Publications

Grand Canonical Monte Carlo GCMC simulations are used to study the gravimetric and volumetric hydrogen storage capacities of different carbon nanopores shapes: Slit-shaped nanotubes and torusenes at room temperature 298.15 K and at pressures between 0.1 and 35 MPa and for pore diameter or width between 4 and 15 A. The influence of the pore shape or curvature on the storage capacities as a function of pressure temperature and pore diameter is investigated and analyzed. A large curvature of the pores means in general an increase of the storage capacities of the pores. While torusenes and nanotubes have surfaces with more curvature than the slit-shaped planar pores their capacities are lower than those of the slit-shaped pores according to the present GCMC simulations. Torusene a less studied carbon nanostructure has two radii or curvatures but their storage capacities are similar or lower than those of nanotubes which have only one radius or curvature. The goal is to obtain qualitative and quantitative relationships between the structure of porous materials and the hydrogen storage capacities in particular or especially the relationship between shape and width of the pores and the hydrogen storage capacities of carbon-based porous materials.

Policy led decisions aiming at decarbonizing the economy may well exacerbate existing regional economic imbalances. These effects are seldomly recognised in spatially aggregated top-down and techno-economic decarbonization strategies. Here we present a spatial economic framework that quantifies the gross value added associated with low carbon hydrogen investments while accounting for region-specific factors such as the industrial specialization of regions their relative size and their economic interdependencies. In our case study which uses low carbon hydrogen produced via autothermal reforming combined with carbon capture and storage to decarbonize the energy intensive industries in Europe and in the UK we demonstrate that interregional economic interdependencies drive the overall economic benefits of the decarbonization. Policies intended to concurrently transition to net zero and address existing regional imbalances as in the case of the UK Industrial Decarbonization Challenge should take these local factors into account.

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

This paper is the first to explore public perceptions about a particular market niche for hydrogen; mobile generators. By utilising a combined research approach including in-situ surveys and online focus groups this paper explores what festival audience members and residents who live near festival sites think about the displacement of incumbent diesel generator technology with hydrogen alternatives. We investigate if hydrogen production methods are important in informing perceptions and subsequent support including the extent to which participants are influenced by the organisation or entity that produces the fuel and stands to profit from its sale. In addition to a primary focus on hydrogen energy we reflect upon how sustainability might be better conceptualised in a festival context. Our findings reveal broad support for hydrogen generators the use of green hydrogen as a fuel to generate electricity and community-led hydrogen production.

The opportunities and challenges to reducing industrial energy demand and carbon dioxide (CO₂ ) emissions in the Chemicals sector are evaluated with a focus on the situation in the United Kingdom (UK) although the lessons learned are applicable across much of the industrialised world. This sector can be characterised as being heterogeneous; embracing a diverse range of products (including advanced materials cleaning fluids composites dyes paints pharmaceuticals plastics and surfactants). It sits on the boundary between energy-intensive (EI) and non-energy-intensive (NEI) industrial sectors. The improvement potential of various technological interventions has been identified in terms of their energy use and greenhouse gas (GHG) emissions. Currently-available best practice technologies (BPTs) will lead to further short-term energy and CO₂ emissions savings in chemicals processing but the prospects for the commercial exploitation of innovative technologies by mid-21st century are far more speculative. A set of industrial decarbonisation ‘technology roadmaps’ out to the mid-21st Century are also reported based on various alternative scenarios. These yield low-carbon transition pathways that represent future projections which match short-term and long-term (2050) targets with specific technological solutions to help meet the key energy saving and decarbonisation goals. The roadmaps’ contents were built up on the basis of the improvement potentials associated with various processes employed in the chemicals industry. They help identify the steps needed to be undertaken by developers policy makers and other stakeholders in order to ensure the decarbonisation of the UK chemicals industry. The attainment of significant falls in carbon emissions over this period will depends critically on the adoption of a small number of key technologies [e.g. carbon capture and storage (CCS) energy efficiency techniques and bioenergy] alongside a decarbonisation of the electricity supply.

