Publications

IGEM/TD/13 Standard applies to the safe design construction inspection testing operation and maintenance of pressure regulating installations (PRIs) in accordance with current knowledge and operational experience.

This Supplement provides additional requirements for new PRIs to be used for the transmission of Hydrogen including Natural Gas/Hydrogen blended mixtures (subsequently referred to as NG/H blends) and for the repurposing of Natural Gas (NG) PRIs for Hydrogen service.

NG/H blends are considered to be equivalent to 100 mol % Hydrogen with respect to limits on design stresses the potential effect on the material properties and damage and defect categories and acceptance levels unless an additional technical evaluation is carried out to qualify the materials.

NG/H blends containing in excess of 10 mol % Hydrogen are considered to be equivalent to 100 mol.% Hydrogen with respect to all other requirements except for hazardous areas.

This Supplement gives additional recommendations for PRIs and installations:

• with an upstream maximum operating pressure (MOP) not greater than 100 bar
• with an outlet pressure greater than or equal to 7 bar
• for use with Hydrogen or NG/H blends with a Hydrogen content greater than 10 %
• operating with a temperature range between -20°C and 120°C.

The supplement can be purchased on the IGEM website

Decarbonization of the steel industry is one of the pathways towards a fossil-fuel-free environment. The steel industry is one of the top contributors to greenhouse gas emissions. Most of these emissions are directly linked to the use of a fossil-fuelbased reductant. Replacing the fossil-based reductant with green H2 enables the transition towards a fossil-free steel industry. The carbon-free iron produced will cause the refining and steelmaking operations to have a starting point far from today’s operations. In addition to carbon being an alloying element in steel production carbon addition controls the melting characteristics of the reduced iron. In the present study the effect of carbon content and form (cementite/graphite) in hydrogen-reduced iron ore pellets on their melting characteristics was examined by means of a differential thermal analyser and optical dilatometer. Carburized samples with a carbon content < 2 wt % did not show any initial melting at the eutectic temperature. At and above 2 wt % the carburized samples showed an initial melting at the eutectic temperature irrespective of the carbon content. However the absorbed heat varies with varied carbon content. The carbon form does not affect the initial melting temperature but it affects the melting progression. Carburized samples melt homogenously while melting of iron-graphite mixtures occurs locally at the interface between iron and carbon particles and when the time is not long enough melting might not occur to any significant extent. Therefore at any given carbon content > 2 wt % the molten fraction is higher in the case of carburized samples which is indicated by the amount of absorbed melting heat.

The global transition to a clean and sustainable energy infrastructure does not stop at aviation. The European Commission defined a set of environmental goals for the “Flight Path 2050”: 75% CO2 reduction 90% NOx reduction and 65% perceived noise reduction. Hydrogen as an energy carrier fulfills these needs while it would also offer a tenable and flexible solution for intermittent large-scale energy storage for renewable energy networks. If hydrogen is used as an energy carrier there is no better device than a fuel cell to convert its stored chemical energy. In order to design fuel cell systems for passenger aircraft it is necessary to specify the requirements that the system has to fulfill. In this paper a statistical approach to analyze these requirements is presented which accounts for variations in the flight mission profile. Starting from a subset of flight data within the desired class (e.g. mid-range inter-European flights) a stochastic model of the random mission profile is inferred. This model allows for subsequent predictions under uncertainty as part of the aircraft design process. By using Monte Carlo-based sampling of flight mission profiles the range of necessary component sizes as well as optimal degrees of hybridization with a battery is explored and design options are evaluated. Furthermore Monte Carlo-based sensitivity analysis of performance parameters explores the potential of future technological developments. Results suggest that the improvement of the specific power of the fuel cell is the deciding factor for lowering the energy system mass. The specific energy of the battery has a low influence but acts in conjunction with the specific power of the fuel cell.

