Hydrogen Blending

"Hydrogen is expected to play a critical role in the move to a net-zero economy. However large-scale deployment is still in its infancy and there is still much to be done before we can blend hydrogen in large volumes into gas networks and ramp up the production that is required to meet demands of the energy transport and industry sectors. KTN Global Alliance will host two webinars to explore these challenges and opportunities in hydrogen blending on the 2nd and 3rd March 2021.



Exciting pilot projects are being conducted and explored in the UK Canada and US states such as California to determine the technical feasibility of blending hydrogen into existing natural gas systems. Whilst the deployment of hydrogen is in its early stages there is increasing interest around permitting significant percentage blends of hydrogen into gas networks which would enable the carbon intensity of gas supplies to be reduced creating a new demand for hydrogen and with the use of separation and purification technologies downstream support the transportation of pure hydrogen to markets.

Gaps in codes and standards need to be addressed to enable adoption and there may be opportunities for international collaboration and harmonisation to ensure that best practices are shared globally and to facilitate the growth of trade and export markets. There is an opportunity for the UK Canada and US three G7 countries to work together and show market making leadership in key enabling regulation for the new hydrogen economy.



Delivered by KTN Global Alliance on behalf of the British Consulate-General in Vancouver and the UK Science and Innovation Network in Canada and the US these two webinars will showcase hydrogen blending pilot projects in the UK Canada and California highlighting challenges and opportunities with regard to standards development for hydrogen blending and supporting further transatlantic collaboration in this area. The events also form part of the UK’s international engagement to build momentum towards a successful outcome at COP26 the UN climate summit that the UK will host in Glasgow in November 2021. The webinars will bring together experts from industry academia and policy from the UK Canada and California. Attendees will have an opportunity to ask questions and interact using Mentimeter."











Part 2 Highlights and Perspectives from Canada and California can be found here.

This Insight provides an overview of the recent EU Commission Hydrogen Strategy Energy System Integration Strategy and Industrial Strategy focusing on regulatory issues impacting hydrogen. It looks at the proposed classification and preferences for different sources of hydrogen financial and regulatory support for development of hydrogen supply demand and infrastructure as well as potential regulation of hydrogen markets. Whilst the Hydrogen Strategy underlines the need for hydrogen to decarbonise the economy the Insight concludes that the EU has shown a clear preference for hydrogen based on renewable electricity at the expense of low carbon hydrogen from natural gas even though it recognises the need for low carbon hydrogen. In addition further detail is required on the support mechanisms and regulatory framework if development of new hydrogen value chain is to succeed. Lastly there is little sign that the Commission recognises the change in regulatory approach from the current natural gas framework which will be needed because of the different challenges facing the development of a hydrogen market.

Paper can be downloaded on their website

Hydrogen is increasingly being positioned as an important component of the UK’s Net Zero ambitions and commitments. In particular hydrogen could be an appropriate way to decarbonise the heat produced for domestic and industrial buildings. It is possible that hydrogen could replace natural gas in the UK gas network achieving key carbon emissions reduction targets while enabling homes to be heated to a similar level and standard as they currently are.<br/>In the interim small amounts of hydrogen will soon be blended into current natural gas supplies. The premise of this idea is to blend hydrogen into the existing gas network in small enough quantities to not require any adjustments to domestic cookers boilers and other gas-fired appliances but in large enough quantities to generate significant immediate reductions in carbon emissions. Three trials will take place between 2019 and 2022 as part of the HyDeploy project with the aim of demonstrating that hydrogen blending can occur at scale with no safety implications and no disruption to users.<br/>Public perceptions and acceptance of hydrogen will be pivotal in this scenario. At present there is very little indication of how acceptable hydrogen will be for heating homes and questions around safety cost and performance are only beginning to be understood and addressed.<br/>This report investigates public perceptions of blended hydrogen as a fuel for UK homes. In March 2019 we administered a survey to a sample (n=742) representative of the UK adult population in terms of age sex ethnicity and personal income. Our survey covered initial perceptions values and knowledge of hydrogen; the possibilities and pitfalls of hydrogen blending; public trust; and participants’ overall support for hydrogen. Key Findings and Conclusions and Recommendations for Policy and Practice follow immediately with the full report beginning on p.6.

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.

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

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.

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 NO_x 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.

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.

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.

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.