Publications

The valorization of integrated steelworks process off-gases as feedstock for synthesizing methane and methanol is in line with European Green Deal challenges. However this target can be generally achieved only through process off-gases enrichment with hydrogen and use of cutting-edge syntheses reactors coupled to advanced control systems. These aspects are addressed in the RFCS project i3 upgrade and the central role of hydrogen was evident from the first stages of the project. First stationary scenario analyses showed that the required hydrogen amount is significant and existing renewable hydrogen production technologies are not ready to satisfy the demand in an economic perspective. The poor availability of low-cost green hydrogen as one of the main barriers for producing methane and methanol from process off-gases is further highlighted in the application of an ad-hoc developed dispatch controller for managing hydrogen intensified syntheses in integrated steelworks. The dispatch controller considers both economic and environmental impacts in the cost function and although significant environmental benefits are obtainable by exploiting process off-gases in the syntheses the current hydrogen costs highly affect the dispatch controller decisions. This underlines the need for big scale green hydrogen production processes and dedicated green markets for hydrogen-intensive industries which would ensure easy access to this fundamental gas paving the way for a C-lean and more sustainable steel production.

Hydrogen eliminates carbon emissions from compression ignition (CI) engines while noble gases eliminate nitrogen oxide (NOx) emissions by replacing nitrogen. Noble gases can increase the in-cylinder temperature during the compression stroke due to their high specific heat ratio. This paper aims to find the optimum parameters for hydrogen combustion in an argon–oxygen atmosphere and to study hydrogen combustion in all noble gases providing hydrogen combustion data with suitable engine parameters to predict hydrogen ignitability under different conditions. Simulations are performed with Converge CFD software based on the Yanmar NF19SK direct injection CI (DICI) engine parameters. The results are validated with the experimental results of hydrogen combustion in an argon–oxygen atmosphere with a rapid compression expansion machine (RCEM) and modifications of the hydrogen injection timing and initial temperature are proposed. Hydrogen ignition in an argon atmosphere is dependent on a minimum initial temperature of 340 K but the combustion is slightly unstable. Helium and neon are found to be suitable for hydrogen combustion in low compression ratio (CR) engines. However krypton and xenon require temperature modification and a high CR for stable ignition. Detailed parameter recommendations are needed to improve hydrogen ignitability in conventional diesel engines with the least engine modification.

Liquid organic hydrogen carriers (LOHC) can be used as a lossless form of hydrogen storage at ambient conditions. The storage cycle consists of the exothermic hydrogenation of a hydrogen-lean molecule at the start of the transport usually the hydrogen production site becoming a hydrogen-rich molecule. This loaded molecule can be transported long distances or be used as long-term storage due to its ability to not lose hydrogen over long periods of time. At the site or time of required hydrogen production the hydrogen can be released through an endothermic dehydrogenation reaction. LOHCs show similar properties to crude oils such as petroleum and diesel allowing easy handling and possibilities of integration with current infrastructure. Using this background this paper reviews a variety of aspects of the LOHC life cycle with a focus on currently studied materials. Important factors such as the hydrogenation and dehydrogenation requirements for each material are analysed to determine their ability to be used in current scenarios. Toluene and dibenzyltoluene are attractive options with promising storage attributes however their dehydrogenation enthalpies remain a problem. The economic feasibility of LOHCs being used as a delivery device were briefly analysed. LOHCs have been shown to be the cheapest option for long distance transport (>200 km) and are cheaper than most at shorter distances in terms of specifically transport costs. The major capital cost of an LOHC delivery chain remains the initial investment for the raw materials and the cost of equipment for performing hydrogenation and dehydrogenation. Finally some studies in developing the LOHC field were discussed such as microwave enhancing parts of the process and mixing LOHCs to acquire more advantageous properties.

This paper discusses the technical specifications of how U.S. petroleum refineries can reduce facility emissions and shift to produce low-carbon fuels for hard to abate sectors by utilizing existing innovative technologies.

