Low cost compact onsite hydrogen generation

High cost and lack of convenient supply infrastructure for hydrogen is believed to the major hurdle to the commercialization of hydrogen energy. Low cost compact onsite hydrogen generator is developed to produce three purity levels of hydrogen for use with high temperature polymer electrolyte membrane (HTPEM) or low temperature polymer electrolyte membrane (LTPEM) fuel cell. The small modular reformer has process efficient higher or equal to large scale central production plant without the penalty of expensive distribution cost. The cost of hydrogen from primary reformate hydrogen to high purity hydrogen ranges from $3.16/kg to $5.84/kg and the corresponding power cost from FC system is $0.352 to $0.408/KWh. The hydrogen costs are much lower than one can obtain from an industrial gas company with central supply system and expensive cost in distribution. These direct power costs without depreciation cost are comparable or lower than the comparable size of diesel power cost.     

PVC生产中氯化氢空冷管的设计

在分析氯化氢合成炉至石墨冷却器间空气冷却管腐蚀机理的基础上,提出了空冷管的设计方案和数学模型.经生产检验设计合理,使用寿命长.并对不同的氯化氢生产能力、环境条件进行了对比计算.     

Technical assessment of cryo-compressed hydrogen storage tank systems for automotive applications

On-board and off-board performance and cost of cryo-compressed hydrogen storage are assessed and compared to the targets for automotive applications. The on-board performance of the system and high-volume manufacturing cost were determined for liquid hydrogen refueling with a single-flow nozzle and a pump that delivers liquid H₂ to the insulated cryogenic tank capable of being pressurized to 272 atm. The off-board performance and cost of delivering liquid hydrogen were determined for two scenarios in which hydrogen is produced by central steam methane reforming (SMR) or by central electrolysis. The main conclusions are that the cryo-compressed storage system has the potential of meeting the ultimate target for system gravimetric capacity, mid-term target for system volumetric capacity, and the target for hydrogen loss during dormancy under certain conditions of minimum daily driving. However, the high-volume manufacturing cost and the fuel cost for the SMR hydrogen production scenario are, respectively, 2–4 and 1.6–2.4 times the current targets, and the well-to-tank efficiency is well short of the 60% target specified for off-board regenerable materials.     

Development of large-scale hydrogen liquefaction processes from 1898 to 2009

This paper presents a review of the development of large-scale hydrogen liquefaction processes throughout the world from 1898 to 2009. First, there is a concise literature review including numerous past, present, and future designs given such as the first hydrogen liquefaction device, long time ago simple theoretical processes, today's actual plants with efficiencies 20–30%, a list of the capacity and location of every hydrogen liquefaction plant in the world, and some modern more efficient proposed conceptual plants with efficiencies 40–50%. After that, further information about the development and improvement potential of future large-scale liquid hydrogen liquefaction plants is given. It is found that every current plant is based on the pre-cooled Claude system, which is still the same as was 50 years ago with little improvement. Methods to resolve the challenges of the future plants include proposing completely new configurations and efficient systems coupled with improved efficiencies of the main system components such as compressors, expanders, and heat exchangers. Finally, a summary and comparison of the process efficiencies are described, including a newly proposed Multi-component Refrigerant (MR) system being developed by NTNU and SINTEF Energy Research AS.     

Performance of a groove-type photobioreactor for hydrogen production by immobilized photosynthetic bacteria

The biofilm technique has been proved to be an effective cell immobilization method for wastewater biodegradation but it has had restricted use in the field of photobiological H₂ production. In the present study, a groove-type photobioreactor was developed and it was shown that a groove structure with large specific surface area was beneficial to cell immobilization and biofilm formation of the photosynthetic bacteria on photobioreactor surface as well as light penetration. A series of experiments was carried out on continuous hydrogen production in the groove-type photobioreactor illuminated by monochromatic LED lights and the performance was investigated. The effects of light wavelength, light intensity, inlet glucose concentration, flow rate and initial substrate pH were studied and the results were compared with those obtained in a flat panel photobioreactor. The experimental results show that the optimum operational conditions for hydrogen production in the groove-type photobioreactor were: inlet glucose concentration 10 g/L, flow rate 60 mL/h, light intensity 6.75 W/m², light wavelength 590 nm and initial substrate pH 7.0. The maximum hydrogen production rate, H₂ yield and light conversion efficiency in the groove-type photobioreactor were 3.816 mmol/m²/h, 0.75 molH₂/molglucose and 3.8%, respectively, which were about 75% higher than those in the flat panel photobioreactor.     

Development of a novel market forecasting tool and its application to hydrogen energy production in Scotland

The authors propose a novel model for forecasting the deployment of hydrogen energy systems based on a company value maximisation algorithm, designed to assist governments and other industry players in decision-making and the development of appropriate policy instruments. Current cost-minimisation approaches, such as MARKAL, have limitations particularly where price arbitrage between energy streams exists. A theoretical relationship between market sector valuations and investment activity is developed and the model is subsequently applied to the Scottish hydrogen energy market. Through the utilisation of net present value, revenue and profitability based valuations, the impact of investing in hydrogen energy infrastructure projects on three key market competitors is considered. It is shown that the three methods for calculating the value impact render different results suggesting that the use of a single method to assess forecast development scenarios, whether cost or value-based methods, may be misleading and that the holistic approach proposed is more realistic. The archivable value of this paper is to demonstrate the impact that investor expectations can have on investment decisions, a facet not captured in traditional methods of forecasting.     

