It may seem ironic, but solar thermal technology could provide a cheap and effective solution to make carbon capture and storage (CCS) technology a commercial viable option for the coal- and gas-fired generation industry.
One of the principal hurdles of CCS technology is the extra energy required to capture the emissions – particularly in post-combustion capture technologies that will likely form the principal mechanism for coal plant retrofits. An enormous amount of heat is needed in the carbon capture process, equivalent to up to one quarter of a coal-fired plant, adding considerably to the costs and reducing the efficiency of the facility. A 600MW coal-fired plant, for instance, would be reduced in capacity to around 450MW.
A new project being undertaken by the CSIRO and partly funded by the Australian Solar Institute is looking at the possibility of using heat produced from solar thermal technology for the carbon capture process. The thinking behind the project is that it could allow the coal-fired coal-fired power stations to maintain their nameplate capacity and present a novel energy storage solution – because the CO2 can be stored while the solar plant is offline.
Project leader James McGregor, the energy systems manager for CSIRO, says the CSIRO will test a re-boiler at one of its carbon capture pilot plants at the Vales Point power station, owned by Delta Electricity in NSW – most likely with some form of parabolic trough technology.
“The first part of this project is to demonstrate the potential and assess the economics,” McGregor said. “The follow up projects will be about exploring the different temperature limitations and opportunities presented by using solar thermal systems.”
McGregor says using solar thermal as a substitute for the steam that a power station would normally have to produce itself presents more options for the carbon capture process will be available because solar thermal can deliver steam at a range of temperatures.
McGregor said CO2 would be initially stored in liquid absorbents that would provide greater flexibility in operation than thermal energy storage and potentially cost less. It will be stored in the liquid absorbents until the solar thermal energy is available to use during the day time for regeneration.
McGregor said if successful, the technology would not just help coal-fired power stations, but also offer the opportunity for more widespread deployment for solar thermal, enabling it to gain economies of scale through deployment.
“Tying solar thermal into coal-fired generation means that you can start getting economies of scale for the deployment of the different components. The more you build, the cheaper it get.”
He said while parabolic trough would be used in the 100kWth pilot plant, any solar thermal technology could be used. He said the fact that the Co2 could be stored meant that instead of having to store solar thermal energy for use 24 hours a day, it could be tapped only when available. The two project is due to commence in June.