Heavy water as a valuable by-product of electrolytic hydrogen

A Combined Electrolysis Catalytic Exchange-Heavy Water Process (CECE-HWP) is being developed at Chalk River with the ultimate aim of producing by-product heavy water from electrolytic hydrogen streams although other earlier potential applications are also discussed. The gross heavy water dollar credit per GJ, based on the higher heating value of hydrogen, has been calculated as a function of the important variables: recovery, feed concentration, and price. Based on preliminary data and cost estimates, the net heavy water dollar credit has been estimated to be at least comparable to the by-product oxygen credit. The potential for by-product heavy water production from hydrogen in general, and from electrolytic hydrogen in particular, in Canada, the U.S.A., and the Western World is discussed in relation to Canada's present primary heavy water production capacity.     

Nuclear power in Canada: a different approach

Canada's Pickering nuclear power station with a total capacity of 2000 MW demonstrates the viability of the CANDU system, which employs heavy water as moderator with natural uranium as fuel. In this article Mr Boyd describes current operating experience and the background to Canada's nuclear programme which is destined to supply about 50% of all electricity generation in that country by 2000.     

Hydrogen refueling station siting of expressway based on the optimization of hydrogen life cycle cost

Hydrogen-energy expressway system planning involves load prediction, hydrogen source planning and hydrogen station planning. Exemplary construction of a run-for-profit hydrogen-energy expressway must attach importance to comprehensive evaluation of the effect of investment. The paper analyzes current situation of hydrogen-energy expressway construction, points out that adequate consideration should be given in all aspects of hydrogen energy's life cycle cost, such as hydrogen production, transport, storage, usage, CO₂ disposal, carbon tax, hydrogen station's annual construction investment and annual operating expenses. The paper suggests that hydrogen made from discarded electricity of clean energies and hydrogen produced as byproduct during chemical plant production should be utilized to reduce production cost. On the basis of hydrogen energy's life cycle cost analysis, the paper creates a hydrogen station siting optimization model, with the constraints of hydrogen station's supply radius, hydrogen source's productivity and geographic information factor, so as to increase the applicability and level of hydrogen-energy expressway planning effectively.     

Hydrogen-oxygen utilization systems

A Hydrogen-energy system embracing production, delivery and utilization or end-use means, can alternatively take on one of two basic configurations: (1) hydrogen (only) or (2) hydrogen + oxygen. The former, which would be analagous to today's natural gas system, implies air-using utilization devices in which the oxygen required for sustaining the using-point energy conversion by way of heat-release or electricity-generation, is extracted from the atmosphere.The second alternative would be represented by a “twin-pipe” delivery system in which both elemental constituents of the basic water-splitting production process are delivered to the utilization sectors. This hydrogen + oxygen alternative configuration offers significant, but not very well-known benefits attributable to hydrogen-oxygen utilization systems, the subject of this paper. The thesis offered is that such systems and end-use devices provide the potential for major gains in energy conversion efficiency, capital costs, operating flexibility, and in environmental impact.However, today concensus seems to favor the “hydrogen only” option in which the oxygen concomitant to hydrogen production is vented to the atmosphere, or at best assumed to be a cheap bulk industrial credit byproduct.If hydrogen-oxygen utilization systems are eventually judged by the ultimate consumer to offer the benefits postulated, production and delivery means supportive of hydrogen + oxygen distribution may be forthcoming. Since this predicates fundamental and large-scale changes in the production and delivery sector so far as physical makeup is concerned, advanced energy system planners are urged to give early heed to the potential and ramifications of hydrogen-oxygen utilization systems, and to voice their judgment.     

Canada’s program on nuclear hydrogen production and the thermochemical Cu–Cl cycle

This paper presents an overview of the status of Canada’s program on nuclear hydrogen production and the thermochemical copper–chlorine (Cu–Cl) cycle. Enabling technologies for the Cu–Cl cycle are being developed by a Canadian consortium, as part of the Generation IV International Forum (GIF) for hydrogen production with the next generation of nuclear reactors. Particular emphasis in this paper is given to hydrogen production with Canada’s Super-Critical Water Reactor, SCWR. Recent advances towards an integrated lab-scale Cu–Cl cycle are discussed, including experimentation, modeling, simulation, advanced materials, thermochemistry, safety, reliability and economics. In addition, electrolysis during off-peak hours, and the processes of integrating hydrogen plants with Canada’s nuclear plants are presented.     

