The Feasibility of the 'All-in-One' Concept in the UK North Sea: Offsetting Carbon Capture and Storage Costs with Methane and Geothermal Energy Co-Production in a Depleted Hydrocarbon Field

Abstract

Co-production of methane and geothermal energy from brine, which is then reinjected with CO2, has been proposed as a means to power offshore carbon storage sites and offset a portion of the costs of carbon capture and injection. This study investigates the feasibility of such a coupled methane production and CO2-brine injection system within a saline formation located in the Inner Moray Firth, UK. A Monte Carlo modelling approach was used to calculate the energy balance of such a system. We find that the system is highly likely to have a positive energy balance and could significantly offset carbon capture costs. Our results show that existing oil & gas infrastructure could be developed for a fraction of the cost of a purpose built site or decommissioning such infrastructure, whilst also helping to overcome the initial financial barriers of developing the North Sea as a large-scale carbon storage resource.