Gasification biochar as a valuable by-product for carbon sequestration and soil amendment

Thermal gasification of various biomass residues is a promising technology for combining bioenergy production with soil fertility management through the application of the resulting biochar as soil amendment. In this study, we investigated gasification biochar (GB) materials originating from two major global biomass fuels: straw gasification biochar (SGB) and wood gasification biochar (WGB), produced by a Low Temperature Circulating Fluidized Bed gasifier (LT-CFB) and a TwoStage gasifier, respectively, optimized for energy conversion. Stability of carbon in GB against microbial degradation was assessed in a short-term soil incubation study and compared to the traditional practice of direct incorporation of cereal straw. The GBs were chemically and physically characterized to evaluate their potential to improve soil quality parameters. After 110 days of incubation, about 3% of the added GB carbon was respired as CO₂, compared to 80% of the straw carbon added. The stability of GB was also confirmed by low H/C and O/C atomic ratios with lowest values for WGB (H/C 0.12 and O/C 0.10). The soil application of GBs exhibited a liming effect increasing the soil pH from ca 8 to 9. Results from scanning electron microscopy and BET analyses showed high porosity and specific surface area of both GBs, indicating a high potential to increase important soil quality parameters such as soil structure, nutrient and water retention, especially for WGB. These results seem promising regarding the possibility to combine an efficient bioenergy production with various soil aspects such as carbon sequestration and soil quality improvements.     

The greenland hydropower as a source of electrolytic hydrogen

A preliminary assessment of the Greenland hydropower potential is presented. Based on classical exploitation techniques the proven mean annual power capacity is estimated at 15–40 GW while the ultimate potential is between 100 GW and 1 TW.

This potential will not only satisfy the energy needs of Greenland itself but will also allow for large scale energy export. One of the best solutions for transporting this energy is the in situ synthesis of ammonia on the basis of liquefied air and electrolytic hydrogen, a suggestion already made in the project “Energy Depot” of the U.S. army. The ammonia would then be shipped overseas by LNG-tankers in liquid form. Expected costs are comparable to current prices on the world's market.     

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.     

Mobile electrolytic hydrogen generators

A small mobile electrolytic hydrogen generator was developed and built in order to provide hydrogen gas for the filling of meteorological balloons in the field and at temporary and remote weather stations. The capacity of the unit is 2 standard m³/h (H₂) and utilizes 25 cells with an electrode area of 0.10 m² each. The hydrogen gas is compressed to fill steel cylinders at 17 MPa gauge. Electrical power for the plant is supplied from a separate generating set on its own trailer. The trailer with plant has a mass of 4.25 tonne on a deck area of 3.92 × 1.64 m².     

Production of hydrogen by the electrolytic decomposition of water in fused sodium hydroxide

Experiments concerning the production of hydrogen by electrolytic decomposition of water in a sodium hydroxide melt were carried out. The electrolytic cell and the two electrodes are made from Al₂O₃ and nickel. The working temperature of the electrolysis ranged between 320 and 400°C. The data necessary for an analysis of economic efficiency such as the current density and overall cell voltage, current efficiency, water vapor surplus and corrosion resistance of the electrodes were tested and determined. The electrochemical phenomena occurring are interpreted.Starting from these investigations an analysis of economic efficiency and an initial assessment of the overall efficiency were carried out on the basis of electrolytic parameters regarded as achievable. If the high temperature reactor (HTR) is taken as the primary energy source, an overall efficiency of 38–39% is obtained.     

Baseline model of a centralized pv electrolytic hydrogen system

This study performs an economic and environmental analysis of a centralized pv electrolytic hydrogen system scaled to supply H₂ to one million light duty vehicles and light commercial trucks. Annual H₂ production is 217-million kg. The size of the pv electrolysis plant to produce this quantity of H₂ is a 5.12-GW_dc-in electrolysis plant and a 6.0-GW_p pv power plant. The land area of the pv electrolysis plant is 260 km². The total capital costs of the pv electrolysis H₂ system is $12.4 billion. The levelized H₂ pump price estimate is $6.48/kg. The life cycle primary energy use is 36 MJ/kg of H₂ consumption, and life cycle CO₂ equivalent emissions are 2.6 kg/kg of H₂ consumption. The replacement of conventional gasoline powered vehicles with H₂ powered vehicles reduces primary energy use and CO₂ emissions by 90%.     