Austria is committed to the net-zero climate goal along with the European Union. This requires all sectors to be decarbonized. Hereby hydrogen plays a vital role as stated in the national hydrogen strategy. A report commissioned by the Austrian government predicts a minimum hydrogen demand of 16 TWh per year in Austria in 2040. Besides hydrogen imports domestic production can ensure supply. Hence this study analyses the levelized cost of hydrogen for an off-grid production plant including a proton exchange membrane electrolyzer wind power and solar photovoltaics in Austria. In the first step the capacity factors of the renewable electricity sources are determined by conducting a geographic information system analysis. Secondly the levelized cost of electricity for wind power and solarphotovoltaics plants in Austria is calculated. Thirdly the most cost-efficient portfolio of wind power and solar photovoltaics plants is determined using electricity generation profiles with a 10-min granularity. The modelled system variants differ among location capacity factors of the renewable electricity sources and the full load hours of the electrolyzer. Finally selected variables are tested for their sensitivities. With the applied model the hydrogen production cost for decentralized production plants can be calculated for any specific location. The levelized cost of hydrogen estimates range from 3.08 EUR/kg to 13.12 EUR/kg of hydrogen whereas it was found that the costs are most sensitive to the capacity factors of the renewable electricity sources and the full load hours of the electrolyzer. The novelty of the paper stems from the model applied that calculates the levelized cost of renewable hydrogen in an off-grid hydrogen production system. The model finds a cost-efficient portfolio of directly coupled wind power and solar photovoltaics systems for 80 different variants in an Austria-specific context.

The impact of hydrogen added to natural gas on the performance of commercial domestic water heating devices has been discussed in several recent papers in the literature. Much of the work focuses on performance at specific hydrogen levels (by volume) up to 20–30% as a near term blend target. In the current work new data on several commercial devices have been obtained to help quantify upper limits based on flashback limits. In addition results from 39 individual devices are compiled to help generalize observations regarding performance. The emphasis of this work is on emissions performance and especially NOx emissions. It is important to consider the reporting bases of the emissions numbers to avoid any unitended bias. For water heaters the trends associated with both mass per fuel energy input and concentration-based representation are similar For carbon free fuels bases such as 12% CO2 should be avoided. In general the compiled data shows that NOx NO UHC and CO levels decrease with increasing hydrogen percentage. The % decrease in NOx and NO is greater for low NOx devices (meaning certified to NOx <10 ng/J using premixing with excess air) compared to conventional devices (“pancake burners” partial premixing). Further low NOx devices appear to be able to accept greater amounts of hydrogen above 70% hydrogen in some cases without modification while conventional water heaters appear limited to 40–50% hydrogen. Reporting emissions on a mass basis per unit fuel energy input is preferred to the typical dry concentration basis as the greater amount of water produced by hydrogen results in a perceived increase in NOx when hydrogen is used. While this effort summarizes emissions performance with added hydrogen additional work is needed on transient operation higher levels of hydrogen system durability/reliability and heating efficiency.

The energy transition calls for natural hydrogen exploration with most occurrences discovered either inadvertently or more recently at the location of potentially diffusive circles observed from a change of vegetation cover at the surface. However some notable hydrogen occurrences are not directly associated with the presence of diffusive circles like the Bourakebougou field in Mali. Thus the objective of this work was to highlight geological areas that have some potential to find natural hydrogen in Quebec a Canadian province where no diffusive circles have yet been documented but which is rich in potential source rocks and where no exploration for natural hydrogen has been undertaken so far. A review of the different geological regions of Quebec was undertaken to highlight the relevant characteristics and geographical distribution of geological assemblages that may produce or have produced natural hydrogen in particular iron-rich rocks but also uranium-rich rocks supramature shales and zones where significant structural discontinuities are documented or suspected which may act as conduits for the migration of fluids of mantle origin. In addition to regional and local geological data an inventory of available geochemical data is also carried out to identify potential tracers or proxies to facilitate subsequent exploration efforts. A rating was then proposed based on the quality of the potential source rocks which also considers the presence of reservoir rocks and the proximity to end-users. This analysis allowed rating areas of interest for which fieldwork can be considered thus minimizing the exploratory risks and investments required to develop this resource. The size of the study area (over 1.5 million km2 ) the diversity of its geological environments (from metamorphic cratons to sedimentary basins) and their wide age range (from Archean to Paleozoic) make Quebec a promising territory for natural hydrogen exploration and to test the systematic rating method proposed here.

