Long term climate change mitigation goals under the nuclear phase out policy: The Swiss energy system transition

- Development and application of Swiss TIMES Energy System Model (STEM) with high temporal resolutions
- Swiss final energy demand continues to decrease but electricity demand increases.
- There are clear linkages between use of natural gas in centralised gas power plants and end-use sectors.
- Electrification of heating and e-mobility contribute to a significant CO2 emission reduction.
- The electrification of end-use sectors shifts some the CO2 emissions to the electricity sector.

The Swiss electricity system is dominated by low-carbon hydro and nuclear generation. The Government's decision to phase-out nuclear energy exacerbates Switzerland's climate change mitigation goals. Response to this challenge requires systemic changes to the energy system, which is generally a long-term, uncertain and systemic process, affected by technology choices across the entire energy system. A comprehensive Swiss TIMES Energy system Model (STEM) with high temporal detail has been developed for the analysis of plausible low-carbon energy pathways focusing on uncertainties related to policy (climate change mitigation and acceptability of new centralised electricity generation) and international fuel prices. Increasing electrification of end-uses is seen across the scenarios, resulting in continuous growth in electricity demands. The electrification of heating and e-mobility substitute direct use of fossil fuels in end-use sectors and contribute to a significant carbon dioxide emission (CO2) reduction. Centralised gas power plants and renewables become key source of electricity supply. Given the phaseout of nuclear generation, clear policy signals are required to ensure capacity is built to achieve a low-carbon energy system. At the same time, it is also essential to ensure consistency between the electricity sector and end-use energy policies. For the long-term carbon reduction target, some non-cost-effective conservation measures are important early in the period because they are available only at the time of building renovation.