The present work addresses the modelling control and simulation of a microgrid integrated wind power system with Doubly Fed Induction Generator (DFIG) using a hybrid energy storage system. In order to improve the quality of the waveforms (voltages and currents) supplied to the grid instead of a two level-inverter the rotor of the DFIG is supplied using a three-level inverter. A new adaptive algorithm based on combined Direct Reactive Power Control (DRPC) and fuzzy logic controls techniques is applied to the proposed topology. In this work two topologies are proposed. In the first one the active power injected into the grid is smoothened by using an economical hybrid battery and supercapacitor energy storage system. However in the second one the excess wind energy is used to produce and store the hydrogen and then a solid oxide fuel cell system (SOFC) is utilized to regenerate electricity by using the stored hydrogen when there is not enough wind energy. To avoid overcharging deep discharging of batteries to mitigate fluctuations due to wind speed variations and to fulfil the requirement of the load profile a power management algorithm is implemented. This algorithm ensures smooth output power in the first topology and service continuity in the second. The modelling and simulation results are presented and analysed using Matlab/Simulin.

The time-range of applicability of various energy-storage technologies are limited by self-discharge and other inevitable losses. While batteries and hydrogen are useful for storage in a time-span ranging from hours to several days or even weeks for seasonal or multi-seasonal storage only some traditional and quite costly methods can be used (like pumped-storage plants Compressed Air Energy Storage or energy tower). In this paper we aim to show that while the efficiency of energy recovery of Power-to-Methane technology is lower than for several other methods due to the low self-discharge and negligible standby losses it can be a suitable and cost-effective solution for seasonal and multi-seasonal energy storage.

Green synthesis of crystalline porous materials for energy-related applications is of great significance but very challenging. Here we create a green strategy to fabricate a highly crystalline olefin-linked pyrazine-based covalent organic framework (COF) with high robustness and porosity under solvent-free conditions. The abundant nitrogen sites high hydrophilicity and well-defined one-dimensional nanochannels make the resulting COF an ideal platform to confine and stabilize the H₃PO₄ network in the pores through hydrogen-bonding interactions. The resulting material exhibits low activation energy (E_a) of 0.06 eV and ultrahigh proton conductivity across a wide relative humidity (10–90 %) and temperature range (25–80 °C). A realistic proton exchange membrane fuel cell using the olefin-linked COF as the solid electrolyte achieve a maximum power of 135 mW cm⁻² and a current density of 676 mA cm⁻² which exceeds all reported COF materials.

Low-carbon hydrogen has the potential to play a significant role in tackling climate change and poor air quality. This policy briefing considers how hydrogen could be produced at a useful scale to power vehicles heat homes and supply industrial processes.

Four groups of hydrogen production technologies are examined:

Thermochemical Routes to Hydrogen

These methods typically use heat and fossil fuels. Steam methane reforming is the dominant commercial technology and currently produces hydrogen on a large scale but is not currently low carbon. Carbon capture is therefore essential with this process. Innovative technology developments may also help and research is underway. Alternative thermal methods of creating hydrogen indicate biomass gasification has potential. Other techniques at a low technology readiness level include separation of hydrogen from hydrocarbons using microwaves.

Electrolytic Routes to Hydrogen

Electrolytic hydrogen production also known as electrolysis splits water into hydrogen and oxygen using electricity in an electrolysis cell. Electrolysis produces pure hydrogen which is ideal for low temperature fuel cells for example in electric vehicles. Commercial electrolysers are on the market and have been in use for many years. Further technology developments will enable new generation electrolysers to be commercially competitive when used at scale with fluctuating renewable energy sources.

Biological Routes to Hydrogen

Biological routes usually involve the conversion of biomass to hydrogen and other valuable end products using microbial processes. Methods such as anaerobic digestion are feasible now at a laboratory and small pilot scale. This technology may prove to have additional or greater impact and value as route for the production of high value chemicals within a biorefinery concept.