Improved energy efficiency of the electrolytic evolution of hydrogen—Comparison of conventional and advanced electrode materials

With the idea to improve the efficiency of the electrolytic production of hydrogen by electrolysis, from water KOH solutions, the intermetallic Hf₂Co was investigated as cathode. This cathode was used single or in combination with ionic activators, and compared with several intermetallics previously investigated: Hf₂Fe, TiPt, and PtMo₃. A comparison with conventional cathode, nickel, was also evaluated. An significant upgrade of the electrolytic efficiency using intermetallics was achieved in comparison with conventional cathode materials. The influence of ionic activators on the process efficiency was significant, too.The effects of those cathode materials on the electrolytic evolution of hydrogen were discussed in the context of transition metals features that issue from their electronic configuration.     

Greenhouse gas reduction in oil sands upgrading and extraction operations with thermochemical hydrogen production

This paper examines various methods of reducing CO₂ emissions by a thermochemical copper–chlorine (Cu–Cl) cycle of hydrogen production, for in-situ extraction and upgrading of bitumen to synthetic crude oil in Alberta’s oil sands. Particular focus is given to Canada’s SCWR (Supercritical Water-cooled Reactor) as a nuclear heat source for the Cu–Cl cycle, although other heat sources such as solar or industrial waste heat can be utilized. The feasibility of steam generation from supercritical water of a SCWR power plant is examined for bitumen extraction, as well as hydrogen production for bitumen upgrading via an integrated Cu–Cl cycle with SCWR. The heat requirements for bitumen extraction from the oil sands, and the hydrogen requirements for bitumen upgrading, are examined. A new layout of oil sands upgrading operations with integrated SCWR and a Cu–Cl cycle is presented. The reduction of CO₂ emissions due to the integrated SCWR and Cu–Cl cycle is quantitatively investigated based on the expected bitumen production capacity over the next two decades.     

In-situ experimental characterization of the clamping pressure effects on low temperature polymer electrolyte membrane electrolysis

The recent acceleration in hydrogen production's R&D will lead the energy transition. Low temperature polymer electrolyte membrane electrolysis (LT-PEME) is one of the most promising candidate technologies to produce hydrogen from renewable energy sources, and for synthetic fuel production. LT-PEME splits water into hydrogen and oxygen when the voltage is applied between anode and cathode. Electrical current forces the positively charged ions to migrate to negatively charged cathode through PEM, where hydrogen is produced. Meanwhile, oxygen is produced at the anode side electrode and escapes as a gas with the circulating water.The effects of clamping pressure (P_c) on the LT-PEME cell performance, polarization resistances, and hydrogen and water crossover through the membrane, and hydrogen and oxygen production rate are studied. A 50 cm² active area LT-PEME cell designed and manufactured in house is utilized in this work.Higher P_c has shown higher cell performance this refers to lower ohmic and activation resistances. Water crossover from anode to cathode is slightly decreased at higher P_c resulting in a slight decrease in hydrogen crossover from cathode to anode. Also, the percentage of hydrogen in the produced oxygen at the anode side is significantly reduced at higher P_c and at lower current density.     

A plan for hydrogen use in a rural Alaskan community

The results of a study to plan and design a program to demonstrate an all-hydrogen community in rural Alaska are discussed. The objectives of the study were to assess the prospects of reducing Alaska's dependency on fossil fuels by producing hydrogen from renewable resources and easing the burden of transporting fuel to remote sites. The hydrogen system considers Alaska's unique resources, supply logistics, demographics, and economics.Integration of hydrogen production with transportation, distribution, storage, and utilization equipment is discussed for the representative rural village of Old Harbor on Kodiak Island. A $\text{6}\text{1}\text{2}$ year demonstration program to prudently convert this village from diesel fuel to hydrogen is anticipated. As each phase is successfully completed, one aspect of the community's energy use and supply will be converted to all hydrogen. This includes equipment required for hydrogen production, residential hydrogen utilization, transportation, and electricity generation. In addition to technical requirements the paper describes the social, legal, and economic issues encountered in planning the demonstration.The total estimated cost of the demonstration, including equipment, management, monitoring and testing, is $20 million.     

