 Good morning everybody and thank you for joining us today for this webinar on IGEM's peer review consultation for gas quality and changes to the Gas Safety Management Regulations. Energy Networks Association and the Gasco's green program team at ENA are delighted to be supporting this vital industry engagement process that IGEM are undertaking and I'll say a little bit more on exactly why that is in a moment how we see this work as important and enabling and an enabling step in delivering net zero. First though here are some housekeeping matters to run through whilst we are getting a few more people joining the meeting. So firstly I'm Tom Collard the Gasco's green program lead at Energy Networks. If you have any technical issues during the meeting please do email gascosgreen at energynetworks.org and we'll do our best to resolve those. You'll notice that your microphones have been muted. Please do ensure that your cameras are off as well that helps bandwidth issues and maintains a good connection for everyone on the call. Please do also make use of the chat function. This will be running throughout the meeting and we're really looking forward to getting as many comments and questions as possible through that. We will publish a collection of responses shortly after the meeting and do also as well as asking the questions through the chat. Be sure to raise these through the consultation process itself which will detail later on. The webinar has been recorded and a link to it will be debated shortly afterwards so you can share that with colleagues. If you are having any technical issues and aren't able to use the chat functionality do try joining teams meeting via the web app using incognito or private browsing that we found often resolves those issues. Moving on as you will likely be aware ENA and its gas network companies have been supporting greening of the gas grid for many years now. The gas networks have supported more than 110 biomethane connections to the gas grid commenced practical trials of hydrogen blending and are developing dedicated hydrogen networks. We formed the gas goes green program to build on these successes to date and to put forward an integrated plan for the gas networks that sets out the role we see them having in delivering net zero and the program is a joint initiative between ENA, National Grid, Caden, Northern Gas Networks, SGN and Wales and West Utilities. Through the program we are bringing together the engineering expertise of the gas network companies with the wider energy industry, policy makers, academics to make the changes that we see as being necessary to move the network infrastructure from one that's delivering methane based natural gas today to zero carbon, hydrogen and biomethane in the future and the gas goes green program has six work streams with the second of these as you can see on the screen there focusing on gas quality and safety. And the work that we're undertaking in regards to gas quality and safety is really to focus on ensuring that the safe transportation and distribution of hydrogen and biomethane can be made to the same quality and safety levels that we have today for the natural gas. We know that if gases to play a role in UK energy in the future that existing gas legislation and regulation will need to change to allow for greater proportions of net zero compliant gases. So in this respect IGM's consultation which you hear about more about today is really a crucial next step on the net zero pathway. Our view of the pathway and indeed our gas goes green program and its deliverables for this year were informed by research undertaking last year and the stakeholder engagement we did through that. And as we move to the next slide you can see the changing composition of gas consumption that we envisaged through this pathway to net zero and the different steps we see as needing to be taken on that. So overall there's a decline in the natural gas received by end users and an increase in hydrogen and biomethane. And what I wanted to convey with this chart is that the changes to gas quality regulations to enable injection of low carbon and renewable gases is really a crucial first step of preparing for the transition. This along with introducing some other policy required to support carbon capture and storage or to mandate the requirement for hydrogen ready boilers for example are really key enablers of those later steps in the pathway as a set out in the bars on the top above the chart there. So it's really important that we progress this work. So as you'll hear more about today the gas the changes in gas quality regulations in that first part support the second part of our pathway which is to facilitate more low carbon gases. We would also expect them to give confidence to investors finalizing preparations for hydrogen projects and that second step of the pathway then in turn enables the later step of the pathway to expand more supply. Biomethane from AED in this third stage really ratchets up here again helped by changes in gas specification and it's at that stage where development and testing of thermal gasification technologies for production of biomethane which is crucial for the negative emissions that we see as being required to balance net zero is at that stage when those first projects connect to the network. And then on to the later parts of the pathway from the 2030s after expanding supply in step three on the chart there we need to expand the demand base. So it's at this stage where we see hydrogen clusters develop with anchor customers in industry and transport and then at this time hydrogen storage also develops alongside those clusters to ensure supply. And then in the latter stages of the pathway from the mid 2030s onwards this is where increasing low carbon gases are on the network and these initial hydrogen are expanding and