Hydrogen production from the fermentation of corn stover biomass pretreated with a steam-explosion process

Lignocellulosic biomass contains 70–80% carbohydrates and could serve as the ideal feedstock for fermentative hydrogen production. We conducted the pretreatment of corn stover using a steam-explosion process and studied its fermentability for hydrogen production. Using natural inoculant obtained from the heated sludge of a local wastewater treatment plant, we demonstrated that the indigenous microbes were capable of efficiently fermenting the aqueous hydrolyzate derived from the hemicellulose fraction of the steam-pretreated corn stover with and without acid during pretreatment. Biogas contained equal amounts of hydrogen and carbon dioxide. The carbon mass balance is approximately 84%, with acetic and butyric acids as the major carbon byproducts along with carbon dioxide. Hydrogen molar yields of 2.84 and 3.0 were obtained using the mixed sugars present in the hydrolyzate derived from neutral and acidic steam explosion, respectively. These findings verify that hemicellulose from corn stover could be a suitable feedstock for hydrogen production via dark fermentation.     

Hydrogen production at centralized utilization of agricultural waste

There is a problem of utilization of a large amount of organic waste in the agro-industrial complex. Most of the waste is generated on livestock farms (56%) and crop production (35.6%). Centralized biogas plants are a good solution for efficient processing of agricultural waste and biofuel production. An analysis of the possibilities of cow manure utilizing and dry biomass of amaranth with the subsequent hydrogen production was implemented for Tatarstan Republic. The diagram of five large facilities utilizing waste from 7 to 10 districts included in the region is introduced.The diagram of steam catalytic conversion of biogas is specified. The introduced hydrogen production scheme includes: collection of plant waste and manure of livestock complexes for centralized recycling (the optimal mixture of dry biomass of Amaranthus retroflexus L. leaves and cow manure for organic dry matter is 1:1.5); mixture preparation and ultrasonic treatment at a frequency of 22 kHz and an exposure intensity of 10 W/cm2; anaerobic digestion in the mesophilic mode at a temperature of 310 K, the hydraulic retention time is 12 days; the compressor supplying the resulting biogas into the gasholder for intermediate storage; purification of biogas from carbon dioxide, hydrogen sulfide and other impurities in the scrubber; steam methane reforming: the biomethane is compressed by a compressor to a pressure of 15 atm., then fed to the reformer, heated, mixed with steam in the ratio H2O/CH4 = 2.5 and subjected to conversion at a temperature of 1073 K and a pressure of 1 atm., before exiting, the resulting gas is cooled to 573 K; the catalytic reactor for carrying out a water vapor conversion reaction in which a mixture of carbon monoxide and steam is converted, the products are hydrogen and carbon dioxide; purification of the obtained hydrogen to a purity of 99.99% vol. In the short-cycle adsorption system; hydrogen supply to the consumer. It is possible to utilize of 4.4 million tons of waste annually, and also to produce 107,341 kg/day of hydrogen with a purity of 99.99% by volume.     

Hydrogen production via urea electrolysis using a gel electrolyte

A technology was demonstrated for the production of hydrogen and other valuable products (nitrogen and clean water) through the electrochemical oxidation of urea in alkaline media. In addition, this process remediates toxic nitrates and prevents gaseous ammonia emissions. Improvements to urea electrolysis were made through replacement of aqueous KOH electrolyte with a poly(acrylic acid) gel electrolyte. A small volume of poly(acrylic acid) gel electrolyte was used to accomplish the electrochemical oxidation of urea improving on the previous requirement for large amounts of aqueous potassium hydroxide. The effect of gel composition was investigated by varying polymer content and KOH concentrations within the polymer matrix in order to determine which is the most advantageous for the electrochemical oxidation of urea and production of hydrogen.     

Hydrogen production from biomasses and wastes: A technological review

Biomass and organic solid waste are considered as very potential alternative energy sources in the future, leading to the realization of a clean and CO₂-free energy system. Therefore, the effective conversion of biomass and organic solid waste to a secondary energy source is urgently demanded. In addition, hydrogen is considered very promising among the secondary energy sources due to its advantages of cleanliness, wide range of conversion and utilization technologies, high energy efficiency, and high gravimetric energy density. This paper reviews several possible routes and key conversion technologies of biomass and organic solid waste to hydrogen. Recent progress related to biological and thermochemical conversion technologies is described. Thermochemical route includes gasification, pyrolysis, steam reforming, partial oxidation, and thermochemical cycle; while biological route covers fermentation (dark and photo), biophotolysis (direct and indirect), enzymatic, and microbial electrolysis. In addition, several challenges regarding the conversion and utilization of biomass and organic solid waste to hydrogen are also discussed in order to clarify the feasibility of biomass and the organic solid waste-based hydrogen economy.     

