Hydrogen Blending
Gas Detection of Hydrogen/Natural Gas Blends in the Gas Industry
Sep 2019
Publication
A key element in the safe operation of a modern gas distribution system is gas detection. The addition of hydrogen to natural gas will alter the characteristics of the fuel and therefore its impact on gas detection must be considered. It is important that gas detectors remain sufficiently sensitive to the presence of hydrogen and natural gas mixtures and that they do not lead to false readings. This paper presents analyses of work performed as part of the Office for Gas and Energy Markets (OFGEM) funded HyDeploy project on the response of various natural gas industry detectors to blended mixtures up to 20 volume percent (vol%) of hydrogen in natural gas. The scope of the detectors under test included survey instruments and personal monitors that are used in the gas industry. Four blend ratios were analysed (0 10 15 and 20 vol% hydrogen in natural gas). The laboratory testing undertaken investigated the following:
- Flammable response to blends in the ppm range (0-0.2 vol%);
- Flammable response to blends in the lower explosion limit range (0.2-5 vol%);
- Flammable response to blends in the volume percent range (5-100 vol%);
- Oxygen response to blends in the volume percent range (0-25 vol%); and
- Carbon monoxide response to blends in the ppm range (0-1000 ppm).
Safety and Regulatory Challenges of Using Hydrogen/Natural Gas Blends in the UK
Sep 2019
Publication
The addition of hydrogen to natural gas for heating and cooking is being considered as a route to reducing carbon emissions in the United Kingdom (UK). The HyDeploy programme (hereafter referred to as HyDeploy) aims to demonstrate that hydrogen can be added to the natural gas supply without compromising public safety or appliance performance. This paper relates to the preparatory work for hydrogen injection on a live site at Keele University closed network comprising domestic premises multi-occupancy buildings and light commercial premises. The project is based around the injection of up to 20 %mol/mol hydrogen into mains natural gas at pressures below 2 barg. Work streams addressed during the pre-trial preparation included; assessment of material interaction with hydrogen blends for all distribution system components and appliances; understanding of gas appliance behaviour; review of: gas detection systems fire and explosion considerations routine and emergency procedural considerations; and the design of a new hydrogen injection grid entry unit. This paper describes the safety and regulatory challenges that were encountered during preparation of the project including obtaining the necessary regulatory permissions to blend hydrogen gas.
HyDeploy Webinar - Unlocking the Deployment of Hydrogen in the Grid
May 2020
Publication
A project overview of HyDeploy project led by Cadent Gas and supported by Northern Gas Networks Progressive Energy Ltd Keele University HSE – Science Division and ITM Power.
First Phase:
HyDeploy at Keele is the first stage of this three stage programme. In November 2019 the UK Health & Safety Executive gave permission to run a live test of blended hydrogen and natural gas on part of the private gas network at Keele University campus in Staffordshire. HyDeploy is the first project in the UK to inject hydrogen into a natural gas network.
Second and Third Phases;
Once the Keele stage has been completed HyDeploy will move to a larger demonstration on a public network in the North East. After that HyDeploy will have another large demonstration in the North West. These are designed to test the blend across a range of networks and customers so that the evidence is representative of the UK as a whole. With HSE approval and success at Keele these phases will go ahead in the early 2020s.
The longer term goal:
Once the evidence has been submitted to Government policy makers we very much expect hydrogen to take its place alongside other forms of zero carbon energy in meeting the needs of the UK population.
First Phase:
HyDeploy at Keele is the first stage of this three stage programme. In November 2019 the UK Health & Safety Executive gave permission to run a live test of blended hydrogen and natural gas on part of the private gas network at Keele University campus in Staffordshire. HyDeploy is the first project in the UK to inject hydrogen into a natural gas network.
Second and Third Phases;
Once the Keele stage has been completed HyDeploy will move to a larger demonstration on a public network in the North East. After that HyDeploy will have another large demonstration in the North West. These are designed to test the blend across a range of networks and customers so that the evidence is representative of the UK as a whole. With HSE approval and success at Keele these phases will go ahead in the early 2020s.
The longer term goal:
Once the evidence has been submitted to Government policy makers we very much expect hydrogen to take its place alongside other forms of zero carbon energy in meeting the needs of the UK population.