Renewable electrolytic hydrogen potential in Algeria

The present paper deals with the assessment of the renewable hydrogen production potential in Algeria. The studied system produces hydrogen by electrolysis of water; electricity is supplied by a photovoltaic generator. Adequate mathematical models were used to calculate the electrolytic hydrogen production. Detailed hourly simulations were used to assess the potential for the entire country and to draw it maps. Throughout this study, the influence of the tilt angle of a photovoltaic generator has been investigated. It has been observed that the tilt angle has an impact on solar energy received by the photovoltaic generator, the produced solar electrical power and the rate of hydrogen production. We have calculated the optimal angles to maximize each element. We were particularly interested in the optimal angle to maximize hydrogen production. We found that the solar hydrogen potential for Algeria varies from 0.10 Nm³/m²/d to 0.14 Nm³/m²/d. This potential is quite significant, especially in the arid region of southeastern Algeria. The lowest potential is located in the northeast region. For stand-alone systems, it is important to assess the minimum available level, as their sizing takes into account the most unfavorable case. This level is between 0.07 Nm³/m²/d and 0.13 Nm³/m²/d. This shows that, even for a stand-alone system, the potential is quite high. Finally, we provide robust correlations that allow calculating the potential and the angle of inclination maximizing it for the whole of Algeria.     

The economics of a fuel cell cogeneration system using a by-product hydrogen stream

A site-specific fuel cell cogeneration study was conducted. A molten carbonate fuel cell (MCFC) system, sized at a nominal 25 MW (d.c.) to use an available by-product hydrogen stream, was compared with the alternative of purchased electricity and the use of natural gas to produce steam. The economic analysis objectives were to determine; the savings due to the reduced amount of purchased energy; the cost/benefit ratio; and the payback period for the MCFC cogeneration system. Another objective was to determine if the high capital cost of the first prototype MCFC plant would require a commercialization subsidy to make it attractive to an industrial owner. It was found that a commercialization subsidy would be required for the initial high cost prototype plant, but this technology promises an energy utilization of 84% of the input fuel heating value which represents a strong incentive for commercialization.     

Recent development of large electrolytic hydrogen generators

An overview of the history and market of large electrolysis units is presented. The historical background introduces and explains the thought process behind a new design of Teledyne's Electra Cell alkaline electrolysis hydrogen generators.The new design enables construction of modules capable of 1.6 ton per day of hydrogen. The cost of hydrogen is used as a criterion for the selection of optimum performing cells as a function of user parameters. It is suggested that due to cell costs, the highest efficiency cell does not always produce the cheapest hydrogen.     

The market potential for electrolytic hydrogen

By the year 2000, the potential market for advanced technology electrolytic hydrogen among specialty users is projected to be about half of what the merchant hydrogen market would be in the absence of electrolytic hydrogen. This potential market, representing an annual demand of about 16 billion SCF of hydrogen (approx. 200 MW of installed electrolyzer capacity), will develop from market penetrations of electrolyzers assumed to begin in the early 1980s.     

Areca leaves as a source of carbon: Preliminary investigation as catalyst support for electrolytic hydrogen evolution in acidic medium

Our work tends to establish Green Energy from Waste concept. Refuses/wastes can be a secondary resource for variety of materials which may find applications in domestic, industrial, medical, electronic and energy devices. We have attempted to produce activated carbon powders from a cheap waste namely biomass of areca leaves. The material has been exploited as catalyst support materials in H₂ production through water electrolysis. Catalyst powders of 10% Ni and 1% Pt by weight were supported on the carbon produced from the leaves using NaBH₄ reduction of the respective salts. Physical features of the catalyst powders were evaluated through PXRD, FTIR, density, SEM, surface area. Catalytic activity of the biocarbon supported catalyst powders was assessed by LSV & CV. The carbon produced may attract technological importance because carbon source selected is cheap and green. Further the activated carbon may find applications such as electrode materials, adsorbent for color, odor and hazardous pollutants.     

Effective utilization of by-product oxygen from electrolysis hydrogen production

To avoid fossil-fuel consumption and greenhouse-gas emissions, hydrogen should be produced by renewable energy resources. Water electrolysis using proton exchange membrane (PEM) is considered a promising hydrogen-production method, although the cost of the hydrogen from PEM would be very high compared with that from other mature technologies, such as steam methane reforming (SMR). In this study, we focus on the effective utilization of by-product oxygen from electrolysis hydrogen production and discuss the potential demand for it, as well as evaluating its contribution to improving process efficiency. Taking as an example the utilization of by-product oxygen for medical use, we compare the relative costs of hydrogen production by means of PEM electrolysis and SMR.     

