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To achieve zero carbon emissions, increasing the scale of renewable energy implementation is imperative. Hydrogen is considered the prospective solution for sustainable energy due to its dual nature as a carbon-neutral fuel and an efficient storage medium for renewable energy sources. So, in this work, a standalone new hybrid energy system powered by solar energy for yearly power and freshwater production for building demand in New Borg El-Arab, Egypt. The system comprises photovoltaic (PV) panels, a water electrolyzer, multi-effect mechanical vapor compression desalination (MED-MVC), and fuel cells with hydrogen storage. A complete mathematical system model is built and solved by MATLAB/Simulink to study the daily, monthly, and yearly performance and sizing of the different system components based on the location climate conditions. The results indicate that PV panels of an area of 1824 m2, in conjunction with an electrolyzer, 863 fuel cells, and a storage tank capacity of 3013.4 m3can satisfy the annual building requirements of 255.17 MWh electricity, 766.5 m3 hot water and 876 m3 cold water. The maximum hydrogen storage lies between September and October, with maximum consumption between February and March. The average annual efficiency of PV, electrolyzer, fuel cell, electrolyzer output, fuel cell output, and overall hybrid system is 20.7%, 68.2%, 34.6%, 13.4%, 4.4%, and 16.5%, respectively, and the performance ratio (PR) of MED-MVC is 2.61. The system proves its capability to supply the building with electrical and water requirements with a levelized cost of energy (LCOE) equal to 0.712 $/kWh. Additionally, This system shows the potential to include other activities in remote areas or islands besides its contribution to achieving SDGs 6, 7, and 13. • A Standalone solar system with hydrogen storage for power and water building demand is studied. • The system proved its capability to meet the building's electrical and water demands with LCOE of 0.712 $/kWh. • The average annual PV, electrolyzer, and fuel cell efficiency are 20.7%, 68.2%, and 34.6%, respectively. • The performance ratio of MED-MVC is 2.61, and overall system efficiency is 16.5%. [ABSTRACT FROM AUTHOR]

The installed capacity, electricity generation from wind, and the curtailment of wind power in the UK between 2011 and 2021 showed that penetration levels of wind energy and the amount of energy that is curtailed in future would continue to rise whereas the curtailed energy could be utilised to produce green hydrogen. In this study, data were collected, technologies were chosen, systems were designed, and simulation models were developed to determine technical requirements and levelised costs of hydrogen produced and transported through different pathways. The analysis of capital and operating costs of the main components used for onshore and offshore green hydrogen production using offshore wind, including alternative strategies for hydrogen storage and transport and hydrogen carriers, showed that a significant reduction in cost could be achieved by 2030, enabling the production of green hydrogen from offshore wind at a competitive cost compared to grey and blue hydrogen. Among all scenarios investigated in this study, compressed hydrogen produced offshore is the most cost-effective scenario for projects starting in 2025, although the economic feasibility of this scenario is strongly affected by the storage period and the distance to the shore of the offshore wind farm. Alternative scenarios for hydrogen storage and transport, such as liquefied hydrogen and methylcyclohexane, could become more cost-effective for projects starting in 2050, when the levelised cost of hydrogen could reach values of about £2 per kilogram of hydrogen or lower. • The potential of using offshore electricity for hydrogen production is investigated. • Data for capital and operating costs of the technologies are collected. • Scenarios for hydrogen production, storage and transport are evaluated. • Levelised costs of hydrogen for the different scenarios are calculated. [ABSTRACT FROM AUTHOR]

Hydrogen serves as an important, clean energy carrier, which, however, has a challenge for its storage. Herein, we report the properties of ethylamine dehydrogenation (EDH) to acetonitrile under half-cell conditions and ethylamine electrolysis under full-cell conditions for fast, energy-efficient, ambient hydrogen release, which would couple with spontaneous acetonitrile hydrogenation to ethylamine for hydrogen uptake to realize hydrogen storage cycles under mild conditions. The influences of different reaction parameters on the EDH and ethylamine electrolysis properties are examined. The catalyst deactivation and regeneration mechanisms are investigated with aid of in situ ATR-FTIR characterizations. As fast as 309 μmol/h H 2 production rate with 97% faradaic efficiency (FE) from cathode and acetonitrile production with 100% FE from anode are achieved with a low 0.6 V cell voltage, demonstrating a great potential of this new electrochemical approach for hydrogen storage application. [Display omitted] • New knowledge of ethylamine dehydrogenation and electrolysis discovered. • Ethylamine enabled as liquid organic hydrogen carrier for ambient hydrogen storage. • Highly selective ethylamine electrolysis to hydrogen and acetonitrile achieved. • Efficient hydrogen production realized from ethylamine electrolysis. [ABSTRACT FROM AUTHOR]

