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 (H 2 ) emerging as a key solution. Chemical looping H 2 generation (CLHG) offers a flexible approach using biomass (BM) or natural gas (NG) as feedstocks. This study integrates CLHG, an organic Rankine cycle, NH 3 synthesis, and a 559 MW NG combined cycle (NGCC), utilizing blended NH 3 -H 2 or pure H 2 combustion. Process simulations (Aspen Plus V14) and emission analyses (ANSYS Chemkin-Pro 2024R1) assess four cases: (1) BM-CLHG with NH 3 -H 2 , (2) BM-CLHG with H 2 , (3) NG-CLHG with NH 3 -H 2 , and (4) NG-CLHG with H 2 . NG-CLHG achieves higher H 2 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 CO 2 emissions (−0.76 to −0.63 t-CO 2 /MWh), while NG-CLHG achieves zero CO 2 emissions. NH 3 -H 2 combustion reduces NO x (∼6.2 ppmv) but increases N 2 O (∼222 ppmv). Economic analysis reveals a negative levelized cost of electricity for Cases 1 and 2, primarily due to CO 2 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 CO 2 storage and differentiated NG taxation can improve economic viability. • Four decarbonization paths of NGCC using biomass and natural gas CLHG were explored, with H 2 and H 2 -NH 3 as NGCC fuel. • NG-CLHG achieves higher H 2 production efficiency than BM-CLHG, while BM-CLHG systems exhibit negative CO 2 emissions. • NH 3 -H 2 co-combustion results in low NO x emissions (∼6.2 ppmv) but produces high N 2 O emissions (∼222 ppmv). • BM-CLHG achieves negative LCOE from CO 2 offset revenue, while NG-CLHG with H 2 combustion offers a competitive LCOE comparable to NGCC. • Policy implications such as higher carbon prices, tax incentives, and optimized CO 2 storage strategies are crucial to improving the system competitiveness.