Impact of CO2 and humidified air on micro gas turbine performance for carbon capture

There is overwhelming evidence for anthropogenically driven climate change and as such it is
critical to reduce the emissions of greenhouse gases. A large source of these is combustion for
energy.
Combined Cycle Gas Turbine (CCGT) power generation is going to be a significant part of the
future of base power load generation in the UK and internationally. The CO2 emissions of gas
turbines are significantly lower than coal, but must still be addressed.
Gas exhaust emissions also present a challenge due to the low volume percentage of CO2 in the
exhaust, as the current most mature technology for carbon capture is post combustion capture
using solvents, which is significantly more efficient with higher CO2 partial pressures.
This thesis looks at potential ways to increase CO2 partial pressure in the gas turbine exhaust for
improved capture efficiency. To do this exhaust gas recirculation (EGR), and humidified air (HAT)
or a combination could be beneficial. There is a lack of bench and pilot scale experimental
research into this area. A Turbec T100 Microturbine was used to investigate the impacts of EGR
and HAT, through the addition of CO2 and Steam before the combustor.
In addition the turbine particulate emissions were analysed. This is as gas combustion has high
emissions of fine particulate matter. Particulates are of increasing consideration as an
environmental pollutant, and may contribute to solvent degradation.
The investigations found that the performance of the turbine is largely dependant upon ambient
temperature. The results matched with the literature showing impact on the combustion
process reducing peak temperatures, and an increase in unburned hydrocarbons, and carbon
monoxide. This resulted in a slightly reduced generation efficiency. However this loss in turbine
efficiency is potentially superseded by a gain in capture efficiency and net CCGT low carbon
generation with carbon capture and storage.