The potential of sufficiency measures to achieve a fully renewable energy system - A case study for Germany : A case study for Germany

Although behavioural changes during the COVID-19 pandemic lead to a noteable drop in annual emissions, these effects are expected to be negligible, because no sustainable change in behaviour can be observed. The growing body of scientific literature on the required low-carbon transformation of the energy system is mostly focusing technological supply side solutions. On the other hand, the demand side receives far less attention, despite having high potential for mitigation. In contrast to research on energy efficiency, the concept of energy sufficiency remains rather unexplored, although lifestyle changes towards a low-energy-demand future are also increasingly associated with greater human well-being and satisfaction. This paper therefore strives to answer the following question: What is the potential of sufficiency-based demand reductions and what impacts do they have on the supply side of a 100% renewable energy system? Based on a literature review, alternative demand pathways for the sectors heat, mobility and conventional electricity are derived. A demand reduction potential through behavioural changes of up to 20.5% is identified, resulting in total annual demand reductions of 300 TWh. A least-cost capacity expansion model is applied to estimate the impacts of these reductions on a greenfield, renewable energy supply for Germany in a scenario-based approach. Overall results indicate that cost reductions of 11.3% to 25.6% in comparison to no lifestyle changes are possible. The sectoral analysis shows that due to high peak loads, demand reductions in the heat sector are significantly more cost-effective than demand reductions in the mobility and conventional electricity sector. A further sensitivity analysis confirms that by cutting demand peaks, less than 1% of overall demand reduction decreases the cost-optimal generation capacity by 2% and storage capacity by 5%. Overall, this paper finds that (a) human lifestyle changes have great potential to reduce energy consumption, (b) the impacts on the supply side are significant and (c) should therefore be included in energy modeling and policy advice