Hydrogen production by biomass gasification in supercritical water using concentrated solar energy: System development and proof of concept

A novel system of hydrogen production by biomass gasification in supercritical water using concentrated solar energy has been constructed, installed and tested at the State Key Laboratory of Multiphase Flow in Power Engineering (SKLMF). The “proof of concept” tests for solar-thermal gasification of biomass in supercritical water (SCW) were successfully carried out. Biomass model compounds (glucose) and real biomass (corn meal, wheat stalk) were gasified continuously with the novel system to produce hydrogen-rich gas. The effect of direct normal solar irradiation (DNI) and catalyst on gasification of biomass was also investigated. The results showed that the maximal gasification efficiency (the mass of product gas/the mass of feedstock) in excess of 110% were reached, hydrogen fraction in the gas product also approached to 50%. The experimental results confirmed the feasibility of the system and the advantage of the process, which supports future work to address the technical issues and develop the technology of solar-thermal hydrogen production by gasification of biomass in supercritical water.     

Hydrogen production via catalytic pyrolysis of biomass in a two-stage fixed bed reactor system

This study introduces an innovative process of generating hydrogen-rich gas from biomass through the catalytic pyrolysis of biomass in a two-stage fixed bed reactor system. Water hyacinth was used as the biomass feedstock. The effects of various factors such as pyrolysis temperature, catalytic bed temperature, residence time, catalyst, and the nickel content of the catalyst on the pyrolysis productivity were investigated and the yields of H₂, CO, CH₄, and CO₂ were obtained. Results showed that the high productivity of hydrogen can be obtained particularly by increasing the catalytic bed temperature, residence time, and catalysts. The favorable reaction conditions are as follows: a first-stage pyrolysis temperature of 650 °C–700 °C, a second-stage catalytic bed temperature of 800 °C, a catalytic pyrolysis reaction time of 17 min, and a nickel content of 9% (wt %).     

Hydrogen production using AlGaInSn alloy with semi-solid structures

Semi-solid AlGaInSn bulk was fabricated for hydrogen production by Al-water reaction, of which the semi-solid structure was characterized by near-sphere primary phases dispersed within active metals enriched fine secondary-solidification-structures. The unique structure gives rise to a dramatic hydrogen production compared with the cast counterpart, although uneven throughout the whole bulk and hard to control. The underlying mechanism is demonstrated that owing to the fracturing of the secondary-solidification-structures into fine particles the semi-solid outperforms the cast largely initially and gradually hydrolyzing of primary phases then maintains the advance in the rest period.     

Hydrogen production by aluminum corrosion in hydrochloric acid and using inhibitors to control hydrogen evolution

This study reports on the systematic assessment of hydrogen (H₂) production by corrosion of aluminum alloy (AA) in hydrochloric acid (HCl) at different temperature. Rare earth inhibitors, lanthanum (La) and cerium (Ce) have been applied to control the H₂ production process. The production process is based on electrochemical reaction of aluminum (anodic reaction) in the HCl solution, which has a high concentration of hydrogen ions (H⁺), the H⁺ ions are reduced and H₂ is evolved. Preliminary results showed that an increase in temperature of working solution produced an increase of the H₂ production rate. The H₂ production rate increases because acid can prevent aluminum passivation during H₂ evolution. The rare earth inhibitors La and Ce control the H₂ evolution, especially, when using mixture of both inhibitors. This result demonstrates a synergistic effect between the La and the Ce inhibitors. X-ray diffraction studies were performed on the surface structure before and after immersion, and a scanning electron microscope (SEM) was used to study the morphology of the AA.     

