United Kingdom

This is the Committee’s seventh report on Scotland’s progress towards meetings emissions targets as requested by Scottish Ministers under the Climate Change (Scotland) Act 2009.

Overall Scotland continues to outperform the rest of the UK in reducing its greenhouse gas emissions but successful strategies for energy and waste mask a lack of progress in other parts of the Scottish economy.

The report shows that Scotland’s total emissions fell by 10% in 2016 compared to 2015. The lion’s share of this latest drop in emissions came from electricity generation.

The key findings are:

• Overall Scotland met its annual emissions targets in 2016. 
• Scotland’s progress in reducing emissions from the power sector masks a lack of action in other areas particularly transport agriculture forestry and land use.
• Low-carbon heat transport agriculture and forestry sector policies need to improve in order to hit 2032 emissions targets.
• The Scottish Government’s Climate Change Plan – published in February 2018 – now has sensible expectations across each sector to reduce emissions.

Simulation of hydrogen-air mixture explosions in a closed large-scale vessel with uniform and nonuniform mixture compositions was performed by the group of partners within the EC funded project “Hydrogen Safety as an Energy Carrier” (HySafe). Several experiments were conducted previously by Whitehouse et al. in a 10.7 m3 vertically oriented (5.7-m high) cylindrical facility with different hydrogen-air mixture compositions. Two particular experiments were selected for simulation and comparison as a Standard Benchmark Exercise (SBEP) problem: combustion of uniform 12.8% (vol.) hydrogen-air mixture and combustion of non-uniform hydrogen-air mixture with average 12.6% (vol.) hydrogen concentration across the vessel (vertical stratification 27% vol. hydrogen at the top of the vessel 2.5% vol. hydrogen at the bottom of the vessel); both mixtures were ignited at the top of the vessel. The paper presents modelling approaches used by the partners comparison of simulation results against the experiment data and conclusions regarding the non-uniform mixture combustion modelling in real-life applications.

This paper is concerned with predicting the impact on the probability of failure of adding hydrogen to the natural gas distribution network. Hydrogen has been demonstrated to change the behaviour of crack like defects which may affect the safety of pipeline or make it more expensive to operate. A tool has been developed based on a stochastic approach to assess the failure probability of the gas pipeline due to the existence of crack-lie defects including the operational aspects of the pipeline such as inspection and repair procedures. With various parameters such as crack sizes material properties internal pressure modelled as uncertainties a reliability analysis based on failure assessment diagram is performed through direct Monte Carlo simulation. Inspection and repair procedures are included in the simulation to enable realistic pipeline maintenance scenarios to be simulated. In the data preparation process the accuracy of the probabilistic definition of the uncertainties is crucial as the results are very sensitive to certain variables such as the crack depth length and crack growth rate. The failure probabilities of each defect and the whole pipeline system can be obtained during simulation. Different inspection and repair criteria are available in the Monte Carlo simulation whereby an optimal maintenance strategy can be obtained by comparing different combinations of inspection and repair procedures. The simulation provides not only data on the probability of failure but also the predicted number of repairs required over the pipeline life thus providing data suitable for economic models of the pipeline management. This tool can be also used to satisfy certain target reliability requirement. An example is presented comparing a natural gas pipeline with a pipeline containing hydrogen.

This is the tenth consecutive year of the World Energy Council’s (the Council) annual survey of key challenges and opportunities facing energy leaders in managing and shaping Energy Transitions. This year’s Issues Monitor report provides seven global maps six regional maps and fifty national maps.

These maps have been developed by analysing the responses of nearly 2300 energy leaders drawn from across the Council’s diverse and truly global energy community.

The Council’s Issues Monitor identifies the strategic energy landscape of specific countries and regions in the world through an analysis of 42 energy issues and 4 digitalisation-specific issues affecting the energy system. It provides a unique reality check and horizon scanning of persistent and emerging concerns involved in whole energy systems transition. This year’s report welcomes a significant increase in both the participation of global leaders (up over 75% from 1300 to nearly 2300) as well as the participation of 86 countries.