Alternatives to cope with the challenges of high shares of renewable electricity in power systems have been addressed from different approaches such as energy storage and low-carbon technologies. However no model has previously considered integrating these technologies under stability requirements and different climate conditions. In this study we include this approach to analyse the role of new technologies to decarbonise the power system. The Spanish power system is modelled to provide insights for future applications in other regions. After including storage and low-carbon technologies (currently available and under development) batteries and hydrogen fuel cells have low penetration and the derived emission reduction is negligible in all scenarios. Compressed air storage would have a limited role in the short term but its performance improves in the long term. Flexible generation technologies based on hydrogen turbines and long-duration storage would allow the greatest decarbonisation providing stability and covering up to 11–14 % of demand in the short and long term. The hydrogen storage requirement is equivalent to 18 days of average demand (well below the theoretical storage potential in the region). When these solutions are considered decarbonising the electricity system (achieving Paris targets) is possible without a significant increase in system costs (< € 114/MWh).

For the first time we quantify cost footprint and reliability implications of deploying hydrogen-based generation in off-grid electric vehicle charging stations (CS) using an optimization model coupled with a geographic information system (GIS) analysis for the city of Riyadh Saudi Arabia. We also account for the challenges associated with wind energy deployment as a candidate generation technology within city centers. The analysis was restricted to carbon-free technologies: photovoltaics (PV) wind battery and hydrogen fuel-cells. At current prevailing technology costs hydrogen can reduce the required footprint of off-grid CSs by 25% at a small incremental cost increase without impacting the charging reliability. By 2030 however hydrogen will simultaneously provide the footprint and cost advantages. If we allow as little as 5% of the annual load to be unmet the required footprint of the CS decreases by 60%. The levelized cost of energy values for the CS by 2030 can range between 0.13 and 0.20 $/kWh depending on learning-curve assumptions. The footprints calculated are then mapped to five land parcel categories in Riyadh: gas station hospital mall school and university. Incorporating hydrogen in CS design increases the number of parcels that could accommodate CSs by 15e45% via reducing the required PV array (i.e. footprint).

Both marine renewables and hydrogen are being tested by the European Marine Energy Centre in the Orkney Islands Scotland. Given their emerging nature there is opportunity and risk pertaining to their development and deployment. This research will contribute conceptually and methodologically through the integration of energy justice and RRI conceptual frameworks strengthening justice analyses in relation to emerging energy technologies. This integrated model will be mobilized to critically scrutinize marine energy and green hydrogen as two future energy sources within the energy system. Following a technology-centered exploration of these technologies this work will then contextualise them into place-based considerations of Orkney’s just energy futures. Placing the technologies at the centre of the justice analysis insights will have the potential to inform their development and deployment in other locations. Exploring them within the local Orkney context will initiate an essential and important discussion of energy futures in this specific location. This presentation sets out the empirical and conceptual context for this work and presents a novel conceptual and methodological model combining energy justice and RRI frameworks. Moreover preliminary methods are discussed including methods and outcomes from co-creation workshops held at research design phase.

Uncertainty surrounding the total cost of ownership system costs and life cycle environmental impacts means that stakeholders may lack the required information to evaluate the risks of transitioning to low-carbon fuels and powertrains. This paper assesses the life cycle costs and well-to-wheel environmental impacts of using electricity and electrofuels in Heavy Good Vehicles (HGVs) whilst considering input parameter uncertainty. The complex relationship between electricity cost electrolyser capacity factor CO2 capture cost and electricity emissions intensity is assessed within a Monte Carlo based framework to identify scenarios where use of electricity or electrofuels in heavy goods vehicles makes economic and environmental sense. For vehicles with a range of less than 450 km battery electric vehicles achieve the lowest total cost of ownership for an electricity cost less than 100 €/MWh. For vehicles that require a range of up to 900 km hydrogen fuel cell vehicles represent the lowest long-term cost of abatement. Power-to-methane and power-to-liquid scenarios become economically competitive when low-cost electricity is available at high-capacity factors and CO2 capture costs for fuel synthesis are below 100 €/tCO2; these fuels may be more applicable to decarbonise shipping and aviation. Battery electric HGVs reduce greenhouse gas emissions by 50% compared to the diesel baseline with electricity emissions of 350 gCO2e/kWh. Electricity emissions less than 35 gCO2e/kWh are required for the power-to-methane and power-to-liquid scenarios to meet EU emissions savings criteria. High vehicle capital costs and a lack of widespread refuelling infrastructure may hinder initial uptake of low-carbon fuels and powertrains for HGVs.

