To many the concept of power generated from solar energy and fossil fuels seem diametrically opposed. One fuel source is deemed as futuristic, green and renewable whilst the other is seen as old, dirty and finite. But recent projects being undertaken around the world at the moment demonstrate the synergies that can exist when these two energy sources are combined. The question is: is the combination of solar and coal a first step in the path towards renewable energy, or is it nothing more than propaganda with the intention of slowing the progress of emerging renewable technologies?

Examples of the marriage between solar and coal fired power stations are emerging all over the world. One recent example is the case of the Kogan Creek Power Station, located in eastern Australia. In this hybrid solar-coal power station, Compact Linear Fresnel Reflector (CLFR) technology will be used to ‘boost’ the station’s coal-fired steam generation system. The Kogan Creek Power Station is expected to be the world’s largest solar integrated coal power station and will reliably increasing the station’s electrical output and fuel efficiency, as well as reduce it's greenhouse intensity.

Chief Executive of CS Energy, developers of the Kogan Creek Power Station, David Brown added “CLFR is the most land-efficient solar technology, generating 1.5 to 2.6 times more peak power per acre of land than competing solar technologies and is the only CLFR provider to supply superheated steam which has specific application to the power generation market.”

The science behind the technology is relatively simple: In a traditional coal-fired power station, coal is consumed to boil cold water driving turbines that create electricity. Solar thermal power technology fits in nicely by pre-heating water before it enters the turbine, offsetting some of the work needed to be performed by the coal.  

Diagram of the Kogan Creek Power Station. Source: http://www.areva.com/EN/solar-240/areva-solar-kogan-creek.html

One important factor to consider when planning a utility scale energy project, is space. In most cases coal power stations are given a generous buffer area and built away from urban areas, all important factors when it comes to the planning of solar power systems. This was the case in Kogan Creek, where the space required for the solar thermal system was already available thanks to the existing power station.  

These synergies also extend across to the use of Natural Gas as an emerging fuel source. A recent report by the Worldwide Institute entitled Powering the Low-Carbon Economy: The Once and Future Roles of Renewable Energy and Natural Gas, examines the synergies between renewable energy and natural gas in the power sector. The report concludes that four key mechanisms can enable the combination of renewable energy and natural gas to displace coal and provide needed reductions in power-sector emissions.

First, air pollutants such as nitrogen oxide, sulfur dioxide, and mercury must be tightly regulated. Second, a cost must be attached to emitting carbon dioxide. Third, electricity system operators should allow wind and solar plants to balance their own output with on-site resources. And finally, the markets on which system operators purchase electricity must be highly responsive, allowing them to react to fluctuations in electricity supply and demand as rapidly as possible.

The growing trend of hybrid “booster” projects could significantly boost the market for concentrated solar power in the U.S. and aborad “Here in the U.S., primarily the opportunities we’re pursuing right now are booster opportunities,” says John Robbins, senior director of North American sales at Areva Solar, a leading manufacturer of Concentrated Solar Power (CSP) technologies. “I think those projects are going to be the largest share of our U.S. market in the near term. I think, overseas, it’s going to be more balanced between standalone and booster projects. Markets overseas have been very active for us.”

As this article shows, by working together, renewable energy and natural gas can accelerate the decarbonization of the world’s electricity system and form the foundation of tomorrow’s low-carbon economy. One of the most positive aspects of hybrid solar-coal technologies is that they can be used to retrofit exisiting power station, generating cleaner, more efficient energy without having to build an entirely new power station.