Power to gas plant for the production of bio-methane: Technoeconomic optimization

In this work, a power to bio-methane plant in which the biogas is produced from an anaerobic digester plant and the hydrogen is generated by using an electrolysis unit powered by a renewable plant (photovoltaic or wind-based), is designed and sized. The plant sizing is carried out by applying a techno-economic multi-objective black box optimization approach. A numerical code, built by using the Matlab software package, is used to evaluate components sizes and to assess plant costs. This code is implemented in an optimization workflow developed in the modeFRONTIER environment. This approach allows to identify the optimal size of the plants components with the aim of maximizing the annual bio-methane producibility and minimizing its levelized cost. The results show that for a low-price electricity scenario (45/MWh) the minimum levelized cost of bio-methane (LCOBM), equal to 84.6/MWh, is obtained adopting the PV-based configuration. On the contrary, considering an high-price scenario (135/MWh), the minimum LCOBM is obtained for the Wind-based plant and is equal to 34.9/MWh.