Raising efficiency of hydrogen generation from alkaline water electrolysis – Energy saving

This paper presents an attempt to make the alkaline electrolytic production of hydrogen more efficient by adding in situ activating compounds in ionic and complex form. Cobalt and tungsten based ionic activators (i.a.), added directly into the electrolyte during the electrolytic process, reduce energy requirements per mass unit of hydrogen produced for about 15%, compared to non-activated system, for a number of current densities in a wide temperature range. Energy saving is higher at higher temperatures and on higher current densities. Structural and morphological characteristic of deposit formed on the cathode during the electrolytic process reveal very interesting and unique pattern with highly developed surface area and uniform distribution of the pores. Obtained deposit also exhibit a long term stability.     

Commodity hydrogen from off-peak electricity

This paper considers the use of off-peak electrical power as an energy source for the electrolytic production of hydrogen. The present industrial uses for hydrogen are examined to determine if hydrogen produced in this fashion would be competitive with the industry's onsite production or existing hydrogen prices. The paper presents a technical and economic feasibility analysis of the various components required and of the operation of the system as a whole including production, transmission, storage, and markets.     

Chimie douce hydrogen production from Hg contaminated water,with desirable throughput,and simultaneous Hg-removal

Hydrogen's widespread use is fraught with many difficulties. The challenges currently are to do with safety concerns in gas storage and transportation, and low rate of production leading to non-viability of technologies at the point-of-use. Another global concern of immediate relevance involves heavy-metal ion pollution. Viable processes which can simultaneously remove and result in beneficiation of the contaminants are hitherto rarely reported. In this context we report a single-step, in situ co-reduction approach which has the dual advantage of (i) Hg contaminant removal, and (ii) room temperature hydrogen production. Hydrogen is produced via galvanic corrosion of in situ synthesized nanoaluminium amalgam. The production rate (720 mL/min for 0.5 g-Al salt) is far superior to what would be expected from the use of pure hydrides, and/or using bulk amalgams at room temperature. The method is simple, chimie douce (i.e soft chemical), hence potentially affordable, and capable of providing a means of beneficiating Hg contaminated water present in effluents from certain industries (for example, industries which uses chlor-alkali process). The in situ co-reduction approach helps in bypassing the usual rate limiting step which involves formation of an alumina passivation layer on hydrolytic material surface. Given the potential that exists in scale down and up, this approach offers a method to address the long standing challenge of point-of-use hydrogen availability.     

Study of hydrogen generation from heavy oil gasification based on ramped temperature oxidation experiments