Fossil fuel consumption has triggered worries about energy security and climate change; this has promoted hydrogen as a viable option to aid in decarbonizing global energy systems. Hydrogen could substitute for fossil fuels in the future due to the economic political and environmental concerns related to energy production using fossil fuels. However currently the majority of hydrogen is produced using fossil fuels particularly natural gas which is not a renewable source of energy. It is therefore crucial to increase the efforts to produce hydrogen from renewable sources rather from the existing fossil-based approaches. Thus this study investigates how renewable energy can accelerate the production of hydrogen fuel in the future under three hydrogen economy-related energy regimes including nuclear restrictions hydrogen and city gas blending and in the scenarios which consider the geographic distribution of carbon reduction targets. A random effects regression model has been utilized employing panel data from a global energy system which optimizes for cost and carbon targets. The results of this study demonstrate that an increase in renewable energy sources has the potential to significantly accelerate the growth of future hydrogen production under all the considered policy regimes. The policy implications of this paper suggest that promoting renewable energy investments in line with a fairer allocation of carbon reduction efforts will help to ensure a future hydrogen economy which engenders a sustainable low carbon society.

Within integrated steelmaking industries significant research efforts are devoted to the efficient use of resources and the reduction of CO2 emissions. Integrated steelworks consume a considerable quantity of raw materials and produce a high amount of by-products such as off-gases currently used for the internal production of heat steam or electricity. These off-gases can be further valorized as feedstock for methane and methanol syntheses but their hydrogen content is often inadequate to reach high conversions in synthesis processes. The addition of hydrogen is fundamental and a suitable hydrogen production process must be selected to obtain advantages in process economy and sustainability. This paper presents a comparative analysis of different hydrogen production processes from renewable energy namely polymer electrolyte membrane electrolysis solid oxide electrolyze cell electrolysis and biomass gasification. Aspen Plus® V11-based models were developed and simulations were conducted for sensitivity analyses to acquire useful information related to the process behavior. Advantages and disadvantages for each considered process were highlighted. In addition the integration of the analyzed hydrogen production methods with methane and methanol syntheses is analyzed through further Aspen Plus®-based simulations. The pros and cons of the different hydrogen production options coupled with methane and methanol syntheses included in steelmaking industries are analyzed

The path to the mitigation of global climate change and global carbon dioxide emissions avoidance leads to the large-scale substitution of fossil fuels for the generation of electricity with renewable energy sources. The transition to renewables necessitates the development of large-scale energy storage systems that will satisfy the hourly demand of the consumers. This paper offers an overview of the energy storage systems that are available to assist with the transition to renewable energy. The systems are classified as mechanical (PHS CAES flywheels springs) electromagnetic (capacitors electric and magnetic fields) electrochemical (batteries including flow batteries) hydrogen and thermal energy storage systems. Emphasis is placed on the magnitude of energy storage each system is able to achieve the thermodynamic characteristics the particular applications the systems are suitable for the pertinent figures of merit and the energy dissipation during the charging and discharging of the systems.

The green hydrogen–electric coupling system can consume locally generated renewable energy thereby improving energy utilization and enabling zero-carbon power supply within a certain range. This study focuses on a green hydrogen–electric coupling system that integrates photovoltaic energy storage and proton exchange membrane electrolysis (PEME). Firstly the impact of operating temperature power quality and grid auxiliary services on the characteristics of the electrolysis cell is analyzed and a voltage model and energy model for the cell are established. Secondly a multi-operating conditions adaptability experiment for PEME grid-connected operation is designed. A test platform consisting of a grid simulator simulated photovoltaic power generation system lithium battery energy storage system PEME and measurement and acquisition device is then built. Finally experiments are conducted to simulate multi-operating conditions such as temperature changes voltage fluctuations frequency offsets harmonic pollution and current adjustment speed. The energy efficiency and consumption is calculated based on the recorded data and the results are helpful to guide the operation of the system.

