A comparative techno-economic and sensitivity analysis of Power-to-X processes from different energy sources

In this paper, green hydrogen produced via water electrolysis and its conversion into three alternative fuels, such as methane, methanol, and ammonia, are considered. The four different Power-to-Fuel solutions are investigated and compared from both the technical and economic points of view aiming at providing a comprehensive overview of the Power-to-Fuel feasibility. At first, the global process efficiency, the storage capacity, the annual costs, and the production cost of the different fuels (in terms of mass, energy, and hydrogen content) are calculated for a reference scenario. Then, a sensitivity analysis is carried out analyzing the influence of many parameters (i.e. electricity cost, electrolyser CAPEX, operating hours, etc) on the economic viability of all the processes. Finally, map plots are developed reporting the fuel production cost for considering different renewable energy sources and their availability. They can be considered as a useful tool for pre-feasibility analysis of power to fuel processes enabling to analyze and compare the different solutions in different scenarios. It is found that the highest efficient process is the Power-to-Hydrogen (about 61.5%) followed by the methanol and ammonia processes and in the end the methane processes. In terms of energy storage and energy density by volume, the methanol resulted in the most suitable solution, while the ammonia resulted in the best H2 storage medium in terms of kg of H2 per m3 of storage (108 kgH2/m3). From the economic perspective, the annual cost breakdown showed that, in all the cases, the major expenditures are related to the electrical energy purchase and CAPEX and OPEX of the electrolyzer (around 90% of total costs), and a 50% reduction in electricity cost and electrolyzer CAPEX could lead to a reduction of about 30% and 18% on fuel production cost, respectively. The cheapest fuel in terms of mass and energy content are methanol (1.02 €/kg) and Hydrogen (0.16€/kWh), respectively. The ammonia production cost in terms of hydrogen content in mass resulted almost comparable with the Hydrogen one (5.76€/kgH2 and 5.31€/€/kgH2, respectively). The contribution of the co-produced oxygen sale has been estimated in around a 15% reduction of fuel production cost in all the cases.