and allow for the efficient recovery of an additional 50 percent waste heat," said Bruno Michel, manager, advanced thermal packaging at IBM Research, in a statement. "We believe that we can achieve this with a very practical design that is made of lightweight and high-strength concrete, which is used in bridges, and primary optics composed of inexpensive pneumatic mirrors--it's frugal innovation, but builds on decades of experience in microtechnology.”