Long-term implications of reduced gas imports on the decarbonization of the European energy system

Russia is the largest contributor of gas to Europe. It supplied 34% of the EU27 + GB gas consumption in 2019. Due to Russia's invasion of Ukraine, these imports may be discontinued, challenging Europe's energy supply. Here, we investigate the subsequent medium- to long-term implications of gas scarcity on the European green transition. Short-term implications are discussed, but not analyzed. Using an open-sector-coupled model of the European energy system, we show that faster integration of heat pumps and renewables is necessary to maintain climate ambitions, while additional biomass and the postponed phaseout of coal is cost-optimal to ensure energy security. We analyze transition pathways based on CO2 budgets corresponding to 1.5 degrees C and 2 degrees C of temperature increase. We find that the 1.5 degrees C pathway quickly relieves Europe's dependency on imported gas but relies on high build-out rates and has high investment costs. In the 2 degrees C pathway, gas and electricity prices are more affected by the uncertainty in gas supply.