Hydrogen Blending
Thermodynamic and Technical Issues of Hydrogen and Methane-Hydrogen Mixtures Pipeline Transmission
Feb 2019
Publication
The use of hydrogen as a non-emission energy carrier is important for the innovative development of the power-generation industry. Transmission pipelines are the most efficient and economic method of transporting large quantities of hydrogen in a number of variants. A comprehensive hydraulic analysis of hydrogen transmission at a mass flow rate of 0.3 to 3.0 kg/s (volume flow rates from 12000 Nm3/h to 120000 Nm3/h) was performed. The methodology was based on flow simulation in a pipeline for assumed boundary conditions as well as modeling of fluid thermodynamic parameters for pure hydrogen and its mixtures with methane. The assumed outlet pressure was 24 bar (g). The pipeline diameter and required inlet pressure were calculated for these parameters. The change in temperature was analyzed as a function of the pipeline length for a given real heat transfer model; the assumed temperatures were 5 and 25 ◦C. The impact of hydrogen on natural gas transmission is another important issue. The performed analysis revealed that the maximum participation of hydrogen in natural gas should not exceed 15%–20% or it has a negative impact on natural gas quality. In the case of a mixture of 85% methane and 15% hydrogen the required outlet pressure is 10% lower than for pure methane. The obtained results present various possibilities of pipeline transmission of hydrogen at large distances. Moreover the changes in basic thermodynamic parameters have been presented as a function of pipeline length for the adopted assumptions.
Next for Net Zero Podcast: Unlock & Understand, Achieving a More Sustainable Future
Sep 2022
Publication
This episode examines how we are tackling a sustainable future – with Net Zero hurtling towards us at great pace. We’re around a year on from the pledges made at COP26 the UK’s Green Recovery initiative is well under way and by next year Britain is aiming to blend up to 20 per cent hydrogen into its gas networks. So now is the time to continue to unlock new insight and understand further the realities of both the challenges and opportunities ahead.
The podcast can be found here.
The podcast can be found here.
Pressure Management in Smart Gas Networks for Increasing Hydrogen Blending
Jan 2022
Publication
The injection of hydrogen into existing gas grids is acknowledged as a promising option for decarbonizing gas systems and enhancing the integration among energy sectors. Nevertheless it affects the hydraulics and the quality management of networks. When the network is fed by multiple infeed sites and hydrogen is fed from a single injection point non-homogeneous hydrogen distribution throughout the grid happens to lead to a reduction of the possible amount of hydrogen to be safely injected within the grid. To mitigate these impacts novel operational schemes should therefore be implemented. In the present work the modulation of the outlet pressures of gas infeed sites is proposed as an effective strategy to accommodate larger hydrogen volumes into gas grids extending the area of the network reached by hydrogen while keeping compliance with quality and hydraulic restrictions. A distribution network operated at two cascading pressure tiers interfaced by pressure regulators constitutes the case study which is simulated by a fluid-dynamic and multi-component model for gas networks. Results suggest that higher shares of hydrogen and other green gases can be introduced into existing distribution systems by implementing novel asset management schemes with negligible impact on grid operations.
Analyzing the Competitiveness of Low-carbon Drive-technologies in Road-freight: A Total Cost of Ownership Analysis in Europe
Nov 2021
Publication
In light of the Paris Agreement road-freight represents a critically difficult-to-abate sector. In order to meet the ambitious European transport sector emissions reduction targets a rapid transition to zero-carbon road-freight is necessary. However limited policy assessments indicate where and how to appropriately intervene in this sector. To support policy-makers in accelerating the zero-carbon road-freight transition this paper examines the relative cost competitiveness between commercial vehicles of varying alternative drive-technologies through a total cost of ownership (TCO) assessment. We identify key parameters that when targeted enable the uptake of these more sustainable niche technologies. The assessment is based on a newly compiled database of cost parameters which were triangulated through expert interviews. The results show that cost competitiveness for low- or zero-emission niche technologies in certain application segments and European countries is exhibited already today. In particular we find battery electric vehicles to show great promise in the light- and medium-duty segments but also in the heavy-duty long-haul segments in countries that have enacted targeted policy measures. Three TCO parameters drive this competitiveness: tolls fuel costs and CAPEX subsidies. Based on our analysis we propose that policy-makers target OPEX before CAPEX parameters as well utilize a mix of policy interventions to ensure greater reach increased efficiency and increased policy flexibility.