Each Issue Map provides a visual snapshot of the uncertainties and action priorities that energy policymakers CEOs and leading experts strive to address to shape and manage successful Energy

Transitions. Maps can be used in the following ways:

• To promote a shared understanding of successful Energy Transitions
• To appreciate and contrast regional variations to better understand differing priorities and areas of concern
• To follow the evolution of specific technology trends related to the energy sector

The paper presents an overview of the main results of the EC NOE HySafe activity to estimate an allowable hydrogen permeation rate for automotive legal requirements and standards. The work was undertaken as part of the HySafe internal project InsHyde.<br/>A slow long term hydrogen release such as that due to permeation from a vehicle into an inadequately ventilated enclosed structure is a potential risk associated with the use of hydrogen in automotive applications. Due to its small molecular size hydrogen permeates through the containment materials found in compressed gaseous hydrogen storage systems and is an issue that requires consideration for containers with non-metallic (polymer) liners. Permeation from compressed gaseous hydrogen storage systems is a current hydrogen safety topic relevant to regulatory and standardisation activities at both global and regional levels.<br/>Various rates have been proposed in different draft legal requirements and standards based on different scenarios and the assumption that hydrogen dispenses homogeneously. This paper focuses on the development of a methodology by HySafe Partners (CEA NCSRD. University of Ulster and Volvo Technology) to estimate an allowable upper limit for hydrogen permeation in automotive applications by investigating the behaviour of hydrogen when released at small rates with a focus on European scenario. The background to the activity is explained. reasonable scenarios are identified a methodology proposed and a maximum hydrogen permeation rate from road vehicles into enclosed structures is estimated The work is based on conclusions from the experimental and numerical investigations described by CEA NCSRD and the University of Ulster in related papers.

Hydrogen vehicles may emerge as a leading contender to replace today’s internal combustion engine powered vehicles. A Phenomena Identification and Ranking Table exercise conducted as part of the European Network of Excellence on Hydrogen Safety (HySafe) identified the use of hydrogen vehicles in road tunnels as a topic of important concern. An internal project called HyTunnel was duly established within HySafe to review identify and analyse the issues involved and to contribute to the wider activity to establish the true nature of the hazards posed by hydrogen vehicles in the confined space of a tunnel and their relative severity compared to those posed by vehicles powered by conventional fuels including compressed natural gas (CNG). In addition to reviewing current hydrogen vehicle designs tunnel design practice and previous research a programme of experiments and CFD modelling activities was performed for selected scenarios to examine the dispersion and explosion hazards potentially posed by hydrogen vehicles. Releases from compressed gaseous hydrogen (CGH2) and liquid hydrogen (LH2) powered vehicles have been studied under various tunnel geometries and ventilation regimes. The findings drawn from the limited work done so far indicate that under normal circumstances hydrogen powered vehicles do not pose a significantly higher risk than those powered by petrol diesel or CNG but this needs to be confirmed by further research. In particular obstructions at tunnel ceiling level have been identified as a potential hazard in respect to fast deflagration or even detonation in some circumstances which warrants further investigation. The shape of the tunnel tunnel ventilation and vehicle pressure relief device (PRD) operation are potentially important parameters in determining explosion risks and the appropriate mitigation measures.

A techno-economic analysis has been used to evaluate three processes for hydrogen production from advanced steam reforming (SR) of bio-oil as an alternative route to hydrogen with BECCS: conventional steam reforming (C-SR) C-SR with CO2 capture (C-SR-CCS) and sorption-enhanced chemical looping (SE-CLSR). The impacts of feed molar steam to carbon ratio (S/C) temperature pressure the use of hydrodesulphurisation pretreatment and plant production capacity were examined in an economic evaluation and direct CO2 emissions analysis. Bio-oil C-SR-CC or SE-CLSR may be feasible routes to hydrogen production with potential to provide negative emissions. SE-CLSR can improve process thermal efficiency compared to C-SR-CCS. At the feed molar steam to carbon ratio (S/C) of 2 the levelised cost of hydrogen (USD 3.8 to 4.6 per kg) and cost of carbon avoided are less than those of a C-SR process with amine-based CCS. However at higher S/C ratios SE-CLSR does not have a strong economic advantage and there is a need to better understand the viability of operating SE-CLSR of bio-oil at high temperatures (>850 ◦C) with a low S/C ratio (e.g. 2) and whether the SE-CLSR cycle can sustain low carbon deposition levels over a long operating period.

