SUSTEPS Project responds to Europe’s goals of achieving climate neutrality by 2050 and cutting greenhouse gas emissions by 55% by 2030. With transportation, especially aviation, being difficult to decarbonize, sustainable algae-based biofuels emerge as a promising solution.
Algae grow rapidly, need neither arable land nor fresh water, and absorb significant CO2. Once harvested, they can be converted into drop-in fuels that integrate seamlessly with existing engines. However, algae-based biofuels face technical, economic, and systemic challenges across their value chain. SUSTEPS aims to deliver cost-effective, scalable solutions to accelerate commercialization and adoption.
SUSTEPS develops a novel bio-refinery concept that utilizes CO2 from high-emission facilities and nutrients from wastewater, lowering costs and reducing environmental impact. It integrates green hydrogen and the recovery of value-added chemicals to enhance process viability and fosters international cooperation to build global knowledge for the scaling-up and sustainability assessment of algae-based biofuel value chains.
SUSTEPS couples biological ingenuity with advanced thermochemical processing in four integrated stages:
Circular feedstock strategy: Algae are cultivated using CO2 captured from cement and steel plants and nutrients recovered from industrial and municipal wastewater. This not only delivers a productive use for waste gases but also lowers the cost of algal growth by displacing synthetic fertilizers.
Hydrothermal liquefaction (HTL): The wet algal slurry is directly converted into a crude-like bio-oil via HTL with the need of energy-intensive drying.
On-site upgrading: The bio-oil undergoes hydrotreatment to refine it into fuel fractions utilizing hydrogen, a portion of which is generated in-house by reforming the light HTL gases, while the remainder is provided as green hydrogen produced via renewable power.
Total valorisation: Membrane and chromatographic separations recover at least three valuable chemicals from the HTL wastewater. The cleaned water is then recycled to the algal ponds, minimizing freshwater demand.
SUSTEPS is expected to advance microalgae cultivation, CO2 fixation, HTL and upgrading technologies, aqueous recycling, and green hydrogen integration. Leveraging industrial waste streams, it aims for carbon-neutral or carbon-negative fuel production. Compliance with EU sustainability standards is ensured through lifecycle and safety assessments.
Through techno-economic analyses and stakeholder engagement, SUSTEPS offers a blueprint for economically viable scaling, strengthens policy frameworks, and supports the development of future algae-based fuel standards. With partners across Europe, America, and Africa, it promotes international knowledge exchange.
Beyond technological innovation, SUSTEPS aims to transform the biofuel sector by demonstrating a TRL 4–5 integrated pilot refinery. By producing negative-emission drop-in fuels, the project is expected to stimulate green investments, create jobs, support EU Green Deal objectives, and enable localized sustainable fuel production globally.
During the first 18 months of the SUSTEPS project (M1–M18), progress has been achieved across all specific objectives, setting a strong foundation for the integrated development of an algae-based biofuel value chain. Key advancements were realized in fostering international collaboration, performing an integrated process design, preliminary experimental trials, and sustainability assessments.
