Deep eutectic solvents:Green multi-task agents for sustainable super green hydrogen technologies

While reliance on renewable energy resources has become a reality, there is still a need to deploy greener and more sustainable methods in order to achieve sustainable development goals. Indeed, green hydrogen is currently believed to be a reliable solution for global warming and the pollution challenges arising from fossil fuels, making it the resilient fuel of the future. However, the sustainability of green hydrogen technologies is yet to be achieved. In this context, generation of green hydrogen with the aid of deep eutectic solvents(DESs) as green mixtures has been demonstrated as a promising research area. This systematic review article covers green hydrogen generation through water splitting and biomass fermentation when DESs are utilized within the generation process. It also discusses the incorporation of DESs in fuel cell technologies. DESs can play a variety of roles such as solvent, electrolyte, or precursor;colloidal suspension and reaction medium;galvanic replacement, shape-controlling, decoration, or extractive agent;finally oxidant. These roles are relevant to several methods of green hydrogen generation, including electrocatalysis, photocatalysis, and fermentation. As such, it is of utmost importance to screen potential DES formulations and determine how they can function in and contribute throughout the green hydrogen mobility stages. The realization of super green hydrogen generation stands out as a pivotal milestone in our journey towards achieving a more sustainable form of development;DESs have great potential in making this milestone achievable. Overall, incorporating DESs in hydrogen generation constitutes a promising research area and offers potential scalability for green hydrogen production, storage,transport, and utilization.

100 W-class green hydrogen production from ammonia at a dual-layer electrode containing a Pt-Ir catalyst for an alkaline electrolytic process

Ammonia allows storage and transport of hydrogen over long distances and is an attractive potential hydrogen carrier.Electrochemical decomposition has recently been used for the conversion of ammonia to hydrogen and is regarded as a future technology for production of CO_(2)-free pure hydrogen.Herein,a heterostructural Pt-Ir dual-layer electrode is developed and shown to achieve successful long-term operation in an ammonia electrolyzer with an anion exchange membrane(AEM).This electrolyzer consisted of eight membra ne electrode assemblies(MEAs)with a total geometric area of 200 cm~2 on the anode side,which resulted in a hydrogen production rate of 25 L h~(-1).We observed the degradation in MEA performance attributed to changes in the anode catalyst layer during hydrogen production via ammonia electrolysis.Furthermore,we demonstrated the relationship between the ammonia oxidation reaction(AOR)and the oxygen evolution reaction(OER).

Advanced Thermochemical Conversion Approaches for Green Hydrogen Production from Crop Residues

The huge volumes of crop residues generated during the production,processing,and consumption of farm products constitute an ecological nuisance when ineffectively managed.The conversion of crop residues to green hydrogen is one of the sustainable management strategies for ubiquitous crop residues.Production of green hydrogen from crop residue sources will contribute to deepening access to clean and affordable energy,mitigating climate change,and ensuring environmental sustainability.However,the deployment of conventional thermochemical technologies for the conversion of crop residues to green hydrogen is costly,requires long residence time,produces low-quality products,and therefore needs to be upgraded.The current review examines the conventional,advanced,and integrated thermochemical conversion technologies for crop residues for green hydrogen production.After a brief overview of the conventional thermochemical techniques,the review delves into the broad narration of advanced thermochemical technologies including catalytic pyrolysis,microwave pyrolysis,co-pyrolysis,hyropyrolysis,and autothermal pyrolysis.The study advocates the deployment of integrated pyrolysis,anaerobic digestion,pyrolysis,and gasification technologies will ensure scalability,decomposition of recalcitrant feedstocks,and generation of high grade green hydrogen.The outlook provides suggestions for future research into cost-saving and sustainable integrated technologies for green hydrogen production towards achieving carbon neutrality and a circular bio-economy.

