Total Hydrogen Production Research Articles

Investigation of green hydrogen production and development of waste heat recovery system in biogas power plant for sustainable energy applications

In this study, biogas power production and green hydrogen potential as an energy carrier are evaluated from biomass. Integrating an Organic Rankine Cycle (ORC) to benefit from the waste exhaust gases is considered. The power obtained from the ORC is used to produce hydrogen by water electrolysis, eliminate the H2S generated during the biogas production process and store the excess electricity. Thermodynamic and thermoeconomic analyses and optimization of the designed Combined Heat and Power (CHP) system for this purpose have been performed. The proposed study contains originality about the sustainability and efficiency of renewable energy resources. System design and analysis are performed with Engineering Equation Solver (EES) and Aspen Plus software. According to the results of thermodynamic analysis, the energy and exergy efficiency of the existing power plant is 28.69% and 25.15%. The new integrated system's energy, exergy efficiencies, and power capacity are calculated as 41.55%, 36.42%, and 5792 kW. The total hydrogen production from the system is 0.12412 kg/s. According to the results of the thermoeconomic analysis, the unit cost of the electricity produced in the existing power plant is 0.04323 $/kWh. The cost of electricity and hydrogen produced in the new proposed system is determined as 0.03922 $/kWh and 0.181 $/kg H2, respectively.

Simulations of Core Damage Progression for TMI-2 Severe Accident Using CINEMA Computer Code

As an integrated computer code development for severe accident sequence analysis in Korea, CINEMA has been developing from an initiation event to a containment failure. The CINEMA computer code is composed of CSPACE, SACAP, and SIRIUS, which are capable of simulating core melt progression with thermal hydraulic analysis of the RCS (reactor coolant system), severe accident analysis of the containment, and fission product analysis in the vessel and the containment, respectively. The severe accident progression in TMI unit 2 has been analyzed as a part of a validation of the CINEMA computer code. This analysis has been performed to validate CINEMA models on the core melt progression, in particular, RCS thermal hydraulic behavior during core melt progression, fuel cladding oxidation with hydrogen generation, and fuel melting with relocation to the lower part of the core. The CINEMA results on main parameters, such as RCS pressure and an integrated hydrogen generation mass are compared with the TMI-2 data. The CINEMA results have shown that the RCS pressure is very similar to the TMI-2 data. The CINEMA results and measured total hydrogen production are very similar, which were approximately 465 kg and 460 kg, respectively.

Electrodeposited Ni foam electrodes for increased hydrogen production in alkaline electrolysis

Nickel foam electrodes were treated with a facile and cost-effective electrodeposition method to increase the hydrogen production efficiency in alkaline electrolysis setups. The treated electrodes (Electrodeposited Nickel Foam – ENF) exhibit enhanced electrochemical values compared to a bare nickel foam electrode (NF). A comprehensive analysis is presented on how the electrodeposition time determines the kinetics of hydrogen evolution reaction (HER) and the electrochemical values of the ENF electrodes. It was revealed that deposition time plays a decisive role in the total hydrogen production efficiency. In particular, the ENF electrode with 10 min of electrodeposition, presents a lower Tafel slope, lower overpotentials (|η10|=135 mV, |η100| = 230 mV), and enhanced hydrogen production (1.5 times higher) compared to an NF electrode. The improved characteristics are mainly attributed to the increased electrochemically active area (6.5 times higher than the NF electrode). Field emission scanning electron microscopy (SEM), Energy dispersive X-ray spectroscopy (EDS), and X-ray diffraction (XRD) were used for the structural and morphological analysis of the electrodeposited nickel foam electrodes.

Effect of Corn Straw on Hydrogen Production from Lignite

The conversion of lignite to clean energy has won considerable attention and plays an important role in achieving the goal of carbon reduction. The effects of corn straw on hydrogen production from lignite was explored by using lignite as the substrate and corn straw as an exogenous substance. The fermentation mechanism was elucidated through the analysis of total and daily hydrogen production; the concentration of humic acid, benzoic acid, pyruvate, and glucose, as well as pH value. In addition, total solid (TS), and volatile solid (VS) from activated sludge before and after fermentation are examined. The results showed that corn straw could accelerate hydrogen production from lignite with an optimal content of corn straw of 40%. The fermentative hydrogen production with 40% corn straw was up to 186.20 mL, 3.40 times higher than that of the control group. Corn straw effectively improved the concentration of humic acid and benzoic acid, accelerating the anaerobic fermentation of lignite to produce hydrogen. The concentration of pyruvic acid, glucose, pH, and the changes in TS and VS before and after fermentation showed that the group of 40% corn straw had a better promotion effect than other systems for hydrogen production. This provides a new idea for improving hydrogen production through lignite anaerobic fermentation.