Hydrogen production and storage analysis of a system by using TRNSYS

In this study, hydrogen production and storage were investigated. The Transient System Simulation Program (TRNSYS) and Generic Optimization Program (GenOpt) packages were combined for the design and optimization of a system that produces hydrogen from water and stores the hydrogen it produced in the compressed gas tank. The system design is based on the electricity grid. Electrical energy produced in photovoltaic (PV) panels was used to electrolyze water. The systems for Izmir, Istanbul and Ankara provinces which are in different climate zones of Turkey were optimized and the annual system performances based on the optimum angles were analyzed. For the mentioned provinces, the PV tilt angles which minimize electricity drawn from the grid at the electrolyzer are also investigated. The electrical energy produced in the photovoltaic panels, the hydrogen and oxygen amounts produced, the efficiency of the electrolyzer, the gas and pressure levels in the hydrogen tank were compared. According to the results of the analysis, the annual total power produced in photovoltaic panels is 42803.66 kW in İzmir, 42573.74 kW in Istanbul and 44613.95 kW in Ankara. Hydrogen levels produced in the system are calculated as 10488.39 m³ year⁻¹ in Izmir, 9824.70 m³ year⁻¹ in Istanbul, and 10368.65 m³ year⁻¹ in Ankara.     

Hydrogen production through biomass gasification in supercritical water: A review from exergy aspect

Hydrogen production through supercritical water gasification (SWG) of biomass has been widely studied. This study reviews the main factors from exergy aspect, and these include feedstock characteristics, biomass concentration, gasification temperature, residence time, reaction catalyst, and reactor pressure. The results show that the exergy efficiencies of hydrogen production are mainly in the range of 0.04–42.05%. Biomass feedstock may affect hydrogen production by changing the H₂ yield and the heating value of biomass. Increases in biomass concentrations decrease the exergy efficiencies, increases in gasification temperatures generally increase the exergy efficiencies, and increases in residence times may initially increase and finally decrease the exergy efficiencies. Reaction catalysts also have positive effects on the exergy efficiencies, and the reviewed results show that the effects are followed KOH > K₂CO₃ > NaOH > Na₂CO₃. Reactor pressure may have positive, negative or negligible effects on the exergy efficiencies.     

Hydrogen production from molten metal gasification

As fossil fuel reserves are depleted, more innovative technologies are needed to facilitate fuel production, such as molten media gasification. This technique uses a liquid metal bath in a two-stage process: Stage 1) superheated steam is injected into the melt, with metal oxides formed, and H₂ released; Stage 2) carbon is injected, the oxide is reduced, and CO and CO₂ are released. The main study objective was to develop and test the first stage of this process. The results showed that hydrogen production peaked 100 s into the test, and then levelled off, with a maximum output of 13.6% hydrogen. XRD analysis of the metal samples showed that no tin oxides or magnetite were formed during the process, only a form of wustite (FeO). The syngas produced was very clean, and would need little gas cleaning for use as a feedstock in industrial processes or fuel cells.     

Hydrogen production from butyrate by a marine mixed phototrophic bacterial consort

A newly enriched marine phototrophic bacterial consort was studied for its capability of hydrogen production in batch cultivations using butyrate as the sole carbon source. Analyses of denaturing gradient gel electrophoresis (DGGE) profiles showed that the mixed bacterial consort consisted mainly of Ectothiorhodospira, Sporolactobacillus, and Rhodovulum. Important parameters investigated include temperature, light intensity, initial pH, and butyrate concentration. The pH of the culture medium significantly increased as fermentation proceeded. Optimal cell growth was observed at temperature of 25–35 °C, light intensity of 80–120 μmol photons/m² s, initial pH of 8, butyrate concentration of 20–40 mmol/l. Optimal conditions for hydrogen production were 30 °C, light intensity of 80 μmol photons/m² s, initial pH 8. The increase of butyrate concentration (10–50 mmol/l) resulted in higher hydrogen production, but the yield of hydrogen production (mol H₂/mol butyrate) gradually decreased with increasing butyrate concentration. The maximal hydrogen yield and hydrogen production rate were estimated to be 2.52 ± 0.12 mol H₂/mol butyrate and 19.40 ± 2.32 ml/l h, respectively. These results indicate that optimization of the culture conditions resulted in a simultaneous increase in biohydrogen production and cell growth.     

