Decarbonization path of natural gas combined cycle using chemical looping hydrogen generation: Thermodynamics, emissions, and economics studies

The global energy sector's reliance on fossil fuels necessitates a transition to low-carbon alternatives, with hydrogen (H2) emerging as a key solution. Chemical looping H2 generation (CLHG) offers a flexible approach using biomass (BM) or natural gas (NG) as feedstocks. This study integrates CLHG, an organic Rankine cycle, NH3 synthesis, and a 559 MW NG combined cycle (NGCC), utilizing blended NH3-H2 or pure H2 combustion. Process simulations (Aspen Plus V14) and emission analyses (ANSYS Chemkin-Pro 2024R1) assess four cases: (1) BM-CLHG with NH3-H2, (2) BM-CLHG with H2, (3) NG-CLHG with NH3-H2, and (4) NG-CLHG with H2. NG-CLHG achieves higher H2 efficiency, while all cases increase net power output (613.85–683.59 MW). Case 4 maintains high thermal efficiency (59.93 %), compensating for efficiency losses. BM-CLHG achieves negative CO2 emissions (−0.76 to −0.63 t-CO2/MWh), while NG-CLHG achieves zero CO2 emissions. NH3-H2 combustion reduces NOx (∼6.2 ppmv) but increases N2O (∼222 ppmv). Economic analysis reveals a negative levelized cost of electricity for Cases 1 and 2, primarily due to CO2 credit revenue, while Case 4 remains competitive with NGCC. To support the adoption of CLHG, stricter carbon pricing policies and CO2 storage incentives are necessary. Strategic site selection for CO2 storage and differentiated NG taxation can improve economic viability.