• Energy Research

Um die Treibhausgasemissionen des Pkw-Verkehrs zu verringern, werden seit einiger Zeit biogene Kraftstoffe eingesetzt, die jedoch nahezu ausschließlich aus hierfür angebauten Energiepflanzen erzeugt werden und somit in Konkurrenz zur Nahrungsmittelproduktion stehen. Um diese Probleme zu vermeiden, wurde der Fragestellung nachgegangen, wie Waldrestholz im Pkw-Bereich technisch, ökonomisch und umweltrelevant möglichst effizient als Kraftstoff genutzt werden kann.

Um die Treibhausgasemissionen des Pkw-Verkehrs zu verringern, werden seit einiger Zeit biogene Kraftstoffe eingesetzt, die jedoch nahezu ausschließlich aus hierfür angebauten Energiepflanzen erzeugt werden und somit in Konkurrenz zur Nahrungsmittelproduktion stehen. Um diese Probleme zu vermeiden, wurde der Fragestellung nachgegangen, wie Waldrestholz im Pkw-Bereich technisch, ökonomisch und umweltrelevant möglichst effizient als Kraftstoff genutzt werden kann.

Biochar has an enormous potential to store carbon in the long-term. Differently than BioEnergy Carbon Capture and Storage (BECCS) technologies, biochar incorporates biogenic carbon in a solid form that offers multiple benefits as carbon sink, soil improver or for advanced materials production. The present study proposes an innovative approach, where carbon sequestration through biochar is obtained through the integration of slow pyrolysis with fast pyrolysis in decentralised biorefining systems, and then converted producing drop-in fuels from pyrolysis oil hydrotreating or gasification and Fischer-Tropsch (FT) synthesis. The scope is either to achieve negative GHG emissions assigned to advanced biofuels, or to export the generated carbon credit for the carbon markets (i.e. outside the biofuels carbon intensity). The innovative concept entails process integration and optimisation for the different stages of biomass drying, conversion and upgrading into biofuels in a way to reduce fossil-based inputs, applying a full value chain approach. Methodological choices for the assumptions on life cycle emissions calculation are discussed, evaluating the environmental performances by comparing the new concept to traditional biofuels value chains. Using a tailored lifecycle accounting methodology, this paper demonstrates that high GHG emissions savings can be achieved. The improved scenario shows how the carbon sequestration with biochar further reduces the carbon intensity up to –4.2 gCO2e MJ−1 for pyrolysis oil-based fuels, and to −20.2 gCO2e MJ−1 for FT-based fuels: this demonstrated that carbon negative sustainable biofuels can be obtained. The study demonstrates that an integrated biorefinery of 100 MW capacity can deliver additional 13.3 and 6.8 ktons of CO2e of GHG savings of per year, from drop-in fuels made of hydrotreated pyrolysis oil and FT synthesis, respectively.

Biochar has an enormous potential to store carbon in the long-term. Differently than BioEnergy Carbon Capture and Storage (BECCS) technologies, biochar incorporates biogenic carbon in a solid form that offers multiple benefits as carbon sink, soil improver or for advanced materials production. The present study proposes an innovative approach, where carbon sequestration through biochar is obtained through the integration of slow pyrolysis with fast pyrolysis in decentralised biorefining systems, and then converted producing drop-in fuels from pyrolysis oil hydrotreating or gasification and Fischer-Tropsch (FT) synthesis. The scope is either to achieve negative GHG emissions assigned to advanced biofuels, or to export the generated carbon credit for the carbon markets (i.e. outside the biofuels carbon intensity). The innovative concept entails process integration and optimisation for the different stages of biomass drying, conversion and upgrading into biofuels in a way to reduce fossil-based inputs, applying a full value chain approach. Methodological choices for the assumptions on life cycle emissions calculation are discussed, evaluating the environmental performances by comparing the new concept to traditional biofuels value chains. Using a tailored lifecycle accounting methodology, this paper demonstrates that high GHG emissions savings can be achieved. The improved scenario shows how the carbon sequestration with biochar further reduces the carbon intensity up to –4.2 gCO2e MJ−1 for pyrolysis oil-based fuels, and to −20.2 gCO2e MJ−1 for FT-based fuels: this demonstrated that carbon negative sustainable biofuels can be obtained. The study demonstrates that an integrated biorefinery of 100 MW capacity can deliver additional 13.3 and 6.8 ktons of CO2e of GHG savings of per year, from drop-in fuels made of hydrotreated pyrolysis oil and FT synthesis, respectively.

Background Due to the available volumes, biogenic residues are a promising resource for renewable fuels for passenger cars to reduce greenhouse gas (GHG) emissions. In this study, we compare three fuels from forest residues under German framework conditions: biogenic electricity, substitute natural gas (SNG), and Fischer-Tropsch (FT) diesel. Methods Fuels from forest residues are compared with regard to their technical efficiency (here defined as ‘pkm per kg biomass’), costs, and environmental impacts with a focus on GHG emissions. We took into consideration the real-life driving conditions and corresponding car classes as well as market penetration scenarios for electric and gaseous fuel cars. Results Our results show that the technical efficiency of biogenic electricity is high, while the economic and environmental results strongly depend on the car size and market penetration assumptions. Furthermore, it is essential to clearly define the main goal of introducing fuels from forest residues. If the goal is to reduce GHG emissions at the lowest cost, SNG (and natural gas) in bigger cars is preferable. For high GHG reductions at the lowest forest residue consumption, biogenic electricity in smaller commuter-type cars are found to be a good solution. This also proves true for the aggregated environmental impact score ReCiPe Total. Conclusions It is important to include mobility patterns and a clear goal definition when comparing biogenic fuels. In Germany, biogenic electricity, SNG, and FT diesel can reduce GHG emissions at reduction costs of around 100 €/t CO2-Eq when used the right way.