SUSTAINABLE, SECURE AND COMPETITIVE ENERGY THROUGH SCALING UP ADVANCED BIOFUEL GENERATION

Project Information

SUSTEPS

Grant agreement ID: 101122363

DOI

10.3030/101122363

EC signature date 30 August 2023

Start date 1 September 2023

End date 31 August 2027

Funded under

• Climate, Energy and Mobility

Total cost

€ 2 999 536,25

EU contribution

€ 2 999 536,25

Coordinated by

TURKIYE BILIMSEL VE TEKNOLOJIK ARASTIRMA KURUMU
Türkiye

Periodic Reporting for period 2 - SUSTEPS (SUSTAINABLE, SECURE AND COMPETITIVE ENERGY THROUGH SCALING UP ADVANCED BIOFUEL GENERATION)

Reporting period: 2025-03-01 to 2026-02-28

Summary of the context and overall objectives of the project

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.

Work performed from the beginning of the project to the end of the period covered by the report and main results achieved so far

A simulation developed models the entire biofuel value chain. The model achieved high accuracy in mass balance closure, predicting a theoretical biocrude yield of 50%.
LCA studies identified that while nutrient and CO2 recycling significantly reduce the environmental footprint, industrial steam consumption and the energy required for upgrading remain primary technical challenges.
Process hazards were systematically identified under the Safe and Sustainable by Design (SSbD) framework to inform the next phase of industrial scaling.
Biological development focused on optimizing cultivation using waste resources to maximize biomass for downstream conversion.
A comprehensive high-throughput screening campaign on three candidate species identified Chlorella sorokiniana as the primary lead strain due to its superior growth performance in undiluted wastewater and high-CO2 concentrations (up to 15%).
Testing of an integrated tubular photobioreactor and CO2 capture system achieved up to 56% CO2 removal efficiency from simulated flue gas.
The consortium finalized the design and verified the infrastructure for a 3000 L scale-up mechanical processing line, which includes centrifugal harvesting and cell disruption via high-pressure homogenization and hydrodynamic cavitation.
Activities in WP5 centered on the engineering of continuous processing systems and the optimization of biocrude yield. Infrastructure: The construction and programming of the KONTI-L continuous test rig were completed, and commissioning is nearly finished following successful pressure tests at 300 bar. Process Optimization: Batch experiments established 400°C and 10 minutes as the optimal reaction conditions for C. sorokiniana, achieving a carbon-based biocrude yield of approximately 50%.
Trials demonstrated that increasing dry matter concentration from 5 wt% to 14 wt% significantly improves biocrude yield while enhancing process economics by reducing water heating requirements.
Catalyst Screening: Sulfided Ru/AC was identified as a promising candidate for promoting biocrude deoxygenation while minimizing undesirable gasification.
The upgrading phase involved the synthesis of high-performance catalysts and the validation of internal hydrogen recycling.
Catalytic Performance: Testing of commercial and in-house synthesized catalysts confirmed that NiMo-based formulations (specifically NiMoS/γ-Al2O3) are most effective for heteroatom removal, reaching a high Higher Heating Value (HHV) of 48.9 MJ/kg.
The project achieved Milestone M6 with the successful start-up of the ATR/WGS reformer system, designed to convert light gaseous fractions into internal bio-hydrogen for fuel upgrading.
Laboratory-scale amine scrubbing studies for H2-CO2 separation achieved removal efficiencies exceeding 95%.
A techno-economic design for a renewable hydrogen production system was completed for the Moroccan case study.
WP7 implemented separation technologies to recycle water and recover nutrients from HTL effluents.
The consortium identified and documented a membrane sequence (MF-UF-NF) for purifying the HTL aqueous phase (HTL-AP) in Deliverable D7.1.
Nanofiltration (NF) trials on synthetic solutions achieved approximately 90% rejection of COD, ammonia, and phosphates, reaching the water quality required for recycling back to cultivation.
The production of struvite (a slow-release fertilizer) was demonstrated at a pre-pilot scale with a phosphate recovery efficiency of 85%.
Preliminary trials using real HTL-AP samples successfully validated the membrane workflow for removing biochar particles and high-molecular-weight organic contaminant.

Progress beyond the state of the art and expected potential impact (including the socio-economic impact and the wider societal implications of the project so far)

SUSTEPS results show clear progress toward an integrated algae-based advanced biofuel value chain. The project has established a unified process model covering cultivation, HTL, upgrading and recycling; validated algae cultivation with wastewater and CO2-rich streams; optimised HTL conditions for biocrude production; demonstrated effective catalytic upgrading toward SAF/diesel-range products; initiated internal bio-hydrogen production; and developed an MF–UF–NF route for HTL aqueous-phase recycling and nutrient recovery. Key outcomes include up to 56% CO2 removal, approximately 50% carbon-based biocrude yield, >75% heteroatom removal, upgraded oil HHV of around 49 MJ/kg, around 90% contaminant rejection in aqueous-phase treatment, and 85% phosphate recovery as struvite.

The potential impacts are improved carbon-to-fuel conversion, reduced freshwater and nutrient demand, valorisation of industrial CO2 and wastewater streams, production of fuel-range hydrocarbons relevant to SAF and diesel, and stronger process circularity. The results also provide a technical basis for future TRL 4–5 validation and for assessing environmental, economic and safety performance.

Further uptake will require continuous and integrated demonstration, longer-term validation with real feedstocks and side-streams, improved catalyst stability and fuel-standard characterisation, optimisation of energy and hydrogen integration, robust TEA/LCA with uncertainty analysis, IPR/FTO support, and engagement with refineries, SAF value chains, CO2-emitting industries, wastewater operators and fertiliser producers. Supportive SAF, renewable fuel, CO2 utilisation, wastewater reuse and recovered nutrient regulations will also be important for market uptake.