Blending Hydrogen from Electrolysis into the European Gas Grid
Jan 2022
Publication
In 2020 the European Commission launched a hydrogen strategy for a climate-neutral Europe setting out the conditions and actions for mainstreaming clean hydrogen along with targets for installing renewable hydrogen electrolysers by 2024 and 2030. Blending hydrogen alongside other gases into the existing gas grid is considered a possible interim first step towards decarbonising natural gas. In the present analysis we modelled electrolytic hydrogen generation as a process connecting two separate energy systems (power and gas). The analysis is based on a projection of the European power and gas systems to 2030 based on the EUCO3232.5 scenario. Multiple market configurations were introduced in order to assess the interplay between diverse power market arrangements and constraints imposed by the upper bound on hydrogen concentration. The study identifies the maximum electrolyser capacity that could be integrated in the power and gas systems the impact on greenhouse gas emissions and the level of price support that may be required for a broad range of electrolyser configurations. The study further attempts to shed some light on the potential side effects of having non-harmonised H2 blending thresholds between neighbouring Member States.
Performance of Three Typical Domestic Gas Stoves Operated with Methane-hydrogen Mixture
Dec 2022
Publication
Hydrogen blending into natural gas has attracted significant attention in domestic applications. The paper studied the effects of natural gas mixed with hydrogen at 0% (vol) 5% 10% 15% 20% and 25% on the performance of typical round-port gas stove (TRPGS) swirling strip-port gas stove (SSPGS) and radiant porous media gas stove (RPMGS). The experimental results show that flame length shortens with the increase of hydrogen proportion and the combustion remains stable when the hydrogen proportion is equal to or less than 25%. With increasing hydrogen proportion the measured heat inputs of the three types of domestic gas stoves decrease gradually and the average thermal efficiency of TRPGS and SSPGS increase by 0.82% and 1.18% respectively. In addition the average efficiency of the RPMGS first increases by 1.35% under a hydrogen proportion of 15% and then decreases by 1.36% under a hydrogen proportion of 25%. In terms of flue gas emission CO emission reduces significantly with increasing hydrogen proportion while NOX emissions remain almost unchanged.
Power-to-gas and the Consequences: Impact of Higher Hydrogen Concentrations in Natural Gas on Industrial Combustion Processes
Sep 2017
Publication
Operators of public electricity grids today are faced with the challenge of integrating increasing numbers of renewable and decentralized energy sources such as wind turbines and photovoltaic power plants into their grids. These sources produce electricity in a very inconstant manner due to the volatility of wind and solar power which further complicates power grid control and management. One key component that is required for modern energy infrastructures is the capacity to store large amounts of energy in an economically feasible way.<br/>One solution that is being discussed in this context is “power-to-gas” i.e. the use of surplus electricity to produce hydrogen (or even methane with an additional methanation process) which is then injected into the public natural gas grid. The huge storage capacity of the gas grid would serve as a buffer offering benefits with regards to sustainability and climate protection while also being cost-effective since the required infrastructure is already in place.<br/>One consequence would be however that the distributed natural gas could contain larger and fluctuating amounts of hydrogen. There is some uncertainty how different gas-fired applications and processes react to these changes. While there have already been several investigations for domestic appliances (generally finding that moderate amounts of H2 do not pose any safety risks which is the primary focus of domestic gas utilization) there are still open questions concerning large-scale industrial gas utilization. Here in addition to operational safety factors like efficiency pollutant emissions (NOX) process stability and of course product quality have to be taken into account.<br/>In a German research project Gas- und Wärme-Institut Essen e. V. (GWI) investigated the impact of higher and fluctuating hydrogen contents (up to 50 vol.-% much higher than what is currently envisioned) on a variety of industrial combustion systems using both numerical and experimental methods. The effects on operational aspects such as combustion behavior flame monitoring and pollutant emissions were analyzed.<br/>Some results of these investigations will be presented in this contribution.