Hydrogen consumption and mileage are important economic indicators of fuel cell vehicles. Hydrogen consumption is the fundamental reason that restricts mileage. Since there are few quantitative studies on hydrogen consumption during actual vehicle operation the high cost of hydrogen consumption in outdoor testing makes it impossible to guarantee the accuracy of the test. Therefore this study puts forward a test method based on the hydrogen consumption of fuel cell vehicles under CLTC-P operating conditions to test the hydrogen consumption of fuel cell vehicles per 100 km. Finally the experiment shows that the mileage calculated by hydrogen consumption has a higher consistency with the actual mileage. Based on this hydrogen consumption test method the hydrogen consumption can be accurately measured and the test time and cost can be effectively reduced.

Increasing shares of variable renewable electricity (VRE) generation are necessary for achieving high renewable shares in all energy sectors. This results in increased excess renewable electricity (ERE) at times when supply exceeds demand. ERE can be utilized as a low-emission energy source for sector coupling through hydrogen production via electrolysis which can be used directly or combined with a carbon source to produce electrofuels. Such fuels are crucial for the transport sector where renewable alternatives are scarce. However while ERE increases with raising VRE shares carbon emissions decrease and may become a limited resource with several usage options including carbon storage (CCS). Here we perform a model based analysis for the German case until 2050 with a general analysis for regions with a high VRE reliance. Results indicate that ERE-based electrofuels could achieve a greenhouse gas (GHG) abatement of 74 MtCO2eq yearly (46% of current German transport emissions) by displacing fossil fuels at high fuel-cell electric vehicle (FCEV) shares at a cost of 250–320 V per tCO2eq. The capital expenditure of electrolysers was found not to be crucial for the cost despite low capacity factors due to variable ERE patterns. Carbon will likely become a limiting factor when aiming for stringent climate targets and renewable electricity-based hydrocarbon electrofuels replacing fossil fuels achieve up to 70% more GHG abatement than CCS. Given (1) an unsaturated demand for renewable hydrocarbon fuels (2) a saturated renewable hydrogen demand and (3) unused ERE capacities which would otherwise be curtailed we find that carbon is better used for renewable fuel production than being stored in terms of overall GHG abatement.

As a manufactured fuel hydrogen can be produced in a decentralized way in most countries around the world. This means even in a net zero economy the global trade of hydrogen could look quite different to the current international trade in fossil fuels including natural gas. With further declines in the costs of renewable electricity and electrolyzers regions which have lower cost renewable electricity may develop an economic advantage in the production of low-cost hydrogen but for hydrogen to become a globally traded commodity the cost of imports needs to be lower than the cost of domestic production. Unlike oil or natural gas transporting hydrogen over long distances is not an easy task. Hydrogen liquefaction is an extremely energy-intensive process while maintaining the low temperature required for long-distance transportation and storage purposes results in additional energy losses and accompanying costs. The upside is that hydrogen can be converted into multiple carriers that have a higher energy density and higher transport capacity and can potentially be cheaper to transport over long distances. Among the substances currently identified as potential hydrogen carriers suitable for marine shipping liquid ammonia the so-called ‘liquid organic hydrogen carriers’ in general (toluene-methylcyclohexane (MCH) in particular) and methanol have received the most attention in recent years. This paper compares the key techno-economic characteristics of these potential carriers with that of liquified hydrogen in order to develop a better understanding of the ways in which hydrogen could be transported overseas in an efficient manner. The paper also discusses other factors beyond techno-economic features that may affect the choice of optimum hydrogen carrier for long distance transport as well as the global trade of hydrogen.

The hydrogen economy is one of the possible directions of development for the European Union economy which in the perspective of 2050 can ensure climate neutrality for the member states. The use of hydrogen in the economy on a larger scale requires the creation of a storage system. Due to the necessary volumes the best sites for storage are geological structures (salt caverns oil and gas deposits or aquifers). This article presents an analysis of prospects for large-scale underground hydrogen storage in geological structures. The political conditions for the implementation of the hydrogen economy in the EU Member States were analysed. The European Commission in its documents (e.g. Green Deal) indicates hydrogen as one of the important elements enabling the implementation of a climate-neutral economy. From the perspective of 2050 the analysis of changes and the forecast of energy consumption in the EU indicate an increase in electricity consumption. The expected increase in the production of energy from renewable sources may contribute to an increase in the production of hydrogen and its role in the economy. From the perspective of 2050 discussed gas should replace natural gas in the chemical metallurgical and transport industries. In the longer term the same process will also be observed in the aviation and maritime sectors. Growing charges for CO2 emissions will also contribute to the development of underground hydrogen storage technology. Geological conditions especially wide-spread aquifers and salt deposits allow the development of underground hydrogen storage in Europe.

