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Microorganisms such as green algae and blue-green algae (cyanobacteria) split water into hydrogen and oxygen via direct or indirect bio-photolysis.

Technology

What is it?

Microorganisms such as green algae and blue-green algae (cyanobacteria) split water into hydrogen and oxygen via direct or indirect bio-photolysis. In direct biophotolysis, hydrogenase in green algae drives hydrogen evolution. In indirect biophotolysis, nitrogenase in blue-green algae drives nitrogen fixation.

Why is it important?

Biophotolysis could be used for producing hydrogen from wastewater with sunlight as an energy source.

Characteristics

  • Inputs: Direct: Water, sunlight. Indirect: Carbon monoxide, water, sunlight
  • By-products: Direct: oxygen. Indirect: carbon dioxide
  • Operating temperature: Ambient

Benefits

  • Low-to-net zero carbon
  • Could be used in wastewater or water which cannot be used for drinking or agriculture
  • Biocatalysts are inexpensive and biodegradable

Limitations

  • In the case of direct biophotolysis: Oxygen produced inhibits the hydrogen production reaction. Oxygen that is evolved destroys the hydrogen enzyme. Separate streams of high purity H2 and O2 are not obtainable
  • Indirect biophotolysis: hydrogenase enzyme provides low hydrogen yield, and produces carbon dioxide
  • Requires large surface area
  • Need to cope with the intermittent nature of solar irradiation supply for the process

RD&D priorities

  • Improve production rates and conversion efficiency, both of which are currently low
  • Reduce cost of photobioreactors
  • Develop oxygen resistant hydrogenase
  • Continue materials development, including characteristics such as increased durability
  • Investigate immobilisation of microorganism cultures to achieve improvement
  • Technology development while sustaining high rate of biohydrogen production

Known active organisations

  • The University of Adelaide
  • The University of Queensland

Other opportunities like this

  • Electrical energy produced by microbes via breakdown of organic matter are augmented with a small additional current to facilitate proton reduction forming hydrogen gas.

  • In the absence of light, microorganisms such as bacteria break down organic matter to produce hydrogen gas through dark fermentation. Bacteria can be engineered in order to increase metabolic activity for a higher hydrogen production rate.

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