The UK has committed to significantly reduce greenhouse gas emissions by 2050 to help address climate change. Decarbonising heating is a key part of this and using hydrogen (H2) as a replacement to natural gas (NG) can help in achieving this. The objective of current research including HyDeploy is to demonstrate that NG containing levels of H2 beyond those currently allowed of 0.1 vol% (1000 ppm) [1] can be distributed and utilised safely and efficiently. Initial projects such as HyDeploy are studying the effects of introducing up to 20 vol% H2 in NG but later projects are considering using up to 100 vol% H2.

A key element in the safe operation of a modern gas distribution system is gas detection. However the addition of hydrogen to NG will alter the characteristics of the gas and the impact on gas detection must be considered. It is important that sensors remain sufficiently sensitive to the presence of hydrogen natural gas carbon monoxide (CO) and oxygen (O2) deficiency and that they don’t lead to false positive or false negative readings. The aim of this document is to provide a summary of the requirements for gas detection of hydrogen enriched natural gas for the gas distribution industry and other potentially interested parties. As such it is based on gas detectors presently used by the industry with the only major differences being the effects of hydrogen on the sensitivity of flammable gas sensors and the cross sensitivity of carbon monoxide gas sensors to hydrogen.

There is further information of gas detector concepts and technologies in the appendices.

This report and any attachment is freely available on the ENA Smarter Networks Portal here. IGEM Members can download the report and any attachment directly by clicking on the pdf icon above.

This paper describes a large eddy simulation model of hydrogen spontaneous ignition in a T-shaped channel filled with air following an inertial flat burst disk rupture. This is the first time when 3D simulations of the phenomenon are performed and reproduced experimental results by Golub et al. (2010). The eddy dissipation concept with a full hydrogen oxidation in air scheme is applied as a sub-grid scale combustion model to enable use of a comparatively coarse grid to undertake 3D simulations. The renormalization group theory is used for sub-grid scale turbulence modelling. Simulation results are compared against test data on hydrogen release into a T-shaped channel at pressure 1.2–2.9 MPa and helped to explain experimental observations. Transitional phenomena of hydrogen ignition and self-extinction at the lower pressure limit are simulated for a range of storage pressure. It is shown that there is no ignition at storage pressure of 1.35 MPa. Sudden release at pressure 1.65 MPa and 2.43 MPa has a localised spot ignition of a hydrogen-air mixture that quickly self-extinguishes. There is an ignition and development of combustion in a flammable mixture cocoon outside the T-shaped channel only at the highest simulated pressure of 2.9 MPa. Both simulated phenomena i.e. the initiation of chemical reactions followed by the extinction and the progressive development of combustion in the T-shape channel and outside have provided an insight into interpretation of the experimental data. The model can be used as a tool for hydrogen safety engineering in particular for development of innovative pressure relief devices with controlled ignition.

The site at the Health and Safety Executive’s Science and Research Centre in Buxton will carry out controlled tests to establish the critical safety evidence proving that a 100% hydrogen gas network is equally as safe as the natural gas grid heating our homes and businesses today. The results will be critical in determining if it is safe to convert millions of homes across the country from natural gas to hydrogen. H21 which is led by Northern Gas Networks (NGN) the gas distributor for the North of England in partnership with Cadent SGN and Wales & West Utilities HSE Science and Research Centre and DNV-GL is part of a number of gas industry projects designed to support conversion of the UK gas networks to carry 100% hydrogen. Currently about 30% of UK carbon emissions are from the heating of homes businesses and industry. H21 states that a large-scale conversion of the gas grid from natural gas to hydrogen is vital to meeting the Government’s Net Zero targets.