Green Hydrogen: Perspectives and Challenges in Using the Natural Gas Network in Ceará/Brazil

Climate change, mainly caused by the use of non-renewable fuels, has raised global concerns and led to the search for less polluting energy sources, making hydrogen a promising energy alternative with the potential to contribute to changes in the energy mix of various countries through the use of technologies that enable its production and use with low or zero carbon emissions. In this context, Brazil has aroused great interest from other countries in exploring its renewable resources for the production of hydrogen (green hydrogen). In this sense, the use of natural gas pipelines and the use of hydrogen in mixtures with natural gas have become the subject of studies due to their economically viable alternative for the immediate use of this energy vector. However, there are still technical and regulatory challenges regarding the integration of hydrogen into the existing natural gas pipeline network. In this context, the present study aims to address the effects of hydrogen interaction with the structure of natural gas pipeline steel and the regulatory barriers to the use of this network for the transportation of green hydrogen, particularly in the state of Ceará/Brazil. After extensive analysis of literature and regulatory documents, it was concluded that: 1) Ceará/Brazil has strong potential to meet the demand for green hydrogen through the use of solar and wind energy sources;2) there is feasibility for the adaptation or conversion of natural gas infrastructure for the transportation of green hydrogen;3) discussions regarding the regulatory competence of green hydrogen transportation and distribution through the natural gas network in Brazil are still incipient;4) the current regulation of the natural gas industry can serve as a subsidy for the regulation of green hydrogen and natural gas transportation.

Can Brazil Become a Green Hydrogen Powerhouse?

This paper assesses the feasibility of green hydrogen production in Brazil. By green hydrogen, it is meant the hydrogen produced by the electrolysis of water by consuming electricity produced by renewable sources. The country has large areas with high solar irradiation and favorable wind velocities that help to make wind power and solar PV economical alternatives. Other factors include lower investments and lower grid integration cost with respect to global average, because of the large share of hydropower. As known, hydro plants respond well to the short-term variability of renewable production. Local regulations also incentivize renewable energy. For example, it is possible, according to market rules, for a hydrogen producer to sign a financial Power Purchase Agreement (PPA) contract with a producer or trader to secure a firm, renewable energy supply for the electrolysis process. This market-driven factor, and other key factors, such as low price of electricity, are considered in an economic feasibility model. Results from this model suggest that Brazil could become a green hydrogen powerhouse for the internal market and potential exports to Germany and other European countries.

A Solar Energy System Design for Green Hydrogen Production in South-Western Nigeria, Lagos State, Using HOMER & ASPEN

Solar system design for green hydrogen production has become the most prominent renewable energy research area, and this has also actively fueled the desire to achieve net-zero emissions. Hydrogen is a promising energy carrier because it possesses more energy capacity than fossil fuels and the abundant nature of renewable energy systems can be utilized for green hydrogen production. However, the design of an optimized electrical energy system required for hydrogen production is crucial. Solar energy is indeed beneficial for green hydrogen production and this research designed, discussed, and provided high-level research on HOMER design for green hydrogen production and deployed the energy requirement with ASPEN Plus to optimize the energy system, while also incorporating fuzzy logic and PID control approaches. In addition, a promising technology with a high potential for renewable hydrogen energy is the proton exchange membrane (PEM) electrolyzer. Since its cathode (hydrogen electrode) may be operated over a wide range of pressure, a control process must be added to the system in order for it to work dynamically efficiently. This system can be characterized as an analogous circuit that consists of a resistor, capacitor, and reversible voltage. As a result, this research work also explores the Fuzzy-PID control of the PEM electrolysis system. Both the PID and Fuzzy Logic control systems were simulated using the control simulation program Matlab R2018a, which makes use of Matlab script files and the Simulink environment. Based on the circuit diagram, a transfer function that represents the mathematical model of the plant was created, and the PEM electrolysis control system is determined to be highly significant and applicable to the two control systems. The PI controller, however, has a 30.8% overshoot deficit, but when the fuzzy control system is compared to the PID controller, it is found that the fuzzy control system achieves stability more quickly, demonstrating its benefit over PID.

