Feasibility analysis of e-Hydrogen, e-Ammonia and e-Methanol synthesis compared with methane to fuel production

Process decarbonization is becoming one of the main requirements in the power sector, needing proper carbon capture systems or more eco-friendly technologies based on renewables. Hydrogen is the ideal solution, but its production chain has significant environmental, safety and logistical issues making its carries, such as ammonia and methanol, more suitable commercially. Starting from H2 production paths, a feasibility analysis is presented on e-NH3 and e-MeOH single and combined production for different flowsheets by discussing material and energy consumption. Specific electrical demands are quite high (∼11–12 kWhel/kg e-fuel) due to the energy-consuming electrolyser operation, which also represents more than 85 % of the total need. Nevertheless, these values balance the high fuel consumption of traditional processes based on the natural gas steam reforming (∼21–31 MJ(LHV)/kg product). CO2 emissions are minimized, permitting the CO2 recovery from other plants in the e-MeOH synthesis as well (up to ∼1.6 kg CO2/kg e-fuel). Referring to the current renewable scenario, a hybrid plant combining ammonia and methanol production is more feasible. Indeed, the Methane to Ammonia plant coupled with the Power to Methanol one allows for halving the electrolyser size and providing an in loco CO2 source (∼0.83 kg CO2/kg (NH3 + MeOH)) while increasing the heat requirement (up to a 90 % increase) compared to a single-line e-fuel production. Looking at future scenarios, the electrolyser technology improvement in terms of its electrical demand and working pressure could favour e-fuel synthesis, leading to ∼25 % decrease in the energy consumption and a lower number of compression steps.