Climate impacts & cost of Biogas-based H2 production coupled with carbon capture and storage (CCS)

Sammanfattning

To reach the climate goal set under the Paris Agreement in 2015, which aims to limit the global temperature increase to no more than 2 degrees, a reduction in emissions is required. In Uppsala, biogas is currently produced at Uppsala Vatten’s biogas plant at Kungsg˚arden. The purpose of this study is to examine the climate impact and economic cost of instead producing hydrogen at the plant. To achieve this, a production step is added to the biogas plant to convert methane gas into hydrogen. This way, the carbon is taken out and can be stored in bedrock, creating a carbon sink. The study investigated three methods to achieve this: steam methane reforming, pyrolysis, and dark fermentation. These methods were evaluated through a life cycle analysis of their climate impact and economic cost per kilogram of produced hydrogen. The results showed emissions for steam methane reforming at -2.4 kgCO2/kgH2, pyrolysis at -8.9kgCO2/kgH2, and dark fermentation at 6.5kgCO2/kgH2. The leveled cost was between 4-8e/kg for steam methane reforming, 4-12e/kg for pyrolysis, and -3-(- 0.25)e/kg for dark fermentation. Since steam methane reforming resulted in a balance with negative emissions, significant hydrogen production, and the lowest leveled cost, this method was considered the most suitable for implementation in Uppsala’s biogas plant.