Coupling gas purging with inorganic carbon supply to enhance biohydrogen production with Clostridium thermocellum

Clostridium thermocellum is a desirable biocatalyst for biohydrogen production, with a native ability to simultaneously saccharify cellulose and to metabolize released cellodextrins for hydrogen production. During fermentation with C. thermocellum, partial pressures of two gases - CO2 and H2 - are critical drivers of overall reaction kinetics. Biohydrogen production is enhanced by maintaining a low hydrogen partial pressure, while high concentrations of dissolved CO2 promote microbial biomass synthesis. Our study evaluates the inherent trade-offs between hydrogen stripping and inorganic carbon supply for optimized biohydrogen synthesis. We find that nitrogen sparging at low flow rates increases hydrogen production when compared with an equivalent nitrogen overlay, but that high rates of nitrogen sparging inhibit cell growth and hydrogen production. Decreasing dissolved hydrogen partial pressure via nitrogen sparging also lowers the production of reduced metabolites, including lactate and ethanol. To address potential stripping of inorganic carbon from the production medium, we supplemented CO2 to the sparging gas and co-optimized for gas flow rate and for the CO2 fraction of the sparging gas. Total hydrogen production increased from 50 mmol∙L−1 in the base condition, when the bioreactor was sparged with 0.1 LPM of pure nitrogen, to 181.3 mmol∙L−1 when sparged with 1.3 LPM of 33 % CO2, demonstrating that biohydrogen production is highly sensitive to both parameters. Fine sensitivity of biohydrogen production to sparging conditions highlights the critical importance of bioreactor design and operation to achieve maximum H2 removal without compromising inorganic carbon supply to bacterial central metabolism.

Sustainable city concept based on green hydrogen energy

The current study investigates the green hydrogen production from renewable energy sources for the metropolitan city of Istanbul by using electrolysers. The main idea is to create a hydrogen map for every district in Istanbul, based on renewable energy sources and water splitting technology. The potentially available renewable sources, such as solar (including offshore), wind (including offshore), biomass, geothermal and underwater current are used for calculating the total hydrogen production potential. Istanbul's potential for producing green hydrogen is estimated to be 7.96 Mt. The study results show that Catalca, Şile, Silivri, Arnavutköy, and Beykoz come out as the districts with the highest green hydrogen potential with 1.49 Mt, 1.19 Mt, 1.12 Mt, 0.57 Mt, and 0.46 Mt, respectively. After supplying the necessary power demand for the city, the remaining power is used to produce green hydrogen which may contribute an economic value of over 100 billion US$ with a current price of $13/kg of hydrogen and 23.88 billion US$ with a targeted price of $3/kg of hydrogen, respectively. The available potentials for each district are also specifically studied and discussed. It is more importantly expected to reduce the greenhouse gas emissions by about 90% which will ve very important to achieve a carbon-neutral city and hence country due its dominated role. Furthermore, the results provide a clear guidance to enable policymakers and private sectors to use renewable energy potentials for their investment purposes or promote clean energy programs, tackling carbon-based energy consumption, pollution, and greenhouse effect. This, later on, can be used by policymakers and energy providers to help the city and local communities for achieving the United Nation's sustainable development goals.

Enhanced hydrogen generation in a combined hybrid cycle using aluminum and cooper oxide nanomaterial based on biomass and vanadium chloride cycle: Optimization based on deep learning techniques and Environmental appraisal

The usage of Nanofluid to enhance heat transfer has been investigated by many researchers in small-scale heat transfers; however, in large-scale power plants, it has not been taken care of. In this research paper, a newly proposed energy system for hydrogen generation based on renewable sources is proposed and analyzed in detail. Unlike other power input systems, the vanadium chloride system generates hydrogen because it uses waste heat. In this regard, the nanoparticles of Al2O3 and CuO are utilized in the main heat exchanger to enhance the heat transfer to the reactor of VCLC to generate more hydrogen. Also, the compound system has the gasifier-based internally fired gas turbine as the main system and can generate hydrogen in a more green way. The optimization based on deep learning methods is applied to seek the highest point of operation by the system. The results exhibit that Al2O3 causes more heat transfer and efficiency enhancement, thus in hydrogen production, causing an increase of 18.5% compared to base fluid and 8.3% compared to CuO in H2 Generation In circumstances when it is optimal, the values for exergetic efficiency and total hydrogen production are 64.5% and 4.5 kg/s respectively. In addition, using a nanofluid heat exchanger and biomass energy reduces CO2 emissions to 0.91 kg/kWh.

