Sustainable Biofuel Production: Insights from FLEXBY's Preliminary Life Cycle Assessment

To evaluate the environmental performance of this technology at its early development stage, the consortium has released a comprehensive “Preliminary Life Cycle Assessment” (LCA), led by GreenDelta in collaboration with all project partners.

What Is Being Assessed?

This early-stage LCA focuses on the operational phase of the FLEXBY system and compares it to traditional pyrolysis methods. Key aspects include:

• Microwave pyrolysis vs. conventional slow and flash pyrolysis
• Two feedstocks: microalgae from wastewater and oily sludge from dairy wastewater treatment
• Energy consumption, emissions, and resource use
• System outputs: biofuel, biochar, and electricity from pyro-gas

Key Findings from the Preliminary LCA

The preliminary LCA confirms what the FLEXBY team anticipated: microwave-assisted pyrolysis has the potential to be a far more energy-efficient and environmentally friendly method of biofuel production than traditional pyrolysis techniques. Among the various scenarios analysed, the combination of microalgae feedstock with microwave pyrolysis stood out as the best-performing setup. This approach not only consumed the least energy but also delivered the lowest environmental impact across key indicators, including greenhouse gas emissions, acidification, and fossil resource use.

An added benefit of the FLEXBY process is the production of biochar—a solid by-product that, while not yet fully integrated into the LCA model, holds promise for carbon sequestration and soil improvement. This could make FLEXBY's biofuel system not just low-carbon, but potentially carbon-negative.

Challenges and Opportunities

Despite these promising results, the assessment also highlighted areas for improvement. One of the most significant challenges is the high energy demand for drying wet feedstocks like microalgae and oily sludge, which currently contributes considerably to the overall environmental impact. However, the FLEXBY team is exploring innovative solutions to address this issue. One promising avenue is to repurpose the water content from the feedstock for use in the hydrogen-free hydrodeoxygenation process. If successful, this would eliminate the need for drying altogether, further boosting the system’s sustainability.

The project is also looking into valorising by-products such as ammonia recovered from pyrolysis gas and recovering waste heat from fuel cell systems—both of which could significantly improve energy efficiency and circularity. As with any early-stage research, some data used in the assessment was based on simulations rather than physical measurements. While this introduces a degree of uncertainty, a full cradle-to-grave LCA is planned for later in the project, which will include all life cycle stages, from machinery production to end-of-life, and will be based on refined experimental data.

Next Steps: A Full Sustainability Assessment

FLEXBY plans to build on this preliminary assessment with a full life cycle sustainability assessment (LCSA) by Month 48. This will include:

• Cradle-to-grave evaluation
• Socioeconomic impacts
• Inclusion of machinery, transport, and end-of-life processes
• Refinement of data as experimental results become available

Conclusion

FLEXBY’s preliminary LCA confirms the strong potential of its innovative approach to biofuel production. By harnessing microwave technology and hydrogen-free processes, FLEXBY reduces environmental burdens while making use of waste streams that are often underutilised.

This early analysis provides critical insights for technology development and guides improvements that will support Europe’s transition to a circular, low-carbon bioeconomy.

Download the full report here.