THyGA - Tightness Testing of Gas Distribution Components in 40%H2+60%CH4
Aug 2022
Publication
The present work is concerned with the evaluation of the tightness of the components located on domestic and commercial gas lines from the gas meter to the end user appliance in presence of a mixture 40%H2+60%CH4 at 35 mbar. The components were taken from installations being used currently in Germany Denmark Belgium and France. The current standard methods to evaluate natural gas distribution tightness propose testing duration of several minutes. In this work the components tightness was first evaluated using such standard methods before carrying out tests on longer period of time and evaluate the potential influence of time and the results were compared to admissible leakage rates for natural gas in distribution network and in appliances.
Interchangeability of Hydrogen Injection in Zhejiang Natural Gas Pipelines as a Means to Achieve Carbon Neutrality
Sep 2022
Publication
The blending of hydrogen gas into natural gas pipelines is an effective way of achieving the goal of carbon neutrality. Due to the large differences in the calorific values of natural gas from different sources the calorific value of natural gas after mixing with hydrogen may not meet the quality requirements of natural gas and the quality of natural gas entering long-distance natural gas and urban gas pipelines also has different requirements. Therefore it is necessary to study the effect of multiple gas sources and different pipe network types on the differences in the calorific values of natural gas following hydrogen admixing. In this regard this study aimed to determine the quality requirements and proportions of hydrogen-mixed gas in natural gas pipelines at home and abroad and systematically determined the quality requirements for natural gas entering both long-distance natural gas and urban gas pipelines in combination with national standards. Taking the real calorific values of the gas supply cycle of seven atmospheric sources as an example the calorific and Wobbe Index values for different hydrogen admixture ratios in a one-year cycle were calculated. The results showed that under the requirement of natural gas interchangeability there were great differences in the proportions of natural gas mixed with hydrogen from different gas sources. When determining the proportion of hydrogen mixed with natural gas both the factors of different gas sources and the factors of the gas supply cycle should be considered.
Impact of Hydrogen on Natural Gas Compositions to Meet Engine Gas Quality Requirements
Oct 2022
Publication
To meet the target of reducing greenhouse gas emissions hydrogen as a carbon-free fuel is expected to play a major role in future energy supplies. A challenge with hydrogen is its low density and volumetric energy value meaning that large tanks are needed to store and transport it. By injecting hydrogen into the natural gas network the transportation issue could be solved if the hydrogen–natural gas mixture satisfies the grid gas quality requirements set by legislation and standards. The end consumers usually have stricter limitations on the gas quality than the grid where Euromot the European association of internal combustion engine manufacturers has specific requirements on the parameters: the methane number and Wobbe index. This paper analyses how much hydrogen can be added into the natural gas grid to fulfil Euromot’s requirements. An average gas composition was calculated based on the most common ones in Europe in 2021 and the results show that 13.4% hydrogen can be mixed with a gas consisting of 95.1% methane 3.2% ethane 0.7% propane 0.3% butane 0.3% carbon dioxide and 0.5% nitrogen. The suggested gas composition indicates for engine manufacturers how much hydrogen can be added into the gas to be suitable for their engines.
