Techno-Economic Assessment of Biological Biogas Upgrading Based on Danish Biogas Plants

Biological biogas upgrading with H-2 derived from excess renewable electricity was modeled and simulated in PROII(R) (AVEVA Group plc, Cambridge, UK). An economic analysis was performed for a biogas plant processing 100,000 tons of biomass (substrate) per year. The biogas and biomethane production simulation results were validated with laboratory experimental data, as well as full-scale data obtained from biogas plants. A biomethane production cost of 0.47 euro/Nm(3) was calculated, while the minimum biomethane selling price for NPV = 0 was equal to 0.66 euro/Nm(3), considering a H-2 price of 1.0 euro/kg. The feasibility analysis indicated that the H-2-related costs were the major contributor to the capital and operation costs due to high expenses associated with the in-situ H-2 storage facility and the purchasing of H-2, respectively. Compared to conventional upgrading methods, biological biogas upgrading has a higher capital and production cost, which can be reduced by increasing the plant capacity. The sensitivity analysis showed that the profitability is very sensitive to biomethane prices, capital investment, and the H-2 price.