Abstract The purpose of this paper is to identify a suitable and CO2-neutral geothermal co-produced gas utilization for a use case in the German Molasse Basin. Therefore, different approaches, based on gas engines, are compared to each other. The investigations are based on heating values from existing measurements of the actual co-produced gas composition. An oxyfuel-based concept with flue gas recirculation has been determined to be the best suitable option, since it allows the reinjection of the entire flue gas into the geothermal brine. The approach for the technological adaption of the gas engine is based on the adiabatic flame temperature in order to identify comparable operational regimes and the necessary flue gas recirculation rate. Necessary reinjection pressures are calculated based on hydrogeochemical equilibrium calculations, showing general feasibility of the reinjection as well. An analysis of the energy balance and the resulting energy streams shows an electric power output of 94.9 kW and an additional heat output of at least 256.2 kW, when the power consumption for the air separation unit is taken into account as well.

中文翻译：

---

用于深层地热应用的 CO2 中性联产天然气利用

摘要 本文的目的是为德国 Molasse 盆地的一个用例确定合适的 CO2 中性地热联产天然气利用。因此，基于燃气发动机的不同方法相互比较。调查基于来自实际联产气体成分的现有测量的热值。带有烟道气再循环的基于氧燃料的概念已被确定为最合适的选择，因为它允许将整个烟道气重新注入地热卤水中。燃气发动机技术调整的方法是基于绝热火焰温度，以确定可比较的运行方式和必要的烟气再循环率。根据水文地球化学平衡计算计算必要的回注压力，也显示了回注的一般可行性。对能量平衡和由此产生的能量流的分析表明，如果将空气分离装置的功耗也考虑在内，则电功率输出为 94.9 kW，附加热量输出至少为 256.2 kW。