merging to form hydrogen zones. And this takes us to part six on the pathway where the net zero energy system is achieved and at this point natural gas is only used for the production of hydrogen with CCS. So I wanted to set out that gas goes green vision for meeting net zero really to provide the context for the discussion that we're about to have. So moving on to the objectives for today in hearing from the expert speakers iGEM and ENA has lined up we'll understand the timelines for gas safety management regulation changes understand the timelines for iGEM's gas quality standard understand the evidence base that's been developed to date and also we'll hear about the gaps in understanding where through their consultation iGEM would really like to hear from you all. So as you can see on the agenda on the next slide we really have gathered together some of the UK's leading experts on this work and we have a packed agenda for you. First up we're going to hear from Ian McCluskey who's the head of technical services and policy at iGEM and Ian's going to provide us with an overview of the new iGEM gas quality standard for net zero emissions. We're then going to hear from Dave Lander. Dave Lander consulting has been working on a number of elements in regards gas quality and he's going to discuss the Dutton method. Dr. Martin Brown principal specialist at DMVGL will then present on the domestic customer's case for change and Dr. Sarah Kimpton senior principal consultant at DMVGL will then discuss gas quality variations and industrial and commercial customer case for change and we'll then hear from Dave Lander on the network safety impacts before we then finish with a further Q&A hosted by Ian. So final thing for me is just to remember please do ask questions throughout any of the presentations via the chat and as they say we'll do our best to answer them after each presentation and then there will be that further opportunity at the end. So without further ado I'll pass to Ian McCluskey. Okay thank you Tom and good morning everyone. It's great to see you actually so many people on the call this morning and thank you all for coming along. So I'm Ian McCluskey head of technical services and policy at the institution. I'm here today to introduce the new gas quality standard and I'll describe the process. It's taken us some four years to reach the stage and summarise the changes which are being proposed in the new standard. This is an extremely important stage in the development of the standard. The standards have been prepared based on the scientific evidence and the debate by an industry working group. And we're now at this industry comment stage. We'll be working with comments and on the proposed changes and we invite you to review the evidence which supports those changes some of which we will be presenting to you today. Next slide please. But first I'd like to begin with a brief introduction to the institution as it's important to understand a strategic and historic role in supporting the industry as it has evolved through significant periods of change. From over 157 years ago the institution is among the oldest of engineering institutions in the UK and has awarded a Royal Charter in 1929. We're a global membership organisation of individuals and registered companies and we're also operating from wider public benefit. We're also licensed by the engineering council to work with professional sectors for engineering and technician and corporate and engineering and chartered engineer. Perhaps what many will know why GM4 is a publication of a suite of standards which are respected by industry and by regulators covering engineering requirements from butch to burner and everything in between. Now we've been publishing these standards since the 60s where safety considerations are paramount. They're developed through a qualitative should governance process and the standards are drafted by practising qualified engineers, scientists and professionals in their own field, both members and non-members, through expert panels and working groups which allows for robust debate and peer review. But once passed this stage and the experts have agreed on the content of the standard the governance process requires this wider industry consultation the period that we're in now. They're then submitted for further scrutiny through IGN's committee structure and approval prior to being published. An extremely important point to note is that IGN's standards are continually viewed and we're required updated to reflect the latest research, innovation and technological developments. Next slide please. So I'm going to set the scene for the IGN standards. It's important to understand well why an IGN gas quality standard, why now? It's no surprise and everyone understands now that gas supplies have changed dramatically since the 70s and the current requirements for gas quality which is simplified in schedule three of the gas safety management regulations were developed by British gas search apps in the 70s and the 80s and based on the requirements for safe combustion of domestic appliances the ring was at that time. The data that gets quality parameters were then published by IGN or IGE back then in 1984 and you'll hear more on that and the specifics and the details from Dave Lander later. So as we look to the supply study the picture is obviously dramatically different with the less and healthy gas coming in from the Ross Sea as the UK CS supplies dwindle and reliance on more and ever more imported sources of gas. But also as we move forward to the journey to net zero as Tom has explained we're going to be introducing more more biogas as a more hydrogen will become part of the gas supply mix and all these gases as you can see from the the chart below in terms of the wobby limits have got varying different degrees of characteristics but