National Implementation Plans (NIP) in regard hydrogenation motor transport are in place in European Union (EU) countries e.g.Germany France or Belgium Denmark Netherlands. Motor transport hydrogenization plans exist in the Japan and USA. In Poland the methodology deployment Hydrogen Refuelling Stations (HRS) developed in Motor Transport Institute is of multi-stage character are as follows: Stage I: Method allowing to identify regions in which HRS should be located. Stage II: Method allowing to identify urban centres in which should be located the said stations. Stage III: Method for determining the area of the station location. The presentation of the aforesaid NIPS and based on that and the mentioned methodology the conditions for hydrogenization of motor transport in Poland is the purpose of this article which constitutes its novelty. The scope of the article concerns the hydrogenization of motor transport in the abovementioned countries. With the above criteria the order the construction in Poland of a HRS in the order of their creation along the TEN-T corridors is as follows: 1 - Poznan 2 - Warsaw 3 - Bialystok 4 - Szczecin 5 - the Lodz region 6 - the Tri-City region 7 - Wrocław 8 - the Katowice region 9 – Krakow. The concluding discussion sets out the status of deployment HRS and FCEVs in the analysed countries.

This study presents the results of economic and environmental analysis for two types of zero-emission ships (ZESs) that are receiving more attention to meet strengthened environmental regulations. One of the two types of ZES is the ZES using only the energy storage system (All-ESS) and the other is the ZES with fuel cell and ESS hybrid system (FC–ESS). The target ship is a tug operating in South Korea and the main parameters are based on the specific circumstances of South Korea. The optimal capacity of the ESS for each proposed system is determined using an optimization tool. The total cost for a ship’s lifetime is calculated using economic analysis. The greenhouse gas (GHG) emission for the fuel’s lifecycle (well-to-wake) is calculated using environmental analysis. The results reveal that the proposed ZESs are 1.7–3.4 times more expensive than the conventional marine gas oil (MGO)-fueled ship; however it could be reduced by 1.3–2.4 times if the carbon price is considered. The proposed ZESs have 58.7–74.3% lower lifecycle GHG emissions than the one from the conventional ship. The results also highlight that the electricity- or hydrogen-based ZESs should reduce GHG emissions from the upstream phase (well-to-tank) to realize genuine ZESs.

This paper presents a wind-methanol-fuel cell system with hydrogen storage. It can manage various energy flow to provide stable wind power supply produce constant methanol and reduce CO2 emissions. Firstly this study establishes the theoretical basis and formulation algorithms. And then computational experiments are developed with MATLAB/Simulink (R2016a MathWorks Natick MA USA). Real data are used to fit the developed models in the study. From the test results the developed system can generate maximum electricity whilst maintaining a stable production of methanol with the aid of a hybrid energy storage system (HESS). A sophisticated control scheme is also developed to coordinate these actions to achieve satisfactory system performance.

China is the world’s largest producer and consumer of hydrogen. The country has adopted a domestic strategy that targets significant growth in hydrogen consumption and production. Given the importance of hydrogen in the low-carbon energy transition it is critical to understand China’s hydrogen policies and their implementation as well as the extent to which these contribute to the country’s low-carbon goals.<br/>Existing research has focused on understanding policies and regulations in China and their implications for the country’s hydrogen prospects. This study aims to improve our understanding of central-government initiatives and look at how China’s hydrogen policies are implemented at the local level. The paper examines the three cities of Zhangjiakou (in China’s renewable-rich Hebei province) Datong (in the country’s coal-heartland of Shanxi province) and Chengdu which is rich in hydropower and natural gas. To be sure the three cities analysed in this paper do not cover all regional plans and initiatives but they offer a useful window into local hydrogen policy implementation. They also illustrate the major challenges facing green hydrogen as it moves beyond the narrow highly subsidized field of fuel cell vehicles (FCVs). Indeed costs as well as water land availability and technology continue to be constraints.<br/>The hydrogen policies and road maps reviewed in this paper offer numerous targets—often setting quantitative goals for FCVs hydrogen refuelling stations hydrogen supply chain revenue and new hydrogen technology companies—aligning with the view that hydrogen development is currently more of an industrial policy than a decarbonisation strategy. Indeed hydrogen’s potential to decarbonise sectors such as manufacturing and chemicals is of secondary importance if mentioned at all. But as the cities analysed here view hydrogen as part of their industrial programmes economic development and climate strategies support is likely to remain significant even as the specific incentive schemes will likely evolve.<br/>Given this local hydrogen development model rising demand for hydrogen in China could ultimately increase rather than decrease CO₂ emissions from fossil fuels in the short run. At the same time even though the central government’s hydrogen targets (as laid out in its 2022 policy documents) seem relatively conservative Chinese cities’ appetite for new sources of growth and the ability to fund various business models are worth watching.

