Highest Hydrogen Production Potential Research Articles

Biohydrogen production by co-digestion of food waste and corn industry wastewater

Food waste (FW) and corn industry wastewater (cornWW) are residues with a high potential for hydrogen production in the dark fermentation process. The study aimed to identify the co-digestion of FW and cornWW ratios for improving hydrogen production and evaluating the synergistic effect on biohydrogen production potential (BHP) in batch test. The inoculum consisted of a mixed culture plus the native microbiota of each substrate. The adjustment of the initial pH to 7.5 was compared to the co-digestion without control of the initial pH of the experiments. The highest hydrogen and metabolites production were obtained with a co-digestion FW:cornWW ratio. When no pH adjustment is applied, pH values above 10 completely inhibit the metabolic activity of bacteria in the process. The cornWW not only provided alkalinity to the system but also can be applied to adjust the organic matter content of FW, adjusting the initial concentration of organic matter. The growth of microbial communities was formed mainly by Clostridium sp. The co-digestion of FW:cornWW can be technically feasible to improve the production of H2 through the dark fermentation process.

Light metal hydride-based hydrogen storage system: Economic assessment in Argentina

Motivated by the high potential for hydrogen production from renewable resources in Argentina, the economic feasibility of employing light complex metal hydrides as hydrogen storage materials for mobile applications in Argentina is explored for the first time. Three main costs are analyzed: green H2, H2 storage system based on Mg(NH2)2–LiH and storage tank. Considering the production of H2 by electrolysis using wind energy, a cost of ~5 USD/kg H2 is obtained. The cost of hydride matrix is crucial and competitive values are viable only if the synthesis route starts from Mg0 and Li0, allowing reducing the total hydride matrix cost from ~2200 to ~4900 USD. The cost of a modular configuration tank with 4 kg of H2 capacity is estimated to be ~5300–6700 USD. A cost ratio higher than of 2:1 is obtained between storage systems based on amides and high pressure systems.

A technical and economical assessment of hydrogen production potential from solar energy in Morocco

In this study, a techno-economic analysis of the capacity of Morocco to produce hydrogen from solar energy has been conducted. For this reason, a Photovoltaic-electrolyze system was selected and the electricity and hydrogen production were simulated for 76 sites scattered all over the country. The Global Horizontal Irradiation (GHI) data used for the simulation were extracted from the CAMS-Rad satellite database and meteorological stations at ground level.Before simulations, the accuracy of the GHI values from the satellite dataset has been checked, and their uncertainties was calculated against accurate data measured in-situ. After that, the simulated values of the hydrogen mass were interpolated using a GIS software to create a Hydrogen production map of Morocco. Finally, an economical investigation of electricity and hydrogen production costs has been conducted by calculating the LCOE and LCOH2.Results show that the satellite dataset has a mean average deviation of 6.8% which is a very acceptable error rang. Also, it was found that Morocco have a high potential for hydrogen production, with a daily annual production that varies between 6489 and 8308 Tons/km2. Moreover, the cost of electricity and hydrogen production in the country are in the range of 0.077–0.099 $/kWh and 5.79–4.64 $/Kg respectively.The findings of this study are with high importance as they provide an overall perspective of the country potential of hydrogen production for policy makers and investors, and it was motivated by the lack of information on the subject in the literature since it's, at the best of our knowledge, the first study assessing the hydrogen production from solar for the whole country.

Spontaneous Direct Band Gap, High Hole Mobility, and Huge Exciton Energy in Atomic-Thin TiO2Nanosheet

The quasi-particle band structure, carrier mobility, and optical response of atomic-thin TiO2 nanosheets were accurately predicted with the many-body perturbation theory of G0W0+BSE calculations. The lepidocrocite-type TiO2 exhibits an unexpected direct band gap of 5.3 eV, different from the retaining indirect band gap character in anatase-type TiO2 nanosheet. Because of the dispersive valence band maxima from the strong overlap between O-2p orbitals, an extremely high hole mobility of 1069 cm2 V–1 s–1 was proposed for the lepidocrocite-type TiO2 nanosheet. Including the electron–hole exchange of excitonic effect, our simulations well reproduce the experimental absorption spectra implying a huge exciton binding energy. The strong anisotropic exciton originates from the crystal dependent effective mass in the lepidocrocite-type TiO2 nanosheet due to the asymmetric orbital overlaps. The strongly bound exciton still renders a sufficiently high potential for hydrogen production from aqueous solution, although...

