Sun and coal

Solar thermal energy is emerging as a potentially cost-competitive source of electrical power, especially in combination with clean coal, a new study has found. Fossil fuels and renewable sources are not mutually exclusive as energy sources - in fact they can go hand in hand, says CRC for Coal in Sustainable Development (CCSD) chief executive, Frank van Schagen.

Among the most promising uses for solar thermal power is to provide supplementary steam energy to bolster the efficiency of the nation's 39 coal-fired power plants and cut greenhouse emissions, says the study's lead author, Dr Louis Wibberley.

It can also provide the low-grade energy needed to filter CO2 out of the exhaust gases of existing coal and gas-fired power stations for long-term storage. Furthermore, sunlight can be used to re-form natural gas and coalbed methane, to produce clean energy, industrial chemicals and badly-needed transport fuels.

Dr Wibberley says, "What makes solar thermal particularly attractive is the fact that it integrates very well with existing technologies including coal, gas, biomass, photovoltaics and wind power.

"It is suitable for base and peak-load grid power, and for distributed or standalone generation. In contrast to photovoltaic and wind electricity, the energy from solar thermal can be stored far more cheaply in the form of heat and so provide more continuous power," he says.

A major solar-coal trial is taking place at Liddell power station in NSW by Solar Heat and Power for extra steam production. This is now being expanded to produce 6000 MWh per year (saving around 6000 tonnes of CO2 annually).