Decarbonising energy is fundamental in the transition towards a sustainable future. Our Future Energy Scenarios aim to stimulate debate to inform the decisions that will help move us towards achieving carbon reduction targets and ultimately shape the energy system of the future.

Supporting policies to achieve a green revolution and ecological transition is a global trend. Although the maritime transport of goods and people can rightly be counted among the least polluting sectors much can be done to further reduce its environmental footprint. Moreover to boost the ecological transition of vessels a whole series of international regulations and national laws have been promulgated. Among these the most impactful on both design and operational management of ships concern the containment of air-polluting emissions in terms of GHG NOx SOx and PM. To address this challenge it might seem that many technologies already successfully used in other transport sectors could be applied. However the peculiar characteristics of ships make this statement not entirely true. In fact technological solutions recently adopted for example in the automotive sector must deal with the large size of vessels and the consequent large amount of energy necessary for their operation. In this paper with reference to the case study of a medium/large-sized passenger cruise ship the use of different fuels (LNG ammonia hydrogen) and technologies (internal combustion engines fuel cells) for propulsion and energy generation on board will be compared. By imposing the design constraint of not modifying the payload and the speed of the ship the criticalities linked to the use of one fuel rather than another will be highlighted. The current limits of application of some fuels will be made evident with reference to the state of maturity of the relevant technologies. Furthermore the operational consequences in terms of autonomy reduction will be presented. The obtained results underline the necessity for shipowners and shipbuilders to reflect on the compromises required by the challenges of the ecological transition which will force them to choose between reducing payload or reducing performance.

Traditional charging stations have a single function which usually does not consider the construction of energy storage facilities and it is difficult to promote the consumption of new energy. With the gradual increase in the number of new energy vehicles (NEVs) to give full play to the complementary advantages of source-load resources and provide safe efficient and economical energy supply services this paper proposes the optimal operation strategy of a PV-charging-hydrogenation composite energy station (CES) that considers demand response (DR). Firstly the operation mode of the CES is analyzed and the CES model including a photovoltaic power generation system fuel cell hydrogen production hydrogen storage hydrogenation and charging is established. The purpose is to provide energy supply services for electric vehicles (EVs) and hydrogen fuel cell vehicles (HFCVs) at the same time. Secondly according to the travel law of EVs and HFCVs the distribution of charging demand and hydrogenation demand at different periods of the day is simulated by the Monte Carlo method. On this basis the following two demand response models are established: charging load demand response based on the price elasticity matrix and interruptible load demand response based on incentives. Finally a multi-objective optimal operation model considering DR is proposed to minimize the comprehensive operating cost and load fluctuation of CES and the maximum–minimum method and analytic hierarchy process (AHP) are used to transform this into a linearly weighted single-objective function which is solved via an improved moth–flame optimization algorithm (IMFO). Through the simulation examples operation results in four different scenarios are obtained. Compared with a situation not considering DR the operation strategy proposed in this paper can reduce the comprehensive operation cost of CES by CNY 1051.5 and reduce the load fluctuation by 17.8% which verifies the effectiveness of the proposed model. In addition the impact of solar radiation and energy recharge demand changes on operations was also studied and the resulting data show that CES operations were more sensitive to energy recharge demand changes.

Tropical countries can approach their natural resources to produce low-carbon H2 from solar wind hydro and biomass resources to satisfy their domestic demand and to export it. To do so Colombia published the National Hydrogen Roadmap in which green H2 was prioritized. This study estimates Colombia's potential to produce green H2 and a timeline of scenarios displaying the required installed capacity capital investment and environmental analysis related to water utilization and CO2 capture. Accordingly Colombia can produce H2 at a rate of 9 Mt/a by 2050 by installing 121 GW renewables while processing 303 Mt/a of residual biomass. In this scenario Colombia's share of the H2 international market can reach 1.2% with a cumulative investment of over 244 billion USD by 2050. This study provides insights into potential global resources for low-carbon H2 generation.

