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. • Climate and economic performance of biomethane with CO₂ capture and utilization. • Willingness to pay for biomethane with improved climate performance. • CO₂ use reduces climate impact by avoiding methane slip and substituting fossil CO₂. • CO₂ capture and liquefaction slightly increases production costs of biomethane. • Private actors are more positive to pay for lower climate impact than public ones.