In response to the difficulty in absorbing the large-scale wind power generation connected to the grid, a hydrogen storage system composed of alkaline electrolyzers, hydrogen tanks, and oxyhydrogen fuel cells was built to convert the abandoned wind into hydrogen which can be used to meet the external hydrogen load demand or converted into electricity to supplement the grid during peak load periods. Firstly, the models of the uncertainty of wind power output and hydrogen energy storage system were established. In order to reduce the conservative degree of the traditional robust optimization solution, the robust optimization box set considering the adjustable conservative degree was used to describe the wind power output. On this basis, with the goal of reducing wind curtailment and improving the overall economy of the system, an economic dispatch model of a large-scale wind power power system based on hydrogen storage was established. The calculation example shows that the optimal scheduling model established takes into account the robustness and economy of the solution, and can significantly reduce the abandonment of wind and reduce the total cost of the system. [ABSTRACT FROM AUTHOR]

Hydrogen energy and polymer electrolyte membrane (PEM) fuel cells become concerned issues in recent years. Nevertheless, the construction of hydrogen refueling infrastructure and hydrogen storage and transportation constrains the commercial development of fuel cells. In this review, sources, production, storage, transportation, and purification methods of hydrogen are extensively reviewed and compared. The advantages of utilizing industrial by-product hydrogen and steam reforming gas in PEM fuel cell systems are analyzed. Using industrial wasted hydrogen can significantly reduce the cost of hydrogen. Also, it is indicated that the onboard hydrogen generation by steam methanol reforming can solve the difficulties of efficient storage and transportation of gaseous hydrogen, which means that methanol has great potential to be a convenient carrier of hydrogen. The effects of impurities contained in the reformate gas are generally introduced. After the methanol steam reforming and pretreatment purification processes, the reformate gas can be fed to PEM fuel cells. Thus, a fuel cell system integrated with onboard hydrogen production and impure hydrogen treatment subsystems is introduced, and key technologies therein for pretreatment purification and in-situ poisoning mitigation methods are reviewed. Finally, suggestions are proposed for further studies. Image 1 • H 2 production, storage, and transportation methods are introduced and compared. • Utilizing impure H 2 and fuel reforming reduce H 2 cost and solve pain points of H 2 storage and incomplete infrastructure. • Key technologies for impure H 2 utilization are reviewed in terms of PEM fuel cell system applications. • A PEM fuel cell system integrated with onboard SMR and PROX is promising to facilitate hydrogen energy development. • Further studies regarding material science and technology related to this field are suggested. [ABSTRACT FROM AUTHOR]

This study presents an assessment of the energy, exergy, economic, and environmental aspects of a novel wind-solar-hydrogen multi-energy supply (WSH-MES) system. The design of the electric-thermal-hydrogen generation system utilizes photovoltaic, wind power, solar thermal power generation, electrolytic cell, hydrogen storage tank, and proton exchange membrane fuel cell. The fuel cell serves as a peak power source and shares the power load with the other renewable energy sources, smoothing out the fluctuations in wind and photovoltaic power generation through controlled solar thermal power generation and hydrogen production. A case study of the proposed system was conducted in Zhangbei, China, using MATLAB/Simulink software. The results show that the system has the potential to produce 931.39 kg of hydrogen per year, with an energy efficiency of 16.03% and an exergy efficiency of 17.94%. The economic analysis reveals that Zhangbei has the lowest levelized cost of energy (LCOE) of 0.2755 $/kWh and the highest net present value (NPV) of 5.06 M$. The payback time is approximately 3 years, and the system is expected to reduce 4,220,000 tons of CO 2 over its lifetime. The integration of multiple renewable energy sources and hydrogen production in the WSH-MES system enhances the utilization rate of renewable energy and offers a promising solution for sustainable energy production and utilization. • A novel WSH-MES system is proposed to improve the renewable energy utilization rate，and 4 E analysis are performed. • Annual electricity generation is 253,187 MW h, electrolyzer consumption abandoned electricity is 131,458 MW h. • Annual production of hydrogen is 10506.12 m3 (931.39 kg). • Energy and exergy of the whole system are 12.31% and 13.16%, respectively. • Payback period is from 3 to 8 years and CO 2 emission reduction is 4,220,000 tons. [ABSTRACT FROM AUTHOR]

Syngas produced from coal gasification or methane reforming contains a significant amount of carbon dioxide (CO 2 ) that has to be removed. Semiclathrate hydrates have been considered as a possible medium for gas separation and CO 2 capture. Here, we apply Paricaud's approach [J. Phys. Chem. B 2011, 115, 288–299] to model the dissociation conditions of hydrogen (H 2 ) + CO 2 semiclathrate hydrates formed with tetra- n -butyl ammonium bromide (TBAB), tetra- n -butyl ammonium chloride (TBAC), tetra- n -butyl ammonium fluoride (TBAF), tetra-n-butyl phosphonium bromide (TBPB), and tetra-n-butyl phosphonium nitrate (TBANO 3 ). A very good description of the melting temperatures of H 2 semiclathrate hydrates is obtained over wide ranges of pressure and salt composition. It is predicted that the H 2 storage capacities of semiclathrate hydrates is rather low (about 0.05 wt% at 4 MPa), showing that semiclathrate hydrates are not good candidates to store H 2 . However, high separations factors are predicted at moderate salt concentrations, confirming the possibility of using semiclathrate hydrates to separate H 2 and CO 2 . It is predicted that the dissociation conditions of semiclathrates in presence of gas mixture significantly depend on the global composition of the mixture: in particular, the melting point is changed by varying the initial amount of water even if the global mole fraction ratio between H 2 and CO 2 is kept constant. It is shown that an increase of the salt concentration gives rise to a decrease of the separation factor, and the sudden drop of CO 2 capture observed for high salt concentrations is explained by a change of hydrate structure. [ABSTRACT FROM AUTHOR]