Hydrogen has recently been proposed as a versatile energy carrier to contribute to archiving universal access to clean cooking. In hard-to-reach rural settings decentralized produced hydrogen may be utilized (i) as a clean fuel via direct combustion in pure gaseous form or blended with Liquid Petroleum Gas (LPG) or (ii) via power-to-hydrogen-to-power (P2H2P) to serve electric cooking (e-cooking) appliances. Here we present the first techno-economic evaluation of hydrogen-based cooking solutions. We apply mathematical optimization via energy system modeling to assess the minimal cost configuration of each respective energy system on technical and economic measures under present and future parameters. We further compare the potential costs of cooking for the end user with the costs of cooking with traditional fuels. Today P2H2P-based e-cooking and production of hydrogen for utilization via combustion integrated into the electricity supply system have almost equal energy system costs to simultaneously satisfy the cooking and electricity needs of the isolated rural Kenyan village studied. P2H2P-based e-cooking might become advantageous in the near future when improving the energy efficiency of e-cooking appliances. The economic efficiency of producing hydrogen for utilization by end users via combustion benefits from integrating the water electrolysis into the electricity supply system. More efficient and cheaper hydrogen technologies expected by 2050 may improve the economic performance of integrated hydrogen production and utilization via combustion to be competitive with P2H2P-based e-cooking. The monthly costs of cooking per household may be lower than the traditional use of firewood and charcoal even today when applying the current life-line tariff for the electricity consumed or utilizing hydrogen via combustion. Driven by likely future technological improvements and the expected increase in traditional and fossil fuel prices any hydrogen-based cooking pathway may be cheaper for end users than using charcoal and firewood by 2030 and LPG by 2040. The results suggest that providing clean cooking in rural villages could economically and environmentally benefit from utilizing hydrogen. However facing the complexity of clean cooking projects we emphasize the importance of embedding the results of our techno-economic analysis in holistic energy delivery models. We propose useful starting points for future aspects to be investigated in the discussion section including business and financing models.

Although polymer electrolyte water electrolyzers (PEWEs) have been used in small-scale (kW to tens of kW range) applications for several decades PEWE technology for hydrogen production in energy applications (power-to-gas power-to-fuel etc.) requires significant improvements in the technology to address the challenges associated with cost performance and durability. Systems with power of hundreds of kW or even MWs corresponding to hydrogen production rates of around 10 to 20 kg/h have started to appear in the past 5 years. The thin (∼0.2 mm) polymer electrolyte in the PEWE with low ohmic resistance compared to the alkaline cell with liquid electrolyte allows operation at high current densities of 1–3 A/cm2 and high differential pressure. This article after an introductory overview of the operating principles of PEWE and state-of-the-art discusses the state of understanding of key phenomena determining and limiting performance durability and commercial readiness identifies important ‘gaps’ in understanding and essential development needs to bring PEWE science & engineering forward to prosper in the energy market as one of its future backbone technologies. For this to be successful science engineering and process development as well as business and market development need to go hand in hand.

Electrochemical ammonia generation allows direct low pressure synthesis of ammonia as an alternative to the established Haber-Bosch process. The increasing need to drive industry with renewable electricity central to decarbonisation and electrochemical ammonia synthesis offers a possible efficient and low emission route for this increasingly important chemical. It also provides a potential route for more distributed and small-scale ammonia synthesis with a reduced production footprint. Electrochemical ammonia synthesis is still early stage but has seen recent acceleration in fundamental understanding. In this work two different ammonia electrolysis systems are considered. Balance of plant (BOP) requirements are presented and modelled to compare performance and determine trade-offs. The first option (water fed cell) uses direct ammonia synthesis from water and air. The second (hydrogen-fed cell) involves a two-step electrolysis approach firstly producing hydrogen followed by electrochemical ammonia generation. Results indicate that the water fed approach shows the most promise in achieving low energy demand for direct electrochemical ammonia generation. Breaking the reaction into two steps for the hydrogen fed approach introduces a source of inefficiency which is not overcome by reduced BOP energy demands and will only be an attractive pathway for reactors which promise both high efficiency and increased ammonia formation rate compared to water fed cells. The most optimised scenario investigated here with 90% faradaic efficiency (FE) and 1.5 V cell potential (75% nitrogen utilisation) gives a power to ammonia value of 15 kWh/kg NH3 for a water fed cell. For the best hydrogen fed arrangement the requirement is 19 kWh/kg NH3. This is achieved with 0.5 V cell potential and 75% utilisation of both hydrogen and nitrogen (90% FE). Modelling demonstrated that balance of plant requirements for electrochemical ammonia are significant. Electrochemical energy inputs dominate energy requirements at low FE however in cases of high FE the BOP accounts for approximately 50% of the total energy demand mostly from ammonia separation requirements. In the hydrogen fed cell arrangement it was also demonstrated that recycle of unconverted hydrogen is essential for efficient operation even in the case where this increases BOP energy inputs

