Technological evolution and sustainable deployment of synthetic natural gas from coal gasification: a review, recommendations, and prospects

Coal-derived synthetic natural gas (SNG) represents a prospective component within the energy diversification strategies of coal-abundant economies, yet its systemic benefits and burdens remain contested. This review synthesizes the technological evolution, industrial deployment, environmental footprints, and economic viability of SNG using bibliometric mapping and multidimensional comparative analysis. Analysis indicates that while SNG can mitigate local air pollution and enhance gaseous energy security relative to direct coal combustion, its lifecycle greenhouse gas (GHG) emissions and freshwater intensity typically exceed those of conventional natural gas. Market competitiveness is found to be highly sensitive to the coal-to-SNG price spread and emerging carbon pricing frameworks, presenting a risk of infrastructural lock-in. A credible integration of SNG into net-zero trajectories requires coordinated advancements across three pillars: targeted process innovation (including high-efficiency methanation and CO2 capture), system level integration (coupling with renewable H2 and biomass), and aligned policy frameworks (standardized emissions accounting and robust carbon pricing). When managed through these synergistic measures, SNG may function as a strategic, albeit constrained, balancing resource in specific energy-security contexts.