Hydrogen and fuel cell technologies have experienced cycles of high expectations followed by impractical realities. This time around however falling renewable energy and fuel cell prices stringent climate change requirements and the discrete involvement of China are step changes. The combination of these factors is leading to realistic potential for hydrogen’s role in the Grand Transition.<br/>Having conducted exploratory interviews with leaders from all around the globe the World Energy Council is featuring eight use cases which illustrate hydrogen’s potential. These range from decarbonising hard-to-abate sectors such as heat industry and transport to supporting the integration of renewables and providing an energy storage solution.<br/>Dr Angela Wilkinson Secretary General and former Senior Director Scenarios and Business Insights: “Green and blue hydrogen can refresh those parts of the energy system transition that electrification cannot reach.”<br/>This Innovation Insights Brief is part of a series of publications by the World Energy Council focused on Innovation. In a fast-paced era of disruptive changes this brief aims at facilitating strategic sharing of knowledge between the Council’s members and the other energy stakeholders and policy shapers.

Hydrogen is expected to have an important role in decarbonising several parts of the UK energy system. This white paper examines the opportunities for hydrogen and fuel cell technologies (H2FC) to contribute to clean growth in the UK.



We assess the strength of the sector by surveying 196 companies working in the area and using other key metrics (for example publication citations and patents). There is already a nascent fuel cell industry working at the cutting edge of global innovation. The UK has an opportunity to grow this industry and to develop an export-focused hydrogen industry over the next few decades. However this will require public nurturing and support. We make a series of recommendations that include:

• Creating separate national fuel cell and hydrogen strategies. These should take UK energy needs capabilities and export opportunities into account. There is a need to coordinate public R&D support and to manage the consequences if European funding and collaboration opportunities become unavailable due to Brexit.
• Creating a public–private “Hydrogen Partnership” to accelerate a shift to hydrogen energy systems in the UK and to stimulate opportunities for businesses.
• Putting in place infrastructure to underpin nascent fuel cell and hydrogen markets including a national refuelling station network and a green hydrogen standard scheme.
• Study what would constitute critical mass in the hydrogen and fuel cell sectors in terms of industry and academic capacity and the skills and knowledge base and consider how critical mass could be achieved most efficiently.
• Consider creating a “Hydrogen Institute” and an “Electrochemical Centre” to coordinate and underpin national innovation over the next decade.

This White Paper has been commissioned by the UK Hydrogen and Fuel Cell (H2FC) SUPERGEN Hub to examine the roles and potential benefits of hydrogen and fuel cell technologies in delivering energy security for the UK. The H2FC SUPERGEN Hub is an inclusive network encompassing the entire UK hydrogen and fuel cells research community with around 100 UK-based academics supported by key stakeholders from industry and government. It is funded by the UK EPSRC research council as part of the RCUK Energy Programme. This paper is the second of four that were published over the lifetime of the Hub with the others examining: (i) low-carbon heat; (iii) future energy systems; and (iv) economic impact.

• Fuel cells can contribute to UK energy system security both now and in the future.
• Hydrogen can be produced using a broad range of feedstocks and production processes including renewable electricity.
• Adopting hydrogen as an end-use fuel in the long term increases UK energy diversity.

This White Paper has been commissioned by the UK Hydrogen and Fuel Cell (H2FC) SUPERGEN Hub to examine the roles and potential benefits of hydrogen and fuel cell technologies within each sector of future energy systems and the transition infrastructure that is required to achieve these roles. The H2FC SUPERGEN Hub is an inclusive network encompassing the entire UK hydrogen and fuel cells research community with around 100 UK-based academics supported by key stakeholders from industry and government. It is funded by the UK EPSRC research council as part of the RCUK Energy Programme. This paper is the third of four that were published over the lifetime of the Hub with the others examining: (i) low-carbon heat; (ii) energy security; and (iv) economic impacts.

• Hydrogen and fuel cells are now being deployed commercially for mainstream applications.
• Hydrogen can play a major role alongside electricity in the low-carbon economy.
• Hydrogen technologies can support low-carbon electricity systems dominated by intermittent renewables and/or electric heating demand.
• The hydrogen economy is not necessary for hydrogen and fuel cells to flourish.

