Robotics And Machine ANalytics Laboratory (RAMAN LAB) Malaviya National Institute of Technology Jaipur

Power Plant that Runs on Carbon Dioxide

A new coal-fired power plant emits roughly 8 kg of CO2 per kilowatt-hour with an efficiency of 33-40%. Recently, the governments of developed nations are trying to reduce the C02 emission to curb the environment pollution. N.C.–based NET Power is being built in the Houston industrial suburb of LaPorte which uses CO2 in supercritical fluid to run the turbine. It can also capture and sequester carbon dioxide at virtually no additional cost and works on The Allam Cycle as illustrated in the figure.

At temperature and pressure above 31.10 °C and 7.39 megapascals, carbon dioxide turns supercritical fluid. It can expand like a gas and yet it still move with the density of liquid.

The Allam Cycle is a power cycle that utilizes a recirculating, trans-critical CO2 working fluid in a high-pressure, low-pressure-ratio. The cycle operates with a single turbine.

A pressurized gaseous fuel is combusted in the presence of a hot oxidant flow containing a mixture of CO2 and nominally pure oxygen (provided by a co-located Air Separation Unit (ASU)) and a hot CO2 diluent recycle stream.

The exhaust flow exiting the combustor is expanded through a turbine. Following the turbine, the exhaust flow enters a recuperating heat exchanger which transfers heat from the hot exhaust flow to the aforementioned high pressure CO2 recycle stream.

Exiting the primary heat exchanger, the turbine exhaust flow is cooled and combustion derived water is separated. The predominantly CO2 fluid stream is then recompressed, cooled, and pumped where it then reenters the cold end of the recuperative heat exchanger. At a point before entering the heat exchanger, a portion of the recycle CO2 is mixed with oxygen to form an oxidant mix stream which is fed separately to the heat exchanger and turbine. Within the main process heat exchanger, the recycle flows undergo reheating against the hot turbine exhaust before returning to the combustor.

A portion of the high purity CO2 process gas is exported at a point within recompression to a high pressure CO2 pipeline for sequestration or utilization. This net export is approximately 5% of the total recycle flow, meaning the majority of the process inventory is recirculated.

This combination delivers an efficiency of up to 52 percent (based on the total energy content of natural gas) and emits around 0.4 kilograms of CO2 per kilowatt-hour.


  2. Allam, Rodney, et al. “Demonstration of the Allam Cycle: an update on the development status of a high efficiency supercritical carbon dioxide power process employing full carbon capture.” Energy Procedia 114 (2017): 5948-5966.


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