Decarbonisation Technology - November 2024 Issue

biomass feedstocks is essential for successful integration. It is important to note that the selection of the insertion point depends on factors such as the availability and characteristics of the biomass feedstock, existing refinery configuration, desired product slate, and the technical and economic feasibility of integration. Detailed techno-economic assessments, process simulations, and pilot-scale studies are typically conducted to determine the optimal insertion point for integration in a specific petroleum refinery. Standalone biorefinery integration Integrating a standalone biorefinery with an existing petroleum refinery offers a way to leverage renewable biomass resources alongside conventional fossil feedstocks, creating a more sustainable and versatile refining operation. A standalone biorefinery operates independently to process biomass into valuable products such as biofuels, biochemicals, and bioplastics. These biorefineries typically use processes like gasification, hydrothermal liquefaction (HTL), or fermentation to convert biomass into intermediates or final products. Several strategies can create synergies between a biorefinery and a conventional petroleum refinery: • Product blending: One common approach is to blend biofuels from a biorefinery, such as biodiesel or biojet fuel, with traditional fossil fuels. This blending can be done at various points in the refinery, including during storage or as a component in the blending pool to meet the product specifications prior to distribution. This method allows the refinery to utilise existing infrastructure while incorporating renewable components into its product slate. • Feedstock substitution: Biomass-derived intermediates, like biocrude from hydrothermal liquefaction (HTL), can be co-processed with conventional crude oil in the refinery’s distillation or upgrading units. This approach helps to reduce the carbon footprint of the refinery’s products while using existing refining technology. • Hydrogen integration: Many biorefineries produce hydrogen as a byproduct, which can be valuable for petroleum refineries. Hydrogen can be used in hydrocracking and hydrotreating (desulphurisation) processes to improve the quality of petroleum products. Integrating this hydrogen into the refinery’s operations can

enhance the overall efficiency and sustainability of the refining process. • Energy and heat recovery: Biomass-based biorefineries often produce excess energy or heat that can be utilised by adjacent petroleum refineries. This integration allows for the use of renewable energy to meet some of the refinery’s energy demands, reducing reliance on external energy sources and improving overall energy efficiency. Challenges in biomass integration As the push for sustainability drives the integration of biomass into fossil fuel refineries and petrochemical industries, it is crucial to acknowledge and address the challenges inherent in this transformative process. While biomass integration offers promising solutions, several complexities must be navigated for successful implementation: • Feedstock variability: Biomass feedstocks vary widely in composition, moisture content, and energy density. This variability requires adaptation of existing refinery processes, which involves optimising and controlling new parameters. Ensuring the sustainability of biomass production is also crucial. Current certification schemes, such as those under the EU Renewable Energy Directive ( EU, 2018 ), cover only a small fraction of biomass sources and often focus on immediate practices rather than long-term sustainability. Effective integration necessitates a more rigorous and long-term commitment to sustainable biomass management. • Catalyst deactivation: Biomass feedstocks can introduce compounds that poison or deactivate catalysts, impacting their efficiency and longevity. A particular challenge is coke formation, where carbonaceous deposits build up on the catalyst surface, causing a reduction in catalytic activity and potentially leading to permanent deactivation. Additionally, the high heat release during the processing of renewable feedstocks, due to their increased presence of unsaturated molecules and oxygen, can exacerbate catalyst deactivation. This requires robust quenching systems to manage the thermal load. Furthermore, the increased water content in biomass-derived products necessitates the use of drainage systems or salt filters to control moisture levels effectively.