The role of biogenic wastes and residues in a climate-neutral society: Carbon source, bioenergy and negative emissions

But how can theory be put into practice? Using the industrialized country Germany as an example, this paper outlines the current state of developments as well as necessary future measures, with a focus on the sustainable use of biogenic residues and wastes. Germany should lead the way in climate-neutrality, but is, in fact, light-years away from this at the moment. Current figures of the German Federal Environmental Agency do not show any positive developments (UBA, 2022). In 2021, Germany emitted 762 Mt CO2 eq, which is roughly 33 Mt more than in 2020. First figures for 2022 (761 Mt CO2 eq) even show stagnation, and reduction rates in relation to 1990 are below 39% (Agora Energiewende, 2023). In order to achieve the legally binding goal of climate neutrality by 2045, Germany needs to implement quick-acting, tangible and forceful measures. First and foremost, current energy consumption must be reduced by half. This requires both consistent energy saving measures and significant increases in energy efficiency. Secondly, Germany’s energy supply must switch to renewables completely and in all sectors over the coming decades. Wind, solar, geothermal, hydro and bioenergy will need to be seamlessly integrated, also across the sectors of heating/cooling, electricity and mobility, and especially the three former will require massive new installations as well. The share of renewables in Germany’s primary energy consumption was only about 17% in 2022 (Arbeitsgemeinschaft Energiebilanzen, 2023), and roughly 60% of this was supplied by bioenergy (Fachagentur Nachwachsende Rohstoffe, 2022). Energetic use of biomass meant that about 79 Mt CO2 eq Greenhouse Gas were avoided in 2021. Thus, it made a substantial contribution to climate protection. In future, bioenergy will especially be needed to fill supply gaps in a system relying entirely on renewable energies. The energetic use of biogenic wastes and residues will see increasing importance, as will negative emissions, which can be generated by storing ‘green’ carbon. Thirdly, we need to develop our ‘linear’ economic system to a truly circular one – again, we are still far from success on this path. As a key prerequisite, industry supply with organic compounds largely needs to switch from fossil-based to biobased raw materials. Biomass therefore both needs to be integrated into a sustainable energy system (‘Energiewende’) and form the basis of a bioeconomy (‘Rohstoffwende’, ‘raw material turnaround’). Such an ambitious goal can only be reached if biomass is deployed in an efficient and environmentally friendly way, and to maximum economic benefit. This will require new technological concepts as well as combined and cascading uses. Moreover, biomass must be supplied from sustainable production and in form of wastes and residues. Flexible use of biomass, together with other renewable energies, provides the highest systemic benefit in the different energy sectors. Synergies of bioenergy with other elements of energy and climate politics, such as hydrogen or atmospheric carbon removal (e.g. BECCS, bioenergy with carbon capture and storage), are of increasing importance. With any application, one needs to bear in mind that the use of biogenic resources is not sustainable per se. Suitable methods and tools of applied sustainability assessment are needed to provide comprehensive monitoring of established and new processes, concepts and products in the bioeoconomy. A matching regulatory framework is also critical. The key role an optimized material and energetic use of biogenic wastes and residues will play is increasingly being recognized, and acted upon, by relevant national and international stakeholders in the circular economy. The International Solid Waste Association (ISWA) has, for example, numerous ongoing actions on material as well as energetic utilization of bio-wastes. In the German National Biomass Strategy which the German government is planning to finish by 2023, the topic also plays an important role. Lastly, it also makes up focal areas of research of both the Deutsches Biomasseforschungszentrum gGmbH, German Biomass Research Centre (DBFZ) in Leipzig and the Chair of Waste and Resource Management in Rostock (see also Nelles et al., 2022). In order to assess quantities and availability of biogenic resources – the basis for any evaluation of chances and risks of current and future uses – the DBFZ develops and implements resource monitoring systems for different geographical regions and makes them available in a standardized format. All results and documentation can be accessed free of charge for individual analyses (DBFZ, 2020). As of today, the database already takes into account over 100 different biogenic residues from numerous sectors, for example, agricultural and forestry side products, The role of biogenic wastes and residues in a climate-neutral society: Carbon source, bioenergy and negative emissions 1161506WMR0010.1177/0734242X231161506Waste Management & ResearchEditorial editorial2023