| Home | Member login | Register |
|
| ||||||
|
Introduction In natural environments, hydrogen is produced during anaerobic degradation of organic matter. However as this hydrogen is consumed by methane producing bacteria, this hydrogen remains unnoticed and unavailable. This project is aimed at the development of a bioprocess in which a) hydrogen production is uncoupled from methane production and b) the efficiency of hydrogen production from biomass is increased. Thermophilic Hydrogen Production Hydrogen production was established by growing pure cultures of extremophilic bacteria on glucose. The hydrogen production rate of commercially available strains and new isolates is shown in table 1. The efficiency of hydrogen production from glucose was tested in a chemostat culture as shown in figure 1 and 2. Thermotoga elfii, growing at 65°C produced 4 mol of H2 and 2 mol of acetic acid per mol of glucose consumed. The standard Gibbs free energy change for this reaction is DG°’ = – 206 kJ/mol. Further conversion of acetate to hydrogen and CO2 is hampered by a positive DG°’ meaning that the reaction is thermodynamic unfavourable. Nevertheless some bacteria are able to oxidise acetate to hydrogen provided that the hydrogen is immediately removed. On the other hand, photoheterotrophic bacteria are able to perform the same reaction with utilisation of energy from light. Both possibilities will be explored for further efficiency increase, aiming at a final production of 12 mol H2 per mol glucose consumed. 
Photo 1: Growth of Thermotoga elfii in a bioreactor Table 1: Maximum hydrogen production rate of an enrichment culture with starch as substrate compared to rates of other organisms found in literature 
Figure 1: Hydrogen production during growth of Thermotoga elfii on glucose 
Figure 2: Hydrogen production during growth of Thermotoga elfii on glucose Acknowledgement This research project is supported by the Dutch EET program. The partners are ATO-DLO, Wageningen Agricultural University, TNO-MEP and Paques Biosystems B.V. Corresponding author: P.A.M.Claassen@ato.wag-ur.nl This poster was presented at the Third European Motor Biofuels Forum. International Conference and Trade Show. October 10 – 13, Brussels, Belgium
| |||||
|