Effect of inoculum concentration, pH, light intensity and lighting regime on hydrogen production by phototrophic microbial consortium

Photobiological hydrogen production using a bacterial consortium has advantages over pure cultures regarding application to wastewater treatment. Photo-H2 production from organic acids, which were produced by dark fermentation, must be studied in detail to make a hydrogen production process in two stages efficient. In this scenario, our study aimed to determine the optimized culture conditions for hydrogen production by a phototrophic bacterial consortium. The inoculum concentration, pH, light intensity and illumination protocols were the parameters that we evaluated. The optimal conditions for hydrogen production were inoculum concentration of 0.2 g VSS L−1, pH 7.0, light intensity of 5 klux, with a constant illumination regime. The highest hydrogen production potential (P) and substrate conversion efficiency (SCE) were 41.5 mmol H2 L−1 culture and 25.4%, respectively, with a COD removal of 95%.

Optimization of medium components for hyrogen production of anaerobic bacterial strain Thermoanaerobacterium aciditolerans Trau DAt isolated from Vietnam by using response surface methodology

The 21st century is era of renewable energy in which biohydrogen is the most potential candidate that may replace the fossil fuel. Many countries pay more attention to biohydrogen since it can produce by bacteria via fermentation and gas-biosynthesis has many advantages. Bacterial strain Thermoanaerobacterium aciditolerans Trau DAt isolated from Vietnam is capable of biohydrogen production in anaerobic condition. The gas volume as well as the gas components produced by the strain Trau DAt depends on nutrient and fermentation conditions. Hydrogen production of strain Trau DAt was highly affected by glucose, yeast extract and FeSO4.7H2O. By using response surface methodology (RSM) with central composite design, the mutual effects of these factors on hydrogen production of strain Trau DAt were studied. RSM analysis showed that the highest hydrogen production potential (176.02 ml/150 ml culture medium) was obtained under the condition of glucose 12 g/l, yeast extract 2.5 g/l, FeSO4.7H2O 400 mg/l. Under optimized condition, the maximum H2 volume of 420 ml/600 ml culture medium was obtained by dark fermentation.

Enhancement in hydrogen production by thermophilic anaerobic co-digestion of organic fraction of municipal solid waste and sewage sludge--optimization of treatment conditions.

Batch dry-thermophilic anaerobic co-digestion (55°C) of organic fraction of municipal solid waste (OFMSW) and sewage sludge (SS) for hydrogen production was studied under several sludge combinations (primary sludge, PS; waste activated sludge, WAS; and mixed sludge, MS), TS concentrations (10-25%) and mixing ratios of OFMSW and SS (1:1, 2.5:1, 5:1, 10:1). The co-digestion of OFMSW and SS showed a 70% improvement in hydrogen production rate over the OFMSW fermentation only. The co-digestion of OFMSW with MS showed 47% and 115% higher hydrogen production potential as compared with OFMSW+PS and OFMSW+WAS, respectively. The maximum hydrogen yield of 51 mL H2/g VS consumed was observed at TS concentration of 20% and OFMSW to MS mixing ratio of 5:1, respectively. The acetic and butyric acids were the main acids in VFAs evolution; however, the higher butyric acid evolution indicated that the H2 fermentation was butyrate type fermentation.

