The circular economy is calling for the rapid use of already-developed renewable energies. However, the successful implementation of those new fuels is limited by economic and political issues. For instance, in the Brandenburg region, Germany, biogas production from anaerobic digestion of biomass and wastes is a current alternative. However, the upgrading biogas to biomethane is still challenging and the economic viability is unknown. Therefore, we performed an economic analysis for biogas upgrading to biomethane in the Brandenburg region. Five biogas plant sizes were analyzed by the method of discounted cash flow. This method yields the net present value of the projects, thus revealing the profitability or non-profitability of the plants. Results indicate profitable outputs for medium and large plants, with net present values between 415 and 7009 k€. However, the smallest plants have net present values from -4250 to -3389 k€, thus needing further economic efforts or subsidies to reach profitability. Indeed, biomethane prices should range between 52.1 and 95.6 €/MWh to make these projects profitable. Combinations of 50% of investment subsidized and 11.5 €/MWh feed-in tariffs subsidies could make the projects reach profitability. These findings reveal that political actions such as green policies and subsidies are needed to implement green energy. This case study should serve as a potential tool for policy-makers toward a sustainable bioeconomy.

循环经济要求迅速使用已经开发的可再生能源。但是，这些新燃料的成功实施受到经济和政治问题的限制。例如，在德国勃兰登堡州，通过生物质和废物的厌氧消化生产沼气是当前的替代方案。然而，将沼气升级为沼气仍具有挑战性，经济可行性尚不明确。因此，我们对勃兰登堡州沼气升级为沼气进行了经济分析。通过现金流量折现法分析了五个沼气厂规模。这种方法得出项目的净现值，从而揭示了工厂的盈利能力或非盈利能力。结果表明，中型和大型工厂的利润丰厚，净现值介于415到7009 k€之间。但是，最小的工厂的净现值在-4250到-3389 k€之间，因此需要进一步的经济努力或补贴才能实现盈利。实际上，生物甲烷的价格应在52.1至95.6欧元/兆瓦时之间，以使这些项目有利可图。结合50％的投资补贴和11.5欧元/兆瓦时的上网电价补贴，可以使项目实现盈利。这些发现表明，实施绿色能源需要采取政治行动，例如绿色政策和补贴。该案例研究应成为决策者实现可持续生物经济的潜在工具。1和95.6€/ MWh，以使这些项目盈利。结合50％的投资补贴和11.5欧元/兆瓦时的上网电价补贴，可以使项目实现盈利。这些发现表明，实施绿色能源需要采取诸如绿色政策和补贴之类的政治行动。该案例研究应成为决策者实现可持续生物经济的潜在工具。1和95.6€/ MWh，以使这些项目盈利。结合50％的投资补贴和11.5欧元/兆瓦时的上网电价补贴，可以使项目实现盈利。这些发现表明，实施绿色能源需要采取诸如绿色政策和补贴之类的政治行动。该案例研究应成为决策者实现可持续生物经济的潜在工具。