One of the major challenges to be met in a transition to a hydrogen energy and transportation economy is actually producing the H2 in an energy-efficient and emissions-limited manner. If we end up relying on coal-generated electricity to produce hydrogen from a natural gas feedstock (currently the predominant approach in the US), that still leaves us with a sizable emissions hurdle to overcome as well as continuing reliance on a limited fossil fuel (natural gas).
Accordingly, researchers are increasing efforts to discover viable methods for producing hydrogen from renewable feedstocks (biohydrogen). At the 228th meeting of the American Chemical Society in Philadelphia this week, scientists are highlighting some of that new biohydrogen work.
Charring Biowaste for Hydrogen. A scientist from the USDA’s Agricultural Research Service (ARS) is working with the inventor of a patent-pending process to turn agricultural biomass-wastes like peanut shells into hydrogen fuel and charcoal fertilizer. The inventor is also working with DOE scientists who hold a patent on a related technology.
Volatiles and steam released by charring biomass produce hydrogen. The charring turns the biomass into charcoal pieces. This charcoal becomes a nitrogen-enriched fertilizer with the addition of ammonia formed by combining a third of the hydrogen with nitrogen. The remaining hydrogen can be sold as fuel, both for a hydrogen-based, clean diesel and to run fuel cells.
One of the additional benefits of this approach is that the technique returns a large portion of harvested carbon to the soil, since plants are not completely burned.
Sunflower Oil to Hydrogen. Researchers at Leeds University in England described a process that mixes sunflower oil with steam and puts the result through a catalytic process to produce hydrogen. An earlier paper on this work is here.
As with biodiesel, a variety of oil stocks could in theory be used as the feedstock for this process: rapeseed oil, soybean oil, etc. Furthermore, the ongoing buildout of a biodiesel production infrastructure would support this deployment of this process, enabling more decentralized production of hydrogen.
Hydrogen from Biomass. Another approach to converting biomass to hydrogen comes from two scientists at the Pacific Northwest National Laboratory who are developing a new reforming technique. The technique (aqueous phase reforming with new catalysts) allows them to include sugars and sugar alcohols as potential feedstocks. An earlier presentation of their work is here.
Hydrogen from Ethanol. Researchers from Waseda University, the University of Tokyo and Nissan described a new low-energy, ambient-pressure, room-temperature technique for reforming ethanol into hydrogen.
Biohydrogen from Wastewater. Researchers from Penn State University describe a new bioreactor that uses dark fermentation to process wastewater into hydrogen. This is one of many papers in a program track that described hydrogen production as a useful byproduct of wastewater processing: BioEnergy Production: BioHydrogen and Electricity Generation Using Microbial Fuel Cells.
Hydrogen from Water. Generating hydrogen from water using sunlight is one of the long-term goals for renewable energy. Researchers at the Korea Research Institute of Chemical Technology have created a new mixed metal oxide semiconductor photocatalyst that shows significant activity for photochemical hydrogen production from water under illumination with either UV or visible light.
And a group at Virginia Tech has created supramolecular complexes that could enable the photochemical production of hydrogen from water.
I’m sure I missed some of the biohydrogen papers; there were well more than 100 on different aspects of hydrogen production alone. Some of the processes may be able to scale and to lead to actual solutions in the market, others will not. The global knowledge gained through this research process is critical, however, and thus the increasing research focus on hydrogen—including biohydrogen—is very encouraging.