To reduce pollution from ships in coastal and international navigation shipping companies are turning to various technological solutions mostly based on electrification and the use of alternative fuels with a lower carbon footprint. One of the alternatives to traditional diesel fuel is the use of hydrogen as a fuel or hydrogen fuel cells as a power source. Their application on ships is still in the experimental phase and is limited to smaller ships which serve as a kind of platform for evaluating the applicability of different technological solutions. However the use of hydrogen on a large scale as a primary energy source on coastal and ocean-going vessels also requires an infrastructure for the production and safe storage of hydrogen. This paper provides an overview of color-based hydrogen classification as one of the main methods for describing hydrogen types based on currently available production technologies as well as the principles and safety aspects of hydrogen storage. The advantages and disadvantages of the production technologies with respect to their application in the maritime sector are discussed. Problems and obstacles that must be overcome for the successful use of hydrogen as a fuel on ships are also identified. The issues presented can be used to determine long-term indicators of the global warming potential of using hydrogen as a fuel in the shipping industry and to select an appropriate cost-effective and environmentally sustainable production and storage method in light of the technological capabilities and resources of a particular area.

Hydrogen storage is expected to play a crucial role in the comprehensive defossilization of energy systems. In this context the focus is typically on underground hydrogen storage (e.g. in salt caverns). However aboveground storage which is independent of geological conditions and might offer other technical advantages could provide systemic benefits and thereby gain shares in the hydrogen storage market. Against this background this paper examines the market relevance of aboveground compared to underground hydrogen storage. Using the opensource energy system model and optimization framework of Europe PyPSA-Eur the influence of geological independence storage cost relations and technical storage characteristics (i.e. efficiencies) on mentioned market relevance of aboveground hydrogen storage are investigated. Further the expectable market relevance based on current cost projections for the future is assessed. The studies show that in terms of hydrogen capacities aboveground hydrogen storage plays a considerably smaller role compared to underground hydrogen storage. Even when assuming comparatively low aboveground storage cost it will not exceed 1.7% (1.9 TWhH2LHV) of total hydrogen storage capacities in a cost-optimal European energy system. Regarding the amounts of annually stored hydrogen aboveground storage could play a larger role reaching a maximum share of 32.5% (168 TWhH2 LHV a-1) of total stored hydrogen throughout Europe. However these shares are only achievable for low cost storage in particularly suited energy system supply configurations. For higher aboveground storage costs or lower efficiencies shares drop below 10% sharply. The analysis identifies some especially influential factors for achieving higher market relevance. Besides storage costs the demand-orientation of a particular aboveground storage system (e.g. hydrogen storage at demand pressure levels) plays an essential role in market relevance. Further overall efficiency can be a beneficial factor. Still current projections of future techno-economic characteristics show that aboveground hydrogen storage is too expensive or too inefficient compared to underground storage. Therefore to achieve notable market relevance rather drastic cost reductions beyond current expectations would be needed for all assessed aboveground hydrogen storage technologies.

Environmental emissions global warming and energy-related concerns have accelerated the advancements in conventional vehicles that primarily use internal combustion engines. Among the existing technologies hydrogen fuel cell electric vehicles and fuel cell hybrid electric vehicles may have minimal contributions to greenhouse gas emissions and thus are the prime choices for environmental concerns. However energy management in fuel cell electric vehicles and fuel cell hybrid electric vehicles is a major challenge. Appropriate control strategies should be used for effective energy management in these vehicles. On the other hand there has been significant progress in artificial intelligence machine learning and designing data-driven intelligent controllers. These techniques have found much attention within the community and state-of-the-art energy management technologies have been developed based on them. This manuscript reviews the application of machine learning and intelligent controllers for prediction control energy management and vehicle to everything (V2X) in hydrogen fuel cell vehicles. The effectiveness of data-driven control and optimization systems are investigated to evolve classify and compare and future trends and directions for sustainability are discussed.