Mitigation of CO Poisoning Hazard in Malfunctioning Gas Appliances Through Use of Hydrogen Blended Gas
Sep 2021
Publication
The HyDeploy project [1] has undertaken an extensive research programme to assess safety and performance of the existing UK gas appliances population fueled with natural gas / hydrogen admixtures (hydrogen blended gas). The first stage of this work [2] focused on well maintained and normally functioning appliances. This work demonstrated that unmodified gas appliances can operate safely with hydrogen blended gas (up to 20 vol% hydrogen) and the key hazard areas of carbon monoxide (CO) production light back and flame out and the operation of flame failure devices are unaffected. It is widely recognized that due to aging and variable degrees of maintenance that the combustion performance of a gas appliance will depreciate over time. In extreme cases this can lead to situations where high levels of CO may be released back into the dwelling resulting in CO poisoning to the occupants. To obtain a universal appreciation of the effect of hydrogen addition on the safety and performance of all gas appliances operation under sub optimal conditions is required and therefore it is important that the operation of malfunctioning appliances fuelled with hydrogen blended gas is assessed. A review of failure modes identified six key scenarios where the composition of the fuel gas may lead to changes in safety performance - these primarily related to the resulting composition of the flue gas but also included delayed ignition. Gas appliance faults that will increase the CO production were tested through a series of experiments to simulate fault conditions and assess the effect of hydrogen blended gas. The fault modes examined included linting flame chilling incorrect appliance set up and modification of gas valve operation. The programme utilized six different appliances tested with three methane-hydrogen fuel blends (containing 0 20 and 28.4 vol% hydrogen). In all cases the switch to hydrogen blended gas reduced CO production. The change in CO production when using hydrogen blended gas is a consequence of a decrease in the theoretical air requirement to achieve complete combustion. In some cases the amount of CO produced was identical to the nonfault baseline performance on methane thereby fully mitigating the consequence of the malfunction. In the case of very high CO production a 90% reduction was recorded when using 20 vol% hydrogen blended gas. In situations such as non-optimal boiler set up the addition of hydrogen to the gas supply would prevent the production of high levels of CO. The findings here together with the results from HyDeploy 1 [2] indicate that the safety and performance of unmodified existing UK gas appliances are not detrimentally affected when using hydrogen blended gas. Furthermore the addition of hydrogen to the fuel gas has been shown to reduce CO production under fault conditions therefore the introduction of hydrogen into the gas network may serve to mitigate the hazard posed by existing faulty appliances that are producing elevated levels of CO.
Green Hydrogen Blends with Natural Gas and Its Impact on the Gas Network
Oct 2022
Publication
With increasing shares of variable and uncertain renewable generation in many power systems there is an associated increase in the importance of energy storage to help balance supply and demand. Gas networks currently store and transport energy and they have the potential to play a vital role in longer-term renewable energy storage. Gas and electricity networks are becoming more integrated with quick-responding gas-fired power plants providing a significant backup source for renewable electricity in many systems. This study investigates Ireland’s gas network and operation when a variable green hydrogen input from excess wind power is blended with natural gas. How blended hydrogen impacts a gas network’s operational variables is also assessed by modelling a quasi-transient gas flow. The modelling approach incorporates gas density and a compressibility factor in addition to the gas network’s main pressure and flow rate characteristics. With an increasing concentration of green hydrogen up to 20% in the gas network the pipeline flow rate must be increased to compensate for reduced energy quality due to the lower energy density of the blended gas. Pressure drops across the gas pipeline have been investigated using different capacities of P2H from 18 MW to 124 MW. The results show significant potential for the gas network to store and transport renewable energy as hydrogen and improve renewable energy utilisation without upgrading the gas network infrastructure.
The Direct Effect of Enriching the Gaseous Combustible with 23% Hydrogen in Condensing Boilers’ Operation
Dec 2022
Publication
Following the international trend of using hydrogen as combustible in many industry branches this paper investigates the impact of mixing methane gas with 23% hydrogen (G222) on condensing boilers’ operation. After modeling and testing several boilers with heat exchange surface different designs the authors gathered enough information to introduce a new concept namely High-Performance Condensing Boiler (HPCB). All the boilers that fit into this approach have the same operational parameters at nominal heat load including the CO2 concentrations in flue gases. After testing a flattened pipes condensing boiler a CO2 emission reduction coefficient of 1.1 was determined when converting from methane gas to G222 as combustible. Thus by inserting into the national grid a G222 mixture an important reduction in greenhouse gases can be achieved. For a 28 kW condensing boiler the annual reduction in CO2 emissions averages 1.26 tons value which was experimentally obtained and is consistent with the theoretical evaluation.
