Are 2050 energy transition plans viable? A detailed analysis of projected Swiss electricity supply and demand in 2050

The majority of OECD governments pursue energy policies designed to meet CO2 reduction targets. Many of these plans have a gross approach where, for example, 1 TWh of coal generation may be substituted by 1 TWh of solar. This approach overlooks the importance of dispatch and diurnal, seasonal and weather-related cycles in, for example, solar supply. Switzerland has a detailed energy plan for the year 2050 a key element of which is to phase out existing 2.9GWe of nuclear power, about one-third of current generation, and to substitute this with solar PV that will increase by factor-20. We provide hourly reconstructions of Swiss electricity supply and demand for the months of January and July for the years 2017 and, scaling these reconstructions to 2050, we use them to make a preliminary assessment of viability of the 2050 plan. We find the Swiss plan is viable in July 2050 where surplus daytime solar may be shifted to fill night time deficit using storage. In January 2050, feeble solar supply leaves a supply deficit of 6 TWh for January alone, 69% of projected demand. We urge Swiss authorities, and other European countries, to review and overhaul existing energy policies to ensure the plans add up.