Hydrogen has received increased attention in the last decades as a green energy carrier and a promising future fuel. The integration of hydrogen as well as the development of cogeneration plants makes the energy sector more eco-friendly and sustainable. The aim of this paper is the investigation of a solar-fed cogeneration system that can produce power and compressed green hydrogen. The examined unit contains a parabolic trough collector solar field a thermal energy storage tank an organic Rankine cycle and a proton exchange membrane water electrolyzer. The installation also includes a hydrogen storage tank and a hydrogen compressor. The unit is analyzed parametrically in terms of thermodynamic performance and economic viability in steady-state conditions with a developed and accurate model. Taking into account the final results the overall energy efficiency is calculated at 14.03% the exergy efficiency at 14.94% and the hydrogen production rate at 0.205 kg/h. Finally the payback period and the net present value are determined at 9 years and 122 k€ respectively.

At present the energy shortage and environmental pollution are the burning global issues. For centuries fossil fuels have been used to meet worldwide energy demand. However thousands of tons of greenhouse gases are released into the atmosphere when fossil fuels are burned contributing to global warming. Therefore green energy must replace fossil fuels and hydrogen is a prime choice. Photocatalytic water splitting (PWS) under solar irradiation could address energy and environmental problems. In the past decade solar photocatalysts have been used to manufacture sustainable fuels. Scientists are working to synthesize a reliable affordable and light-efficient photocatalyst. Developing efficient photocatalysts for water redox reactions in suspension is a key to solar energy conversion. Semiconductor nanoparticles can be used as photocatalysts to accelerate redox reactions to generate chemical fuel or electricity. Carbon materials are substantial photocatalysts for total WS under solar irradiation due to their high activity high stability low cost easy production and structural diversity. Carbon-based materials such as graphene graphene oxide graphitic carbon nitride fullerenes carbon nanotubes and carbon quantum dots can be used as semiconductors photosensitizers cocatalysts and support materials. This review comprehensively explains how carbon-based composite materials function as photocatalytic semiconductors for hydrogen production the water-splitting mechanism and the chemistry of redox reactions. Also how heteroatom doping defects and surface functionalities etc. can influence the efficiency of carbon photocatalysts in H2 production. The challenges faced in the PWS process and future prospects are briefly discussed.

This study sheds light on the Hydrogen technology in transportation for reaching the sustainability goals of societies illustrated by the case of Mexico. In terms of the affected supply chains the study explores how the packaging and distribution of a fuel-saving tool that allows the adoption of hydrogen as complementary energy for maritime transportation to improve economic and environmental performance in Mexico. This exploratory study performs interviews observations simulations and tests involving producers suppliers and users at 26 ports in Mexico. The study shows that environmental and economic performance are related to key processes in Supply Chain Management (SCM) in which packaging and distribution are critical for achieving logistics and transportation sustainability goals. Reusable packaging and the distribution of a fuel-saving tool can help decrease costs - of transport and downstream/upstream processes in SCM while at the same time increasing the environmental performance.

Adopting proton exchange membrane fuel cells fuelled by hydrogen presents a promising solution for the shipping industry’s deep decarbonisation. However the potential safety risks associated with hydrogen leakage pose a significant challenge to the development of hydrogen-powered ships. This study examines the safe design principles and leakage risks of the hydrogen gas supply system of China’s first newbuilt hydrogen-powered ship. This study utilises the computational fluid dynamics tool FLACS to analyse the hydrogen dispersion behaviour and concentration distributions in the hydrogen fuel cell room based on the ship’s parameters. This study predicts the flammable gas cloud and time points when gas monitoring points first reach the hydrogen volume concentrations of 0.8% and 1.6% in various leakage scenarios including four different diameters (1 3 5 and 10 mm) and five different directions. This study’s findings indicate that smaller hydrogen pipeline diameters contribute to increased hydrogen safety. Specifically in the hydrogen fuel cell room a single-point leakage in a hydrogen pipeline with an inner diameter not exceeding 3 mm eliminates the possibility of flammable gas cloud explosions. Following a 10 mm leakage diameter the hydrogen concentration in nearly all room positions reaches 4.0% within 6 s of leakage. While the leakage diameter does not impact the location of the monitoring point that first activates the hydrogen leak alarm and triggers an emergency hydrogen supply shutdown the presence of obstructions near hydrogen detectors and the leakage direction can affect it. These insights provide guidance on the optimal locations for hydrogen detectors in the fuel cell room and the pipeline diameters on hydrogen gas supply systems which can facilitate the safe design of hydrogen-powered ships.