Hydrogen Blending and the Gas Commercial Framework - Report on Conclusions of NIA study
Sep 2020
Publication
Blending hydrogen into the gas grid could be an important stepping stone during the transition to a sustainable net zero system. In particular it may: provide a significant and reliable source of demand for hydrogen producers supporting the investment case for hydrogen; provide learnings and incremental change towards what could potentially become a 100% hydrogen grid; and immediately decarbonise a portion of the gas flowing through the grid. Technical questions relating to hydrogen blending are being taken forward by the industry (e.g. through the HyDeploy project in relation to the maximum potential blend of hydrogen that can be accommodated without end user appliances needing to be altered or replaced). But if blending is to take place changes to commercial arrangements will be necessary as today these assume a relatively uniform gas quality. In particular the commercial framework will need to ensure that limits on the percentage of hydrogen that can safely be blended (currently expected to be around 20% by volume) are not exceeded. We have been commissioned by Cadent to undertake a Network Innovation Allowance (NIA) project to identify the changes required to the gas commercial framework that will enable hydrogen blending in the GB gas grid and to set out a roadmap for how these can be delivered. This report sets out our recommendations.
Detecting Hydrogen Concentrations During Admixing Hydrogen in Natural Gas Grids
Aug 2021
Publication
The first applications of hydrogen in a natural gas grid will be the admixing of low concentrations in an existing distribution grid. For easy quality and process control it is essential to monitor the hydrogen concentration in real time preferably using cost effective monitoring solutions. In this paper we introduce the use of a platinum based hydrogen sensor that can accurately (at 0.1 vol%) and reversibly monitor the concentration of hydrogen in a carrier gas. This carrier gas that can be nitrogen methane or natural gas has no influence on the accuracy of the hydrogen detection. The hydrogen sensor consists of an interdigitated electrode on a chip coated with a platinum nanocomposite layer that interacts with the gas. This chip can be easily added to a gas sensor for natural gas and biogas that was already developed in previous research. Just by the addition of an extra chip we extended the applicability of the natural gas sensor to hydrogen admixing. The feasibility of the sensor was demonstrated in our own (TNO) laboratory and at a field test location of the HyDeploy program at Keele University in the U.K
HyDeploy: Demonstrating Non-destructive Carbon Savings Through Hydrogen Blending
Aug 2021
Publication
The project has successfully developed the safety case and delivered a hydrogen blend via the gas network into customers’ homes. The demonstration of safety for the specific network was based on robust evidence and clear operational procedures. Alongside the enabling safety case the HyDeploy project has demonstrated the first steps of hydrogen deployment are safe technically feasible and non-disruptive both for the network and domestic users.
The key outcomes of the HyDeploy project were:
The key outcomes of the HyDeploy project were:
- Successful achievement of the first regulatory approval from the HSE to operate a live gas network above the current hydrogen limit of 0.1 vol%. The approval allowed blending up to 20 vol%.
- Development of the technical and procedural precedents to generate evidence for review by the HSE which have informed subsequent safety case submissions through HyDeploy2 and the wider hydrogen safety case industry.
- The design fabrication installation and operation of the UK’s first hydrogen grid entry unit.
- Integration of novel hydrogen production and blending technologies to create the first hydrogen delivery system based on electrolytic generation into a live gas grid.
- Safe delivery of the UK’s first hydrogen blend trial to 100 homes and 30 faculty buildings. The trial delivered over 42000 cubic metres of hydrogen and abated over 27 tonnes of CO2.
- Collaboration with appliance and equipment providers to build a robust evidence base to demonstrate equipment suitability.
- Evidencing the suitability of hydrogen blends with domestic appliances as well as larger commercial appliances including catering equipment and boilers up to 600 kW.
- Evidencing the suitability of hydrogen blends with medium and low-pressure distribution systems relating to key performance metrics such as: pressure control; odour intensity and uniform gas compositions.
- Promotion of supply chain innovation through facilitating trials to develop gas detection and analysis technologies.
- Establishing a robust social science evidence base to understand the attitudes and experience of consumers actually using hydrogen blends.
