Substitution of fossil fuels with alternative energy carriers has become necessary due to climate change and fossil fuel shortages. Fermentation as a way of producing biohydrogen, an attractive and environmentally friendly future energy carrier, has captured received increasing attention in recent years because of its high H2 production rate and a variety of readily available waste substrates used in the process. This paper discusses the state-of-the-art of fermentative biohydrogen production, factors affecting this process, as well as various bioreactor configurations and performance parameters, including H2 yield and H2 production rate.
Hydrogen is the fuel of the future, therefore many hydrogen production methods are developed. At present, fuel cells are of great interest due to their energy efficiency and environmental benefits. A brief review of effective formation methods of hydrogen was conducted. It seems that hydrogen from steam reforming of methanol process is the best fuel source to be applied in fuel cells. In this process Cu-based complex catalysts proved to be the best. In presented work kinetic equations from available literature and catalysts are reported. However, hydrogen produced even in the presence of the most selective catalysts in this process is not pure enough for fuel cells and should be purified from CO. Currently, catalysts for hydrogen production are not sufficiently active in oxidation of carbon monoxide. A simple and effective method to lower CO level and obtain clean H2 is the preferential oxidation of monoxide carbon (CO-PROX). Over new CO-PROX catalysts the level of carbon monoxide can be lowered to a sufficient level of 10 ppm.
HY2SEPS was an EU-funded project directed at the reduction of CO2 emissions. The principal objective of the project was to develop a hybrid membrane-adsorptive H2/CO2 separation technique that would form an integral element of the pre-combustion process. Specific tasks included the derivation of simplified mathematical models for the membrane separation of H2/CO2 mixtures. In the present study one of the developed models is discussed in detail, namely that with the countercurrent plug flow of the feed and the permeate. A number of simulations were carried out concerning the separation of binary mixtures that may appear following steam conversion of methane. The numerical results were then compared with the experimental data obtained by FORTH/ICEHT. The estimated fluxes of pure CO2, H2, CH4 and N2 are shown alongside those measured experimentally as a function of temperature and CO2 partial pressure in Figs 2 - 7. It is concluded that, in general, CO2 flux increases monotonically with both temperature and CO2 partial pressure. It is also found that the fluxes of hydrogen, methane and nitrogen reach a minimum at a temperature slightly above 323 K. Overall, a good agreement was obtained between the simulations and experiments.