What is the climate and economic impact of incorporating food-grade CO2 production in biomethane production plants? A Swedish case study

Biomethane production plays a significant role in the bioeconomy and for defossilization. However, the potential of CO2 utilization from biomethane is largely untapped, with only a handful of existing cases in Europe. Diverse applications of CO2 exist, but food-grade liquefied CO2 is usually demanded by the market, requiring biomethane facilities to implement conditioning steps, increasing costs. By applying life cycle assessment and costing, this study identified the effects of introducing food-grade CO2 production in an existing biomethane production plant. Interviews were conducted to assess consumers' willingness to pay for biomethane with lower climate impact. The results showed that when the captured CO2 is used to substitute fossil-based CO2, there is a potential emissions reduction of approximately 220 %. There is also a minor reduction of emissions (around 2 %) with only CO2 capture by reducing the methane slip. Moreover, an increase of around 7 % in costs is expected in biomethane systems producing CO2, without considering potential income from sales. In the studied Swedish context, private actors are willing to pay a higher price for fuel with lower climate impact since it can be used in marketing, while public actors are neutral or negative to a price increase.