Investigation of Mixing Behavior of Hydrogen Blended to Natural Gas in Gas Network
Apr 2021
Publication
Hydrogen is of great significance for replacing fossil fuels and reducing carbon dioxide emissions. The application of hydrogen mixing with natural gas in gas network transportation not only improves the utilization rate of hydrogen energy but also reduces the cost of large-scale updating household or commercial appliance. This paper investigates the necessity of a gas mixing device for adding hydrogen to existing natural gas pipelines in the industrial gas network. A three-dimensional helical static mixer model is developed to simulate the mixing behavior of the gas mixture. In addition the model is validated with experimental results. Parametric studies are performed to investigate the effect of mixer on the mixing performance including the coefficient of variation (COV) and pressure loss. The research results show that based on the the optimum number of mixing units is three. The arrangement of the torsion angle of the mixing unit has a greater impact on the COV. When the torsion angle θ = 120◦ the COV has a minimum value of 0.66% and when the torsion angle θ = 60◦ the COV has a maximum value of 8.54%. The distance of the mixing unit has little effect on the pressure loss of the mixed gas but has a greater impact on the COV. Consecutive arrangement of the mixing units (Case A) is the best solution. Increasing the distance of the mixing unit is not effective for the gas mixing effect. Last but not least the gas mixer is optimized to improve the mixing performance.
Modelling and Analyzing the Impact of Hydrogen Enriched Natural Gas on Domestic Gas Boilers in a Decarbonization Perspective
Aug 2020
Publication
Decarbonization of energy economy is nowadays a topical theme and several pathways are under discussion. Gaseous fuels have a fundamental role for this transition and the production of low carbon-impact fuels is necessary to deal with this challenge. The generation of renewable hydrogen is a trusted solution since this energy vector can be promptly produced from electricity and injected into the existing natural gas infrastructure granting storage capacity and easy transportation. This scenario will lead in the near future to hydrogen enrichment of natural gas whose impact on the infrastructures is being actively studied. The effect on end-user devices such as domestic gas boilers instead is still little analyzed and tested but is fundamental to be assessed. The aim of this research is to generate knowledge on the effect of hydrogen enrichment on the widely used premixed boilers: the investigations include pollutant emissions efficiency flashback and explosion hazard control system and materials selection. A model for calculating several parameters related to combustion of hydrogen enriched natural gas is presented. Guidelines for the design of new components are provided and an insight is given on the maximum hydrogen blending bearable by the current boilers.
Domestic Gas Meter Durability in Hydrogen and Natural Gas Mixtures
Nov 2021
Publication
Blending hydrogen into the natural gas infrastructure is becoming a very promising practice to increase the exploitation of renewable energy sources which can be used to produce “green” hydrogen. Several research projects and field experiments are currently aimed at evaluating the risks associated with utilization of the gas blend in end-use devices such as the gas meters. In this paper the authors present the results of experiments aimed at assessing the effect of hydrogen injection in terms of the durability of domestic gas meters. To this end 105 gas meters of different measurement capabilities and manufacturers both brand-new and withdrawn from service were investigated in terms of accuracy drift after durability cycles of 5000 and 10000 h with H2NG mixtures and H2 concentrations of 10% and 15%. The obtained results show that there is no metrologically significant or statistically significant influence of hydrogen content on changes in gas meter indication errors after subjecting the meters to durability testing with a maximum of 15% H2 content over 10000 h. A metrologically significant influence of the long-term operation of the gas meters was confirmed but it should not be made dependent on the hydrogen content in the gas. No safety problems related to the loss of external tightness were observed for either the new or 10-year-old gas meters.
Effect of Hydrogen Blending on the Energy Capacity of Natural Gas Transmission Networks
Dec 2022
Publication
In this paper the effects of hydrogen on the transport of natural gas-hydrogen mixture in a high-pressure natural gas transmission system are investigated in detail. Our research focuses on the decrease in transferable energy content under identical operating conditions as hydrogen is blended in the gas transmission network. Based on the extensive literature review the outstanding challenges and key questions of using hydrogen in the natural gas system are introduced. In our research the transmissible energy factor - TEF - is defined that quantifies the relative energy capacity of the pipeline caused by hydrogen blending. A new equation is proposed in this paper to find the value of TEF at specific pressure and temperature conditions for different hydrogen concentrations. This practical equation helps the natural gas system operators in the decision-making process when hydrogen emerges in the gas transmission system. In this paper the change of the compression power requirement which increases significantly with hydrogen blending is investigated in detail.
