Technology
What is it?
Photosynthetic microbes use sunlight to break down organic matter via fermentation.
Why is it important?
Photo-fermentation could be used for producing hydrogen from wastewater or other organic waste with sunlight as an energy source.
Characteristics
- Inputs: Organic matter (hydrocarbons), water, sunlight
- By-products: Carbon dioxide
- Operating temperature: Ambient
- Energy efficiency: <10%
Benefits
- Low-to-net zero carbon
- Could be used in wastewater or water which cannot be used for drinking or agriculture
- Converts organic substrate
- Nearly complete substrate conversion into biohydrogen
- Can extract additional hydrogen from dark fermentation effluents
Limitations
- Large surface areas required
- Oxygen inhibits hydrogen production
- Operation variability depending on solar irradiation supply
- Less flexible than dark fermentation regarding the type of substrate
- It is usually necessary to convert complex substrates into a mixture of carboxylic acids and alcohols prior to H2 production by photofermentation
RD&D priorities
- Develop inexpensive photobioreactors
- Strain improvement through metabolic engineering
- Investigate replacement of nitrogenase with hydrogenase enzyme
- Overcome low hydrogen production rate
- Overcome low solar-to-hydrogen efficiency
- Reduce cost of photobioreactors
Known active organisations
- The Australian National University