This paper investigates how experiences from the deployment of the Solrød biogas plant in Denmark - a large scale centralized biogas plant - can assist future biogas technologies in achieving circular economic benefits. Departing from a theoretical understanding of a circular economy provided by the Ellen MacArthur Foundation, the paper analyzes three areas: 1) biogas production, 2) nitrogen, phosphorous & green house gas (GHG) emissions, and 3) re-cycle/cascade materials. It consequently elaborates on the environmental benefits obtained, in terms of CO2 emission from biogas production substituted for fossil fuels, improved water quality and hence reduced GHG emissions due to lower nitrogen effluents, and re-cycling of nutrients on farmland thereby recovering finite resources and improving crop yield. Economic spin-off effects are presented, including new jobs created in the local community. Learning from Solrød Biogas, this paper further proposes to include the following activities when planning for future biogas plants: waste-stream identification and coupling in the local community, measuring the value of digestate as a fertilizer, short distance to farmers delivering manure, and plant design adapted to the local energy market. Finally, the paper suggests how to qualify the circular economic concept based on the findings from the Solrød biogas plant. It is here concluded, that emphasis should be on cascading energy from biogas production by means of combined heat and power (CHP), district heating or process heat to industry. Besides this, cascades in the manufacturing chain must also be intensified, allowing a more efficient materials and energy utilization and re-cycling in this part of the production chain. This will consequently reduce the total quantity of waste being generated by manufacturing industries, and thus benefit re-cycling strategies that only capture and seek to re-use a limited fraction of the waste being generated from industry.