Sustainable marina concept with green hydrogen utilization: A case study

The current study investigates the green hydrogen production from renewable energy for a sustainable yacht marina. The main idea is to create a sustainable harbor for utilizing renewable energy sources using electrolysers to produce hydrogen and providing power for both marina energy demand and transportation fuel needs. Generating electricity from renewable energy resources and converting into green hydrogen in marinas are the main objectivesof the current study. Solar and wave energy resources are used for calculating total hydrogen production potential. Four different sizes of luxury yachts are considered in the calculations. The considered three yacht marinas are located in Malaga, Mugla, and Istanbul. The average annual green hydrogen production potential of a marina from offshore solar energy is estimated to be 1.34, 1.38, 1.47 kt, and annual green hydrogen production from wave energy is 2.66, 3.06, 3.99 kt for the considered marinas locates in Marbella, Bodrum, and Atakoy, respectively. During the summer season, 400 small-sized, 250 medium-sized, or 100 large-sized yachts are potentially considered for fueling with green hydrogen. At maximum capacity, in Atakoy marina, which is chosen for the case study, a total of 243 hydrogen-fueled mega-yachts can potentially be refueled with green hydrogen. The study results show that the marinas selected in the specified locations appear to feasible for sustainable hydrogen applications.

Optimal design and management for hydrogen and renewables based hybrid storage micro-grids

In an energy sustainability perspective, the renewables penetration is expected to importantly increase over the next decade, requiring modifications in the current electric system in terms of flexibility and reliability. In this respect, storage systems will play a central role and the production of green hydrogen is seen as a promising solution for both short-term and seasonal storage.In this context, the aim of this paper is the development of a methodology for the optimal design of hybrid storage micro-grids based on renewables and hydrogen and the definition of an optimal management strategy in a perspective of hydrogen employment as seasonal storage. In detail, an optimization code – based on mathematical models for each component and on specifically developed optimization strategies for the management of the components interaction – will be presented and applied to a case study. The code optimizes the sizes of the integrated electrolyzer and fuel cell, based on an objective function that maximizes the storage efficiency. It has been applied to the S.A.P.I.E.N.T.E. micro-grid installed at the ENEA Research Centre near Rome (Italy) – composed of photovoltaic panels, batteries, heat pump and thermal storage systems – obtaining the optimal design of the hydrogen section to be integrated as seasonal storage strategy. Furthermore, a parametric analysis on the battery size has been performed. The application of the developed optimization routine resulted in the introduction of a 3.7 kW electrolyzer and 4 kW fuel cell coupled with 36 kWh of battery capacity, enabling a total hydrogen production of about 87.5 kg (corresponding to 1159 kWh of electricity produced during the thermal year).

Numerical simulation on flow and reaction characteristics for catalytic region in helium-heated steam reformer coupled with HTR-10

In this paper, one dimension steady-state and pseudo-homogeneous model of the hydrogen production reformer in the steam methane reforming (SMR) process using the high temperature gas-cooled test reactor of 10 MW (HTR-10) as heat source (HTR-10/SMR) is simulated based on the semi-coupled solution method using matlab2016b. Firstly, The axial variations of hydrogen production performance including temperature (T2), methane conversion rate (XCH4), carbon monoxide conversion rate (XCO) and hydrogen production per mole methane (YH2/CH4 or total hydrogen production (YtH2)) as well as thermal efficiency (η) are investigated. Then, it is noted that YH2/CH4 decreases from 2.92 mol H2/mol CH4 to 2.53 mol H2/mol CH4. However, YtH2 increases from 2.33 kmol/h to 3.23 kmol/h with the increase of the inlet process gas flow rate (F2inlet) from 4 kmol/h to 6 kmol/h. Finally, YtH2 increases with steam to carbon ratio (S) when S < 4 and decreases when S > 4. The maximum value of YtH2 with 3.03 kmol/h is obtained at S = 4. Especially, XCH4, XCO, YH2/CH4 and η are in the range of 70.54%–90.78%, 38.56%–54.30%, 2.50–3.07 mol/mol CH4 and 54.55%–64.57%, respectively, when T3_inlet is in the range of 850–950 °C. The effect of the process gas temperature and pressure on the system performance can be neglected.

