IBM solar array will 'harness the energy of 2000 suns'

Several teams of scientists, including IBM Research, have announced a collaboration to develop an affordable solar array capable of concentrating the captured energy by 2000.

Renewable energy is thankfully on the rise, but our harvesting methods could be — and will need to be, if it is to become mainstream — more efficient. In fact, according to a study by European Solar Thermal Electricity Association and Greenpeace International, the entire world's electricity needs could be met with just 2 per cent of the solar energy from the Sahara Desert — but our current solar technologies just aren't up to the task.

To remedy this, IBM Research, along with Airlight Energy, ETH Zurich and the Interstate University of Applied Sciences Buchs NTB have been awarded a three-year, US$2.5 million grant from the Swiss Commission for Technology to develop a High Concentration PhotoVoltaic Thermal (HCPVT) system.

The system, currently being tested in the prototype stage, is based on a parabolic dish lined with mirror facets, and will be attached to a sun tracking system to capture the maximum sunlight possible. The sun's light is reflected off the mirrors onto micro-channel liquid-cooled receivers with hundreds of triple-junction photovoltaic chips — each of which is capable of converting 200 to 250 watts over an eight-hour period. Overall, the system could provide 25 kilowatts of electrical power per day.

It is thanks to the liquid coolant, inspired by the branched blood supply in the human body, that the HCPVT system is able to concentrate the solar radiation by 2000. Far more effective than passive air cooling, it maintains a consistent safe temperature for the chips, and can keep those temperatures safe for a solar concentration rate of up to 5000 times.

But the HCPVT has a few more tricks up its sleeve. Not only does the dish convert solar energy to electrical energy, it also converts solar energy to thermal energy. This thermal energy can aid in the supply of fresh water, and provide cool air via adsorption cooling.

The heat will be collected using a method IBM Research developed for cooling high performance computers. Water will be used to absorb the heat from the system. It will then be used to heat salty water, which is passed through a porous membrane distillation system, where it is converted to steam, removing the salt.

To cool air, the HCPVT would provide heat for a thermal-driven adsorption chiller.

Because of its high power output, the teams believe they can reduce the cost of electricity by two thirds. This would be particularly useful in developing nations, but the scientists are setting no upper limit on its potential applications. They are particularly interested in southern Europe, Africa, the Arabic peninsula, the south-western part of the United States, South America and Australia.