A number of factors are likely to affect the future configuration of the Swiss energy system. Besides the development of global energy prices, decisions on climate change mitigation policies and the future role of nuclear will have an important impact. However, there exists significant uncertainty about exactly how such policies may affect the development of the energy system. For instance, after the recent decisions of the Swiss Parliament to phase out nuclear energy (BFE, 2011a), it remains unclear as to which alternative generation technologies will be most suitable. Options under discussion include gas combined-cycle or combined heat and power (CHP) generation plants, and an accelerated deployment of renewables, but there remain significant technical, economic, environmental and political uncertainties about the suitability of these options. It is also unclear as to the extent to which efficient end-use technologies (e.g. heat pumps) and energy saving measures (e.g. building insulation) could contribute. Moreover, any possible transition away from nuclear energy needs to be consistent with Switzerland’s objectives regarding the mitigation of climate change to avoid serious damages to natural and human systems, including agriculture, health, and infrastructure. This likely requires the pursuit of relatively ambitious mitigation targets, such as those recommended by the Advisory Body on Climate Change (OcCC, 2007).
To understand more about the options for the long-term development of the Swiss energy system in the context of climate policy and uncertainty related to new nuclear investments, we analyse a number of scenarios. These what-if descriptions of the future help to identify robust trends and technology options that may be attractive for realizing a sustainable energy system, and thus help to inform decision makers. These scenarios are analysed with the Swiss MARKAL model (SMM), a least-cost optimisation model with a bottom-up depiction of the entire Swiss energy system. This model provides a detailed representation of energy supply and end-use technologies, including energy efficiency options. For this paper, we present scenarios reflecting stringent climate policy (OcCC, 2007) with two levels of support for nuclear power.
While SMM covers the full energy system, there are some features of the electricity sector in Switzerland that the model is unable to fully represent, and which could affect the suitability of different technology options for the development of the energy system. These include large variations in the electricity load and supply curve at different times of the day, and in different seasons. In SMM, this variation is represented in aggregate, by dividing the annual load curve into six different sub-periods (or "timeslices"). Thus, we couple SMM with an experimental TIMES (The Integrated MARKAL EFOM System) model of the Swiss electricity sector to provide complementary insights (KANNAN and TURTON, 2011). This Swiss TIMES electricity model (ST model) has an hourly electric load curve for several representative seasons and days, over a long time horizon.
The objective of this work is to show how a climate target can be met under different levels of support for future nuclear electricity generation and how the Swiss energy system is influenced. The results of this work are intended to support decision making on energy-related issues by identifying some of the options for achieving policy objectives, some of the trade-offs between different objectives, and the technologies that may be important for realising a sustainable Swiss energy system. Section 2 provides an overview of the two modelling tools and their key assumptions. Section 3 describes three scenarios that are analyzed in the paper. The results from the modelling analysis of these scenarios are then presented in Sections 4 and 5. Section 6 compares the results of the two modelling approaches, while Section 6 discusses some of the policy insights from this analysis. In Section 6, our analytical results are compared with the Swiss Energy Strategy 2050 (BFE, 2011b). Section 6 draws key conclusions and an outlook for future model development.