The use of forecast information for cascade hydropower stations is one of the effective ways to increase the electricity generation reliability and economic benefit. However, the uncertainty of forecast is high when the forecast horizon is long. It is a common practice for hydropower stations to abandon water during flood seasons due to the limited capacity of the associated reservoirs. If forecast is accurate, the stored water can be discharged early before the flood peak arrives. This would effectively reduce the amount of water being abandoned and increase electricity generation. But there is a risk that the water stored in reservoirs would become less than expected if the forecast fails or in dry periods. In order to reduce the negative impact of forecast uncertainty, hydrogen production and storage as energy harvested by electrolysis of water using the electricity from the cascade hydropower stations is proposed and used in this study. Hun River cascade hydropower stations in China are selected as a case study. By integrating ten-day inflow forecast with hedging rule curves (HRCs-TDIF), the feasibility of optimal operation of cascade hydropower stations using hydrogen as energy storage is analyzed. Hedging rules curves of hydrogen production (HRCs-HP) is established for analyzing the relationship between electricity generation reliability (EGR) of the cascade hydropower stations and equipment utilization (EU) of hydrogen production under different equipment scales (ES). The results show that the proposed methods for the selected cascade hydropower stations may lead to high EGR and less water being abandoned. [ABSTRACT FROM AUTHOR]

Abstract: Fuel cell (FC) propulsion for small (MTOW < 25 kg) Unmanned Aerial Vehicles (UAVs) provides a route for lower capital cost, environmentally friendlier and low noise operation. Most FC-based UAVs tested to date rely on compressed gas cylinders delivered to the point of use and used to refill the UAV hydrogen tanks on-site or chemical hydride systems to produce hydrogen on-board. An attractive alternative option is to produce hydrogen on-site from an off-grid renewable source according to the UAV fuel demand. A prototype off-grid solar-based hydrogen refuelling station for UAVs was developed for that purpose by Boeing Research & Technology Europe. A test program was carried out to evaluate the dynamic response of the hydrogen UAV refuelling system operating in an off-grid manner (disconnected from the AC grid). The system comprises a concentrated photovoltaic (CPV) array, an alkaline electrolyser, a low pressure hydrogen buffer tank and the required power electronics. The electrolyser was connected to the CPV source in an off-grid manner. The results from the off-grid tests are presented in this paper. From the results obtained, the operation of the CPV array and the CPV inverter connected to the electrolyser were both satisfactory, and no significant operational issues were observed. The overall energy efficiency of the CPV-inverter-electrolyser system was below 40%, mainly due to the excessively long start-up periods during which the electrolyser is not producing hydrogen, the slow dynamic response due to regular pressurization and depressurization cycles of the electrolyser and the excessive power consumption of the electrolyser auxiliaries. It is expected that if some optimization is carried out, mainly related to the control system of the electrolyser, the overall energy efficiency should increase and the dynamic response of the electrolyser can be improved. [Copyright &y& Elsevier]

Abstract: Climate change concerns, increasing global energy demand, coupled with pending peak supply of fossil fuels, calls for development of new power source. The rapid price drops for solar technologies and combined with international and national policy changes makes solar energy more affordable and accessible for widespread adoption. Solar energy also contributes towards the reduction of greenhouse gas emissions. The combination of electrolysis of water and fuel cells, which use hydrogen as an energy carrier extends the utility of the solar energy. For an integrated solar powered hydrogen production, storage and utilisation system, one of the elements that needs to be designed carefully is the power management system. Power management strategy has a complex function in this type of solar hydrogen system. This paper presents a power management strategy based on fuzzy logic technology to address the problems. The target of this power management strategy is to use the solar power to meet the power demand, then utilise any addition power to maximise the hydrogen production, and minimise the usage of battery at the same time. Therefore, the overall system''s efficiency will be increased and lifetime of the battery pack will be extended. The numerical results based on real solar data for a one year period shown that the proposed fuzzy logic controller can direct the power flow wisely between different elements such as load, electrolyser, fuel cell and battery, it is capable of meeting the daily power demand of an office block and using the excess solar power to produce hydrogen as far as possible while maintaining the battery''s state of charge in a desired region in order to extend the lifespan of the battery. [Copyright &y& Elsevier]