Supercritical carbon dioxide has huge potential in low-carbon future

Low-carbon, low-cost, scaleable and on-demand electricity is one of the great prizes in the race to decarbonise our energy systems.

That is one reason why there is growing interest in the supercritical carbon dioxide (s-CO₂) cycle. When CO₂ is heated above 31.10C at 73.9bar it has the density of a liquid yet retains gas-like characteristics. In its supercritical state, CO₂ offers tremendous opportunities for power generation with efficient heat transfer and a substantially smaller-sized power block, while operating at pressures that are much lower than supercritical steam. 

The process can operate in a closed-cycle formation in which a wide variety of suitable energy sources, such as nuclear or solar, can be used to heat the closed-loop CO₂ system through a heat exchanger. In the semi-open cycle, fossil fuels are combusted directly with oxygen and excess CO₂ is removed from the cycle for sequestration or reuse. Supercritical CO₂ also offers potential as a refrigerant. 

The Indian Institute of Science in Bangalore has been a pioneer in research on s-CO₂ power generation and it has developed a state-of-the-art Brayton test loop to address research issues that have been impediments for technology deployment. The challenge for India is to develop a pilot plant and scale it up sufficiently to become an attractive technological option and not wait for demonstration plants elsewhere, for example the NET Power facility in the US. Successful development of the s-CO₂ technologies will not only help in reducing the carbon footprint but also to a great extent replace the distributed captive power generator market.

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