Potential for Green Hydrogen Production from Biomass, Solar and Wind in Togo

Potential of green hydrogen producing from biomass, solar and wind in Togo has been performed. The availability of these three resources has been depicted with maps showing them per cantons in Togo, thus, by using the datasets from ESA Biomass Climate Change Initiative, the global solar atlas and the global wind atlas. The conversions rates used were: for solar resource, 3% of land was allocated for the analysis after removing the exclusions with a conversion rate of 52.5 kWh/kg of hydrogen;for biomass hydrogen, the conversion rate of 13.4 kg BS/kg H2 was assumed. Wind resources at 50 m above ground were not sufficient to evaluate the potential as it is lower than class 3 winds. QGIS version 3.6.4 and R version 4.0.4 were used. Results showed that biomass is the leading resource for producing green hydrogen from renewable energy resources;with good impact in these two cantons: Bassar, Gobe/ Eketo/Gbadi N’Kugna. However, this resource is still decreasing and in some cantons it is null.

Production of Green Hydrogen by Efficient and Economic Electrolysis of Water with Super-alloy Nanowire Type Electrocatalysts

Green hydrogen production from the electrolysis of water has good appli­cation prospect due to its renewability.The applied voltage of 1.6-2.2V is required in the traditional actual water electrolysis process although the the­oretical decomposition potential of electrolyzing water is 1.23V.The high overpotential in the electrode reaction results in the high energy-consuming for the water electrolysis processes.The overpotentials of the traditional Ru,Ir and Pt based electrocatalysts are respectively 0.3V,0.4V and 0.5V,furthermore use of the Pt,Ir and Ru precious metal catalysts also result in high cost of the water electrolysis process.For minimizing the overpoten­tials in water electrolysis,a novel super-alloy nanowire electrocatalysts have been discovered and developed for water splitting in the present pa­per.It is of significance that the overpotential for the water electrolysis on the super-alloy nanowire electrocatalyst is almost zero.The actual voltage required in the electrolysis process is reduced to 1.3V by using the novel electrocatalyst system with zero overpotential.The utilization of the su­per-alloy nanowire type electrocatalyst instead of the traditional Pt,Ir and Ru precious metal catalysts is the solution to reduce energy consumption and capital cost in water electrolysis to generate hydrogen and oxygen.

Green hydrogen energy production:current status and potential

The technique of producing hydrogen by utilizing green and renewable energy sources is called green hydrogen production.Therefore,by implementing this technique,hydrogen will become a sustainable and clean energy source by lowering greenhouse gas emissions and reducing our reliance on fossil fuels.The key benefit of producing green hydrogen by utilizing green energy is that no harmful pollutants or greenhouse gases are directly released throughout the process.Hence,to guarantee all of the environmental advantages,it is crucial to consider the entire hydrogen supply chain,involving storage,transportation and end users.Hydrogen is a promising clean energy source and targets plan pathways towards decarbonization and net-zero emissions by 2050.This paper has highlighted the techniques for generating green hydrogen that are needed for a clean environment and sustainable energy solutions.Moreover,it summarizes an overview,outlook and energy transient of green hydrogen production.Consequently,its perspective provides new insights and research directions in order to accelerate the development and identify the potential of green hydrogen production.

Assessing the biennial conference on science and technology(BICOST IX)2023 technical output on renewable energy,energy storage,and green hydrogen in line with UN SDG commitments

