Epsilon Archive for Student Projects

Abstract

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.