Design Options for GHG Reduction of Gas Turbine Driven LNG Plants

Gas turbines have been traditionally used as drivers of refrigeration compressors in LNG liquefaction plants. The current trend is toward increasing the overall efficiency while reducing greenhouse gas emissions. The main sources of carbon emissions in LNG liquefaction plants include CO2 in feed gas and CO2 in flue gas from the exhaust of gas turbines and fired heaters. In LNG liquefaction plants, CO2e/tonne LNG produced is typically in the range of 0.2 to 0.4. In order to further reduce the CO2e/tonne LNG produced a combination of hybrid drives (e.g., gas turbine and steam turbine, or gas turbine and motor) can be used for the refrigeration compressors. Also, bottoming power cycle(s) such as steam Rankine cycle or organic Rankine cycle can be employed to recover the waste heat energy from the gas turbine exhaust. This paper explains the design options and challenges involved in decarbonization of gas turbine driven LNG liquefaction plants in both brownfield and greenfield applications. Moreover, challenges associated with burning high hydrogen-content fuels in gas turbines and different transcritical CO2 compression pathways are briefly addressed.