Hybrid plant design could cut down power station emissions

Retrofitting this hybrid design to existing power stations could achieve a 25–50 per cent reduction in fuel use and associated emissions, according to the researchers at Tel Aviv University.

Solar thermal technology is relatively mature now, with full-scale power plants being demonstrated in Spain recently.

In a solar thermal power plant, sunlight is harvested to create hot high-pressure steam, approximately 400–500ºC. This solar-produced steam is then used to rotate the turbines that generate electricity.

However, it is a complex and expensive technology. The materials alone, which include pipes made from expensive metals designed to handle high pressures and temperatures, as well as fields of large mirrors needed to harvest and concentrate enough light, make the venture too costly to be widely implemented.

Instead, a team headed by Prof Kribus at Tel Aviv is developing an alternative technology, called a steam-injection gas turbine.

‘We combine a gas turbine, which works on hot air and not steam, and inject the solar-produced steam into the process,’ he explains. ‘We still need to burn fuel to heat the air, but we add steam from low-temperature solar energy, approximately 200ºC.’

This hybrid cycle is not only efficient in terms of energy production, but the lowered pressure and heat requirements allow the solar part of the technology to use more cost-effective materials, such as common metals and low-cost solar collectors.

The researchers are now starting a collaboration with a university in India to develop this method in more detail, and are looking for corporate partnerships that are willing to put hybrid technology into use.