Metabolic regulation of NADH supply and hydrogen production in Enterobacter aerogenes by multi-gene engineering

Biohydrogen is a sustainable clean energy source that has received significant attention in recent years. In this study, the strategies to regulate NADH supply and metabolic flux via disruption of nuoF gene in complex Ⅰ, over-expression formate hydrolyase activator (fhlA) and phosphoenolpyruvate carboxykinase (pckA) were taken to improve hydrogen production in Enterobacter aerogenes IAM1183. After knocking out nuoF and overexpressing pckA, experimental results indicated that the intracellular NADH/NAD+ ratio was significantly increased, which was 115.6% higher than before in the optimal strain EaΔCDEF/P (ΔnuoCDEF/pckA), thereby improving the hydrogen production of NADH pathway. After overexpressing fhlA, the hydrogen production of Ea/F via formate pathway increased by 16.8%. Through the multi-gene engineering strategy, the metabolic flux of mutants was reallocated and the concentration of fermentation metabolites was changed. The total hydrogen production of EaΔCDEF/P reached 4.5 L after 44 h in 5-L fermenter, which was 17.2% higher than that of the original strain. This study provides new concepts for the use of genetic engineering to promote bacterial hydrogen production.

Development of a waste tires-based integrated energy system for multiple useful outputs in sustainable communities

In this study, a geothermal energy-supported integrated gasification system fed with waste tires for multigenerational purposes is developed to generate multiple useful commodities, including ethanol, sulfuric acid, hydrogen, electricity, cooling, and heat to achieve cleaner applications and meet the essential needs of the community in a sustainable manner. A potential application of this conceptually designed system is for a community identified in the Tuscany region of Italy's Larderello field. The proposed system is then analyzed and assessed by utilizing sensitive the thermodynamic simulations and software. The effects of operational and state-related parameters, such as steam, oxygen, waste tire input rate, reference temperature, and gasifier temperature are examined to analyse and evaluate the integrated waste tire gasification system's performance. The present study further aims to determine the effects of varying system parameters and operating circumstances on the ethanol and hydrogen production rates, with the goal of increasing energy and exergy efficiencies while minimizing hazardous wastes and gas emissions. Furthermore, numerous parametric studies on the waste tire-powered multigeneration system are undertaken accordingly. Both Engineering Equation Solver (EES) and Aspen Plus software packages are utilized as potential tools to perform analysis andsimulation studiesfor this system. The proposed system is fed with 10 kg/s of waste tires, and the energy production is supported by using 14.7 kg/s of geothermal spring water. While the net electricity generation, cooling and heating capacities of this system are obtained to be 18752 kW, 49236 kW and 5363 kW, respectively, while the total hydrogen and ethanol production rates within the integrated system are found to be 3.02 kg/s and 0.13 kg/s. The results also show that the waste tire-based integrated gasification system's overall energetic and exergetic efficiencies become 71.45 % and 69.87 %, respectively.

Hydrogen Production by CO2 Deprived Photoautotrophic Chlamydomonas reinhardtii Cultures.

Light-dependent hydrogen production by microalgae attracts attention of researchers because of the potential practical application. It is generally recognized that Calvin-Benson-Bassham cycle competes with hydrogen production process for electrons, and substrate (CO2) limitation of the cycle can increase hydrogen production rate. Furthermore, photosystem II is not destroyed by CO2 deficiency. We studied photoautotrophic cultures of Chlamydomonas reimhardtii under CO2 deficiency. Under the flow of air with removed CO2 the cultures reached stationary phase of growth and the photosystem II was downregulated due to overreduction of plastoquinone pool followed by degradation of the entire photosynthetic machinery. Under the Ar flow in the absence of CO2 the cultures were brought to microaerobic conditions producing small amounts of hydrogen (5 ml H2 day-1 liter-1 culture). Similar to the case of incubation under air atmosphere, prolonged incubation of cultures under microaerobic conditions resulted in down-regulation of photosystem II due to overreduction of plastoquinone pool with following degradation of whole photosynthetic machinery. Following removal of CO2, transfer of cultures into dark anaerobic conditions (2.5 h), and illumination with low-intensity light resulted in the cultures producing H2 with high initial rate. Total microalgal hydrogen production under these conditions was 56 ml H2 liter-1 culture. Thus, the CO2-deprived photoautotrophic cultures produce hydrogen. Hydrogen production was limited by the toxic effect of oxygen on hydrogenase but not by the Calvin-Benson-Bassham cycle competition with hydrogen production process.