The development,production and utilization of renewable energy,energy storage and green hydrogen and the associated technologies in Sri Lanka have great potential to contribute to the United Nations’Sustainable Development Goals(SDGs).The island aims to achieve 70%electricity generation from renewable energy sources by 2030(within the target of 40%utilization of renewable energy sources for the entire energy generation of the country by 2030).The power sector has to invest US$11 billion from 2023 to 2030 to contribute to reaching this target.This commentary aims to provide a critical perspective on the recommendations of the report from the National Science and Technology Commission’s 9th biennial conference in 2023 on science and technology,the sub-thematic technical report on clean energy,energy storage and green hydrogen in line with the SDGs in the Sri Lankan context.The technical report provides insightful recommendations for Sri Lanka’s energy sector under three main sections:renewable energy,energy storage and green hydrogen.Also,it explores the potential of various renewable energy sources,energy storage systems and green hydrogen as sustainable solutions to address the country’s energy challenges while emphasizing the spillover effects of them,which could contribute to the enterprise’s job creation and uplift the economy.

Optimized system for combined production of electricity/green hydrogen for multiple energy pathways:a case study of Egypt

By optimal sizing of a wind/photovoltaic hybrid renewable-energy(RE)system,trimming the surplus capacity to reduce the fluctuations in the electricity supplied to the grid,and using it to produce green hydrogen through electrolysis,a stable output with maximum possible capacity factor(CF)is generated to maintain the electricity grid stability.Simultaneously,the trimmed energy is used in a secondary conversion path that minimizes the weighted average cost of the energy generated from the entire plant.This surplus power-to-gas conversion allows the use of green hydrogen to produce electricity,methanol,or ammonia subject to the resource availability,site characteristics,and financial feasibility.Based on robust site selection criteria,the best performance is obtained at two sites:Ras Ghareb and Minya,achieving the lowest energy cost with some variance in their performance.For the Ras Ghareb site,the optimally sized RE plant provided the grid with a quasi-steady capacity of 423 MW with a CF of 80.04%and was capable of injecting 2965.8648 GWh throughout the year with the lowest cost of 2.4355¢/kWh.A surplus of 3.9%of the total energy produced from the plant was directed to produce 1922-ton H_(2)/year,achieving the lowest cost of hydrogen production of$1.9745/kg H_(2).For the other selected site,Minya,the clipped energy is used to produce 3330.47-ton H_(2)/year with an optimized lowest cost of$3.5268/kg H_(2).The difference in hydrogen costs was attributed to the number of full operating hours of the electrolyser in both sites.The cost is mainly affected by the electricity price and the electrolyser cost.With both tending to decrease,future forecasts show hydrogen cost reductions.

Techno-economic analysis of green hydrogen production by a floating solar photovoltaic system for industrial decarbonization

This study proposes a conceptual design of green hydrogen production via proton exchange membrane electrolysis powered by a floating solar photovoltaic system.The system contributes to industrial decarbonization in which hydrogen blending with natural gas is proposed as an approach to smooth the energy transition.The proposed design addresses the challenge of supplying a continuous flow-rate of green hydrogen,which is typically demanded by industrial end users.This study particularly considers a realistic area required for the installation of a floating solar photovoltaic system.To enable the green hydrogen production of 7.5 million standard cubic feet per day,the required structure includes the floating solar photovoltaic system and Li-ion batteries with the nominal capacities of 518.4 megawatts and 780.8 megawatt-hours.This is equivalent to the requirement for 1524765 photovoltaic modules and 3718 Li-ion batteries.The assessment confirms the technical viability of the proposed concept of green hydrogen production,transportation and blending.While the present commercialization is hindered by economics due to a high green hydrogen production cost of USD 26.95 per kg,this green hydrogen pathway is expected to be competitive with grey hydrogen produced via coal gasification and via natural gas steam reforming by 2043 and 2047,respectively.