Solar to Fuels Routes to Hydrogen

A number of experimental techniques have been reported the most developed of which is ‘solar to fuels’ - a suite of technologies that typically split water into hydrogen and oxygen using solar energy. These methods have close parallels with the process of photosynthesis and are often referred to as ‘artificial photosynthesis’ processes. The research is promising though views are divided on its ultimate utility. Competition for space will always limit the scale up of solar to fuels.

The briefing concludes that steam methane reforming and electrolysis are the most likely technologies to be deployed to produce low-carbon hydrogen at volume in the near to mid-term providing that the challenges of high levels of carbon capture (for steam methane reforming) and cost reduction and renewable energy sources (for electrolysis) can be overcome.

Hydrogen energy with environment amicable renewable efficiency and cost-effective advantages is the future mainstream substitution of fossil-based fuel. However the extremely low volumetric density gives rise to the main challenge in hydrogen storage and therefore exploring effective storage techniques is key hurdles that need to be crossed to accomplish the sustainable hydrogen economy. Hydrogen physically or chemically stored into nanomaterials in the solid-state is a desirable prospect for effective large-scale hydrogen storage which has exhibited great potentials for applications in both reversible onboard storage and regenerable off-board storage applications. Its attractive points include safe compact light reversibility and efficiently produce sufficient pure hydrogen fuel under the mild condition. This review comprehensively gathers the state-of-art solid-state hydrogen storage technologies using nanostructured materials involving nanoporous carbon materials metal-organic frameworks covalent organic frameworks porous aromatic frameworks nanoporous organic polymers and nanoscale hydrides. It describes significant advances achieved so far and main barriers need to be surmounted to approach practical applications as well as offers a perspective for sustainable energy research.

The rapid increase in anthropogenic greenhouse gas concentrations in the last several decades means that the effects of climate change are fast becoming the familiar horsemen of a planetary apocalypse. Catalysis one of the pillars of the chemical and petrochemical industries will play a critical role in the effort to reduce the flow of greenhouse gases into the atmosphere. This Special Issue is timely as it provides a collection of high-quality manuscripts in a diverse range of topics which include the production of green hydrogen via water electrolysis the steam reforming of ethanol propane or glycerol the dry reforming of methane and the autothermal reforming of diesel surrogate fuel. The topic of the transformation of biomass waste to chemicals is also well represented as is the tackling of CO₂ emissions via novel utilization technologies. The Editors are grateful to all authors for their valuable contributions and confident that this Special Issue will prove valuable to scholars university professors and students alike.

There is a growing conversation around the role that hydrogen can play in the future of the UK and how to best harness its potential to secure jobs show climate leadership promote industrial competitiveness and drive innovation. The Government’s ‘Ten Point Plan for a Green Industrial Revolution’ included hydrogen as one of its ten actions targeting 5GW of ‘low carbon’ hydrogen production by 2030. Britain is thus joining the EU US Japan Germany and a host of other countries seeking to be part of the hydrogen economy of the future.<br/><br/>A focus on clean green hydrogen within targeted sectors and hubs can support multiple Government goals – including demonstrating climate leadership reducing regional inequalities through the ‘levelling up’ agenda and ensuring a green and cost-effective recovery from the coronavirus pandemic which prioritises jobs and skills. A strategic hydrogen vision must be honest and recognise where green hydrogen does not present the optimal pathway for decarbonisation – for instance where alternative solutions are already readily available for roll-out are more efficient and cost-effective. A clear example is hydrogen use for heating where it is estimated to require around 30 times more offshore wind farm capacity than currently available to produce enough green hydrogen to replace all gas boilers as well as adding costs for consumers.<br/><br/>This paper considers the offer of hydrogen for key Government priorities – including an inclusive and resilient economic recovery from the pandemic demonstrating climate leadership and delivering for all of society across the UK. It assesses existing evidence and considers the risks and opportunities and how they might inform a strategic vision for the UK. Ahead of the forthcoming Hydrogen Strategy it sets expectations for Government and outlines key recommendations.

