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[en] In the future a transfer from the fossil fuel-based economy to hydrogen-based economy is expected. Therefore the development of systems for efficient H_2 production becomes important. The several conventional methods of mass-scale (or central) H_2 production (methane, natural gas and higher hydrocarbons reforming, coal gasification reforming) are well developed and their costs of H_2 production are acceptable. However, due to the H_2 transport and storage problems the small-scale (distributed) technologies for H_2 production are demanded. However, these new technologies have to meet the requirement of producing H_2 at a production cost of $(1-2)/kg(H_2) (or 60 g(H_2)/kWh) by 2020 (the U.S. Department of Energy's target). Recently several plasma methods have been proposed for the small-scale H_2 production. The most promising plasmas for this purpose seems to be those generated by gliding, plasmatron and nozzle arcs, and microwave discharges. In this paper plasma methods proposed for H_2 production are briefly described and critically evaluated from the view point of H_2 production efficiency. The paper is aiming at answering a question if any plasma method for the small-scale H_2 production approaches such challenges as the production energy yield of 60 g(H_2)/kWh, high production rate, high reliability and low investment cost. (authors)
[en] To meet the reduction of the emission of CO2 imposed by the Kyoto protocol, hydrogen should be produced from renewable primary energy. Besides the indirect production of hydrogen by electrolysis using electricity from renewable resources, such as sunlight, wind and hydropower, hydrogen can be directly produced from biomass. At present, there are two strategies for the production of hydrogen from biomass: the thermochemical technology, such as gasification, and the biotechnological approach using micro-organisms. Biological hydrogen production delivers clean hydrogen with an environmental-friendly technology and is very suitable for the conversion of wet biomass in small-scale applications, thus having a high chance of becoming an economically feasible technology. Many micro-organisms are able to produce hydrogen from mono- and disaccharides, starch and (hemi)cellulose under anaerobic conditions. The anaerobic production of hydrogen is a common phenomenon, occurring during the process of anaerobic digestion. Here, hydrogen producing micro-organisms are in syn-trophy with methanogenic bacteria which consume the hydrogen as soon as it is produced. In this way, hydrogen production remains obscure and methane is the end-product. By uncoupling hydrogen production from methane production, hydrogen becomes available for recovery and exploitation. This study describes the use of extreme thermophilic bacteria, selected because of a higher hydrogen production efficiency as compared to mesophilic bacteria, for the production of hydrogen from renewable resources. As feedstock energy crops like Miscanthus and Sorghum bicolor and waste streams like domestic organic waste, paper sludge and potato steam peels were used. The feedstock was pretreated and/or enzymatically hydrolyzed prior to fermentation to make a fermentable substrate. Hydrogen production by Caldicellulosiruptor saccharolyticus, Thermotoga elfii and T. neapolitana on all substrates was observed. Nutrient requirements and inhibitory effects differed depending on the strain and the feedstock applied. Fermentations on a larger scale under controlled conditions allowed accurate determinations of hydrogen yields and hydrogen production rates for these extreme thermophilic microorganisms. The first results of a new FP 6 Integrated Project 'Hyvolution' (start date 01/01/2006; co-ordinated by Agro-technology and Food Innovations) will be presented. This IP is aimed at the development of a blue-print for an industrial bio-process for decentralized hydrogen production from locally produced biomass. (authors)
[en] Hydrogen production by water electrolysis represents nearly 4 % of the world hydrogen production. Future development of hydrogen vehicles will require large quantities of hydrogen. Installation of large scale hydrogen production plants will be needed. In this context, development of low cost large scale electrolysers that could use 'clean power' seems necessary. ALPHEA HYDROGEN, an European network and center of expertise on hydrogen and fuel cells, has performed for its members a study in 2005 to evaluate the potential of large scale electrolysers to produce hydrogen in the future. The different electrolysis technologies were compared. Then, a state of art of the electrolysis modules currently available was made. A review of the large scale electrolysis plants that have been installed in the world was also realized. The main projects related to large scale electrolysis were also listed. Economy of large scale electrolysers has been discussed. The influence of energy prices on the hydrogen production cost by large scale electrolysis was evaluated. (authors)