Atmospheric pressure microwave plasma source for hydrogen production

Nowadays hydrogen is considered as a clean energy carrier and fuel of the future. That is why the interest in production and storage of hydrogen is still increasing. One of the promising technology is using microwave plasma for hydrogen production. In this study we propose two types of an atmospheric pressure microwave plasma source (MPS) for hydrogen production via methane conversion. The first one was a nozzleless waveguide-supplied coaxial-line-based. The second one was a nozzleless waveguide-supplied metal-cylinder-based. They can be operated with microwave frequency of 2.45 GHz and power up to a few kW with a high gas flow rates (up to several thousands l/h). We present experimental results concerning electrical properties of the MPS, plasma visualization, spectroscopic diagnostics and hydrogen production. The experiment was carried out with methane flow rate up to 12,000 l/h. An additional nitrogen or carbon dioxide swirl flow was used. The absorbed microwave power was up to 5000 W. Our experiments show that MPSs presented in this paper have a high potential for hydrogen production via hydrocarbon conversion.

Using of response surface methodology for optimization of biohydrogen production by Clostridium sp. tr2 isolated in Vietnam

Biohydrogen is a clean, renewable, sustainable energy resource due to the highest energy density among all fuels and its combustion has no contribution to the environmental pollution and climate change. Biohydrogen production depends on a number of nutritional and environmental variables. The present paper is to determine the optimum condition for enhanced hydrogen production by a fermentative hydrogen-producing bacterium (designated as Clostridium sp. Tr2) isolated from buffalo-dung in Vietnam. The response surface methodology (RSM) was employed to determine the mutual effects of glucose, yeast extract and iron concentration on its hydrogen production in a batch condition. RSM analysis showed that the highest hydrogen production potential (Ps) was obtained under the condition of 10.18 g L-1 glucose, 2.5 g L-1 yeast extract and 58 mg L-1 FeSO4.7H2O. All three factors had significant influences on the Ps. Glucose and iron concentration, yeast extract and iron concentration were interdependent or there was a significant interaction on Ps. Glucose and yeast extract concentration was slightly interdependent, or their interactive effect on Ps was not significant. Under optimum conditions, the maximum H2 volume of 1080 ml (L medium)-1 were found after 22 h facultative anaerobic fermentation. The experiment results show that the RSM analysis with the central composite design was useful for optimizing the biohydrogen-producing process by newly isolated Clostridium sp. Tr2 in Vietnam.

Enhanced biohydrogen production by the N 2-fixing cyanobacterium Anabaena siamensis strain TISTR 8012

The efficiency of hydrogen production depends on several factors. We focused on external conditions leading to enhanced hydrogen production when using the N 2-fixing cyanobacterium Anabaena siamensis TISTR 8012, a novel strain isolated from a rice paddy field in Thailand. In this study, we controlled key factors affecting hydrogen production such as cell age, light intensity, time of light incubation and source of carbon. Our results showed an enhanced hydrogen production when cells, at log phase, were adapted under N 2-fixing condition using 0.5% fructose as carbon source and a continuous illumination of 200 μE m −2 s −1 for 12 h under anaerobic incubation. The maximum hydrogen production rate was 32 μmol H 2 mg chl a −1 h −1. This rate was higher than that observed in the model organisms Anabaena PCC 7120, Nostoc punctiforme ATCC 29133 and Synechocystis PCC 6803. This higher production was likely caused by a higher nitrogenase activity since we observed an upregulation of nifD. The production did not increase after 12 h which was probably due to an increased activity of the uptake hydrogenase as evidenced by an increased hupL transcript level. Interestingly, a proper adjustment of light conditions such as intensity and duration is important to minimize both the photodamage of the cells and the uptake hydrogenase activity. Our results indicate that A. siamensis TISTR 8012 has a high potential for hydrogen production with the ability to utilize sugars as substrate to produce hydrogen.