Type-I SnSe2/ZnS heterostructure improving photoelectrochemical photodetection and water splitting

Two-dimensional van der Waals heterostructures have been widely designed and applied to numerous optoelectronic devices such as photoelectrochemical (PEC)-type photodetectors, water splitting, and solar cells. The understanding of the influence of band alignment in type-I heterostructures on the photoelectric response remains incomplete yet essential for designing new optoelectronic devices. Herein, two-step physical vapor deposition is used to construct a type-I SnSe2/ZnS heterostructure, which is confirmed by ultraviolet photoelectron spectroscopy and X-ray photoelectron spectroscopy. The type-I heterostructure-based PEC-type photodetector exhibits excellent photoresponse, high stability, and high sensitivity in the ultraviolet-visible range. Furthermore, the photoresponsivity of SnSe2/ZnS is up to 172.60 µA W−1, which is 7.4- and 2.0-fold larger than that of pure ZnS and SnSe2, respectively. Moreover, the SnSe2/ZnS heterostructure possesses high photoelectrocatalytic activity in water splitting, and the total hydrogen production within 2 h is up to 81.25 µmol cm−2. The high PEC-type photodetector and water splitting performances in SnSe2/ZnS are due to the synergistic effect of high light utilization and efficient charge transport. Our work provides a new method for improving photoelectric response by forming type-I heterostructures and for designing high-performance optoelectronic devices for photodetectors and water splitting.

Anaerobic Fungi Isolated From Bactrian Camel Rumen Contents Have Strong Lignocellulosic Bioconversion Potential.

This study aims to obtain anaerobic fungi from the rumen and fecal samples and investigates their potential for lignocellulosic bioconversion. Multiple anaerobic strains were isolated from rumen contents (CR1–CR21) and fecal samples (CF1–CF10) of Bactrian camel using the Hungate roll tube technique. After screening for fiber degradability, strains from rumen contents (Oontomyces sp. CR2) and feces (Piromyces sp. CF9) were compared with Pecoramyces sp. F1 (earlier isolated from goat rumen, having high CAZymes of GHs) for various fermentation and digestion parameters. The cultures were fermented with different substrates (reed, alfalfa stalk, Broussonetia papyrifera leaves, and Melilotus officinalis) at 39°C for 96 h. The Oontomyces sp. CR2 had the highest total gas and hydrogen production from most substrates in the in vitro rumen fermentation system and also had the highest digestion of dry matter, neutral detergent fiber, acid detergent fiber, and cellulose present in most substrates used. The isolated strains provided higher amounts of metabolites such as lactate, formate, acetate, and ethanol in the in vitro rumen fermentation system for use in various industrial applications. The results illustrated that anaerobic fungi isolated from Bactrian camel rumen contents (Oontomyces sp. CR2) have the highest lignocellulosic bioconversion potential, suggesting that the Bactrian camel rumen could be a good source for the isolation of anaerobic fungi for industrial applications.

Investigation of the thermodynamic analysis of solar Energy-Based multigeneration plant for sustainable multigeneration

Renewable energy-based multigeneration plants are a huge potential to tackle environmental problems and also to the passing of the carbon-free future. The main goal of the present research is to design and examine the combined cycle motivated by solar energy for multigeneration which is power, hydrogen, ammonia, and freshwater generation. The innovative design multigeneration system is made up of a parabolic trough solar collector, a steam Rankine cycle with high and low-pressure turbines, a transcritical Rankine cycle with a carbon-dioxide fluid, a desalination part, a Proton Exchange Membrane electrolysis, and an ammonia reactor. A comprehensive thermodynamic analysis, environmental impact assessment, and exergo-environmental analysis are addressed to determine the performance and carbon dioxide emission reduction of the overall plant. Furthermore, in this planned research, a thorough parametric evaluation is performed to define how the variation of some significant parameters (e.g., ambient temperature, solar radiation, and collector outlet temperature) has an impact on the cycle’s efficiency and useful outputs. The findings of the research analysis indicated that the total net power and hydrogen production capacities are 1654 kW and 0.0025 kgs-1. The irreversibility rate is determined as 7047 kW and the parabolic trough solar collector has the uppermost rate among the components. Furthermore, energetic and exergetic performances of the modeled cycle are computed as 29.04% and 27.43%, respectively. Finally, freshwater and ammonia production rates are determined as 1.182 kgs-1 and 0.004842 kgs-1, respectively.