Development of a simple bio-hydrogen production system through dark fermentation by using unique microflora

In order to ensure efficient functioning of hydrogen fermentation systems that use Clostridium as the dominant hydrogen producer, energy-intensive process such as heat pretreatment of inoculum and/or substrate, continuous injection, and control of anaerobic conditions are required. Here, we describe a simple hydrogen fermentation system designed using microflora from leaf-litter cattle-waste compost. Hydrogen and volatile fatty acid production was measured at various hydraulic retention times, and bacterial genera were determined by PCR amplification and sequencing. Although hydrogen fermentation yield was approximately one-third of values reported in previous studies, this system requires no additional treatment and thus may be advantageous in terms of cost and operational control. Interestingly, Clostridium was absent from this system. Instead, Megasphaera elsdenii was the dominant hydrogen-producing bacterium, and lactic acid-producing bacteria (LAB) were prevalent. This study is the first to characterize M. elsdenii as a useful hydrogen producer in hydrogen fermentation systems. These results demonstrate that pretreatment is not necessary for stable hydrogen fermentation using food waste.     

Efficiency analysis of a combined PEFC and bioethanol‐solar‐reforming system for individual houses

In this research, the development of a bioethanol reforming system for fuel cells (FBSR: fuel cell with bioethanol steam reforming) using sunlight as a heat source was investigated. The system was investigated using the experimental result of catalyst performance, and numerical analysis. If ethanol purity is high, the production method of the bioethanol used for the proposal system will not be limited. The overall efficiency of the production of electricity and heat power of this system was determined by examining its thermal output characteristic. The FBSR was introduced into standard individual houses in Sapporo, Japan, for analysis. The amount of hydrogen production, the production‐of‐electricity characteristic, and the thermal output characteristic were examined using meteorological data on representative days in March and August. Compared with the representative day in March (28.0 MJ day⁻¹), the solar radiation of the representative day in August (37.0 MJ day⁻¹) is large. However, the amount of solar radiation fluctuation of the representative day in August in this analysis is large compared with the representative day in March. It depends for the overall efficiency of the system on the amount of solar radiation fluctuation rather than the amount of solar radiation. As a result, the overall efficiency of the system, defined as the rate of power and heat output compared with the amount of solar heat collected, was calculated to be 47.4 and 41.9% on the representative days in March and August, respectively. Copyright © 2009 John Wiley & Sons, Ltd.     

Experimental study on hydrogen peroxide-free processing machine-made silk floss北大核心CSCD

Silk is a kind of natural fiber with good luster strength elasticity dyeability hygroscopicity and other advantages. Silk products are quite popular to the customers because of their excellent performance such as heat preservation air permeability and so on which make them comfortable to use. Silk floss which is made from pupa lining secondary cocoon etc. can be used as floc and filler materials and is an important part of silk products. According to its production mode silk floss can be divided into manual silk floss and machine-made silk floss and the latter has become the main processing mode of silk floss production due to its high production efficiency. In terms of composition silk flossing generally contains 20% - 30% sericin pupa oil and impurities so in the degumming process in addition to adding sodium carbonate and other degumming agents to remove sericin a large amount of hydrogen peroxide with strong oxidation property is also used to increase the cleanliness and smoothness. Unfortunately hydrogen peroxide is highly flammable and explosive and poses a risk in transportation and storage causing potential safety hazards to the silk processing industry. In order to solve this problem we innovatively propose two hydrogen peroxide-free processing methods of machine-made silk floss by using sodium percarbonate degumming or sodium carbonate-ozone. As an environmentally friendly solid oxidant sodium percarbonate can produce hydrogen peroxide and sodium carbonate after decomposition and is often used to degrade organic harmful substances. Similarly ozone is a common strong oxidant with broad-spectrum antibacterial properties and because ozone can be produced instantly by ozone generators there is no risk of transport and storage. Silk is composed of silk fibroin and sericin. Among them silk fibroin is fibrous protein which will swell in hot water while sericin is globular protein which is easy to dissolve in hot water. As a result in this paper heated sodium percarbonate solution and sodium carbonate-ozone system were used to deglue silk floss. The methods were as follows silk floss was degummed three times in boiling 0. 78 g / L sodium percarbonate solution for 30 minutes each time or was degummed three times in boiled 0. 5 g / L Na2 CO3 solution with ozone continuously flow at a rate of 100 mg / L - h for 30 minutes each time. After cleaning and drying the degummed silk floss can be obtained. After the experiment the apparent morphology sericin residual efficiency impurity rate compression resilience whiteness and other silk floss quality indexes of the two methods were analyzed and compared with superior machine-made silk floss processed by commercial way with hydrogen peroxide. The results show that both two processing methods got uniform degumming effect of silk floss and the surface of the single fiber was smooth and the degumming effect was basically the same as that of commercial products prepared with hydrogen peroxide. The sericin residual rate of silk floss was between 3% - 4% which was in line with the requirements of less than 5% of superior silk floss. There was no significant difference between silk floss obtained and commercial superior products in smoothness and whiteness. In conclusion the performance of silk floss in all aspects has reached the standard of superior products that is the sericin content is not more than 5% the impurity content is not more than 0. 1% the compression rate is not less than 45% and the response rate is not less than 92% . Based on the experimental results and analysis it can be concluded that the machine-made silk floss with good performance can be prepared without hydrogen peroxide showing the feasibility of processing machine-made silk floss without hydrogen peroxide which is of great significance to the research and development of a safe and reliable oxidant system for the removal of impurities in silk floss and to further improve the safety of machine-made silk floss production process. © 2022 China Silk Association. All rights reserved.