Green hydrogen production from photovoltaic power station as a road map to climate change mitigation

The increasing recognition of hydrogen as a critical element in the global net-zero transition and its clear role in decarbonizing challenging sectors coincide with the growing urgency to address climate change.Africa's favourable renewable-energy capacity,ranging from 28%to 36%for solar,has been reported by the global solar irradiance index.However,the majority of hydrogen production today relies on fossil fuels(96%),with only a small fraction(4%)being produced through water electrolysis.Even though there have been many studies on climate change mitigation with a focus on Africa,a green hydrogen production from a photovoltaic power station approach has not been reported.Also,literature with a focus on Nigeria is lacking.This study focuses on the African green hydrogen production industry,utilizing Nigeria as a case study to explore the feasibility of generating clean hydrogen vectors from a percentage of photovoltaic power output in various regions of the country through stand-alone solar grid electrification projects.Analyses of the usage and effectiveness of the produced hydrogen fuel in each region are carried out,with the highest region having an annual output of 12247278 kg of green hydrogen and 8573094 kg of ammonia and the lowest region having an output of 511245 kg of green hydrogen and 357871 kg of ammonia,and the expected production from the proposed usage of 50%of the power generation output of the installed 1.6-MWp and 80-kWp solar power minigrids in the regions is calculated.The analyses were repeated for the other considered regions in the country.The results showcased the enormous advantages of the electrolytic production of hydrogen and how the greener economy project can play a major role in mitigating climate change effects and overreliance on fossil fuels as the driver of the economy in many African countries.

Forward perspective on the development and strategic pathway of green hydrogen in China

Fundamental transformations are taking place in the areas of energy structure on the supply side and on the energy-consumption side towards clean,low-carbon and safe energy.Furthermore,a new energy system is being constructed with renewable energy as its core in China with energy transition and‘carbon peak and carbon neutral’as the overall goal.China’s hydrogen-industry plan,‘Mid-to-long term hydrogen industry development plan(2021-2035)’,has an emphasis on hydrogen generation by using renewable energies as the centre piece,which points in the right direction for hydrogen’s green development.In this paper,the current status of China’s hydrogen industry is analysed;strategic needs for green hydrogen’s development and its hurdles in its paths are sorted out.Integrated demonstration at provincial levels,development of a‘great hydrogen base’and the green-hydrogen development path by gradual substitution with renewable hydrogen are proposed.Scaled-up hydrogen production,expanded consumer hydrogen usage and established hydrogen commodity exchange are recommended to safeguard its development and promote its high-quality development in China.

Wind energy as a source of green hydrogen production in the USA

The study incorporates an overview of the green hydrogen-production potential from wind energy in the USA,its application in power generation and the scope of substituting grey and blue hydrogen for industrial usage.Over 10 million metric tons of grey and blue hydrogen is produced in the USA annually to fulfil the industrial demand,whereas,for 1 million metric tons of hydrogen generated,13 million metric tons of CO_(2) are released into the atmosphere.The research aims to provide a state-of-the-art review of the green hydrogen technology value chain and a case study on the production of green hydrogen from an 8-MW wind turbine installed in the southern plain region of Texas.This research estimates that the wind-farm capacity of 130 gigawatt-hours is required to substitute grey and blue hydrogen for fulfilling the current US annual industrial hydrogen demand of 10 million metric tons.The study investi-gates hydrogen-storage methods and the scope of green hydrogen-based storage facilities for energy produced from a wind turbine.This research focuses on the USA’s potential to meet all its industrial and other hydrogen application requirements through green hydrogen.

Techno-economic analysis of green hydrogen as an energy-storage medium for commercial buildings

Green-hydrogen production is vital in mitigating carbon emissions and is being adopted globally.In its transition to a more diverse energy mix with a bigger share for renewable energy,United Arab Emirates(UAE)has committed to investing billions of dollars in the production of green hydrogen.This study presents the results of the techno-economic assessment of a green-hydrogen-based commercial-building microgrid design in the UAE.The microgrid has been designed based on the building load demand,green-hydrogen production potential utilizing solar photovoltaic(PV)energy and discrete stack reversible fuel cell electricity generation during non-PV hours.Given the current market conditions and the hot humid climate of the UAE,a performance analysis is derived to evaluate the technical and economic feasibility of this microgrid.The study aims at maximizing both the building microgrid’s independence from the main grid and its renewable fraction.Simulation results indicate that the designed system is capable of meeting three-quarters of its load demand independently from the main grid and is supported by a 78%renewable-energy fraction.The economic analysis demonstrates a 3.117-$/kg levelized cost of hydrogen production and a 0.248-$/kWh levelized cost for storing hydrogen as electricity.Additionally,the levelized cost of system energy was found to be less than the current utility costs in the UAE.Sensitivity analysis shows the significant impact of the capital cost and discount rate on the levelized cost of hydrogen generation and storage.

