Wednesday, 8 November 2006

Sun and wind small players with great future

Weekend Australian
Saturday 4/11/2006 Page: 38

SOLAR energy and wind power have long been seen as holding great promise, but systems currently in place have needed government support to be even close to commercial viability.

But key problems are slowly being overcome, and costs slowly coming down. While a cost structure for renewable energy that is comparative with power from conventional sources is not exactly around the corner, it is at least foreseeable.

Ray Prowse of the Australian National University's Centre of Excellence for Solar Energy Systems, regarded as the leading research body in the field in Australia, points to inverters to allow solar electric (photovoltaic) systems to be seamlessly linked into the national power grid as a crucial turning point.

Solar cells create an electric current that is "direct' (DC), not the "alternating' (AC) current required by the grid. "The grid requires 240 volts AC current at 50 Hertz," notes Prowse. "The Commonwealth Government, through the Australian Greenhouse Office, has supported the uptake of solar systems through various rebate programs.

The requirements of the programs are that the systems must be safe, reliable and affordable. These parameters have been met and costs are starting to fall." There are about 9000 grid-connected solar systems in Australia, mostly small in scale and located on buildings such as homes, schools and offices. However, the contribution of solar energy to the grid is presently only about 1 per cent of the total.

Another crucial element of solar systems, the high cost of hyper-pure silicon required for PV cells, is also being addressed. Researchers at Australian National University have developed a solution which they call sliver technology.

"Essentially, it means using a much smaller amount of hyper-pure silicon, only about one-tenth, to deliver the same electrical output as conventional cells," Prowse says. "It's a remarkable breakthrough. Most of the project funding was put up by Origin Energy, which is building a plant in Adelaide to manufacture PV cells using sliver technology.

Origin Energy will have invested up to $50 million by the time solar panels made from sliver cells are commercially available in the latter half of 2007." These developments, Prowse believes, have the potential to reduce the cost of solar generated electricity from the current price of 45-50 cents per kilowatt hour to a figure competitive with the current retail price of electricity generated from fossil fuels, about 12-18 cents per kilowatt hour. There is potential not only for a greater number of small-scale PV cells, but for large-scale arrays to collect and utilise solar energy on an industrial scale.

The development path of the other main renewable energy source, wind power, is similar to that of solar energy, but might be seen as a bit further along the curve. Wind turbines currently only account for about 740 megawatts of Australia's installed electricity capacity (total capacity is around 50,000MW), but the figure is growing.

Professor Chem Nayar of Curtin University, an engineer specialising in wind power, believes Australia, with a high average annual wind speed, is well-placed for the technology. The 3000km of southern coastline, where wind is strong and fairly constant, is particularly significant," he says. "The problem there is accessibility to the national electricity grid. There is also the issue of consistency of output from wind turbines.

Compared to conventional coal power plants, the rated power utilisation time of a wind farm is significantly lower, even though the capacity factor of turbines in Australia compares very well internationally." An answer to the variability of power generation from wind might be to increase the number of turbines and the number of sites, so that reduced output in one area would be balanced by an increase from another area, or by inputs from other sources.

The current cost of wind-generated electricity, according to Nayar, is somewhat higher than electricity from fossil fuels, although much depends on the location of a particular turbine site. Costs are decreasing with more research and economies of scale.