Effective use of geothermal energy for hydrogen production: A comprehensive application

The present study aims to investigate the geothermal energy potential for green hydrogen production in Turkey. Geothermal energy potential varies based on each city's location and underground resources (particularly on their flowrates, temperatures and composotion). Alkaline electrolysers (ALELs) are considered for water splitting and hence hydrogen production. The total hydrogen production potential for Turkey using geothermal resources is estimated to be 559.76 kilotons. In this regard, Aydın, Manisa, and Denizli appear to be the cities with the largest hydrogen production potentials. Hydrogen generation potentials for all Turkish cities are provided and discussed for a feasible hydrogen economy. It furthermore gives a countrywide spectrum of how an effective role geothermal energy can play in making the country leader in this field. The study results may serve as a good base for planning and strategizing purposes as required for the country and help in developing new energy policies for exploiting renewable energy resources.

Green hydrogen production potential in Turkey with wind power

ABSTRACT The present study aims to investigate the renewable energy-based hydrogen production potential using onshore and offshore wind power, along with the available undersea currents in Turkey. Wind energy potential varies based on the cities location, for both onshore and applicable offshore applications. Furthermore, undersea current turbines are considered for generating renewable energy potential. Proton Exchange Membrane (PEM) electrolyzers are considered for water splitting and hydrogen production. The total hydrogen production potential for Turkey is estimated to be 248.56 million tons. The onshore wind, offshore wind, and undersea current hydrogen production potentials are found to be 233.38, 15.17, and 6.65 million tons, respectively. In this regard, Erzurum, Van, Konya, and Sivas appear to be the cities with maximum hydrogen production potentials of 13.83, 12.81, 12.05, and 11.82 million tons, respectively. The hydrogen generation potentials for all Turkish cities are provided and discussed for a hydrogen economy platform. It may help promote Turkey to a hydrogen hub leadership position in the region through creating jobs supporting energy sector, and providing a sustainable future by establishing local, national, and international connections and networks. It furthermore gives a country-wide spectrum of how effective role the wind energy can play in paving the road for a sustainable energy country. The study results may serve as a reliable base for planning and strategizing purposes as required for the country and help create new energy policies for exploiting renewable energy resources.

Hydrogen production via anaerobic digestion of coal modified by white-rot fungi and its application benefits analysis

White-rot fungi have received widespread attention owing to their strong ability of lignocellulosic degradation. However, research on applying white-rot fungal to alter coal (lignin-like polymers) for hydrogen production is scarce, also the related mechanism is unclear. In this study, white-rot fungi were utilized to decompose the high volatile bituminous coal. The results showed that hydrogen production from anaerobic digestion (AD) of white-rot fungi pretreated coal (C3) was accelerated, the total hydrogen production was 20.3 times AD of coal (C4). It was attributed to C3 had a higher hydrogenase activity, lower acidity and more stable reducing environment than C4, resulting in more intermediates, such as alkanes, acids/alcohols, and esters. Additionally, fungal pretreatment enhanced the competitiveness of the important hydrogen synthetic Clostridium, the relative abundance remained at about 21.0% compared with other bacterial communities. Finally, the study evaluated the benefit of this strategy from economic and environmental perspective, as well as a preliminary analysis of field application. It illustrated that C3 significantly reduced the CO content in flue gas, which was 28.7% lower than coal (C1) in flue gas from coal combustion and showed an approximate 20.1 times C4 in terms of output.

Effect of continuous micro-aeration on hydrogen production by coal bio-fermentation

ABSTRACT In order to study the effect of micro-aeration on hydrogen production from coal, bituminous coal D from the Yima mining area was selected. An experiment to simulate hydrogen production by bio-fermentation was carried out with mine water as the source of bacteria. The results show that with an increasing aeration rate, the hydrogen production continuously decreased. At the end of gas production, the total hydrogen production under aeration rates of 0.0015 L/h, 0.015 L/h and 0.15 L/h was 3.60 mL/g, 1.50 mL/g and 0.58 mL/g, respectively. The molar concentrations of volatile fatty acids (VFAs) in the reaction liquid increased continuously, and the pH decreased overall. The COD content of the liquid phase first increased and then decreased. The COD degradation rates of three different aeration rates at the end of hydrogen production were 43.67%, 16.26% and 5.87%, respectively. With the increasing aeration rate, the dominant hydrogen producing bacteria during bio-fermentation gradually changed from Clostridium to Propionibacterium, and the type of fermentation also changed from butyric acid-type fermentation to propionic acid-type fermentation. In conclusion, the experimental results provide a theoretical basis for exploring hydrogen production via coal bio-fermentation under continuous micro-aeration.