importantly of wobby limits as well. Next slide please. So in 2016 in meetings which were held with off-gem health and safety executive DEC, NAVAS and IGN to explore setting up an expert working group to investigate the potential changes to gas quality and it was agreed that IGN would develop a new industry standard that would meet the current and future gas supplies for the UK. Now at that time it was proposed to initially examine the evidence base for the changes to the upper wobby limit based on extensive research undertaken by SGN on the urban project opening up the gas market. The expert working group would then later consider examining the evidence for the widening of the lower wobby index and other parameters and it was essential that the review process considered the previous studies in this area was also to look at the current and new research things that are not just domestic but also assess the impacts of any changes on industrial and commercial equipment and also assess the impacts from network safety. Next slide please. So the gas quality expert working group was set up made up of such a matter of experts some of whom you hear from today and in the next and this slide here you can see an example of those organizations stakeholders that have part of that expert working group includes the health and safety executive gas producers networks as well as organizations representing appliance manufacturers. I'd like to take this time to thank all members of the expert working group for their support and contributions to drafting of the standard and in particular I'd like to thank Gus McIntosh of SGN who's chair of the working group. Next slide please. So the gas the primary objective of the the gas quality standard for the for the expert group is the production of an iGEM standard covering UK gas quality specifications in order to facilitate a change from GSMR that reflects the declining supplies in UK CS and the available alternative sources of gases. The standard aims to facilitate the safe injection of a wide range of gases securing UK gas supplies without the need for additional processing and help to facilitate deep carbonization by reducing processing missions and allowing more hydrogen to the network. That's important to remember the gas safety management regulations are primarily intended to ensure the safety of the public and that will continue to be the primary aim of the new gas quality standard. Next slide please. During the period of the view over the past four years we've researched extensively many many existing reports on this area and on this slide you see some of the reports that we're going to be outlining today include for example the SGN opening up of the gas market that I mentioned earlier is perhaps one of the most extensive areas of research ever undertaken. SGN's operating under an exemption to supply four Scottish towns will hide what the gases provides an evidence base for domestic and small commercial appliances some 8,000 properties some 11,000 installed appliances and since the project ended in 2016 it continued with random checks totaling about approximately 4,000 checks. Another important report is the industrial and commercial research of anti-appliances and applied research into the effects of the wider range of wobby gases that was undertaken. It was also an impact study which is under the lower wobby index gases. The aim of that study was to provide the evidence of the impact of utilization of gas of quality down to the existing emergency wobby index lower limit. Another important report that Dave Lander outlined is that some 40 years since conversion UK appliance types and designs are now widely different as if I consider appropriate to revisit the different approach and assess its usefulness for both for existing and future gas supplies and finally Dave will also talk about the work and the study which was comparing pipeline fracture propagation risks from natural gases of different wobby index and the report examines whether there would be an increase in risk of pipeline fracture propagation in the event of any pipeline failure and details and assessment of the change in risk associated with the conveyance of natural gases of higher wobby gases. Next slide please. So now we've reached as I've mentioned this came milestone which is the industry-wide consultation stage and to support the consultation we've published this evidence report. It's called a key step on the pathway to net zero emissions and the report explains the proposed changes to the gas specification which I'll look around in a second and provides reference to all the extensive supporting technical evidence. The report outlines the existing gas quality issues, the updated dust and interchangeability diagram, the case for domestic and industrial and commercial plants as well as the impact on network safety. Now the proposed item standard will be a dynamic framework for changes in gas quality but the enduring safety of domestic consumers will be paramount and the HSE will continue to have a veto on any proposals that could compromise safety. Next slide please. So I'll now introduce the changes that are being proposed and within the report there is a table and that table provides a summary of the proposed changes from schedule three to the new item standard. The final to those invites you'll see there's no change to hydrogen sulfide content, there is no change to the total sulfur content or at this stage though we are preparing for it there is no change to hydrogen at this stage being proposed that still remains at 0.1 percent. Oxygen content will move up from 0.2 to up to 0.1 percent for networks operating below 30 bar which reflects the current class exemption from biomethane will also widen the lobby index by decreasing the lower limit and increasing the upper limit. So the decrease to the