Arup have conducted interviews with targeted industry and government stakeholders to gather data and perspectives to support the development of this study. Arup have also utilised private and publicly available data sources building on recent work undertaken by Geoscience Australia and Deloitte and the comprehensive stakeholder engagement process to inform our research. This study considers the supply chain and infrastructure requirements to support the development of export and domestic hubs. The study aims to provide a succinct “Hydrogen Hubs” report for presentation to the hydrogen working group.



The hydrogen supply chain infrastructure required to produce hydrogen for export and domestic hubs was identified along with feedback from the stakeholder engagement process. These infrastructure requirements can be used to determine the factors for assessing export and domestic hub opportunities. Hydrogen production pathways transportation mechanisms and uses were also further evaluated to identify how hubs can be used to balance supply and demand of hydrogen.



A preliminary list of current or anticipated locations has been developed through desktop research Arup project knowledge and the stakeholder consultation process. Over 30 potential hydrogen export locations have been identified in Australia through desktop research and the stakeholder survey and consultation process. In addition to establishing export hubs the creation of domestic demand hubs will be essential to the development of an Australian hydrogen economy. It is for this reason that a list of criteria has been developed for stakeholders to consider in the siting and design of hydrogen hubs. The key considerations explored are based on demand supply chain infrastructure and investment and policy areas.



Based on these considerations a list of criteria were developed to assess the viability of export and domestic hydrogen hubs. Criteria relevant to assessing the suitability of export and domestic hubs include:

• Health and safety provisions;
• Environmental considerations;
• Economic and social considerations;
• Land availability with appropriate zoning and buffer distances & ownership (new terminals storage solar PV industries etc.);•
• Availability of gas pipeline infrastructure;
• Availability of electricity grid connectivity backup energy supply or co-location of renewables;
• Road & rail infrastructure (site access);
• Community and environmental concerns and weather. Social licence consideration;
• Berths (berthing depth ship storage loading facilities existing LNG and/or petroleum infrastructure etc.);
• Port potential (current capacity & occupancy expandability & scalability);
• Availability of or potential for skilled workers (construction & operation);
• Availability of or potential for water (recycled & desalinated);
• Opportunity for co-location with industrial ammonia production and future industrial opportunities;
• Interest (projects priority ports state development areas politics etc.);
• Shipping distance to target market (Japan & South Korea);
• Availability of demand-based infrastructure (i.e. refuelling stations).

A framework that includes the assessment criteria has been developed to aid decision making rather than recommending specific locations that would be most appropriate for a hub. This is because there are so many dynamic factors that go into selecting a location of a hydrogen hub that it is not appropriate to be overly prescriptive or prevent stakeholders from selecting the best location themselves or from the market making decisions based on its own research and knowledge. The developed framework rather provides information and support to enable these decision-making processes.

Because of differences in irradiation levels it could be more efficient to produce solar electricity and hydrogen in North Africa and import these energy carriers to Europe rather than generating them at higher costs domestically in Europe. From a global climate change mitigation point of view exploiting such efficiencies can be profitable since they reduce overall renewable electricity capacity requirements. Yet the construction of this capacity in North Africa would imply costs associated with the infrastructure needed to transport electricity and hydrogen. The ensuing geopolitical dependencies may also raise energy security concerns. With the integrated assessment model TIAM-ECN we quantify the trade-off between costs and benefits emanating from establishing import-export links between Europe and North Africa for electricity and hydrogen. We show that for Europe a net price may have to be paid for exploiting such interlinkages even while they reduce the domestic investments for renewable electricity capacity needed to implement the EU’s Green Deal. For North African countries the potential net benefits thanks to trade revenues may build up to 50 billion €/yr in 2050. Despite fears over costs and security Europe should seriously consider an energy partnership with North Africa because trade revenues are likely to lead to positive employment income and stability effects in North Africa. Europe can indirectly benefit from such impacts.