Hydrogen is a clean energy because of its high energy density and pollution-free combustion. The main ways of hydrogen generation are from coal and methane, as well as hydrogen generation from by-products of chemical plants. It had been reported that heavy oil reservoir in Margaret Lake in Canada produced up to 15 mol% hydrogen indicating that it is feasible to produce hydrogen by in-situ gasification (ISG) from heavy oil reservoir. However, there are relatively few studies on the mechanism and characteristics of hydrogen generation from ISG of heavy oil, the lower limit of hydrogen-production temperature, the interaction of produced gas and so on. Previous studies focused on the upgrading of heavy oil rather than hydrogen generation. In order to study the hydrogen generation mechanisms of different samples, The 4 types samples covering heavy oil, light oil, carbon samples were used and the saturate, aromatic, resin and asphaltene (SARA) components was measured by thin layer chromatography and flame ionization detection (TLC-FID). Then, the ramped temperature oxidation (RTO) experiments of 7 Runs of reservoir cores and sand-filling model were designed. The compositions and molar contents of produced gas were analyzed combined with gas chromatography (GC), and the lower limit temperature and the advantages of hydrogen generation from heavy oil were analyzed under different air/nitrogen injection rates based on a constant water injection rate. The results showed that the lower limit temperature of hydrogen generation from crude oil was about 500–550 °C and that of carbon was 700–750 °C. The reservoir core may had catalytic effect, which can promote hydrogen production. The highest hydrogen rate of RTO experiment with reservoir core can reach 55–60mol%, while that of sand-filling experiment was only 5–10mol%. The main chemical reactions for hydrogen generation from crude oil were coke gasification and water-gas shift. Therefore, the hydrogen production of heavy oil with high hydrocarbon ratio was significantly greater than that of thin oil. It showed the advantages of hydrogen generation from heavy oil. In addition, in order to quantitatively evaluate the efficiency of hydrogen production by gasification, the definition and calculation equation of hydrogen generation efficiency (HGE) were given. The HGE was defined as the ratio of hydrogen production volume and hydrogen consumption volume in a certain period of time (Δt). The E_hg can be used to quantitatively represent HGE, and the calculation of E_hg is the ratio of hydrogen production and twice of oxygen consumption in a period of time. The E_hg of Run1 and Run3 were calculated to be 1.47 and 0.15. It indicated that the hydrogen production efficiency of Run1 was about 10 times higher than that of Run3.     

Wind-hydrogen utilization for methanol production: An economy assessment in Iran

This study investigates the feasibility to synthesis methanol from its flue gas and wind hydrogen. The concept is to mitigate CO₂ emission through flue gas recovery. Synthesizing methanol, on the other hand requires hydrogen at the rate of 3 kmol/kmol of carbon dioxide. Electrolysis is one method by which hydrogen can be produced cleanly from renewable source. Here it is assumed that the electrolysis unit is fed with the electricity from neighbor wind farms. Oxygen will be produced as a byproduct in electrolysis unit. However, electrolytic oxygen could be utilized for partial oxidation of methane in autothermal reactor (ATR). Onboard water electrolysis facilitates the oxygen and hydrogen storage, delivery and marketing. This study focuses on an integrated system of methanol production which enables green methanol synthesis through a system with zero carbon emission. Green methanol synthesis is comprised of CO₂ capturing and recycling along with renewable hydrogen generation. The produced hydrogen and CO₂ will be directed to methanol synthesis unit. By employing the integrated system for methanol synthesis, we could reduce the cost of using renewable energy technology.     

Intermetallics as cathode materials in the electrolytic hydrogen production

The intermetallics of transition metals have been investigated as cathode materials for the production of hydrogen by electrolysis from water–KOH solutions, in an attempt to increase the electrolytic process efficiency. We found that the best effect among all investigated cathodes (Hf₂Fe, Zr–Pt, Nb–Pd(I), Pd–Ta, Nb–Pd(II), Ti–Pt) exhibits the Hf₂Fe phase. These materials were compared with conventional cathodes (Fe and Ni), often used in the alkaline electrolysis. A significant upgrade of the electrolytic efficiency using intermetallics, either in pure KOH electrolyte or in combination with ionic activators added in situ, was achieved.The effects of these cathode materials on the process efficiency were discussed in the context of transition metal features that issue from their electronic configuration.     

The Sono-Hydro-Gen process (Ultrasound induced hydrogen production): Challenges and opportunities

Producing hydrogen using ultrasonic waves offers tremendous opportunities, which could lead to a clean, affordable and reliable energy source. Introducing high-frequency ultrasonic waves to liquid water could provide an efficient way to produce efficient and clean hydrogen. This particular review makes a focus on the application of power ultrasound in hydrogen production and discusses the challenges, opportunities and future directions. This new, ultrasonic based hydrogen production technology is given the name of “Sono-Hydro-Gen”. It is well known that hydrogen can be formed from the dissociation of water molecules subjected to ultrasound via the so-called sonolysis process. Factors affecting the hydrogen production rate and the theory beyond these effects are described herein. The average hydrogen production-rate reported from the Sono-Hydro-Gen process is 0.8 μMol per minute at an acoustic intensity of 0.6 W cm⁻². This review also compares the Sono-Hydro-Gen technology with the most commonly used technologies and it is found that this technology could lead to a prosperous and secure hydrogen energy for the future. Recent numerical and experimental investigations on the hydrogen production pathways have been reviewed showing various numerical simulations for different experimental configurations. Finally, performance and efficiency criteria are discussed along with the challenges associated with the Sono-Hydro-Gen process.     