Reliable off-grid power supply utilizing green hydrogen

Green hydrogen produced from wind,solar or hydro power is a suitable electricity storage medium.Hydrogen is typically employed as mid-to long-term energy storage,whereas batteries cover short-term energy storage.Green hydrogen can be produced by any available electrolyser technology[alkaline electrolysis cell(AEC),polymer electrolyte membrane(PEM),anion exchange membrane(AEM),solid oxide electrolysis cell(SOEC)]if the electrolysis is fed by renewable electricity.If the electrolysis operates under elevated pressure,the simplest way to store the gaseous hydrogen is to feed it directly into an ordinary pressure vessel without any external compression.The most efficient way to generate electricity from hydrogen is by utilizing a fuel cell.PEM fuel cells seem to be the most favourable way to do so.To increase the capacity factor of fuel cells and electrolysers,both functionalities can be integrated into one device by using the same stack.Within this article,different reversible technologies as well as their advantages and readiness levels are presented,and their potential limitations are also discussed.

Recent advances in thermochemical conversion of woody biomass for production of green hydrogen and CO_(2)capture:A review

Hydrogen as a clean energy carrier has attracted great interests world-wide for substitution of fossil fuels and for abatement of the climate change concerns.However,green hydrogen from renewable resources is less than 0.1%at present in the world hydrogen production and this is largely from water electrolysis which is beneficial only when renewable electricity is used.Hydrogen production from diverse renewable resources is desirable.This review presents recent advances in hydrogen production from woody biomass through biomass steam gasification,producer gas processing and H_(2)/CO_(2)separation.The producer gas processing includes steam-methane reforming(SMR)and water-gas shift(WGS)reactions to convert CH_(4)and CO in the producer gas to H_(2)and CO_(2).The H_(2)storage discussed using liquid carrier through hydrogenation is also discussed.The CO_(2)capture prior to the SMR is investigated to enhance H_(2)yield in the SMR and the WGS reactions.

20 ppm Anhydrous Ammonia Odor Agent Proposed for Hydrogen Fuel for Safe Detection of Leaks

Preferably 20 ppm anhydrous ammonia (NH3) is proposed to be added to hydrogen fuel (H) made from renewable energy sources (green hydrogen), so that H leaks may be easily detectable by smell, but not dangerously toxic. Including this odor agent, would allow H to be distributed safely in pipes, as required by law, and it would allow H to be safely stored, transported, and exported for sale, and widely commercialized. Further research is suggested to identify optimum pressure, temperature, and automated technique for injecting NH3 into H, and to chart the minimum concentration needed, as a function of temperature and humidity. An application to make hypersonic H burning aircraft safer for ground maintenance crews is proposed. An ability to make, store and distribute H, made from local sources of renewable energy, would reduce a need for fossil fuels, especially in poor, remote communities, where it could improve their economy by creating an export product for sale, while reducing pollution.

同位素信息在确定Green-Ampt入渗模型参数中的应用

针对单独水文信息确定水文模型参数的信息量不足问题,以Green-Ampt入渗模型为例,结合同位素混合模型,应用氢氧稳定同位素信息确定Green-Ampt入渗模型参数,并通过室内降雨入渗实验验证。实验结果表明,同位素信息确定的Green-Ampt入渗模型参数与实测值接近,同位素信息和水文信息有效结合确定的模型参数比单一水文信息确定模型参数好。