Underground gas storage as a promising natural methane bioreactor and reservoir?

Abstract

Employing deep reservoirs as UGS (underground gas storage) has a long history across continents. In 2018, 689 underground gas reservoirs with a total volume of 417 bcm were in operation worldwide. It is known that many microbial processes take place in the deep underground, even under the conditions of underground gas reservoirs. In this review, we focus mainly on methanogenesis and discuss related topics such as optimal environmental conditions, description of different types of UGS and microbial communities inhabiting these environments. We elucidate the potential of UGS as natural bioreactors for non-fossil methane production in the context of Power to Methane technology and the extension/expansion of the low-carbon economy. The role of carbon-neutral methane in the energy mix is likely to play a significant role in the coming decades. The safe production, transportation and storage of methane are well managed as well the existing infrastructure has been in place for a long time without problems. We also have experience in the long-term operation of underground gas storage systems. Methane technology thus appears to be a very promising approach and, together with the functioning UGS infrastructure, could be an important step towards the potential use of biomethanation in underground gas storage facilities as a way to reduce greenhouse gas emissions in the future.