• Energy Research

Biorefineries hold the potential to provide products and energy carriers at reduced environmental impact compared to their fossil-based counterparts. Thus, they can contribute to the decarbonization of sectors in which electrification of demands is challenging, such as freight transportation or aviation. Furthermore, operating biorefineries in line with renewable electricity availability can help to balance mismatches between electricity availability and demand. This paper investigates the potential of industrial biorefineries to assist the energy transition by providing fossil fuel alternatives and balancing opportunities for the electricity grid. At the example of a Kraft pulp mill, biofuel production potential is explored in consideration of power-to-X technologies. Furthermore, emission reduction and resource efficiency increase by means of carbon capture, utilization and storage applications are investigated. Results reveal that the mill's carbon efficiency can be increased from 50% to 90%, profiting from carbon capture, utilization and storage. Proposed mill configurations provide energy mixes with environmental impact factors well below the average of comparable conventional products. Furthermore, significant shares of energy from imported electricity can be stored over the course of one year, and provided either in form of electricity or biofuels. The profitability and emission mitigation potential of the analyzed system are highly dependent on the available electricity mix and the respective market portfolio. Therefore, future work requires a detailed analysis of the mill's environment in order to identify relevant investment decisions for the provision of low-impact heat, fuels, and storage opportunities for renewable electricity.

A shift from fossil fuels to renewable energy sources is essential to reduce global greenhouse gas emissions and climate change effects. Biofuels represent a promising low-carbon alternative for sectors that are hard to electrify, such as freight transport or aviation. This work investigates possible pathways for increasing the value of biomass at a Kraft pulp mill, focusing on black liquor and bark streams. Mathematical programming is coupled with superstructure optimization and systematic solution exploration to identify meaningful process configurations. The analysis of solutions under market variations allows for the identification of robust and competitive configurations for the co-production of pulp and fossil fuel alternatives. The results show that the integration of biorefineries in pulp mills results in better resource use and higher energy efficiency - diversifying the product portfolio and providing bio-based fuel products to the market while being economically viable. By incorporating fuel production in the conventional Kraft process, the carbon conversion efficiency of the mill can be increased from 48% to up to 67%. Extending the analysis, up to 2% of the European road freight transportation fuel could be provided with combined pulp and fuel production, and 5% of the worldwide fuel demand for passenger aviation.

Exploiting synergies between industrial biorefineries and residential districts allows to reduce emissions and fossil fuel dependency at reasonable economic compromises.

Abstract The design of efficient energy systems, through the development of new technologies and the improvement of current ones, requires the use of rigorous process synthesis methods for generating and analysing design alternatives. We introduce a digital twin of process and energy system design that interactively translates needs and preferences of decision makers into an optimization-based model and generates meaningful solutions. The Interactive Digital Twin (InDiT) assists decision makers in steering the exploration of the solution space and guiding them towards relevant system design decisions, taking into account multiple aspects such as the impact of uncertainties and multi-criteria analysis. InDiT enhances step-by-step communication with the decision maker, relying on visual aids to keep the communication during solution generation and exploration intuitive and flexible. In this way, decision makers are guided towards relevant solutions and improve their understanding of relations between the problem definition and system design decisions, while InDiT builds on the decision makers’ preferences and can, after training, suggest solutions that are best-suited to their interests. The novelty of this work lies in the holistic approach of addressing both (i) the systematic generation and exploration of solutions with the assistance of a digital consultant, which translates the decision maker’s needs into machine language and vice versa, and (ii) the interactive step-by-step technique on filtering and evaluating solutions intuitively. This guarantees that the decision maker does not only get solutions based on the design specifications made, but that personal preferences are taken into account during the solution synthesis step, and that the solution space can easily be explored under different criteria. The proposed methodology is demonstrated and applied to the design case of an integrated multi-product biorefinery.