TECHNO-ECONOMIC ASSESSMENT OF HYDROGEN-NATURAL GAS BLENDS FOR OPEN CYCLE GAS TURBINES

Hydrogen’s use at large scale for electricity generation in the current fleet of gas turbines (GTs) could present several technical, economic and environmental challenges, including high flame temperature and flame propagation velocity, potential to produce high levels of nitrogen oxides (NOx), the change in volumetric and mass flow rate, which could affect the overall power output, and the high cost of H2, which will affect the price of generated electricity. The objective of this study was to carry out a techno-economic assessment (TEA) of the use of hydrogen/natural gas (H2/NG) blends in open cycle gas turbines (OCGTs). Two NG-fuelled aero-derivative OCGTs are used as case studies, a 41-MW GE LM6000PA and a 50-MW Mitsubishi FT8 SWIFTPAC, both of which were selected based on survey of the power generation industry in Ireland. The presented method entails two steps: (1) thermodynamic modelling and (2) economic assessment. Thermodynamic modelling is performed using Thermoflex 30.0, with the purpose of evaluating the effects of H2/NG blending on the GT's electrical efficiency, power output, and CO2 emission intensity. Variables considered for the two OCGTs in this stage are H2 blend volume fractions and GT loads. Economic assessment is then performed in an Excel-based cash flow model, with the purpose of determining the levelized cost of electricity (LCOE) of the GTs operating under different commercial conditions, including H2 and NG prices, CO2 tax, and annual OCGT capacity factor. The results shows that H2 improve the efficiency and power output of the gas turbines. Moreover, H2 blending reduces electricity generation CO2 emissions intensity. However, high LCOE are observed as the H2 blending percentage volume increases because of the current price H2, the LOCE are even higher at lower capacity factor.