Hydrogen production from instant noodle wastewater by organic electrocatalyst coated on PVC surface

The potential of electron-donating capability in methoxy groups of antioxidant containing protein (ACAP) as organic catalyst is restricted by its low isoelectric point. The goal of this study is to construct endure ACAP based metal-free organic catalyst for hydrogen production from electrolysis of noodle wastewater. The ACAP was coated thermomechanically on PVC sheet and its performance was tested during electrolysis of noodle wastewater. The morphological analysis, phase analysis, and elemental analysis of coated materials have shown a simultaneous pattern with electrolysis performances. The use of graphite flake to cover turmeric ACAP obstructs the electron to attack directly the positive charge of ACAP so that the electrocatalytic endurance increases while maintaining the hydrogen production rate. The combination of phenolic and enzymatic ACAPs is found to have the slowest reaction rate and lowest hydrogen production. The phenolic compound inhibits the enzymatic reaction.     

Towards the Hydrogen Economy in Paraguay: Green hydrogen production potential and end-uses

This study was conducted to estimate the potential for green H₂ in Paraguay. A total production potential of 22.5 × 10⁶ tons/year was obtained with a main contribution (93.34%) from solar photovoltaic. The greatest potential for producing H₂ from solar and wind resources is in the Western region, and from hydro resources is in the Eastern region of the country. Two end-uses of green H₂ were assessed: (1) automotive transportation, replacing gasoline and diesel; and (2) residential energy, replacing firewood and LPG for cooking in households across the country. In 16 of the 17 departments, green H₂ is able to replace the overall consumption of gasoline and diesel, as well as firewood and LPG. Finally, energy service cost (mobility), environmental aspects and CO₂ emissions were considered for three urban mobility technologies for the Metropolitan Area of Asunción. Results show that the mobility cost of fuel cell hybrid electric buses is still very high in comparison to diesel buses and battery electric buses. However, when a longer driving range is required, fuel cell hybrid electric buses could become a viable alternative in the long term. From an environmental point of view, green H₂ used in fuel cell hybrid electric buses has the potential to save about 96% of CO₂ emissions in comparison to diesel buses. It is concluded that the estimated green H₂ production potential favors the incorporation of the Hydrogen Economy in Paraguay.     

Hydrogen production via supercritical water gasification of glycerol enhanced by simple structured catalysts

The supercritical water gasification (ScWG) technology is a promising alternative for H₂-rich gas production from renewable sources, such as residual glycerol from biodiesel manufacture. Combined with heterogeneous catalysts, the ScWG process can achieve improved selectivity towards the desired products and high conversion efficiency in short reaction times. In this work, the efficiency of a synthesized Ni-based catalyst supported in cordierite (CRD) honeycomb structure on the ScWG of glycerol was evaluated and compared with two commercial automotive catalysts. Initially, to determine the best experimental conditions, the ScWG experiments were conducted in the absence of catalysts at constant conditions pressure (25 Mpa) and volumetric flow rate (10 mL min⁻¹). The temperature range of 400–700 °C and glycerol feed composition between 10 and 34 wt% were evaluated. The catalysts evaluated were characterized by SEM-EDS, XRD, N₂ adsorption/desorption, XRF, WDS and TGA. The liquid and gaseous products were analyzed by TOC and gas chromatography, respectively. Results indicated that Ni/CRD catalyst showed the highest H₂ yield (5.38 mol H₂ per mol of glycerol fed) and long-term stability. Additionally, a comparison between the experimental results on the ScWG of glycerol and simulated thermodynamic equilibrium data was also reported. Thus, results demonstrated the great potential of the prepared catalyst to improve H₂-rich gas production from glycerol gasification.     

Towards The Hydrogen Economy: Estimation of green hydrogen production potential and the impact of its uses in Ecuador as a case study

The estimation of the green hydrogen (H₂) production potential represents the initial stage on the road to integrating the Hydrogen Economy into the energy systems of a country or region. This article has two purposes; the first focuses on identifying and analyzing studies on the amount of green H₂ obtainable in countries and regions across the globe. In total, 64 studies in 29 countries are reported, of which the geographical distribution of the estimates of green H₂ potential is obtained. Additionally, the most widely used renewable energy sources and the conversion technologies favored for their production were identified. The Americas and Argentina were the continents and the country, respectively, with the largest number of studies. At the same time, solar photovoltaic (PV) and electrolysis are the most studied production methods. The second purpose is to quantify the total potential of green H₂ in the Republic of Ecuador and explore its uses as an energy vector and chemical input in niches of opportunity detected from the analysis of its energy balance. In this regard, the total potential of green H₂ in Ecuador of 4.38 × 10⁸ tons/year is obtained, being the production of electrolytic H₂ with PV electricity the one with the highest contribution. The amount of H₂ available satisfies, in excess, the demand for the proposed uses: as fuel and chemical input. These results contribute to the knowledge of the object of study by making visible the interest of the countries in having such estimates and identifying the most attractive production route in the first place, and secondly, providing essential elements for the development of more detailed research and energy planning on the gradual incorporation of the Hydrogen Economy in Ecuador.     