In the present study the phenomena of blast wave and fireball generated by high pressure (35 MPa) hydrogen tank (72 l) rupture have been investigated numerically. The realizable k-ε turbulence model was applied. The simulation of the combustion process is based on the eddy dissipation model coupled with the one step chemical reaction mechanism. Simulation results are compared with experimental data from a stand-alone hydrogen fuel tank rapture following a bonfire test. The model allows the study of the interaction between combustion process and blast wave propagation. Simulation results (blast wave overpressure fireball shape and size) follow the trends observed in the experiment.

Consequence modelling of high potential risks of usage and transportation of cryogenic liquids yet requires substantial improvements. Among the cryogenics liquid hydrogen (LH2) needs especial treatments and a comprehensive understanding of spill and spread of liquid and dispersion of vapor. Even though many of recent works have shed lights on various incidents such as spread dispersion and explosion of the liquid over land less focus was given on spill and spread of LH2 onto water. The growing trend in ship transportation has enhanced risks such as ships’ accidental releases and terrorist attacks which may ultimately lead to the release of the cryogenic liquid onto water. The main goal of the current study is to present a computational fluid dynamic (CFD) approach using OpenFOAM to model release and spread of LH2 over water substrate and discuss previous approaches. It also includes empirical heat transfer equations due to boiling and computation of evaporation rate through an energy balance. The results of the proposed model will be potentially used within another coupled model that predicts gas dispersion]. This work presents a good practice approach to treat pool dynamics and appropriate correlations to identify heat flux from different sources. Furthermore some of the previous numerical approaches to redistribute or in some extend manipulate the LH2 pool dynamic are brought up for discussion and their pros and cons are explained. In the end the proposed model is validated by modelling LH2 spill experiment carried out in 1994 at the Research Centre Juelich in Germany.

Scotland’s Achievements and Ambitions for Clean Hydrogen - a joint webinar between the Scottish Hydrogen and Fuel Cell Association and the Pipeline Industries Guild (Scottish branch).

 

Nigel Holmes. CEO Scottish Hydrogen & Fuel Cell Association provides an update on Scotland’s ambitions backed up by progress in key areas. This will show the potential for hydrogen at scale to support the delivery of policy targets highlighting areas of key strengths for Scotland.



You will also hear about the need to build up scale for hydrogen production and supply in tandem with hydrogen pipeline and distribution networks in order to meet demand for low carbon energy and achieve key milestones on the pathway to Net Zero by 2045.

Previous studies have demonstrated that while blowdown pressure is reproduced well by both adiabatic and isothermal analytical models the dynamics of temperature cannot be predicted well by either model. The reason for the last is heat transfer to cooling during expansion gas from the vessel wall. Moreover when exposed to an external fire the temperature inside the vessel increases i.e. when a thermally activated pressure relief device (TPRD) is still closed with subsequent pressure increase that may lead to a catastrophic rupture of the vessel. The choice of a TPRD exit orifice size and design strategy are challenges: to provide sufficient internal pressure drop in a fire when the orifice size is too small; to avoid flame blow off expected with the decrease of pressure during the blowdown; to decrease flame length of subsequent jet fire as much as possible by the decrease of the orifice size under condition of sufficient fire resistance provisions to avoid pressure peaking phenomenon etc. The adiabatic model of blowdown [1] was developed using the Abel-Nobel equation of state and the original theory of underexpanded jet [2]. According to experimental observations e.g. [3] heat transfer plays a significant role during the blowdown. Thus this study aims to modify the adiabatic blowdown model to include the heat transfer to non-ideal gas. The model accounts for a change of gas temperature inside the vessel due to two “competing” processes: the decrease of temperature due to gas expansion and the increase of temperature due to heat transfer from the surroundings e.g. ambience or fire through the vessel wall. This is taken into account in the system of equations of adiabatic blowdown model through the change of energy conservation equation that accounts for heat from outside. There is a need to know the convective heat transfer coefficient between the vessel wall and the surroundings and wall size and properties to define heat flux to the gas inside the vessel. The non-adiabatic model is validated against available experimental data. The model can be applied as a new engineering tool for the inherently safer design of hydrogen tank-TPRD system.

