Techno-economic and life cycle analysis of bio-hydrogen production using bio-based waste streams through the integration of dark fermentation and microbial electrolysis†

Hydrogen derived from bio-based sources, or biohydrogen (bioH₂), has the potential to reduce GHG emissions from industrial and transportation sectors, owing to the low carbon footprint and myriad applications like refinery operation, ammonia production, steel production, fuel cell, etc. To evaluate the commercialization potential of bioH₂ production, we modeled bioH₂ production and conducted techno-economic analysis (TEA) and life cycle analysis (LCA) of two facilities producing 50 metric tonnes of bioH₂ per day from cheese whey (CW) and solid food waste (SFW) through the integration of dark fermentation (DF) and microbial electrolysis cell (MEC) technologies. LCA results showed that CW and SFW can produce carbon-negative bioH₂, with emissions of −8.6 and −8.0 kg GHG kg⁻¹ bioH₂ with carbon sequestration and renewable electricity resources, respectively, making bioH₂ potentially eligible for a tax credit of $3 kg⁻¹ H₂ based on provision 45 V of the U.S. Inflation Reduction Act (IRA). In this study, bioH₂ production treats waste streams to generate fresh water, thus, potentially can receive waste water treatment fee that varies with regions. The MEC capital cost dominates the bioH₂ cost, which is mainly determined by current density. With a current density of 20 A m⁻², the production cost for CW input varied between $17 and $24 kg⁻¹ bioH₂, while that for SFW input ranged from $29 to $30 kg⁻¹ bioH₂ under different operating conditions, considering the 45 V tax credit, waste water treatment fee and production revenue. If the current density increases to 100 A m⁻², the bioH₂ cost decreases to a range of $4.0–$6.9 for CW and $5–$6 for SFW scenarios. This study also shows that low-cost bioH₂ can be produced using CW waste stream as feedstock.