Hydrogen production by partial oxidative gasification of biomass and its model compounds in supercritical water

Partial oxidative gasification in supercritical water is a new technology for hydrogen production from biomass. Firstly in this paper, supercritical water partial oxidative gasification process was analyzed from the perspective of theory and chemical equilibrium gaseous product was calculated using the thermodynamic model. Secondly, the influence of oxidant equivalent ratio on partial oxidative gasification of model compounds (glucose, lignin) and real biomass (corn cob) in supercritical water was investigated in a fluidized bed system. Experimental results show that oxidant can improve the gasification efficiency, and an appropriate addition of oxidant can improve the yield of hydrogen in certain reaction condition. When ER equaled 0.4, the gasification efficiency of lignin was 3.1 times of that without oxidant. When ER equaled 0.1, the yield of hydrogen from lignin increased by 25.8% compared with that without oxidant. Thirdly, the effects of operation parameters including temperature, pressure, concentration, and flow rate of feedstock on the gasification were investigated. The optimal operation parameters for supercritical water partial oxidative gasification were obtained.     

Hydrogen rich syngas production from biomass gasification using synthesized Fe/CaO active catalysts

Biomass gasification for hydrogen rich syngas production was investigated using the Fe/CaO catalysts in a fluidized bed reactor. The synthesized catalysts were prepared by an impregnation method with different Fe/CaO mass ratios (5%, 10%, 15%, 20%) for enhancing H₂ concentration and syngas yields and then characterized using X-ray diffraction (XRD), nitrogen adsorption and desorption isotherms test, scanning electron microscopy (SEM) and CO₂ absorption capacity test. The results showed that the Fe load had significant influences on the composition, textural properties and CO₂ adsorption capacity. Results of gasification experiments verified that the presence of Fe enhanced the concentration and yield of H₂. The highest syngas yield of 38.21 mol/kg biomass, H₂ yield of 26.40 mol/kg biomass, LHV values of 8.69 MJ/kg and gasification efficiency of 49.15% were obtained at an optimized mass ratio of Fe/CaO = 5%. In addition, the characterization results indicated that Ca₂Fe₂O₅ phase was formed. The Ca₂Fe₂O₅ had less CO₂ absorption capacity and effect on the gasification, but was considered to be a catalyst for tar cracking thus preventing the CaO deactivation.     

生物制氢和氢能发电

本文阐述了光发酵生物制氢技术和厌氧发酵生物制氢技术制氢的机理以及光合–发酵杂交技术的优势。采用生物制氢技术有利于减少环境污染,节约不可再生能源,应该成为未来能源制备技术的发展方向。随着氢能规模化、工业化生产,借助于氢的输送成本低,损失小的输电优势。氢与燃料电池相结合可提供一种高效、清洁、无传动部件、无噪声的发电技术。氢能发电技术将不断发展和日趋成熟并逐步获得广泛应用。     

Hydrogen production from human and cow urine using in situ synthesized aluminium nanoparticles

Hydrogen production from wastewater system has the potential to add a new dimension to the energy economy. Urine is an abundant waste and contains about 90–96% of water. While there have been efforts to generate electricity from urine (using microbial fuel cells), direct hydrogen production from urine using any technique is less explored. We report human and cow urine pretreatment with simultaneous hydrogen production using a simple redox reaction. This is achieved via in situ formation of aluminium nanoparticles in urine through reduction of aluminum salt using sodium borohydride; the key novelty of the process is the use of Al salt/NaBH₄. The in situ prepared aluminium nanoparticles instantly react with urine to produce hydrogen. The volume of hydrogen produced is observed to be sensitive to pH, amount of Al salt, and ageing (storage time of urine). Interestingly, ageing does not impact the kinetics of initial hydrolysis in cow urine as much as it affects in the case of human urine. Fresh urine is found to be better in both the cases. Total carbon, total organic carbon, total nitrogen and total phosphorus removal efficiencies are found to be a maximum of 69.93%, 71.88%, 64.16% and 50.9% respectively for human urine; these values are 67.8%, 70.1%, 61.3% and 48.9% for cow urine at pH 3.