Consumer Perceptions of Blended Hydrogen in the Home: Learning from HyDeploy
Apr 2022
Publication
This report presents the results of research into consumer perceptions and the subsequent degree of acceptance of blended hydrogen in domestic properties. Evidence from two trial sites of the HyDeploy programme: i) a private site trial at Keele University North Staffordshire; ii) and a public site trial at Winlaton Gateshead are discussed.
Steady State Analysis of Gas Networks with Distributed Injection of Alternative Gas
Jun 2015
Publication
A steady state analysis method was developed for gas networks with distributed injection of alternative gas. A low pressure gas network was used to validate the method. Case studies were carried out with centralized and decentralized injection of hydrogen and upgraded biogas. Results show the impact of utilizing a diversity of gas supply sources on pressure distribution and gas quality in the network. It is shown that appropriate management of using a diversity of gas supply sources can support network management while reducing carbon emissions.
A Preliminary Assessment of the Potential of Low Percentage Green Hydrogen Blending in the Italian Natural Gas Network
Oct 2020
Publication
The growing rate of electricity generation from renewables is leading to new operational and management issues on the power grid because the electricity generated exceeds local requirements and the transportation or storage capacities are inadequate. An interesting option that is under investigation by several years is the opportunity to use the renewable electricity surplus to power electrolyzers that split water into its component parts with the hydrogen being directly injected into natural gas pipelines for both storage and transportation. This innovative approach merges together the concepts of (i) renewable power-to-hydrogen (P2H) and of (ii) hydrogen blending into natural gas networks. The combination of renewable P2H and hydrogen blending into natural gas networks has a huge potential in terms of environmental and social benefits but it is still facing several barriers that are technological economic legislative. In the framework of the new hydrogen strategy for a climate-neutral Europe Member States should design a roadmap moving towards a hydrogen ecosystem by 2050. The blending of “green hydrogen” that is hydrogen produced by renewable sources in the natural gas network at a limited percentage is a key element to enable hydrogen production in a preliminary and transitional phase. Therefore it is urgent to evaluate at the same time (i) the potential of green hydrogen blending at low percentage (up to 10%) and (ii) the maximum P2H capacity compatible with low percentage blending. The paper aims to preliminary assess the green hydrogen blending potential into the Italian natural gas network as a tool for policy makers grid and networks managers and energy planners.
Innovative Combustion Analysis of a Micro-gas Turbine Burner Supplied with Hydrogen-natural Gas Mixtures
Sep 2017
Publication
The author discusses in this paper the potential of a micro gas turbine (MGT) combustor when operated under unconventional fuel supplied. The combustor of C30 gas turbine is a reverse flow annular combustor. The CFD analysis of the reacting flow is performed with the 3D ANSYS-FLUENT solver. Specific computational experiments refer to the use of hydrogen – natural gas mixtures in order to define the optimal conditions for pilot and main injections in terms of combustion stability and NOx production. The author's methodology relies on an advanced CFD approach that compares different schemes like eddy dissipation concept together with the flamelet- PDF based approach coupled with an accurate study of the turbulent chemistry interaction. Extended kinetic mechanisms are also included in the combustion model. Some test cases are examined to make a comparison of combustion stability and efficiency and pollutant production with high hydrogen / natural gas ratios.
