The Role of Biomass and Synthetic Energy Carriers in the Buildings Sector - From a Sectoral to a Cross-sectoral Perspective

Explorative bottom-up models simulate possible development paths from a sectoral perspective. Aspects such as decision-making, intermediaries and the impact of policy instruments can be mapped. In comparison, cross-sectoral energy system models can find the cost-optimal system solutions and inherently generate the minimum cost solution for the individual sectors. What effects in the cross-sectoral energy system arise when the results of an explorative simulation for the buildings sector are fixed in a cross-sectoral energy system model, taking a policy mix into account? For this purpose the results of the final energy consumption of the Invert/ee-Lab simulation model were determined for a "policy scenario" in the cross-sectoral energy system model REMod. This means that the buildings sector is not optimized in terms of heating system replacement and refurbishment, as is the case in the normative approach. The emerging results allow interesting conclusions. When restricting the solution space in the energy system model, it first becomes apparent that the mathematical model cannot determine a solution under standard boundary conditions. The reason for this is that the high shares of biomass in the heating systems resulting from the bottom-up simulation exert pressure on the overall energy system. In the normative case, the optimizer can freely optimize the use of biomass between the sectors. A bottleneck is created that can only be solved by increasing the assumptions for biomass potential. The analysis with regard to sectoral effects is presented here. These results show a high political relevance with regard to the distribution of limited available climate-neutral energy carriers, as without sectoral attributions, higher system costs and resource bottlenecks can result, which in turn impair the achievement of climate protection targets.