Tuesday, 12 October 2010
Future of solar energy continues to brighten
BY PAUL HANLEY, THE STARPHOENIX OCTOBER 12, 2010 1:02 PM
STORYPHOTOS ( 1 )
New technologies could make today's solar cells much more efficient and much cheaper.
Photograph by: Joe Raedle, Getty Images
Sunlight is a potentially limitless source of environmentally friendly electrical energy. Trouble is, most of its applications are more costly than mainstream alternatives like coal or natural gas.
But that may be changing as the costs of solar technology decline and we begin to appreciate the full costs of mainstream sources, including environmental costs.
Already, solar is cheaper than nuclear energy, according to a study called Solar and Nuclear Costs -- the Historic Crossover. The controversial report, prepared for a U.S. non-profit, concludes that the crossover -- the point where rising costs of nuclear intersect with the declining costs of solar -- happened this year at 0.16 $/kWh.
Importantly, the comparison of final power costs to consumers is dependent on local conditions, such as the average amount of sunshine in an area and the various subsidies, rebates and tax credits available.
The study shows the cost to a consumer of power from a solar system they install in their home is equivalent to about 0.35$/kWh. However, when various government incentives are accounted for, the cost drops to just under 0.16$/kWh.
On the nuclear side, costs are in the 0.12-0.20$/kWH range, but the report concludes that the transmission and distribution costs increase the cost to 0.22$/kWh. The average cost of nuclear power to the consumer, subsidies in, would be 0.16$/kWh, just above those of solar.
What the comparison does not appear to include is the environmental costs and liabilities of the two energy systems, which clearly favour the solar approach.
Even if this report is right, solar is still much more expensive than coal and gas as a source of power. But green energy advocates are working on that. The Rocky Mountain Institute, for example, has been working with the solar industry to figure out how to reduce "balance of system" costs for solar.
Balance of system (BoS) costs are all the costs associated with solar energy except the actual photovoltaic panel that produces the electricity. These would include business processes, installation, racks, site preparation, wiring, inverters and so on. Currently, BoS costs are about $1.60 per watt of solar power capacity, but RMI is working with industry to introduce changes that would reduce these costs to nearly half that amount.
The next step would be to reduce the costs of photovoltaic panels themselves and/or to substantially improve their efficiency. The goal is to get solar power costs down to 0.10$kWh unsubsidized, which would be a real game changer.
Fact is, solar power costs are already much lower than they used to be. This has made solar the cheapest option in a number of situations, such as small-scale applications in remote areas. Thousands of Saskatchewan farmers, for example, use solar to pump water for pastured livestock.
Now Scientists at the Center for Advanced Molecular Photovoltaics at Stanford have published research that promises to increase the output of solar cells by 1,000 per cent, while reducing costs. The key is nanotechnology.
According to their report, ultra-thin solar cells can absorb sunlight more efficiently than the thicker, more expensive-to-make silicon cells used today. This is because light behaves differently at scales around a nanometer (a billionth of a metre). They calculate that by properly configuring the thicknesses of several thin layers of films, an organic polymer thin film could absorb as much as 10 times more energy from sunlight than previously thought possible.
Light trapping has been used for several decades with silicon solar cells and is done by roughening the surface of the silicon to cause incoming light to bounce around inside the cell for a while rather than reflecting right back out.
The Stanford researchers have discovered that light can be confined for a much longer time when the materials in the solar cell are extremely thin. Overcoming the conventional limit opens a new door to designing highly efficient solar cells.
Nanoscale solar cells also offer savings in material costs, as the organic polymer thin films and other materials used are less expensive than silicon and, being nanoscale, the quantities required for the cells are much smaller.
© Copyright (c) The StarPhoenix
Posted by Reg Illingworth at 21:28