Hydrogen Addition to Natural Gas in Cogeneration Engines: Optimization of Performances Through Numerical Modeling
Aug 2021
Publication
A numerical study of the energy conversion process occurring in a lean-charge cogenerative engine designed to be powered by natural gas is here conducted to analyze its performances when fueled with mixtures of natural gas and several percentages of hydrogen. The suitability of these blends to ensure engine operations is proven through a zero–one-dimensional engine schematization where an original combustion model is employed to account for the different laminar propagation speeds deriving from the hydrogen addition. Guidelines for engine recalibration are traced thanks to the achieved numerical results. Increasing hydrogen fractions in the blend speeds up the combustion propagation achieving the highest brake power when a 20% of hydrogen fraction is considered. Further increase of this last would reduce the volumetric efficiency by virtue of the lower mixture density. The formation of the NOx pollutants also grows exponentially with the hydrogen fraction. Oppositely the efficiency related to the exploitation of the exhaust gases’ enthalpy reduces with the hydrogen fraction as shorter combustion durations lead to lower temperatures at the exhaust. If the operative conditions are shifted towards leaner air-to-fuel ratios the in-cylinder flame propagation speed decreases because of the lower amount of fuel trapped in the mixture reducing the conversion efficiencies and the emitted nitrogen oxides at the exhaust. The link between brake power and spark timing is also highlighted: a maximum is reached at an ignition timing of 21° before top dead center for hydrogen fractions between 10 and 20%. However the exhaust gases’ temperature also diminishes for retarded spark timings. Lastly an optimization algorithm is implemented to individuate the optimal condition in which the engine is characterized by the highest power production with the minimum fuel consumption and related environmental impact. As a main result hydrogen addition up to 15% in volume to natural gas in real cogeneration systems is proven as a viable route only if engine operations are shifted towards leaner air-to-fuel ratios to avoid rapid pressure rise and excessive production of pollutant emissions.
Analysis of Hydrogen Gas Injection at Various Compositions in an Existing Natural Gas Pipeline
Jul 2021
Publication
The lack of hydrogen (H2) transportation infrastructure restricts the development of the H2 industry. Owing to the high investment of building specific facilities using existing natural gas (NG) pipelines to transport a blend of H2 and NG (H2NG) is a viable means of transportation and approach for large-scale long-time storage. However variation in the thermo-physical properties of an H2NG blend will impact the performance of pipeline appliances. To address the gaps in H2 transmission via an NG system in the context of energy consumption in the present paper a one-dimensional pipeline model is proposed to predict the blended flow in a real existing pipeline (Shan–Jing I China). The data of NG components were derived from real gas fields. Furthermore the influence of H2 fractions on pipeline energy coefficient and the layout of pressurization stations are comprehensively analyzed. In addition the case of intermediate gas injection is investigated and the effects of injection positions are studied. This study serves as a useful reference for the design of an H2NG pipeline system. The present study reveals that with the increasing in H2 fraction the distance between pressure stations increases. Furthermore when the arrangement of original pressure stations is maintained overpressure occur. Intermediate gas injection results in the inlet pressure of subsequent pressurization stations reducing. Using existing pipeline network to transport H2NG it is necessary to make appropriate adjustment.
Impact of Grid Gas Requirements on Hydrogen Blending Levels
Oct 2021
Publication
The aim of the article is to determine what amount of hydrogen in %mol can be transferred/stored in the Estonian Latvian and Lithuanian grid gas networks based on the limitations of chemical and physical requirements technical requirements of the gas network and quality requirements. The main characteristics for the analysis of mixtures of hydrogen and natural gas are the Wobbe Index relative density methane number and calorific value. The calculation of the effects of hydrogen blending on the above main characteristics of a real grid gas is based on the principles described in ISO 6976:2016 and the distribution of the grid gas mole fraction components from the grid gas quality reports. The Wärtsila methane number calculator was used to illustrate the effects of hydrogen blending on the methane number of the grid gas. The calculation results show that the maximum hydrogen content in the grid gas (hydrogen and natural gas mix) depending on the grid gas quality parameters (methane number gross heat of combustion specific gravity and the Wobbe Index) is in the range of 5–23 %mol H2. The minimum hydrogen content (5 %mol H2) is limited by specific gravity (>0.55). The next limitation is at 12 %mol H2 and is related to the gross heat of combustion (>9.69 kWh/m3). It is advisable to explore the readiness of gas grids and consumers in Estonia Latvia and Lithuania before switching to higher hydrogen blend levels. If the applicability and safety of hydrogen blends above 5 %mol is approved then it is necessary to analyse the possible reduction of the minimum requirements for the quality of the grid gas and evaluate the associated risks (primarily related to specific gravity).
