Solar-Biomass Co-Electrolysis Slashes Green Hydrogen Costs Below Fossil Fuel Levels: Study

Solar and energy storage have recently emerged as prominent solutions to resolve electricity intermittency, a problem further exacerbated by extreme weather events. A recent report by Chinese Root Global Impact revealed that green hydrogen can be used to combine with solar to reduce the cost of green hydrogen.

The research aims to address the climate change that has intensified global economic impacts and increased interest in replacing fossil fuels with sustainable energy sources, including wind, tidal, and solar power. Among energy storage solutions in fuels, such as hydrogen produced by water electrolysis, it stands out due to its high energy density, storage capability, and clean combustion. However, the high cost of current water electrolysis systems limits widespread adoption.

PV-Based Green Hydrogen Faces High Costs

Recent research explores green hydrogen (H₂) produced using photovoltaics (PV) to electrolyze water. While promising, this approach remains cost-prohibitive. Currently, water electrolysis produces hydrogen at over USD 10/kg, compared to ∼USD 2/kg via steam methane reforming. Even optimistic projections for PV-water electrolysis place the levelized cost at USD 5.90/kg, assuming a solar-to-hydrogen efficiency of 28 percent.

A primary bottleneck is the oxygen evolution reaction (OER) in water splitting. OER is a slow four-electron process compared to the two-electron hydrogen evolution reaction (HER), diverting energy toward producing low-value oxygen and driving up costs.

Breakthrough: Co-Electrolysis of Glucose and Water

The study demonstrates a novel co-electrolysis system using biomass-derived glucose and water, achieving green hydrogen generation rates exceeding 500 μmol h⁻¹ cm⁻². The system uses a membrane-free, undivided cell with electrocatalysts made entirely of earth-abundant elements, powered by a triple-junction PV.

Key Highlights:

• High Selectivity: Glucose is oxidized to formate with yields up to 80 percent, avoiding the need for expensive membranes to separate hydrogen and oxygen.

• Lower Energy Requirements: The overall electrolysis potential is reduced by ∼400 mV compared to traditional water splitting.

• Cost Reduction: Revenue from formate co-production can reduce the levelized cost of hydrogen by $4.63/kg, making it competitive with grey hydrogen from fossil fuels.

Economic Advantages

Traditional solar-water electrolysis costs are dominated by CAPEX (mainly PV modules and electrolyzers) and OPEX. Using a PV-glucose co-electrolysis system without an ion exchange membrane reduces fabrication and maintenance costs. Additionally, cobalt-based electrocatalysts are far cheaper than platinum, further lowering costs.

Technoeconomic analysis suggests that, incorporating revenue from formate, the cost of green hydrogen production drops to USD 1.54/kg, below the ∼USD 2/kg cost of grey hydrogen from steam methane reforming. Furthermore, this co-electrolysis system produces 21.5 percent more hydrogen under one sun, generating additional revenue and reinforcing competitiveness.

Conclusion

This study demonstrates a breakthrough in green hydrogen production through solar-powered co-electrolysis of glucose and water, achieving a high H2 generation rate (>500 μmol h⁻¹ cm⁻²). The approach combines renewable energy with biomass co-electrolysis to produce cost-effective green hydrogen while upgrading biomass precursors into valuable chemical feedstocks.

The system achieves an 80 percent glucose-to-formate conversion yield and a lower onset potential through Cu-doped CoOOH catalysts. Bypassing membrane requirements lowers overall costs, while revenue from formate co-products offsets hydrogen production expenses, making the approach competitive with fossil-fuel-based grey hydrogen. This paves the way for sustainable energy storage and carbon-neutral energy systems.