Effect of Hydrogen-blended Natural Gas on Combustion Stability and Emission of Water Heater Burner
Jun 2022
Publication
To study the effect of hydrogen-blended natural gas on the combustion stability and emission of domestic gas water heater a test system is built in this paper taking a unit of the partial premixed burner commonly used in water heaters as the object. Under the heat load of 0.7~2.3kW the changes of flame shape burner temperature and pollutant emission of natural gas with hydrogen volume ratio of 0~40% are studied with independent control of primary air supply and mixing. The results show that: with the increase of hydrogen blending ratio the inner flame height increases firstly and then reduces while the change of burner temperature is opposite. The maximum inner flame height and the minimum temperature of the burner both appear at the hydrogen blending ratio of 10~20%. It can be seen that the limit of hydrogen blending ratio which can maintain the burner operate safely and stably under rated heat load is 40% through the maximum temperature distribution on the burner surface. The CO emission in the flue gas gradually decreases with the increase of hydrogen blending ratio while the NOx emission fluctuates slightly when the hydrogen blending ratio is less than 20% but then decreases gradually.
Experiment and Numerical Study of the Combustion Behavior of Hydrogen-blended Natural Gas in Swirl Burners
Oct 2022
Publication
Hydrogen production from renewable energy is gaining increasing attention to enhance energy consumption structure and foster a more eco-friendly and sustainable society. At the same time mixing hydrogen with natural gas and supplying it to civilians is one of the best ways to reduce carbon emissions and increase the reliability of technology while reducing the costs of storing and transporting hydrogen. Even though numerous researchers have conducted experimental and simulation studies on hydrogen-doped natural gas most of these studies have focused on the effects of hydrogen-doped ratio equivalence ratio and fuel combustion mode. The impact of burner structure on hydrogen-enriched natural gas has not received much attention. Compared with conventional direct-flow combustion swirl combustion can improve the mixing effect of the fuel mixture during combustion and the use of regions of reversed flow due to swirl can make the fuel burn more fully to achieve the reduction of pollutant emissions. Swirling flames are widely used in gas turbines and industrial furnaces because of their high stability. However the application of swirl combustion in domestic equipment is still in its infancy which deserves more researchers to explore and enhance the working conditions of domestic combustion equipment. In this paper a three-dimensional swirl burner model is utilized to examine the effect of swirl angle θ and swirl length L of the swirler on the combustion behavior of hydrogen-enriched natural gas in a swirl burner. The results indicate that the swirl angle θ and swirl length L play an essential role in the combustion of natural gas containing hydrogen. As the swirl angle θ increases the flame temperature decreases more slowly the combustion becomes more stable and the length of the flame is slightly increased. Simultaneously CO and NO emissions will gradually decrease and the combustion effect is enhanced when the swirl angle is 45◦. With increased swirl length L the flame length grows the high-temperature region expands and CO and NO emissions decrease. Meanwhile the change in swirl length has little effect on the increase of flame peak temperature when the fuel is thoroughly mixed. When the swirl length is 12 mm CO and NO emissions are lower and NO emissions are reduced by 36.11% compared to a swirl length of 6 mm. This work is a reference point for applying hydrogen-mixed natural gas in the swirl burner but it must be studied and optimized further in future research.
Simulation of Coupled Power and Gas Systems with Hydrogen-Enriched Natural Gas
Nov 2021
Publication
Due to the increasing share of renewable energy sources in the electrical network the focus on decarbonization has extended into other energy sectors. The gas sector is of special interest because it can offer seasonal storage capacity and additional flexibility to the electricity sector. In this paper we present a new simulation method designed for hydrogen-enriched natural gas network simulation. It can handle different gas compositions and is thus able to accurately analyze the impact of hydrogen injections into natural gas pipelines. After describing the newly defined simulation method we demonstrate how the simulation tool can be used to analyze a hydrogen-enriched gas pipeline network. An exemplary co-simulation of coupled power and gas networks shows that hydrogen injections are severely constrained by the gas pipeline network highlighting the importance and necessity of considering different gas compositions in the simulation.
