Low-carbon hydrogen production via molten salt methane pyrolysis with chemical looping combustion: Emission reduction potential and techno-economic assessment

Methane pyrolysis, as a bridge for the transition from fossil fuel to renewable energy, is regarded as a potential low-carbon hydrogen production method. However, there are still critical issues such as the deactivation of catalyst carbon deposits and indirect greenhouse gas emissions caused by combustion for heating. Accordingly, this study put forward a methane pyrolysis system by melting method coupled with chemical looping combustion (MPM-CLC) for heating, aiming to solve the above-mentioned concerns and further demonstrate the thermodynamic and economic feasibility of the system. Thermodynamically, more than 27% of fuel energy input and more than 98% of CO2 emissions can be avoided in the novel system compared with that in conventional standalone production system. The overall system exergy efficiency was calculated to be 85.06%, with CO2 emissions of about 0.51 kg/MWh. Economically, due to lower total equipment costs and lower additional fuel requirements, as well as profit from by-product solid carbon and electricity sales, the levelized cost of hydrogen (LCOH) is only 1.12 $/kg, which is 33% lower than that of steam methane reforming (SMR) and 52% lower than that of SMR with carbon capture. Moreover, although increasing the conversion rate will increase the fuel and total investment costs, the benefits brought by the increased by-product output could offset this part of the cost and help further reduce the LCOH. Importantly, the price of solid carbon played a decisive role in the LCOH. This new system brings a new insight into the low-carbon hydrogen production from methane.