Modelling of Hydrogen Blending into the UK Natural Gas Network Driven by a Solid Oxide Fuel Cell for Electricity and District Heating System
Aug 2023
Publication
A thorough investigation of the thermodynamics and economic performance of a cogeneration system based on solid oxide fuel cells that provides heat and power to homes has been carried out in this study. Additionally different percentages of green hydrogen have been blended with natural gas to examine the techno-economic performance of the suggested cogeneration system. The energy and exergy efficiency of the system rises steadily as the hydrogen blending percentage rises from 0% to 20% then slightly drops at 50% H2 blending and then rises steadily again until 100% H2 supply. The system’s minimal levelised cost of energy was calculated to be 4.64 £/kWh for 100% H2. Artificial Neural Network (ANN) model was also used to further train a sizable quantity of data that was received from the simulation model. Heat power and levelised cost of energy estimates using the ANN model were found to be extremely accurate with coefficients of determination of 0.99918 0.99999 and 0.99888 respectively.
Accurate Predictions of the Effect of Hydrogen Composition on the Thermodynamics and Transport Properties of Natural Gas
Mar 2024
Publication
This work demonstrates the need for accurate thermodynamic models to reliably quantify changes in the thermophysical properties of natural gas when blended with hydrogen. For this purpose a systematic evaluation was carried out on the predictive accuracy of three well-known models the Peng−Robinson equation of state (EoS) the multiparameter empirical GERG-2008 model and the molecular-based polar softSAFT EoS in describing the thermodynamic behavior of mixtures of hydrogen with commonly found components in natural gas. Deviations between the calculated properties and experimental data for phase equilibria critical loci second-order derivative properties and viscosities are used to determine the accuracy of the models with polar soft-SAFT performing either equally or better than the other two examined models. The evaluation for the effect of H2 content on the properties of methane simulated as natural gas at conditions for transportation reveals higher changes in blend density and speed of sound with increasing H2 content within 5% change per 5 mol % H2 added while viscosity is the least affected property changing by 0.4% for every 5 mol % H2.
The Effect of Hydrogen Containing Fuel Blends Upon Flashback in Swirl Burners
Feb 2011
Publication
Lean premixed swirl combustion is widely used in gas turbines and many other combustion Processes due to the benefits of good flame stability and blow off limits coupled with low NOx emissions. Although flashback is not generally a problem with natural gas combustion there are some reports of flashback damage with existing gas turbines whilst hydrogen enriched fuel blends especially those derived from gasification of coal and/or biomass/industrial processes such as steel making cause concerns in this area. Thus this paper describes a practical experimental approach to study and reduce the effect of flashback in a compact design of generic swirl burner representative of many systems. A range of different fuel blends are investigated for flashback and blow off limits; these fuel mixes include methane methane/hydrogen blends pure hydrogen and coke oven gas. Swirl number effects are investigated by varying the number of inlets or the configuration of the inlets. The well known Lewis and von Elbe critical boundary velocity gradient expression is used to characterise flashback and enable comparison to be made with other available data. Two flashback phenomena are encountered here. The first one at lower swirl numbers involves flashback through the outer wall boundary layer where the crucial parameter is the critical boundary velocity gradient Gf. Values of Gf are of similar magnitude to those reported by Lewis and von Elbe for laminar flow conditions and it is recognised that under the turbulent flow conditions pertaining here actual gradients in the thin swirl flow boundary layer are much higher than occur under laminar flow conditions. At higher swirl numbers the central recirculation zone (CRZ) becomes enlarged and extends backwards over the fuel injector to the burner baseplate and causes flashback to occur earlier at higher velocities. This extension of the CRZ is complex being governed by swirl number equivalence ratio and Reynolds Number. Under these conditions flashback occurs when the cylindrical flame front surrounding the CRZ rapidly accelerates outwards to the tangential inlets and beyond especially with hydrogen containing fuel mixes. Conversely at lower swirl numbers with a modified exhaust geometry hence restricted CRZ flashback occurs through the outer thin boundary layer at much lower flow rates when the hydrogen content of the fuel mix does not exceed 30%. The work demonstrates that it is possible to run premixed swirl burners with a wide range of hydrogen fuel blends so as to substantially minimise flashback behaviour thus permitting wider used of the technology to reduce NOx emissions.
Gas Goes Green: Hydrogen Blending Capacity Maps
Jan 2022
Publication
Britain's gas networks are ready for hydrogen blending. Learn more about Britain's hydrogen blending capacity in the National Transmission System and Distribution Networks.
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