The paper presents HyResponse project i.e. a European Hydrogen Safety Training Platform that targets to train First responders to acquire professional knowledge and skills to contribute to FCH permitting process as approving authority. The threefold training program is described: educational training operational-level training on mock-up real scale transport and hydrogen stationary installations and innovative virtual training exercises reproducing entire accident scenarios. The paper highlights how the three pilot sessions for European First Responders in a face to face mode will be organized to get a feedback on the training program. The expected outputs are also presented i.e. the Emergency Response Guide and a public website including teaching material and online interactive virtual training.

Hydrogen has the potential to be used by many countries as part of decarbonising the future energy system. Hydrogen can be used as a fuel ‘vector’ to store and transport energy produced in low-carbon ways. This could be particularly important in applications such as heating and transport where other solutions for low and zero carbon emission are difficult. To enable the safe uptake of hydrogen technologies it is important to develop the international scientific evidence base on the potential risks to safety and how to control them effectively. The International Association for Hydrogen Safety (known as IA HySAFE) is leading global efforts to ensure this. HSE hosted the 2018 IA HySAFE Biennial Research Priorities Workshop. A panel of international experts presented during nine key topic sessions: (1) Industrial and National Programmes; (2) Applications; (3) Storage; (4) Accident Physics – Gas Phase; (5) Accident Physics – Liquid/ Cryogenic Behaviour; (6) Materials; (7) Mitigation Sensors Hazard Prevention and Risk Reduction; (8) Integrated Tools for Hazard and Risk Assessment; (9) General Aspects of Safety.<br/>This report gives an overview of each topic made by the session chairperson. It also gives further analysis of the totality of the evidence presented. The workshop outputs are shaping international activities on hydrogen safety. They are helping key stakeholders to identify gaps in knowledge and expertise and to understand and plan for potential safety challenges associated with the global expansion of hydrogen in the energy system.

Our mission is to put the UK at the forefront of the design and manufacturing of zero emission vehicles and for all new cars and vans to be effectively zero emission by 2040. As set out in the NO2 plan we will end the sale of new conventional petrol and diesel cars and vans by 2040. By then we expect the majority of new cars and vans sold to be 100% zero emission and all new cars and vans to have significant zero emission capability. By 2050 we want almost every car and van to be zero emission. We want to see at least 50% and as many as 70% of new car sales and up to 40% of new van sales being ultra low emission by 2030.<br/>We expect this transition to be industry and consumer led supported in the coming years by the measures set out in this strategy. We will review progress towards our ambitions by 2025. Against a rapidly evolving international context we will seek to maintain the UK’s leadership position and meet our ambitions and will consider what interventions are required if not enough progress is being made.

Although the UK has done a great job of decarbonising electricity generation to get to net zero we need to tackle harder-to-decarbonise sectors like heat transport and industry. Decarbonised gas – biogases hydrogen and the deployment of carbon capture usage and storage (CCUS) – can make our manufacturing more sustainable minimise disruption to families and deliver negative emissions.

Developing the capability to produce hydrogen at scale is one of the key challenges in the race to meet the UK’s ambitious net zero targets. Using the East Neuk of Fife - with its abundant on- and offshore renewables resource and well-developed electricity and gas networks – as a test bed we investigated the use of surplus electricity generated by renewables to produce green hydrogen which could then be used to heat homes and businesses carbon-free.

Aims

The study focused on answering a number of important questions around bringing power-to-hydrogen to Fife including:

How much low-cost low-carbon electricity would be available to a power-to-hydrogen operator in Fife and how much hydrogen could be produced today and in 2040? How much hydrogen storage would be required to meet demand under three end-use cases: injection into the natural gas grid; use in a dedicated hydrogen grid for heating; and use as transport fuel for a small fleet of vehicles? What if any network upgrades could be avoided by implementing power-to-hydrogen? Which hydrogen end-use markets would be most attractive for a power-to-hydrogen operator? What are the regulatory legislative or market barriers to be overcome to realise large-scale deployment of power-to-hydrogen?

