High-calorific bio-hydrogen production under self-generated high-pressure condition

Area of Science:

• Biotechnology
• Renewable Energy
• Chemical Engineering

Background:

• Biological hydrogen (H₂) production necessitates efficient carbon dioxide (CO₂) removal.
• Conventional CO₂ removal methods can be costly and complex.
• There is a need for integrated processes that enhance H₂ purity and reduce operational expenses.

Purpose of the Study:

• To investigate a novel self-generated high-pressure dark fermentation (HPDF) process for direct bio-H₂ production.
• To evaluate the impact of elevated pressure on H₂ content and yield.
• To assess the economic feasibility of HPDF for producing high-calorific bio-H₂.

Main Methods:

• Batch fermentation experiments were conducted with self-generated gas increasing pressure within the fermenter.
• Maximum pressures were controlled at 1, 3, 5, 7, and 10 bar.
• H₂ content, H₂ yield, and microbial community shifts (lactate production, lactic acid bacteria abundance) were analyzed at different pressures.

Main Results:

• H₂ content increased from 55% at 1 bar to 80% at 7 and 10 bar.
• H₂ yield decreased from 1.5 to 0.9 mol H₂/mol hexose_added as pressure increased.
• Elevated pressures (7 and 10 bar) led to increased lactate production and lactic acid bacteria abundance.

Conclusions:

• HPDF is a viable strategy for producing high-purity bio-H₂.
• While H₂ yields decrease at higher pressures, the enhanced H₂ content and reduced CO₂ removal costs make HPDF economically advantageous.
• This process offers a cost-effective solution for high-calorific bio-H₂ production.