The rising demand for cleaner energy sources, along with the global need to reduce greenhouse gas emissions, has increased interest in methane as a transitional fuel. Methane, being a high-energy and low-carbon hydrocarbon, plays a crucial role in energy systems focused on decarbonization. However, effective methane storage presents significant challenges, particularly in managing seasonal demand fluctuations, ensuring supply security, and establishing strategic reserves. Considering this, herein, we employ a comprehensive set of 24 technical, economic, geological, and environmental parameters (criteria) to identify the best sites for methane storage. Additionally, the study uses eight advanced Multi-Criteria Decision-Making (MCDM) methods to assist in the site selection process. It also explores four different types of potential methane storage sites: salt caverns, saline aquifers, depleted oil and gas reservoirs, and shale reservoirs. The evaluation of these subsurface storage alternatives utilizes the eight MCDM methods, integrating a hybrid weighting approach that combines the Analytic Hierarchy Process (AHP) and Entropy. The criteria weights and rankings varied across the different methods; however, the final aggregated results indicated that saline aquifers were the most favorable option, followed by depleted oil and gas reservoirs, salt caverns, and shale reservoirs. Key influential criteria included methane purity, operational expenditures, and site permeability, while the methane gas injection rate consistently ranked as the least important factor. Underground geological formations offer a promising solution, as they provide large-scale and long-term storage capacity with minimal surface impact. These findings contribute to the broader conversation about sustainable energy infrastructure and provide actionable insights for policymakers, energy planners, and subsurface engineers.
Lv et al. (Mon,) studied this question.