A Review of Technical Advances,Barriers,and Solutions in the Power to Hydrogen(P2H)Roadmap

Power to hydrogen(P2H)provides a promising solution to the geographic mismatch between sources of renewable energy and the market,due to its technological maturity,flexibility,and the availability of technical and economic data from a range of active demonstration projects.In this review,we aim to provide an overview of the status of P2H,analyze its technical barriers and solutions,and propose potential opportunities for future research and industrial demonstrations.We specifically focus on the transport of hydrogen via natural gas pipeline networks and end-user purification.Strong evidence shows that an addition of about 10%hydrogen into natural gas pipelines has negligible effects on the pipelines and utilization appliances,and may therefore extend the asset value of the pipelines after natural gas is depleted.To obtain pure hydrogen from hydrogen-enriched natural gas(HENG)mixtures,end-user separation is inevitable,and can be achieved through membranes,adsorption,and other promising separation technologies.However,novel materials with high selectivity and capacity will be the key to the development of industrial processes,and an integrated membrane-adsorption process may be considered in order to produce high-purity hydrogen from HENG.It is also worth investigating the feasibility of electrochemical separation(hydrogen pumping)at a large scale and its energy analysis.Cryogenics may only be feasible when liquefied natural gas(LNG)is one of the major products.A range of other technological and operational barriers and opportunities,such as water availability,byproduct(oxygen)utilization,and environmental impacts,are also discussed.This review will advance readers’understanding of P2H and foster the development of the hydrogen economy.

Thickness estimation of the Longbasaba Glacier:methods and application

A total of 71,177 glaciers exist on the Qinghai-Tibet Plateau,according to the Randolph Glacier Inventory(RGI 6.0).Despite their large number,glacier ice thickness data are relatively scarce.This study utilizes digital elevation model data and ground-penetrating radar thickness measurements to estimate the distribution and variation of ice thickness of the Longbasaba Glacier using Glacier bed Topography(GlabTop),a full-width expansion model,and the Huss and Farinotti(HF)model.Results show that the average absolute deviations of GlabTop,the full-width expansion model,and the HF model are 9.8,15.5,and 10.9 m,respectively,indicating that GlabTop performs the best in simulating glacier thickness distribution.During 1980−2015,the Longbasaba Glacier thinned by an average of 7.9±1.3 m or 0.23±0.04 m/a,and its ice volume shrunk by 0.28±0.04 km3 with an average reduction rate of 0.0081±0.0001 km^3/a.In the investigation period,the area and volume of Longbasaba Lake expanded at rates of 0.12±0.01 km^2/a and 0.0132±0.0018 km3/a,respectively.This proglacial lake could potentially extend up to 5,000 m from the lake dam.

Manifestations and mechanisms of mountain glacier-related hazards

Mountain glacier-related hazards occur worldwide in response to increasing glacier instability and human activity intensity in modern glacierized regions.These hazards are characterized by their spatial aggregation and temporal repeatability.Comprehensive knowledge about mountain glacier-related hazards is critical for hazard assessment,mitigation,and prevention in the mountain cryosphere and downstream regions.This article systematically schematizes various mountain glacier-related hazards and analyzes their inherent associations with glacier changes.Besides,the processes,manifestations,and mechanisms of each of the glacier-related hazards are summarized.In the future,more extensive and detailed systematic surveys,for example,considering integrated ground−air−space patterns,should be undertaken for typical glacierized regions to enhance existing knowledge of such hazards.The use of coupled numerical models based on multisource data is challenging but will be essential to improve our understanding of the complex chain of processes involved in thermal−hydrogeomorphic glacier-related hazards in the mountain cryosphere.