Treatment of olive mill wastewater by different physicochemical methods and utilization of their liquid effluents for biological hydrogen production

Abstract In this study various two-stage processes were investigated for biological hydrogen production from olive mill wastewater (OMW) by Rhodobacter sphaeroides O.U.001. Two-stage processes consist of physicochemical pretreatment of OMW followed by photofermentation for hydrogen production. Explored pretreatment methods were chemical oxidation with ozone and Fenton's reagent, photodegradation by UV radiation, and adsorption with clay or zeolite. Among these different two-stage processes, strong chemical oxidants like ozone and Fenton's reagent have the highest color removal (90%). However, their effluents were observed to be unsuitable for both hydrogen production and bacterial growth. On the other hand, clay treatment method was selected as the optimum process that allows fast and low-cost treatment as well as its effluent found to have the highest hydrogen production potential (31.5 m 3 m −3 ). Spent-clay regeneration was also investigated on the grounds that solid waste minimization is important for the overall efficiency of this process.

Comparison of physicochemical characteristics and photofermentative hydrogen production potential of wastewaters produced from different olive oil mills in Western-Anatolia, Turkey

Abstract Olive oil extraction produces a dark-colored wastewater that contains nutrients that can be further processed using biotechnology, in parallel with treatment for disposal. For instance, olive mill wastewater (OMW) can be used as a substrate for photofermentative hydrogen production by purple bacteria. A comparative study was investigated with several OMW samples from different olive oil mills in Western-Anatolia, Turkey. The composition of OMW varies significantly for each mill; thus, a detailed physicochemical analysis of each sample has been carried out. Subsequently, samples were assessed for their functioning in anaerobic photofermentative hydrogen production by Rhodobacter sphaeroides O.U.001. The highest hydrogen production potential (19.9 m 3 m −3 ) was obtained by the OMW sample with the highest organic content (mainly acetic acid, 9.71 kg m −3 ) and the highest carbon-to-nitrogen (C/N) molar ratio (73.8 M M −1 ). The organic content was found to be composed of primarily acetic, aspartic, and glutamic acids. There was a linear relationship between C/N ratio and hydrogen production potential across the different OMW samples. This study is unique due to the wide range of analyses of OMW samples and the comparison of many parameters for hydrogen production from wastewater. The results obtained throughout this study can aid in the design of systems using wastewater for biohydrogen production. Particularly, the C/N ratio was found to be the best parameter for choosing a proper substrate.

Solar thermochemical production of hydrogen using metal oxide redox systems

A method to analyze the hydrogen production potential (HPP) of photoelectrochemical systems, based on the lumped equivalent circuit model of a photocell driving a current dependent electrochemical load, is presented. Selection of the appropriate circuit and characteristic junction parameters allows analysis of single and multijunction photoelectrodes including those utilizing a semiconductor-electrolyte junction. In this paper, the HPP of single and multijunction photoelectrodes fabricated from high quality crystalline III–V materials is compared with that of the lower cost amorphous silicon and crystalline-amorphous silicon hybrid junction electrodes. The analysis shows that single junction photoelectrodes, even those with exceptional diode characteristics, require semiconductor bandgaps greater than 2.0 eV for efficient operation when realistic catalyst performance is considered. Multiphoton systems are shown to have higher HPP and exhibit greater operational stability when load mismatches, such as would occur from changes in junction characteristics or catalyst properties, are introduced.

Photoelectrochemical production of hydrogen: Engineering loss analysis

A method to analyze the hydrogen production potential (HPP) of photoelectrochemical systems, based on the lumped equivalent circuit model of a photocell driving a current dependent electrochemical load, is presented. Selection of the appropriate circuit and characteristic junction parameters allows analysis of single and multijunction photoelectrodes including those utilizing a semiconductor-electrolyte junction. In this paper, the HPP of single and multijunction photoelectrodes fabricated from high quality crystalline III–V materials is compared with that of the lower cost amorphous silicon and crystalline-amorphous silicon hybrid junction electrodes. The analysis shows that single junction photoelectrodes, even those with exceptional diode characteristics, require semiconductor bandgaps greater than 2.0 eV for efficient operation when realistic catalyst performance is considered. Multiphoton systems are shown to have higher HPP and exhibit greater operational stability when load mismatches, such as would occur from changes in junction characteristics or catalyst properties, are introduced.