BIOLOGICAL HYDROGEN PRODUCTION (BWP) II
The Biological Hydrogen Production project is supported with a grant of the Dutch Programme EET (Economy, Ecology, Technology) a joint initiative of the Ministries of Economic Affairs, Education, Culture and Sciences and of Housing, Spatial Planning and the Environment. The programme is run by the EET Programme Office, a partnership of Senter and Novem. The first phase (BWP I) ran from September 2000 to March 2003; the second phase (BWP II) has started in September 2003 and has lasted till July 2006.
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Kick-off meeting of BWP II on Feb 10th, 2004 at Wageningen UR Agrotechnology & Food innovations
Hydrogen is regarded as the fuel of the future. Conversion of hydrogen in fuel cells has high energetic conversion efficiency and water is the sole end-product. Presently, hydrogen is produced from fossil reserves with the concomitant release of anthropogenic carbon-dioxide. Therefore, new hydrogen production technologies are being developed, based on the utilization of renewable resources.
Biological hydrogen production, i.e. the production of hydrogen from biomass by micro-organisms, is a common phenomenon. In swamps, in rumina of cows, and also in the well-known biogas installations, hydrogen is produced from biomass under anoxic circumstances. However, this hydrogen is being consumed as soon as it is being produced by methanogenic bacteria and methane is the end-product which becomes available. In this project, methane production is uncoupled from hydrogen production by installing a two-stage bioprocess. In the first stage hydrogen and acetic acid are produced from biomass by thermophilic bacteria. In the second stage, the acetic acid in the effluent is converted to hydrogen by purple non-sulfur bacteria.
The Biological Hydrogen Production project addresses the following issues:
-Conversion of biomass from an energy crop or an organic waste stream to fermentable feedstock;
-Selection of thermophilic and photo-heterotrophic micro-organisms and design of optimal growth and production conditions:
-Design of an integrated bioprocess;
-Development of recovery and purification methods for upgrading the gas to fuel cell specifications.
- Pretreatment of biomass
- Identification of optimal (bio)process conditions
- Optimalization of hydrogen recovery
- Identification of gas specifications
- Identification of optimal fuel cell configuration
- Design and sub-scale construction of bioreactors
- Process integration by innovative modular design
- System analysis
- Processing and valorization of residual fractions.
BWP I: September 2000 to March 2003
A large variety of thermophilic bacteria allow efficient hydrogen production from biomass. The metabolic pathways have been partially elucidated to enable careful scrutiny of the fermentation by monitoring simple parameters. Thermophilic fermentations have been done with pure substrates and with hydrolysates of energy crops and agro-industrial waste streams to establish the future applicability of the bioprocess. The off-gas from a thermophilic fermentation gas been tested, successfully, in a PEM fuel cell.
The liquid effluent from the thermophilic fermentation has been fed to a photo-heterotrophic fermentation and was completely converted to hydrogen and carbon dioxide. The efficiency needs further optimisation.
A packed bed reactor with a working volume of 180 L has been built for the thermophilic fermentation. A new hydrogen recovery system has been designed which has enabled continuous operation for several months.
An extensive description of the results, including many pictures, can be found in: Final report BWPI (in Dutch) (summary in English).
BWP II: September 2003 – July 2006
The fundamental knowledge of optimal (bio)process conditions and gas recovery has been augmented and integrated in a sub-scale bioreactor design. Options for cost-effective gas upgrading to meet the industrial specifications have been addressed. The industrial research in this phase has also addressed potential alternative applications for results obtained in the pretreatment of biomass or the thermophilic fermentation.
As a result of findings in BWP I, research in this second phase has also involved utilization of the non-fermentable components in biomass for hydrogen production to further increase total efficiency. Besides, there has been more emphasis on the photofermentation.
The number of participants have been increased to fully cover the whole chain from biomass production up to utilization of hydrogen in dedicated fuel cells.
The findings have been reported in Final report 2007
The main issues are: