CSIRO powers ahead with water-free solar plant

Australian
Thursday 22/7/2010 Page: 28

TOWNS in Australia's vast tracts of dry and sunny terrain could benefit from a new joint venture from Japanese industrial powerhouse Mitsubishi Heavy Industries and the CSIRO. The organisations are working on developing a solar thermal power plant that uses compressed hot air instead of steam to drive a turbine and generate power. The main advantage of the technology is, unlike current solar thermal plants, it can be used in areas with no water, which are often the sunniest places on the planet.

The CSIRO believes the plant, which will be capable of generating up to 10MWs of power, could be deployed in areas such as the Pilbara in Western Australia where mining operations demand lots of power and water is scarce. One of the CSIRO scientists involved in the project. Jim Smitham, said Mitsubishi Heavy Industries saw the technology as a good fit for its current range of high temperature gas turbines and believed it had export potential for north Africa, the US and southern Europe.

Dr Smitham, deputy director of the CSIRO's Energy Transformed Flagship research program, said the plants could be grouped together to form a large solar station or used individually in remote areas. "The scale of the plant in the 2MW to 10MW range means it is modular and can start to be used in small population centres or at the ends of the electricity grid", he said. "The opportunities are there for remote communities and in reinforcing the power grid". He said CSIRO had struck a deal with MHI to provide research assistance and facilities to the company in return for a share of royalties and licensing fees when the technology was commercialised.

The plant works by heating air in a vessel to about 1000C and allowing it to expand through a turbine. The operating temperature is about 600C higher than current "trough"- style steam solar plants. Dr Smitham said CSIRO's intellectual property lay in the technology used to handle the higher temperatures at the point where the energy was concentrated on the tower. It has also developed methods to precisely align the field of curved mirrors below the tower to regulate the temperature.The heat required is generated by focusing the light beams from as many as required of the curved reflectors directly on to the receiver.

Dr Smitham said the higher temperatures used in the waterless plant gave it potential to operate at increased efficiency compared to solar thermal plants using steam, and photovoltaic solar plants, which create electricity directly from cells without turbines. The CSIRO is building a test field of 450 reflectors at its Newcastle, NSW, operation and it will be tested with one of MHI's turbines connected to the 30m-tall tower. By 2013, the two organisations hope to have a demonstration plant of between 1MW and 2.5MW constructed. By 2014 they hope to have a full-scale 10MW plant operating and to have begun commercialising the idea. The plant has no storage capacity, unlike some solar thermal plants, and will generate only while the sun is shining.

But Dr Smitham said the Brayton Cycle turbines used with the plant could easily be powered with natural gas, where it was available, giving 24-hour generating capacity if required. MHI, whose office was closed yesterday, has previously predicted costs for the waterless plant would be about 20% to 30% less than for current technology, which requires pumps and piping for the water. Water consumption for solar thermal plants can be high and the company hopes a waterless plant can find a market niche in the renewable energy field. MHI is believed to have held talks with several state governments and power companies about the technology.

The Japanese government is keen to assist its industrial heavyweights to move into renewable energy and it recently brokered a deal to build a demonstration plant in Tunisia. The plant is expected to use current steam technology. Japan hopes it will give it a foothold in solar power, where it has fallen behind European and US companies, and lead to projects in other areas, including the US and Australia. CSIRO declined to reveal details of its contract with MHI, but Japanese industry magazines have reported the initial development cost to be about $26 million, of which CSIRO will contribute one third. CSIRO received $5m from the federal government's Australian Solar Institute to build the test field and conduct research over two years.