Electrodeposition of self-supported transition metal phosphides nanosheets as efficient hydrazine-assisted electrolytic hydrogen production catalyst

The synthesis of electrocatalysts which used simultaneously as electrodes for the hydrazine oxidation reaction (HzOR), and hydrogen evolution reaction (HER) can significantly improve the efficiency of hydrogen production in the water splitting process. Here, Ni–Co–Fe–P binder-free nanosheets were fabricated using the electrochemical deposition method and used as an effective, stable, and cost-effective electrode for hydrazine-assisted electrochemical hydrogen production. Taking advantage of high surface area, being binder-free, and synergistic effect between the elements in the electrode composition, this electrode showed unique electrocatalytic activity and stability. When this electrode was used as a bifunctional electrode for HzOR-HER, a cell voltage of 94 mV was required to reach a current density of 10 mA cm^?2. The results of this study indicated that the Ni–Co–Fe–P electrode is an excellent candidate for the hydrogen production industry.     

Improved cathodes for industrial electrolytic hydrogen production

Reduced overpotentials for the generation of hydrogen by alkaline water electrolysis can be achieved with a.c. activation of porous Ni electrodes. Reductions of 50–60 mV were attained which would contribute towards reducing costs in commercial pure hydrogen production by electrolysis.     

Steam power-plants fed by high pressure electrolytic hydrogen

The possibility to obtain hydrogen and oxygen at high pressure directly from electrolysis was recently demonstrated at a laboratory scale. At the same time the working pressure of direct steam generator prototypes is increasing. The scaling-up of these devices will make very interesting the production of nuclear or renewable hydrogen (and oxygen) and its use in advanced steam power-plants fed with stoichiometric hydrogen/oxygen mixtures. This is a long-term view, but it is possible to find an interesting application even in the near term. It is the nightly and seasonal storage of energy by means of hydrogen and its use in attached steam power-plants. In this case the thermal energy required at low temperature can be supplied by regeneration and coal, while the combustion of hydrogen and oxygen is employed only in the steam super-heating phases. It results in high steam temperatures, increased specific work and improved thermodynamic efficiency. Moreover the availability of the reactants directly at high pressure, allows to save energy usually needed for storage and to avoid the installation of large compression units.     

Advantages of integration with industry for electrolytic hydrogen production

This paper evaluates possible synergies with industry, such as heat and oxygen recovery from the hydrogen production. The hydrogen production technology used in this paper is electrolysis and the calculations include the cost and energy savings for integrated hydrogen production. Electrolysis with heat recovery leads to both cost reduction and higher total energy efficiencies of the hydrogen production. Today about 15–30% of the energy supplied for the production is lost and most of it can be recovered as heat. Utilization of the oxygen produced in electrolysis gives further advantages. The integration potential has been evaluated for a pulp and paper industry and the Swedish energy system, focusing on hydrogen for the transportation sector. The calculated example shows that the use of the by-product oxygen and heat greatly affects the possibility to sell hydrogen produced from electrolysis in Sweden. Most of the energy losses are recovered in the example; even gains in energy for not having to produce oxygen with cryogenic air separation are shown. When considering cost, the oxygen income is the most beneficial but when considering energy efficiency, the heat recovery stands for the greater part.     

Experimental investigation on dyeing wastewater treatment and by-product hydrogen with a reverse electrodialysis flocculator

Hydrogen production and dye degradation can be achieved simultaneously in a hybrid system of reverse electrodialysis（RED）and electrocoagulation (EC), using current derived from the salinity gradient energy. Under the current, Fe electrode is used as the anode to produce Fe²⁺(subsequently oxidized to Fe³⁺) which combines with OH⁻ produced from the cathode to remove the dyes, while the hydrogen gas produced by the cathode is collected by a hydrogen collection device. The experiments are carried out to investigate the effects of different initial concentrations, pH, currents, electrode rinse solution (ERS) flow rates and the addition of chlorine on the degradation rate and hydrogen production. The results indicate that the degradation rate and hydrogen production could reach 98.3% and 150 m h⁻¹ at alkaline condition (pH = 11) and acidic condition (pH = 3) respectively, with a current of 0.4 A. The degradation rate and hydrogen production increase significantly with an increase in current.