A systematic study of different ratios of CO CO₂ N₂ gas components on the hydrogen storage properties of the Na₃AlH₆ complex hydride with 4 mol% TiCl3 8 mol% aluminum and 8 mol% activated carbon is presented in this paper. The different concentrations of CO and CO₂in H₂ and CO CO₂ N₂ in H₂ mixture were investigated. Both CO and CO₂gas react with the complex hydride forming Al oxy-compounds NaOH and Na₂CO₃ that consequently cause serious decline in hydrogen storage capacity. These reactions lead to irreversible damage of complex hydride under the current experimental condition. Thus after 10 cycles with 0.1 vol % CO + 99.9 vol %H₂ and 1 vol % CO + 99 vol %H₂ the dehydrogenation storage capacity of the composite material decreased by 17.2% and 57.3% respectively. In the case of investigation of 10 cycles with 1 vol % CO₂ + 99 vol % H₂ gas mixture the capacity degradation was 53.5%. After 2 cycles with 10 vol % CO +90 vol % H₂  full degradation was observed whereas after 6 cycles with 10 vol % CO₂+ 90 vol % H₂ degradation of 86.8% was measured. While testing with the gas mixture of 1.5 vol % CO + 10 vol % CO₂+ 27 vol % H₂ + 61.5 vol % N2 the degradation of 94% after 6 cycles was shown. According to these results it must be concluded that complex aluminum hydrides cannot be used for the absorption of hydrogen from syngas mixtures without thorough purification.

To become sustainable the production of electricity has been oriented towards the adoption of local and renewable sources. Distributed electric and thermal energy generation is more suitable to avoid any possible waste and the Micro Gas Turbine (MGT) can play a key role in this scenario. Due to the intrinsic properties and the high flexibility of operation of this energy conversion system the exploitation of alternative fuels and the integration of the MGT itself with other energy conversion systems (solar field ORC fuel cells) represent one of the most effective strategies to achieve higher conversion efficiencies and to reduce emissions from power systems. The present work aims to review the results obtained by the researchers in the last years. The different technologies are analyzed in detail both separately and under a more complete view considering two or more solutions embedded in micro-grid configurations.

This latest report describes the potential for CCUS as an important technology during the UK’s energy transition and focuses on the role that metrology (the science of measurement) could play in supporting its deployment. High priority measurement needs and challenges identified within this report include:

• Measuring and comparing the efficiency of different capture techniques and configurations to provide confidence in investments into technologies;
• Improving equations of state to support the development of accurate models used for controlling operational conditions;
• Improving CO₂ flow measurement to support fiscal and financial metering as well as process control and;
• Improving the understanding and validation of dispersion models for emitted CO₂ including plume migration to support safety assessment.

The report can be downloaded from their website

Driven by a small number of niche markets and several decades of application research fuel cell systems (FCS) are gradually reaching maturity to the point where many players are questioning the interest and intensity of its deployment in the transport sector in general. This article aims to shed light on this debate from the road transport perspective. It focuses on the description of the fuel cell vehicle (FCV) in order to understand its assets limitations and current paths of progress. These vehicles are basically hybrid systems combining a fuel cell and a lithium-ion battery and different architectures are emerging among manufacturers who adopt very different levels of hybridization. The main opportunity of Fuel Cell Vehicles is clearly their design versatility based on the decoupling of the choice of the number of Fuel Cell modules and hydrogen tanks. This enables manufacturers to meet various specifications using standard products. Upcoming developments will be in line with the crucial advantage of Fuel Cell Vehicles: intensive use in terms of driving range and load capacity. Over the next few decades long-distance heavy-duty vehicles and fleets of taxis or delivery vehicles will develop based on range extender or mild hybrid architectures and enable the hydrogen sector to mature the technology from niche markets to a large-scale market.

