Biomethane plays a key role in the green transition, offering a renewable, carbon-neutral substitute for natural gas while enabling the storage and use of intermittent renewable energy. This work presents a techno-economic assessment of biomethane production through the Power-to-Biomethane concept, which combines electrolytic hydrogen from renewable electricity with the direct catalytic methanation of raw biogas from anaerobic digestion. The main objective of this study is to identify the optimal plant size and configuration, taking into account the different operational management strategies of the system’s constituting units. The analysis integrates thermochemical modeling with a techno-economic optimization procedure. Three different configurations for renewable energy production, photovoltaic-based, wind-based, and hybrid photovoltaic–wind, were evaluated for a case study in Southern Italy. Results show that the hybrid configuration provides the best techno-economic balance, achieving the highest annual biomethane output (≈2288 t) and the lowest levelized cost of biomethane (EUR 97.4/MWh). While current biomethane production costs exceed natural gas prices, the proposed pathway represents a viable long-term solution for renewable integration and climate-neutral gas supply.

Biogas-to-hydrogen pathways can support sustainable hydrogen refueling stations through on-site hydrogen production from renewable biogas. This study presents a techno-economic assessment of two on-grid biogas-to-hydrogen configurations based on steam and autothermal reforming, considering three station capacities of 200, 500, and 1000 kg H₂/day. Technical models were integrated with an economic model to assess the effects of plant scale and economic conditions on overall performance. The technical results show that the overall specific energy consumption is approximately 63.7 kWh/kg H₂ for autothermal reforming, compared with 80.0 kWh/kg H₂ for steam reforming. The dispensed levelized cost of hydrogen (LCOH) decreases with increasing station capacity, from 10.61 to 8.06 €/kg H₂ for steam reforming and from 11.28 to 8.08 €/kg H₂ for autothermal reforming. At the assumed hydrogen selling price of 10.66 €/kg H₂, economic performance improves with increasing station capacity. Under baseline conditions, steam reforming is more competitive at 200 and 500 kg H₂/day, whereas the two configurations become nearly equivalent at 1000 kg H₂/day. Sensitivity analyses show that BtH_SR is more competitive below biogas prices of approximately 0.058 and 0.042 €/kWh for the 500 and 1000 kg H₂/day stations, respectively, while BtH_ATR is favored above these thresholds. Higher electricity prices favor BtH_SR, with the 1000 kg H₂/day configurations becoming nearly equivalent at approximately 0.138 €/kWh. The nominal interest rate has the strongest effect on economic feasibility, with all investigated configurations becoming unfeasible above a value of 13.3%.

The decarbonization of maritime transport is a crucial issue in recent times, since this sector continues to account for approximately 2.8% of the global CO ₂ emissions. To address this issue, various proposals have been put forward to promote the utilization of renewable and low/zero carbon fuels in marine applications. In this context, this study aims to define different configurations of innovative naval propulsion systems utilizing Solid Oxide Fuel Cells (SOFC) fed by ammonia. A particular case study has been examined, focusing on a vessel with a known mission profile and engine room hosting a conventional internal combustion engine. The analysis explores the possibility of incorporating the proposed SOFC-based propulsion system into this vessel by considering the weights and volumes of the modules and onboard fuel storage. Each SOFC module includes not only the stacks but also their Balance of Plant (BoP) components, such as the afterburner and multiple heat exchangers designed to enhance heat recovery and maximize system efficiency. In particular, the proposed configuration is assessed in terms of fuel consumption and design compactness, taking into account specific constraints such as its mission profile and the available space in the engine room of the considered vessel. The analysis is carried out through properly developed thermochemical models able to determine the operational characteristics of the system, while also taking into account the thermal management of the modules.