Assessment of transformation strategies for the German power sector under the uncertainty of demand development and technology availability

The long-term energy strategy issued by the German government in 2010 and 2011 embraces a substantial reduction of CO2 emissions and high shares of renewable energy in electricity production, along with energy efficiency improvements and an accelerated nuclear phase-out. While several studies illustrate scenarios reaching these targets, there are substantial uncertainties pertaining to key assumptions, particularly long-term electricity demand and the large-scale availability of offshore wind and carbon capture and storage (CCS). This paper explores conditions under which model-based scenarios for the German electricity sector comply with the official targets for CO2 emission reductions and renewable shares. We apply the energy system model LIMES-D, which allows for a joint optimization of generation and transmission capacities. The results indicate that reducing electricity demand plays a crucial role for attaining the government׳s targets. Scenarios for which either offshore wind or CCS is not available show an even stronger need for a decreasing electricity demand to reach the targets and a different pattern of transmission capacity expansion than is the case with full technology availability. Hence, a broad technology portfolio could in turn hedge against future power demand increases that may challenge the joint attainment of the German decarbonization and renewable energy targets.