The study

Our expert researchers used a high-level model of the European electricity system and established wholesale prices generation volumes by generation type and constrained generation in Fife. Considering both the present day and a 2040 picture based on National Grid’s Two Degrees Future Energy Scenarios our team explored a number of configurations of power generation and hydrogen end-use to assess the value associated with producing hydrogen.

Alongside this modelling our team conducted a comprehensive review of power-to-hydrogen legislation and regulation and reports and academic papers to identify the current characteristics and direction of the sector observe where most progress had been made and identify lessons learned.

This report and any attachment is freely available on the ENA Smarter Networks Portal here. IGEM Members can download the report and any attachment directly by clicking on the pdf icon above.

This study presents a computational fluid dynamic (CFD) study of Dimethyl Ether steam reforming (DME-SR) in a large scale Circulating Fluidized Bed (CFB) reactor. The CFD model is based on Eulerian–Eulerian dispersed flow and solved using commercial software (ANSYS FLUENT). The DME-SR reactions scheme and kinetics in the presence of a bifunctional catalyst of CuO/ZnO/Al₂O₃+ZSM-5 were incorporated in the model using in-house developed user-defined function. The model was validated by comparing the predictions with experimental data from the literature. The results revealed for the first time detailed CFB reactor hydrodynamics gas residence time temperature distribution and product gas composition at a selected operating condition of 300 °C and steam to DME mass ratio of 3 (molar ratio of 7.62). The spatial variation in the gas species concentrations suggests the existence of three distinct reaction zones but limited temperature variations. The DME conversion and hydrogen yield were found to be 87% and 59% respectively resulting in a product gas consisting of 72 mol% hydrogen. In part II of this study the model presented here will be used to optimize the reactor design and study the effect of operating conditions on the reactor performance and products.

The substitution of hydrogen for natural gas within a gas network has implications for the potential rate of leakage from pipes and the distribution of gas flow driven by such leaks. This paper presents theoretical analyses of low-pressure flow through porous ground in a range of circumstances and practical experimental work at a realistic scale using natural gas hydrogen or nitrogen for selected cases. This study considers flow and distribution of 100% hydrogen. A series of eight generic flow regimes have been analysed theoretically e.g. (i) a crack in uncovered ground (ii) a crack under a semi-permeable cover in a high porosity channel (along a service line or road). In all cases the analyses yield both the change in flow rate when hydrogen leaks and the change in distance to which hydrogen gas can travel at a dangerous rate compared to natural gas. In some scenarios a change to hydrogen gas from natural gas makes minimal difference to the range (i.e. distance from the leak) at which significant gas flows will occur. However in cases where the leak is covered by an impermeable membrane a change to hydrogen from natural gas may extend the range of significant gas flow by tens or even hundreds of metres above that of natural gas. Experimental work has been undertaken in specific cases to investigate the following: (i) Flow rate vs pressure curves for leaks into media with different permeability (ii) Effects of the water content of the ground on gas flow (iii) Distribution of surface gas flux near a buried leak

This paper reports a new approach for exposing materials including solar cell structures to atomic hydrogen. This method is dubbed Shielded Hydrogen Passivation (SHP) and has a number of unique features offering high levels of atomic hydrogen at low temperature whilst inducing no damage. SHP uses a thin metallic layer in this work palladium between a hydrogen generating plasma and the sample which shields the silicon sample from damaging UV and energetic ions while releasing low energy neutral atomic hydrogen onto the sample. In this paper the importance of the preparation of the metallic shield either to remove a native oxide or to contaminate intentionally the surface are shown to be potential methods for increasing the amount of atomic hydrogen released. Excellent damage free surface passivation of thin oxides is observed by combining SHP and corona discharge obtaining minority carrier lifetimes of 2.2 ms and J0 values below 5.47 fA/cm2. This opens up a number of exciting opportunities for the passivation of advanced cell architectures such as passivated contacts and heterojunctions.