Experimental impact of exhaust gas recirculation and hydrogen injection on the emissions of a micro gas turbine

Abstract

To achieve a zero-carbon economy with gas turbines, amine-based carbon capture has emerged as a potential solution, though it comes with a significant energy cost. Exhaust gas recirculation (EGR) is therefore used to mitigate the efficiency penalty associated with carbon capture by increasing the CO2 concentration in exhaust gases and reducing the overall gas mass flow. However, operating near stoichiometric combustion conditions elevates CO emissions, thereby limiting the feasible EGR rate. Hydrogen cofiring has been proposed as a promising approach to stabilize combustion under these conditions, where the air-fuel ratio approaches unity. Despite its potential, the impact of hydrogen cofiring on performance and emissions remains largely unexplored. To address this gap, experiments are carried out using a 3 kWe micro gas turbine (MTT EnerTwin ®) fuelled with methane blend containing 20% hydrogen. This study examines the effects on emissions, including CO2, O2, NOx and CO. The modified setup, which supports higher EGR rates, provides valuable insights into how hydrogen cofiring can stabilize combustion and enhance carbon capture efficiency. These findings are crucial for scaling the behaviour of micro gas turbines to industrial applications and assessing the combined potentials of EGR and hydrogen to minimize the energy penalty of carbon capture technologies.