[en] Our report gives an overview of hydrogen production processes with bacteria or algae. 4 main processes are described: water biophotolysis, photo- fermentation biological CO conversion and dark fermentation. Chemical phenomena which lead to hydrogen generation are exp/aired. Performances, limits and outlook are given for each process. Main projects, programs and key players involved in this field of research have been listed. This paper resumes few results of this report. (authors)
[en] For hydrogen production through dark fermentation of glucose, a continuously stirred 1-liter bioreactor was inoculated with yard waste compost and operated at 55 C with fed-batch runs. The reducing pH was regulated automatically by using pH transmitter and kept constant at 5.4. In this way, no methane was generated in any of the fed-batch runs and H2 yield in the range of 0.25 to 1.75 mol H2/mol glucose consumed was obtained by inhibiting methanogenic H2 consumption. Astonishingly, the highest H2 yield was achieved with fresh inoculum which was neither heat treated nor acclimated. However, yield was not steady and decreased due to shift in metabolic pathway from acido-genesis to ethanol fermentation subsequent to high H2 partial pressure. Effluent ethanol concentrations above 400 mg/l after high H2 yielding runs were indication of this metabolic shift. (authors)
[en] Landfill gas (LFG) and biogas can potentially become important feedstocks for renewable hydrogen production. The objectives of this work were: (1) to develop a catalytic process for direct reforming of CH4-CO2 gaseous mixture mimicking LFG, (2) perform thermodynamic analysis of the reforming process using AspenPlus chemical process simulator, (3) determine operational conditions for auto-thermal (or thermo-neutral) reforming of a model CH4-CO2 feedstock, and (4) fabricate and test a bench-scale hydrogen production unit. Experimental data obtained from catalytic reformation of the CH4-CO2 and CH4-CO2-O2 gaseous mixtures using Ni-catalyst were in a good agreement with the simulation results. It was demonstrated that catalytic reforming of LFG-mimicking gas produced hydrogen with the purity of 99.9 vol.%. (authors)
[en] This report summarizes the sulfur-iodine (SI) thermochemical water splitting process for the purpose of supporting the process for evaluating and recommending a hydrogen production technology to deploy with the Next Generation Nuclear Plant (NGNP). This package provides the baseline process description as well as a comparison with the process as it was implemented in the Integrated Lab Scale (ILS) experiment conducted at General Atomics from 2006-2009.
[en] This research and development project is focused on the advancement of a technology that produces hydrogen at a cost that is competitive with fossil-based fuels for transportation. A twostep, solar-driven WS thermochemical cycle is theoretically capable of achieving an STH conversion ratio that exceeds the DOE target of 26% at a scale large enough to support an industrialized economy . The challenge is to transition this technology from the laboratory to the marketplace and produce hydrogen at a cost that meets or exceeds DOE targets.
[en] QuestAir's gas purification products employ a process known as pressure swing adsorption (PSA). PSA is based on the adsorption of gases onto special materials known as adsorbents. These adsorbents remove all contaminants from an impure feed stream to produce a purified product gas. Once the adsorbents are near saturation, the impurities are purged, regenerating the adsorbents for the next PSA cycle. QuestAir's patented technology has reduced the duration of the PSA cycle by up to 10 times, allowing for a similar reduction in the size of system components such as pressure vessels, piping and structural supports. Our simple, compact and reliable technology is a significant improvement over conventional PSA hydrogen purification systems, and it also has significant advantages over other gas purification technologies such as membranes and cryogenic plants
[en] This calculation note analyzes headspace concentrations of hydrogen in single shell tanks dependent upon assumed ventilation flow rates provided by the waste tank ventilation system operation or calculated from Standard Hydrogen Monitoring System data. The analyses are based on measured or estimated steady-state hydrogen release rates. Specific analyses include: 1) The hydrogen generation rate at steady- state hydrogen concentrations and 2)The headspace hydrogen concentration as a function of time, as well as the time required to reach 25% and 100% of the Lower Flammability Limit with barometric breathing in the tank