An Overview on Safety Issues Related to Hydrogen and Methane Blend Applications in Domestic and Industrial Use
Sep 2017
Publication
The share of electrical energy hailing from renewable sources in the European electricity mix is increasing. The match between renewable power supply and demand has become the greatest challenge to cope with. Gas infrastructure can accommodate large volumes of electricity converted into gas whenever this supply of renewable power is larger than the grid capacity or than the electricity demand. The Power-to-Gas (P2G) process chain could play a significant role in the future energy system. Renewable electric energy can be transformed into storable hydrogen via electrolysis and subsequent methanation. The aim of this paper is to provide an overview of the required technical adaptations of the most common devices for end users such as heating plants CHP systems home gas furnaces and cooking surfaces wherever these are fuelled with methane and hydrogen blends in variable percentages by volume. Special attention will be given to issues related to essential safety standards firstly comparing existing Italian and European regulations in this regard and secondly highlighting the potential need for legislation to regulate the suitability of hydrogen methane blends. Finally a list of foreseeable technical solutions will be provided and discussed thoroughly
Review of Release Behavior of Hydrogen & Natural Gas Blends from Pipelines
Aug 2021
Publication
Hydrogen can be used to reduce carbon emissions by blending into other gaseous energy carriers such as natural gas. However hydrogen blending into natural gas has important implications for safety which need to be evaluated. Hydrogen has different physical properties than natural gas and these properties affect safety evaluations concerning a leak of the blended gas. The intent of this report is to begin to investigate the safety implications of blending hydrogen into the natural gas infrastructure with respect to a leak event from a pipeline. A literature review was conducted to identify existing data that will better inform future hazard and risk assessments for hydrogen/natural gas blends. Metrics with safety implications such as heat flux and dispersion behavior may be affected by the overall blend ratio of the mixture. Of the literature reviewed there was no directly observed separation of the hydrogen from the natural gas or methane blend. No literature was identified that experimentally examined unconfined releases such as concentration fields or concentration at specific distances. Computational efforts have predicted concentration fields by modified versions of existing engineering models but the validation of these models is limited by the unavailability of literature data. There are multiple literature sources that measured flame lengths and heat flux values which are both relevant metrics to risk and hazard assessments. These data can be more directly compared to the outputs of existing engineering models for validation.
The paper can be downloaded on their website
The paper can be downloaded on their website
Impact of Hydrogen/Natural Gas Blends on Partially Premixed Combustion Equipment: NOx Emission and Operational Performance
Feb 2022
Publication
Several North American utilities are planning to blend hydrogen into gas grids as a short‐ term way of addressing the scalable demand for hydrogen and as a long‐term decarbonization strat‐ egy for ‘difficult‐to‐electrify’ end uses. This study documents the impact of 0–30% hydrogen blends by volume on the performance emissions and safety of unadjusted equipment in a simulated use environment focusing on prevalent partially premixed combustion designs. Following a thorough literature review the authors describe three sets of results: operating standard and “ultra‐low NOx” burners from common heating equipment in “simulators” with hydrogen/methane blends up to 30% by volume in situ testing of the same heating equipment and field sampling of a wider range of equipment with 0–10% hydrogen/natural gas blends at a utility‐owned training facility. The equipment was successfully operated with up to 30% hydrogen‐blended fuels with limited visual changes to flames and key trends emerged: (a) a decrease in the input rate from 0 to 30% H2 up to 11% often in excess of the Wobbe Index‐based predictions; (b) NOx and CO emissions are flat or decline (air‐free or energy‐adjusted basis) with increasing hydrogen blending; and (c) a minor de‐ crease (1.2%) or increase (0.9%) in efficiency from 0 to 30% hydrogen blends for standard versus ultra‐low NOx‐type water heaters respectively.
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