Incorporating life cycle assessment into energy transition policy: displacing coal with natural gas

The transition from coal to natural gas is widely regarded as a major strategy for decarbonizing the power sector. However, current policies often assess environmental impacts based solely on emissions from fuel combustion, neglecting broader life cycle effects and associated supply chain dependencies. This study combines a comparative policy analysis of coal phase-out strategies in major economies with a life cycle assessment (LCA) of replacing coal-fired power generation with natural gas in South Korea, an energy-importing country actively pursuing energy transition goals. The results show that while natural gas substitution leads to substantial reductions in direct combustion emissions, the overall life cycle greenhouse gas benefits are highly sensitive to upstream supply chains. Variations in extraction practices, liquefaction energy intensity, transportation distances, and exporting-country energy mixes were found to induce significant changes in life cycle outcomes. Sensitivity analysis further demonstrates that modest changes in key upstream parameters can alter the environmental performance of coal-to-LNG transitions. These findings reveal critical blind spots in existing energy transition policies that rely on combustion-based metrics and risk overstating mitigation outcomes. By integrating policy review with life cycle assessment and sensitivity analyses, this study highlights the importance of incorporating full supply-chain perspectives into energy planning. Embedding LCA into policy frameworks enables more robust evaluation of greenhouse gas reduction potential while also informing energy security considerations by revealing upstream dependencies and vulnerabilities. The results support a shift toward more holistic, supply chain-aware energy transition policies that align environmental sustainability objectives with broader energy system resilience.