||The Energy Technologies Institute (ETI) is focused on accelerating the deployment of affordable, secure low-carbon energy systems for 2020 to 2050. One of the key technologies is carbon capture and storage (CCS). CCS could be particularly suitable for decarbonisation of intermediate load power generation, to complement other lower carbon generation technologies. There is currently a large requirement for intermediate load generation in the UK due to the variability of power demand and this requirement is expected to increase in future as greater amounts of variable renewable generation are used.Technologies which may be well suited in this regard are post combustion capture and production, storage, and use of hydrogen in gas turbine power plants. The ETI has requested supporting information on aspects of both of these technology options.
LMS100 gas turbine
The steam cycle of an LMS100 gas turbine could provide more than sufficient steam for an amine CO2 capture unit. The energy efficiency penalty for CO2 capture and compression at an LMS100 combined cycle plant would be about 9 percentage points, the same as at a combined cycle plant based on Frame 9F gas turbines. Simple cycle LMS100 plants are aimed at low-intermediate load power generation. An option for capturing CO2 at such plants would be to install a simple HRSG that generates only low pressure steam for a CO2 capture unit. Whether or not capturing CO2 at such plants would be a feasible option would depend on the dynamic performance capabilities of the capture and compression units and the economics of CO2 capture. There is limited scope to use heat from the LMS100’s compressor intercooler for a steamcycle or to generate low pressure steam for an amine CO2 capture unit, due to the low temperature. Recuperation is unlikely to be an attractive modification to the LMS100 turbine, due to the low temperature difference between the turbine and compressor exit temperatures.
Hydrogen and co-fired gas turbines
A wide range of gas turbines are reported to be suitable for high-H2 fuel gas, with addition of diluents (nitrogen or steam) for control of emissions. Up to 95% H2 gas has been used in commercial turbines. The effects of using hydrogen and a diluent on the power output and efficiency of gas turbines depend on how the turbine is designed and operated and the system boundary, i.e. whether compression of nitrogen diluent is included. If nitrogen compression is outside of the system boundary, use of H2 can resultin a significant increase in the thermal efficiency of a combined cycle plant but if it is within the system boundary there would typically be a small decrease. Published costs of gas turbines and combined cycle plants differ significantly between different sites and studies. Costs in UK£ are particularly uncertain due to variations in currency exchange rates. Typical costs of combined cycle and simple cycle plants based on large H or F class frame gas turbines appear to be around £500/kW and £330/kW respectively. Costs of plants based on smaller frame gas turbines or aero-derivatives appear to be about 50% greater, although this cost difference may be lower if plants based on large numbers of these smaller gas turbines were built.