Modelling Germany's energy transition within a 1.5°C-CO2-budget

To restrict global warming to 1.5°C, greenhouse gas emissions must decline rapidly. However, there is still an open debate how to allocate the remaining global CO2 budgets, as calculated by the IPCC, to national CO2 budgets that limit global warming to a certain temperature increase. Moreover, analyses of transition pathways using one integrated model that restricts national emissions to a 1.5°Cper-capita-budget are missing. This paper discusses different approaches to derive a national CO2 budget for Germany. The energy system model REMod is used to model possible long-term transition pathways for Germany within its national 1.5°C-per-capita CO2 budget. Model results show that rapid action in all aspects of the energy system and fundamental changes in energy policy and in society are needed to comply with the remaining CO2 budget: annual capacity additions of renewable energy sources (wind and solar) need to increase to rates three to five times higher than the historic maxima, direct electrification of all sectors needs to be accelerated by an exchange of technologies even before the end of their lifetime (e.g. gas boilers and ICE vehicles) and demand needs to decrease through behavioural changes in the society (sufficiency).