Enhanced hydrogen production and biological saccharification from spent mushroom compost by Clostridium thermocellum 27405 supplemented with recombinant β-glucosidases

Clostridium thermocellum 27405 is a potential consolidated bioprocessing (CBP) strain due to the efficient lignocellulose degradation ability. Here, the spent mushroom substrate (SMS), a lignocellulosic byproduct of agriculture, was used as a substrate for hydrogen production by C. thermocellum. SMS showed a good performance for hydrogen production and the hydrogen production was significantly enhanced by C. thermocellum supplemented with β-glucosidases, with the highest production reaching 56.0 mM, an increase of 37%. Additionally, β-glucosidase and Triton X-100 had a synergistic effect on biological saccharification, resulted in an accumulation of 5.06 g/L reducing sugars, an increase of 28%. However, fusion β-glucosidase showed no improvement on hydrogen production and biological saccharification. The present study demonstrates the different influences of β-glucosidase and fusion β-glucosidase on hydrogen production and biological saccharification in CBP system and provides valuable information on the biodegradation of SMS using C. thermocellum.     

Comprehensive study on a two-stage anaerobic digestion process for the sequential production of hydrogen and methane from cost-effective molasses

Two-stage anaerobic digestion process has been frequently applied to the sequential production of hydrogen and methane from various organic substrates/wastes. In this study, a cost-effective byproduct of food industry, molasses, was used as a sole carbon source for the two-stage biogas-producing process. The two-stage process consisted of two reactor parts named as the first-stage hydrogenic reactor (HR) operated at pH 5.5 and 35°C and the second-stage methanogenic reactor (MR) at pH 7.0 and 35°C. Microbial community analysis revealed that Clostridium butyricum was the major hydrogen-producing bacteria and methanogens consisted of hydrotrophic bacteria like Methanobacterium beijingense and acetotrophic bacteria like Methanothrix soehngenii. In the first-stage process, hydrogen could be efficiently produced from diluted molasses with the highest production rate of 2.8 (±0.22) L-H₂/L-reactor/d at the optimum HRT of 6 h. In the second-stage process, methane could be also produced from residual sugars and VFAs with a production rate of 1.48 (±0.09) L-CH₄/L-reactor/d at the optimum HRT of 6 d, at which overall COD removal efficiency of the two-stage process was determined to be 79.8%. Finally, economic assessment supported that cost-effective molasses was a potent carbon source for the sequential production of hydrogen and methane by two-stage anaerobic digestion process.     

Thermodynamic analysis of a new process for hydrogen and electric power production by using carbonaceous fuels and high-temperature process heat

A new process for the simultaneous production of hydrogen and electrical power by using carbonaceous fuels and high-temperature process heat is presented in this paper. In an electrolytic cell, sulfur dioxide dissolved in an aqueous solution of sulfuric acid is electrochemically oxidized to sulfuric acid at the anode, while hydrogen gas is evolved at the cathode. The sulfuric acid produced in the cell provides the oxygen for the fuel combustion which subsequently takes place at high pressure. The combustion gas consisting mainly of CO₂, SO₂ and H₂O expands in a turbine in order to produce electrical power. After the expansion, the components sulfur dioxide and water are separated from the combustion gas and fed together with added water into the electrolysis cell.The process shows some advantages compared with already existing or proposed processes for the production of hydrogen or electric power. The influence of the sulfuric acid concentration and some other important process parameters on the energetic and exergetic efficiency of the total process is shown. The results shown in this paper have been obtained by using carbon (as a substitute for coal which is the preferred fuel) and a nuclear heat production plant (as an example of providing the required high-temperature process heat).