Integrated sustainability assessment of repurposing onshore abandoned wells for geothermal power generation.

As global efforts intensify to mitigate climate change through Net-Zero by 2050, the transition from fossil fuels to renewable energy sources is of utmost importance. Within this context, geothermal power generation is an underestimated yet rapidly developing field with immense potential. A notable opportunity arises from repurposing abandoned oil and gas wells (AOGWs) as alternative sources for geothermal power production. This study employs multi-criteria decision analysis (MCDA) to examine the techno-sustainability of four geothermal power systems: i) a business-as-usual geothermal power plant (GEO bau), ii) repurpose two completely AOGWs for geothermal power generation (R-GEO double), iii) repurpose a single completely AOGW (R-GEO single), iv) repurpose semi-AOGWs (i.e., wells still in operation but with high water cut, R-GEO semi). We assessed 30 criteria across technical, environmental, economic, and social dimensions via the analytical hierarchy process. The study identifies R-GEO semi as the most techno-sustainable option due to its superior performance across environmental, economic, and social dimensions. However, GEO bau closely follows R-GEO semi , securing its position as the second-best option, marked by its outstanding technical proficiency and robust environmental and social performance. Conversely, R-GEO double and R-GEO single show limited techno-sustainability competitiveness. When sensitivity analyses are applied to the weighting factors, R-GEO semi demonstrates resilience and remains as the best option in most cases. However, GEO bau could outperform R-GEO semi when the value of technical criteria is increased (weightings >0.255) or when the weightings for environmental or economic aspects decrease (weightings <0.236 and < 0.244 respectively). R-GEO double and R-GEO single only overtake GEO bau when the economic aspect reaches a weighting of 0.659 or more. Despite R-GEO semi being the most promising option, it faces challenges due to limited power generation capacity and the availability of wells approaching their end-of-lives. The findings underline the necessity for broader stakeholder input, inclusion of more technical and social criteria, and data-driven decision-making processes. • First multi-criteria decision analysis of repurposing abandoned wells for geothermal power. • Repurposed semi-abandoned oil & gas wells are the most techno-sustainable option. • Technical criteria can tilt performance favour towards non-repurposed systems. • Drilling activity should be minimised to boost the deployment of repurposed systems. • Repurposed systems excel when economic criteria are prioritised. [ABSTRACT FROM AUTHOR]