This paper reviews the relationship between the production of steel and the environment as it stands today. It deals with raw material issues (availability scarcity) energy resources and generation of by-products i.e. the circular economy the anthropogenic iron mine and the energy transition. The paper also deals with emissions to air (dust Particulate Matter heavy metals Persistant Organics Pollutants) water and soil i.e. with toxicity ecotoxicity epidemiology and health issues but also greenhouse gas emissions i.e. climate change. The loss of biodiversity is also mentioned. All these topics are analyzed with historical hindsight and the present understanding of their physics and chemistry is discussed stressing areas where knowledge is still lacking. In the face of all these issues technological solutions were sought to alleviate their effects: many areas are presently satisfactorily handled (the circular economy—a historical’ practice in the case of steel energy conservation air/water/soil emissions) and in line with present environmental regulations; on the other hand there are important hanging issues such as the generation of mine tailings (and tailings dam failures) the emissions of greenhouse gases (the steel industry plans to become carbon-neutral by 2050 at least in the EU) and the emission of fine PM which WHO correlates with premature deaths. Moreover present regulatory levels of emissions will necessarily become much stricter.

This study proposes a data-driven methodology for modeling power and hydrogen generation of a sustainable energy converter. The wave and hydrogen production at different wave heights and wind speeds are predicted. Furthermore this research emphasizes and encourages the possibility of extracting hydrogen from ocean waves. By using the extracted data from the FLOW-3D software simulation and the experimental data from the special test in the ocean the comparison analysis of two data-driven learning methods is conducted. The results show that the amount of hydrogen production is proportional to the amount of generated electrical power. The reliability of the proposed renewable energy converter is further discussed as a sustainable smart grid application.

Ireland’s Climate Action Plan 2021 has set out ambitious targets for decarbonization across the energy transport heating and agriculture sectors. The Climate Action Plan followed the Climate Act 2021 which committed Ireland to a legally binding target of net-zero greenhouse gas emissions no later than 2050 and a reduction of 51% by 2030. Green hydrogen is recognized as one of the most promising technologies for enabling the decarbonization targets of economies across the globe but significant challenges remain to its large-scale adoption. This research systematically investigates the barriers and opportunities to establishing a green hydrogen economy by 2050 in Ireland by means of an analysis of the policies supporting the optimal development of an overall green hydrogen eco-system in the context of other decarbonizing technologies including green hydrogen production using renewable generation distribution and delivery and final consumption. The outcome of this analysis is a set of clear recommendations for the policymaker that will appropriately support the development of a green hydrogen market and eco-system in parallel with the development of other more mature low-carbon technologies. The analysis has been supplemented by an open “call for evidence” which gathered relevant information about the future policy and roles of hydrogen involving the most prominent stakeholders of hydrogen in Ireland. Furthermore the recommendations and conclusions from the research have been validated by this mechanism.

Green hydrogen—a carbon-free renewable fuel—has the capability to decarbonise a variety of sectors. The generation of green hydrogen is currently restricted to water electrolysers. The use of freshwater resources and critical raw materials however limits their use. Alternative water splitting methods for green hydrogen generation via photocatalysis and photoelectrocatalysis (PEC) have been explored in the past few decades; however their commercial potential still remains unexploited due to the high hydrogen generation costs. Novel PEC-based simultaneous generation of green hydrogen and wastewater treatment/high-value product production is therefore seen as an alternative to conventional water splitting. Interestingly the organic/inorganic pollutants in wastewater and biomass favourably act as electron donors and facilitate the dual-functional process of recovering green hydrogen while oxidising the organic matter. The generation of green hydrogen through the dual-functional PEC process opens up opportunities for a “circular economy”. It further enables the end-of-life commodities to be reused recycled and resourced for a better life-cycle design while being economically viable for commercialisation. This review brings together and critically analyses the recent trends towards simultaneous wastewater treatment/biomass reforming while generating hydrogen gas by employing the PEC technology. We have briefly discussed the technical challenges associated with the tandem PEC process new avenues techno-economic feasibility and future directions towards achieving net neutrality.

