Integration of chemical looping hydrogen generation and ammonia synthesis for power generation at existing natural gas combined cycle

The global energy sector's reliance on fossil fuels necessitates a transition to non-carbon fuels, with H 2 emerging as a promising alternative. Current hydrogen (H 2 ) production predominantly depends on fossil fuels, but chemical looping technology presents a flexible and viable method. While H 2 and ammonia (NH 3 ) have emerged as promising clean fuels, their integration into existing natural gas combined cycle (NGCC) plants is still limited. Moreover, no prior study has systematically examined the impact of different heat transfer strategies in chemical looping H 2 generation (CLHG)—specifically, the use of external heat from the combustor versus directly splitting the oxygen carrier (OC) from the fuel reactor (FR) to the air reactor (AR). This study proposed a system integrating a chemical looping H 2 generation (CLHG), an organic Rankine cycle, an NH 3 synthesis, and an existing NGCC employing a co-combustion approach using NH 3 and H 2 in a 1:1 ratio, ensuring compatibility with existing infrastructure. Two configurations are modeled in ASPEN Plus: Case 1 uses an external heat, while Case 2 directly splits the OC stream from FR to AR. The proposed system achieves thermal efficiencies of 45.98 % and 46.96 % in Case 1 and Case 2, respectively. When excluding fuel production, the NGCC itself achieves an efficiency of 56 %, which is only 0.6 % lower than that of NG combustion. The levelized cost of electricity for Case 1 and Case 2 is 0.115 and 0.108 USD/kWh, respectively, both lower than that of imported fuel. Splitting OC is recommended based on LCOE, thermal, and exergy efficiency. Sensitivity analyses based on TCI, TOC, and electricity price, as well as considerations of CO 2 tax, were performed. This system has the potential to emit negative CO 2 emissions if the CO 2 is sequestered. This multifaceted approach demonstrates the potential for sustainable energy production by integrating CO 2 capture and non-carbon fuel power generation. • Novel integration of CLHG and NH 3 synthesis for NGCC decarbonization is proposed. • Splitting oxygen carriers (Case 2) has better efficiency and LCOE than using external heat. • It achieves 47.1 % energy and 41.6 % exergy efficiencies under autothermal operation. • NH 3 –H 2 co-firing cuts CO 2 emissions and limits NO x to NGCC-equivalent levels. • LCOE of Cases 1 and 2 is 0.108 and 0.115 USD/kWh, respectively, 60 % lower than imported green H 2 –NH 3 .