Prospective Life Cycle Assessment of Alternative Fuels and Carbon Capture in Swiss Gas-Fired Power Plants

Carbon-neutral energy systems will rely heavily on electrification and intermittent renewables, thereby increasing the need for flexible technologies such as gas turbines. Using alternative fuels in gas turbines could reduce greenhouse gas emissions and support net-zero goals, but their full life-cycle emissions impact has not been evaluated yet. This study presents a prospective life cycle assessment (LCA) of simple cycle gas turbines (SCGTs) in Switzerland, evaluating their performance with various alternative fuels and the potential integration of carbon capture technologies. The analysis considers domestically produced biomethane (from wood chips or biogas) and four e-fuels─e-hydrogen, e-methane, e-ammonia, and e-Fischer-Tropsch (e-FT) fuels─synthesized in regions with cost-effective renewable electricity in Spain, Iceland, and the Netherlands. Regarding carbon capture, we investigate both storage (CCS) and utilization (CCU), considering storage sites in Italy and Norway. The assessment covers multiple impact categories across 2035 and 2050. The results show that domestic biomethane provides a practical and climate-friendly option, reducing life-cycle climate impacts by nearly 80% in the near term and approaching 90% in the long term. In contrast, e-methane does not exceed an 80% reduction in the long term even under its most favorable production pathways. Both biomethane and e-methane can offer net-negative emissions if combined with CCS. Domestic CCU does not offer any environmental advantage if liquefying and transporting hydrogen (H2), instead of directly importing e-methane via pipeline. Multimodal transport increases environmental impacts compared to pipeline transport across several categories. Beyond climate impacts, alternative fuel production introduces trade-offs across most categories compared with natural gas. This study underscores that minimizing greenhouse gas emissions alone is insufficient and that system-level assessments are essential to minimize overall environmental impacts in future flexible power systems.