Climate change and global warming as well as growing global demand for hydrocarbons in industrial sectors make great incentives to investigate the utilization of CO₂ for hydrocarbons production. Therefore finding an in-depth understanding of the CO₂ hydrogenation reactors along with simulating reactor responses to different operating conditions are of paramount importance. However the reaction mechanisms for CO₂ hydrogenation and their corresponding kinetic parameters have been disputable yet. In this regard considering the previously proposed Langmuir-Hinshelwood-Hougen-Watson (LHHW) mechanism which considered CO₂ hydrogenation as a combination of reverse water gas shift (RWGS) and Fischer-Tropsch (FT) reactions and using a one-dimensional pseudo-homogeneous non-isothermal model kinetic parameters of the rate expressions are estimated via fitting experimental and modelling data through a novel swarm intelligence optimization technique called dragonfly algorithm (DA). The predicted reactants conversion using DA algorithm are closer to the experimental data (with about 4% error) comparing to those obtained by the artificial bee colony (ABC) algorithm and are in significant agreement with available literature data. The proposed model is used to assess the effect of reactor configuration on the performance and temperature fluctuations. Results show that axial flow spherical reactor (AFSR) and radial flow spherical reactor (RFSR) exhibiting the same surface area with that of the cylindrical reactor (CR) i.e. AFSR-2 and RFSR-2-i are the most efficient exhibiting hydrocarbons selectivity of 40.330% and 40.286% at CO₂ conversion of 53.763% and 53.891%. In addition it is revealed that the location of the jacket has an essential role in controlling the reactor temperature.

Interactions between incident electromagnetic energy and matter are of critical importance for numerous civil and military applications such as photocatalysis solar cells optics radar detection communications information processing and transport et al. Traditional mechanisms for such interactions in the microwave frequency mainly rely on dipole rotations and magnetic domain resonance. In this study we present the first report of the microwave absorption of Al/H₂ treated TiO₂ nanoparticles where the Al/H₂ treatment not only induces structural and optical property changes but also largely improves the microwave absorption performance of TiO₂ nanoparticles. Moreover the frequency of the microwave absorption can be finely controlled with the treatment temperature and the absorption efficiency can reach optimal values with a careful temperature tuning. A large reflection loss of −58.02 dB has been demonstrated with 3.1 mm TiO₂ coating when the treating temperature is 700 °C. The high efficiency of microwave absorption is most likely linked to the disordering-induced property changes in the materials. Along with the increased microwave absorption properties are largely increased visible-light and IR absorptions and enhanced electrical conductivity and reduced skin-depth which is likely related to the interfacial defects within the TiO₂ nanoparticles caused by the Al/H₂ treatment.

Despite the tremendous progress of coupling organic electrooxidation with hydrogen generation in a hybrid electrolysis electroreforming of raw biomass coupled to green hydrogen generation has not been reported yet due to the rigid polymeric structures of raw biomass. Herein we electrooxidize the most abundant natural amino biopolymer chitin to acetate with over 90% yield in hybrid electrolysis. The overall energy consumption of electrolysis can be reduced by 15% due to the thermodynamically and kinetically more favorable chitin oxidation over water oxidation. In obvious contrast to small organics as the anodic reactant the abundance of chitin endows the new oxidation reaction excellent scalability. A solar-driven electroreforming of chitin and chitin-containing shrimp shell waste is coupled to safe green hydrogen production thanks to the liquid anodic product and suppression of oxygen evolution. Our work thus demonstrates a scalable and safe process for resource upcycling and green hydrogen production for a sustainable energy future.

Detailed analysis of pathways to future sustainable energy systems is important in order to identify and overcome potential constraints and negative impacts and to increase the utility and speed of this transition. A key aspect of a shift to renewable energy technologies is their relatively higher metal intensities. In this study a bottom-up cost-minimizing energy model is used to calculate aggregate metal requirements in different energy technology including hydrogen and climate policy scenarios and under a range of assumptions reflecting uncertainty in future metal intensities recycling rate and life time of energy technologies. Metal requirements are then compared to current production rates and resource estimates to identify potentially “critical” metals. Three technology pathways are investigated: 100 percent renewables coal & nuclear and gas & renewables each under the two different climate policies: net zero emissions satisfying the well-below 2 °C target and business as usual without carbon constraints resulting together in six scenarios. The results suggest that the three different technology pathways lead to an almost identical degree of warming without any climate policy while emissions peaks within a few decades with a 2 °C policy. The amount of metals required varies significantly in the different scenarios and under the various uncertainty assumptions. However some can be deemed “critical” in all outcomes including Vanadium. The originality of this study lies in the specific findings and in the employment of an energy model for the energy-mineral nexus study to provide better understanding for decision making and policy development.