Alternative fuels are crucial to decarbonize the European maritime transport but their net climate benefits vary with the type of fuel and production country. In this study we assess the energy potential and climate change mitigation benefits of using agricultural and forest residues in different European countries for drop-in (Fast Pyrolysis Hydrothermal Liquefaction and Gasification to Fischer-Tropsch fuels or Bio-Synthetic Natural Gas) and hydrogen-based biofuels (hydrogen ammonia and methanol) with or without carbon capture and storage (CCS). Our results show the combinations of countries and biofuel options that successfully achieve the decarbonization targets set by the FuelEU Maritime initiative for the next years including a prospective analysis that include technological changes projected for the biofuel supply chains until 2050. With the current technologies the largest greenhouse gas (GHG) mitigation potential per year at a European scale is obtained with bio-synthetic natural gas and hydrothermal liquefaction. Among carbon-free biofuels ammonia currently has higher mitigation but hydrogen can achieve a lower GHG intensity per unit of energy with the projected decarbonization of the electricity mixes until 2050. The full deployment of CCS can further accelerate the decarbonization of the maritime sector. Choosing the most suitable renewable fuels requires a regional perspective and a transition roadmap where countries coordinate actions to meet ambitious climate targets.

Ammonia (NH3) is among the largest-volume chemicals produced and distributed in the world and is mainly known for its use as a fertilizer in the agricultural sector. In recent years it has sparked interest in the possibility of working as a high-quality energy carrier and as a carbon-free fuel in internal combustion engines (ICEs). This review aimed to provide an overview of the research on the use of green ammonia as an alternative fuel for ICEs with a look to the future on possible applications and practical solutions to related problems. First of all the ammonia production process is discussed. Present ammonia production is not a “green” process; the synthesis occurs starting from gaseous hydrogen currently produced from hydrocarbons. Some ways to produce green ammonia are reviewed and discussed. Then the chemical and physical properties of ammonia as a fuel are described and explained in order to identify the main pros and cons of its use in combustion systems. Then the most viable solutions for fueling internal combustion engines with ammonia are discussed. When using pure ammonia high boost pressure and compression ratio are required to compensate for the low ammonia flame speed. In spark-ignition engines adding hydrogen to ammonia helps in speeding up the flame front propagation and stabilizing the combustion. In compression-ignition engines ammonia can be successfully used in dual-fuel mode with diesel. On the contrary an increase in NOx and the unburned NH3 at the exhaust require the installation of apposite aftertreatment systems. Therefore the use of ammonia seems to be more practicable for marine or stationary engine application where space constraints are not a problem. In conclusion this review points out that ammonia has excellent potential to play a significant role as a sustainable fuel for the future in both retrofitted and new engines. However significant further research and development activities are required before being able to consider large-scale industrial production of green ammonia. Moreover uncertainties remain about ammonia safe and effective use and some technical issues need to be addressed to overcome poor combustion properties for utilization as a direct substitute for standard fuels.

The report “Policy Toolbox for Low Carbon and Renewable Hydrogen” is based on an assessment of the performance of hydrogen policies in different stages of market maturity and segments of the value chain. 48 policies were shortlisted based on their economic efficiency and effectiveness and mapped to barriers across the value chain and over time. These policies were subsequently clustered into policy packages for three country archetypes: a self-sufficient hydrogen producer an importer and an exporter of hydrogen.

The paper can be found on their website.