Design of GH4169 diaphragm for combined improvements of yield strength and surface roughness

Diaphragm compressors have become the primary source of on-site hydrogen compression for hydrogen fuelling stations around the world.The most common hydrogen-compressor-failure mechanism has been identified as diaphragm fracture due to low ten-sile strength and poor surface properties.In this study,a new type of GH4169 diaphragm with high yield strength and low surface roughness was fabricated.Microstructures,tensile behaviours and surface properties of the specimens were characterized by using scanning electron microscopy,an electronic universal testing machine and atomic force microscopy,respectively.The evolution of theandphases with temperature has been examined.Bothandphases were precipitant-strengthened phases for GH4169 and the volume and size ofandphases increase with ageing time.In addition,thephase is the main strengthening phase andis the supportive strengthening phase.Tensile strength was increased due to the strengthening phases at the cost of ductility.The roughness of the diaphragm could reach an arithmetic average roughness(Ra)of 0.1μm by applying a cooling-assisted polishing process.This work improves the reliability and reduces the auxiliary steps and down-time for diaphragm compressors.

Development of fuelling protocols for gaseous hydrogen vehicles:a key component for efficient and safe hydrogen mobility infrastructures

Large-scale applications of fuel-cell vehicles(FCVs)are of vital importance to reduce emissions of greenhouse gases in the transportation sector,especially in the heavy-duty and long-distance scenarios.Efficient fuelling for the on-board gaseous hydrogen cylinders of an FCV is essential to achieve a fuelling experience that is comparable to that of traditional fossil-fuel-powered vehicles.However,the heating effect during refuelling leads to potential safety issues when the hydrogen temperature in the cylinder exceeds 85℃.Therefore,fuelling protocols are critical to ensure the efficiency and safety of the hydrogen mobility infrastructure.In this paper,the fuelling protocols for FCV vans and buses with type III cylinders were developed and the pre-cooling temperatures were optimized to minimize the energy consumption.Their performance was demonstrated with a 35-MPa hydrogen fuelling station.We found that FCV vans and buses can be safely refuelled in 3 or 5 minutes at a minimum,respectively,demonstrating a fuelling experience that is similar to that of traditional vehicles.

Research progress and prospects on hydrogen separation membranes

Membrane separation technologies,with a broad application prospect in the field of hydrogen separation,are characterized by the simplicity of the devices,high energy efficiency and environmental friendliness.The performance of separation membranes is the primary factor that determines the efficiency of hydrogen separation.Therefore,the development of hydrogen separation membranes is always a research focus.This paper presents and reviews the research developments and features of organic membranes,inorganic membranes and hybrid matrix membranes for hydrogen separations.First,the characterization methods of key index parameters of membrane materials are presented.Second,the performance parameters of different types of membrane are compared.Finally,the trend of technological development of different types of membrane materials is forecast.

Flow fuel cell powered by combustible agricultural waste

Combustible agricultural waste is a potential source of energy because of its high organic content and heating value.As China’s economy develops,energy demand increases while environmental protection becomes more stringent.These competing demands make it urgent to find environmentally acceptable ways to extract energy from agricultural wastes.In this study,a liquid catalyst flow fuel cell(FFC)directly powered by combustible agricultural waste is investigated.This type of flow fuel cell can directly convert combustible agricultural waste at atmospheric pressure to electricity at 80-150℃and it is environmentally friendly.Polyoxometalates act as catalysts and charge carriers to drive the FFC.Wheat straw and wine residues were used to represent the main components of combustible agricultural waste.Experiment results indicated that the power density reached as high as 111 mW/cm^(2),hundreds of times higher than the output of a microbial cell.

Hydrogen station technology development review through patent analysis

This study is a review of hydrogen station patents using the Derwent Innovation system and also a secondary screening.This was undertaken by the researchers to better understand and identify hydrogen station trends.The review focuses on analyzing the developing trends of patent technologies associated with a hydrogen station.The results of the review indicated that the countries with the major distribution of patents were Japan,China,the USA and Europe.Japan is leading the developmental trajectory of hydrogen stations.The results of the analysis found the leading developers of these patented technologies are Kobe Steel,Nippon Oil,Toyota and Honda.Other active patent developers analyzed include Linde,Hyundai and Texaco.The review concludes with a suggestion that using a patent analysis methodology is a good starting point to identify,evaluate and measure the trend in hydrogen station commercial development.

Corrigendum:Hydrogen station technology development review through patent analysis

This is a correction notice for article zky006(DOI:https://doi.org/10.1093/ce/zky006),published on 10 May 2018.Due to an error,the images for figures 1,2,and 3 were swapped over.These have now been corrected in the published article.