The recommended minimum separation distances in IGEM/TD/1 were based on a research programme that studied the different ways in which a failure of one buried natural gas transmission pipeline can affect another similar pipeline installed adjacent to the first taking account of the initial pressure wave propagating through the ground the size of the ground crater produced and the threat of escalation from fire if the second pipeline is exposed. The methodology developed from the research was first published in 2010 and is implemented in a software program (“PROPHET”). The distances in IGEM/TD/1 are generally cautious and are essentially determined by the size of the ground crater produced by pipeline ruptures as predicted by the methodology.

To assess the impact of hydrogen transmission on the recommended separation distances the possibility of one pipeline transporting natural gas and the other transporting hydrogen was considered as well as both pipelines transporting hydrogen. The following steps were carried out to assess the impact of hydrogen transmission on parallel pipeline separation distances drawing on existing knowledge only:

• Estimate the ground pressure loading predicted from a hydrogen pipeline rupture.
• Consider the ground pressure effect on a parallel natural gas or hydrogen pipeline.
• Evaluate available ground crater formation models and assess if existing natural gas model is cautious for hydrogen.
• Consider effects of thermal loading due to hydrogen fires where recommended natural gas separation distances are not met.

The following conclusions were made as to whether the current methodology for natural gas is cautious when applied to hydrogen:

• Ground pressure loading: The current natural gas methodology is cautious.
• Ground pressure effects: The current natural gas methodology is applicable (no change for hydrogen).
• Ground crater formation: The current natural gas methodology is cautious for ruptures and applicable for punctures (almost no change for hydrogen).
• Thermal loading: The current natural gas methodology is cautious for the thermal loading from ruptures but not necessarily cautious for punctures. Calculations of the minimum flow velocity required to prevent failure of a natural gas pipeline are not cautious for hydrogen.

In summary the recommended minimum separation distances in IGEM/TD/1 for parallel natural gas pipelines should be cautious when applied to parallel hydrogen pipelines. However in cases where the recommended minimum separation distances are not met the calculations to predict the thermal loading and response of the exposed pipeline should take account of the properties of hydrogen as the natural gas results will not necessarily be cautious.

The rotary engine (RE) is a potential power plant for unmanned aerial vehicles (UAVs) and automobiles because of its structural and design merits. However it has some serious drawbacks such as frequent maintenance requirements and excessive fuel consumption. This review paper presents the current status of hydrogen-fueled rotary engine (HRE) technology and identifies the existing research and development gaps in combustion efficiency and performance of this engine that might benefit transportation sector. Focusing primarily on the research from past ten years the crucial challenges encountered in hydrogen-powered rotary engines have been reviewed in terms of knock hydrocarbon (HC) emissions and seal leakages. The paper identifies the recent advances in design concepts and production approaches used in hydrogen-fueled rotary engines such as geometric models of trochoid profiles port configurations fuel utilization systems and currently available computational fluid dynamics (CFD) tools. This review article is an attempt to collect and organize literature on existing design methods up to date and provide recommendations for further improvements in RE technology.

Electrifying transportation is a promising approach to alleviate climate change issues arising from increased emissions. This study examines a system for the production of hydrogen using renewable energy sources as well as its use in buses. The electricity requirements for the production of hydrogen through the electrolysis of water are covered by renewable energy sources. Fuel cells are being used to utilize hydrogen to power the bus. Exergy analysis for the system is carried out. Based on a steady-state model of the processes exergy efficiencies are calculated for all subsystems. The subsystems with the highest proportion of irreversibility are identified and compared. It is shown that PV panel has exergetic efficiency of 12.74% wind turbine of 45% electrolysis of 67% and fuel cells of 40%.