Assessment of Hydrogen Infused In-situ Methanation Systems: Modeling and Analyzing from a Techno-Economic and Climate Perspective

Abstract

The transition away from fossil fuels requires the development of alternative technologies, as no single solution can meet all the requirements for full decarbonization. Hydrogen is a flexible energy carrier, with one potential application being methanation. A methanation process uses hydrogen to convert carbon dioxide from biogas production to bio-e-methane. This thesis offers a comparative assessment of hydrogen-infused in-situ methanation systems operating under different conditions, from a techno-economic and climate perspective, applied to a biogas plant in Linköping operated by Tekniska Verken.

The evaluation was carried out through simulations using Odyssey software, considering three cases: (1) hydrogen used for the methanation process solely, (2) hydrogen used for methanation combined with direct sales, and (3) hydrogen used solely for direct sales. The outcomes were influenced by electrolyzer characteristics, system size, and fluctuating electricity prices. Results indicated that the cost-optimal configuration was highly dependent on the operational strategy and electrolyzer capacity. Furthermore, Case 2 showed strong sensitivity to hydrogen pricing, while Case 3 showed that both methanation and direct hydrogen sales could be more profitable, depending on the specific setup. The key findings of the climate analysis showed that the emissions from the systems were small compared to if the system were placed in another country, due to the difference in grid emission factors.

Uncertainties regarding future electricity prices and market values of hydrogen and bio-e-methane pose challenges for assessing long-term feasibility. Nevertheless, this thesis highlights the importance of resource efficiency by focusing on hydrogeninfused in-situ methanation systems, which increase biogas production without additional substrate, thereby helping to reduce fossil fuel use