Quo vadis, biomass? Long-term scenarios of an optimal energetic use of biomass for the German energy transition

As one of the renewable resources, biomass is in demand for the transformation of the energy system to achieve climate protection targets. At the same time, the availability of biomass is limited. In this paper, the energy system optimisation model BenOpt is used to determine the optimal use of the limited biomass under different frame conditions (scenario settings) in the future German energy system. Previous energy system studies have summarised available biomass and biomass conversion technologies in a very general way, with little differentiation between biomass types, conversion technology options with their technical parameters, and their applications. In this paper, 20 different groups of biogenic residual and waste materials; 15 types of energy crops grown on limited agricultural land; other biomasses such as algae, paludiculture, and log wood; 111 different bioenergy technologies; and a total of 265 renewable and fossil energy technology options for meeting sector-specific energy needs are considered. With this focused and differentiated presentation of biomass and biomass conversion technologies in the energy system, the study is a novelty and fills a research gap. In summary, to achieve the climate protection targets, biomass is most cost-effective in sectors where direct electrification is not possible or only possible on high costs: in high-temperature industrial applications and in the aviation and shipping sector. In addition, biomass especially biogas is also the cost-optimal option used in electricity flexibilisation to cover the residual load. In this study, the political decision on the future role on energy crops and thus the availability of biomass has the greatest influence on the results. Depending on whether a sole use of residues and waste biomass or a maximum availability of residues, waste and cultivated biomass is assumed; the bioenergy used comprises a total of approx. 660 PJ to approx. 1,830 PJ.