RSM approach for stochastic sensitivity analysis of the economic sustainability of a methanol production plant using renewable energy sources

Abstract This study aims at investigating the economic viability, at the pre-feasibility level, of a 5 MW electrolyser base-methanol production plant, coupled with a PV power plant. The Authors investigated the impact of different parameters, such as the PV plant size, the electrical energy cost and the components capital costs on the methanol production cost and on the system economic viability. It was also analyzed the minimum recommended sale price of the methanol in order to assure an adequate time frame for the return of the investment, considering a different combination of the investigated parameters. An economic sensitivity analysis, based on the RSM approach, was performed in order to define the most promising economic conditions under which the plant can be considered a profitable investment in terms of ARR. A guide for an economically viable plant design, allowing for the identification of the most suitable combination of the economic parameters, was proposed as a kind of “maps of existence”. For the reference case, the Methanol Production Cost (MPC) resulted around 324 €/ton and the minimum methanol sale price to achieve a PBP of 10 years. The sensitivity analysis identified the cost of electricity and the capital cost of the electrolyser as the most affecting parameters for the system economic viability. In terms of ARR, the methanol price represents the most significant factor. Considering a methanol sale price ranging between 400 and 1200 €/ton, the ARR varied from 5% (20 year of PBP) to 20% (5years of PBP). From the environmental point of view, it is worth underling that the methanol production plant here proposed allows to recycle about 5800 tons of CO2 per year and to avoid the consumption of about 5.2 MNm3 of NG per year (compared to the traditional production).