Energy consumption is essential for evaluating the competitiveness of fuel cell electric vehicles. A critical step in energy consumption measurement is measuring hydrogen consumption including the mass method the P/T method and the flowmeter method. The flowmeter method has always been a research focus because of its simple operation low cost and solid real-time performance. Current research has shown the accuracy of the flowmeter method under specific conditions. However many factors in the real scenario will influence the test result such as unintended vibration environment temperature and onboard hydrogen capacity calibration. On the other hand the short-cut method is also researched to replace the run-out method to improve test efficiency. To evaluate whether the flowmeter method basing on the short-cut method can genuinely reflect the hydrogen consumption of an actual vehicle we research and test for New European Driving Cycle (NEDC) and China Light-Duty Vehicle Test Cycle (CLTC) using the same vehicle. The results show that the short-cut method can save at least 50% of the test time compared with the run-out method. The error of the short-cut method based on the flowmeter for the NEDC working condition is less than 0.1% and for the CLTC working conditions is 8.12%. After adding a throttle valve and a 4L buffer tank the error is reduced to 4.76% from 8.12%. The test results show that hydrogen consumption measurement based on the flowmeter and short-cut method should adopt corresponding solutions according to the scenarios.

Conventional technologies are largely powered by fossil fuel exploitation and have ultimately led to extensive environmental concerns. Hydrogen is an excellent carbon-free energy carrier but its storage and long-distance transportation remain big challenges. Ammonia however is a promising indirect hydrogen storage medium that has well-established storage and transportation links to make it an accessible fuel source. Moreover the notion of ‘green ammonia’ synthesised from renewable energy sources is an emerging topic that may open significant markets and provide a pathway to decarbonise a variety of applications reliant on fossil fuels. Herein a comparative study based on the chosen design working principles advantages and disadvantages of direct ammonia fuel cells is summarised. This work aims to review the most recent advances in ammonia fuel cells and demonstrates how close this technology type is to integration with future applications. At present several challenges such as material selection NOx formation CO2 tolerance limited power densities and long-term stability must still be overcome and are also addressed within the contents of this review

Power-to-X processes where renewable energy is converted into storable liquids or gases are considered to be one of the key approaches for decarbonizing energy systems and compensating for the volatility involved in generating electricity from renewable sources. In this context the production of “green” hydrogen and hydrogen-based derivatives is being discussed and tested as a possible solution for the energy-intensive industry sector in particular. Given the sharp ongoing increases in electricity and gas prices and the need for sustainable energy supplies in production systems non-energy-intensive companies should also be taken into account when considering possible utilization paths for hydrogen. This work focuses on the following three utilization paths: “hydrogen as an energy storage system that can be reconverted into electricity” “hydrogen mobility” for company vehicles and “direct hydrogen use”. These three paths are developed modeled simulated and subsequently evaluated in terms of economic and environmental viability. Different photovoltaic system configurations are set up for the tests with nominal power ratings ranging from 300 kWp to 1000 kWp. Each system is assigned an electrolyzer with a power output ranging between 200 kW and 700 kW and a fuel cell with a power output ranging between 5 kW and 75 kW. There are also additional variations in relation to the battery storage systems within these basic configurations. Furthermore a reference variant without battery storage and hydrogen technologies is simulated for each photovoltaic system size. This means that there are ultimately 16 variants to be simulated for each utilization path. The results show that these utilization paths already constitute a reasonable alternative to fossil fuels in terms of costs in variants with a suitable energy system design. For the “hydrogen as an energy storage system” path electricity production costs of between 43 and 79 ct/kWh can be achieved with the 750 kWp photovoltaic system. The “hydrogen mobility” is associated with costs of 12 to 15 ct/km while the “direct hydrogen use” path resulted in costs of 8.2 €/kg. Environmental benefits are achieved in all three paths by replacing the German electricity mix with renewable energy sources produced on site or by substituting hydrogen for fossil fuels. The results confirm that using hydrogen as a storage medium in manufacturing companies could be economically and environmentally viable. These results also form the basis for further studies e.g. on detailed operating strategies for hydrogen technologies in scenarios involving a combination of multiple utilization paths. The work also presents the simulation-based method developed in this project which can be transferred to comparable applications in further studies.