Researchers find ways to make solar more efficient

University researchers in Canada and the U.S. are coming up with promising ways to draw on the sun for energy. These solar technologies will eventually mean energy savings for buildings and could even help to clean up the oil sands.

At the University of Western Ontario in London, scientists have found a “game changing” approach that they say could easily be fast-tracked and integrated into the manufacture of solar panels in one or two years.

Giovanni Fanchini, the Canada Research Chair in Carbon-based Nanomaterials and Nano-optoelectronics at Western, led a team that is applying gold as an extremely fine “fishnet” of antennae to solar cells. Because gold’s yellow colour matches the spectrum of light of the sun, it amplifies the solar energy hitting the cell and improves its performance by 10 per cent.

While this ability of gold nanoparticles to magnify the energy was already known, Fanchini’s approach uses only 144 atoms of gold, which he says is a “ridiculously small amount” and 10,000 times less than previous studies. The “gold nanoclusters” are modular so can be added onto the existing production process. The team is already working with manufacturers on potential prototypes.

Also recently reported was the work of a team of electrical engineers at Stanford University in California who have found a way to overcome one of the major problems with solar cells — their tendency to overheat. Solar energy that hits the solar cell and is not converted to light becomes waste heat. Cells can heat up to 130 degrees Fahrenheit, which not only saps their efficiency but also wears them out so they have a shorter lifespan.

Professor Shanhui Fan’s team is adding specially patterned layers of silica glass to the solar cell surface. The silica layer is made of pyramid and microcones, one-thousandth of a millimetre thick. The layers act as a passive means for the cell to send infrared radiation back into the atmosphere and space.

Meanwhile, researchers at Ohio State University have just published details of their invention of a device which is a combination solar cell and battery. It recharges itself using air and light.

Last but not least, civil engineers at the University of Alberta are testing a treatment process for removing toxins found in oilsands tailings ponds. The team led by Professors Mohamed Gamal El-Din and James Bolton is using a process that combines sunlight with chlorine. The renewable energy source is just as effective — removing 75-84% of toxins in lab tests — as UV lamps, but it is much less costly.

To make the solar UV/chlorine process work, the researchers have to find ways to get the solar energy to penetrate the water in the ponds.

Professor Gamel El-Din explained: ”Because we are limited by the sunlight’s penetration of the water, we now must come up with an innovative design for a mixing system, like rafts floating on the ponds, that would circulate the water. Installing this would still be much more cost-effective for companies. It is expected that the UV/chlorine process will treat the oilsands process affected water to the point that the effluent can be fed to a municipal waste water treatment plant, which will then complete the purification process sufficiently so the water can be discharged safely into rivers.”

The professor says that the solar UV/chlorine treatment process could also be adapted for municipal waste water treatment plants.

Tailing ponds can contain suspended solids, hydrocarbons, acids and benzene.

To read about the research at the University of Western Ontario, click here.

To read about the research at Stanford University in California, read the report in phys.org here.

To read about the research at Ohio State University, read the report in phys.org here.

To read about the research at the University of Alberta, click here.