lower limit from 47.2 to 46.5 mega joules per cubic meter will increase the upper lobby index limit from 51.4 to 52.5. The incomplete combustion factor will be removed and on the next slide we'll continue with the summary of the changes the shooting index will be removed by the proposal and having removed those inter-related safety parameters was simplifying in the proposal the GSMR interchangeability diagram to a lobby index of the range it would have described and introducing new maximum relative density of 0.7 and finally removing the upper and lower emergency limits so these will now become the normal limits. Now that's the sum of the changes on the next slide I'd just like to highlight the link to the website now my terms website has the evidence report that also has the standard that has a governance document on there for the changes as well the consultation period in the an example there of the link to the to the website please we welcome your comments on the draft standard particularly any comments relating to the scientific evidence which can be found on that link also and that consultation period ends at the end of July on the 30th of July so thank you for that that's hopefully giving you a setting the scene for what's going to be presented to you and the sessions that will follow and I'd now like to to introduce Dave Land. Dave Land is going to pick up on the the Dutton revisited and I'll manage the questions through Q&A at the end of Dave's session and the end of each of the sessions from from Dave and Martyn and Sarah I'll do some Q&A session after that and the interest of keeping to time I may need to not answer all those questions but as Thomas said at the beginning we will respond to all the questions but please go on to the IGN website putting your comments there as well and we will respond to to all the comments that have been made so Dave if you'd like to pick up from here thank you. Thank you Ian, good morning everyone, can I have the next slide please okay this is just an overview of the the topics I'll be talking about so initially I'll go back and talk a little bit about the the UK approach to natural gas interchangeability as it stands at the moment, a little bit of historical context and in particular discussion of the appliances generally installed at the time. I'll also give you a description of the Dutton method it's quite a complicated method so it will be a simplified explanation and we'll be talking about this thing called the equivalent mixture and the parameters that Dutton used to characterize appliances okay next slide please okay so a little bit of discussion on the choice of the limit values that Dutton made then and maybe a commentary on what we're proposing now and the biggest probably the biggest change is the the actual second of the two interchangeability parameters that are used so we'll be switching or proposing switching from Dutton's GSMR interchangeability diagram to a simplified diagram that involves Wobby index and the relative density. Next slide please okay so from a historical point of view then most of this work really started in the 1970s and the 1980s in that situation we had southern north sea gas fields dominated dominating gas supplies but it was anticipated that there would be a decline in those supplies and those would be replaced by other sources which would be different and more variable and essentially those were northern north sea supplies which tended to have a higher Wobby index but also Dutton noted at the time that eventually these would be replaced by manufactured SMGs that's probably not quite the scenario that we actually planned out I think we were anticipating in the late 1990s for substitute natural gas to be made in quite a significant proportion but that hasn't happened as has it now. Okay so the word drivers for interchangeability methods so principally safety domestic appliances essentially have fairly limited tolerance to variation in combustion characteristics so effectively you have to make the gas to suit the appliance and not vice versa. There's also a commercial driver of course and that is simply that you want to treat gases as little as possible in order to make sure interchangeable. Next slide please so effectively British Gas Corporation adopted the approach that was developed by Brian Dutton from the Watson House Research and Development Division and there were a series of research papers that were published but summarized in what is now the well-recognized IGE communication 1246 so that was published in 1984 but based on experiments that were carried out in the 70s and the early 80s. It was a new approach at the time prior to then appliance effects and flame phenomena that were related to gas composition were essentially related to functions that were effectively measured and very often based on properties like burning velocity but Dutton's approach was to relate those two compositional variations and that was also consistent you have to remember as well at the time that there were significant developments in gas analysis and some of the early process gas chromatographs were being developed at around that time too so it was a convergence of the ability to analyze routinely cheaply gas analysis and use that data to correlate properties of of the gas being conveyed and Dutton's approach was effectively implemented into the gas safety management regulations in 1996 and that essentially was at around the time of the initial start of gas privatization too. Next slide please. So in developing his approach Dutton recognized that there were three key combustion indicators, poor combustion indicators. First of those is incomplete combustion where significant quantities of carbon monoxide can be formed in addition to carbon dioxide and that's generally seen at high wobby index and to a certain extent at low wobby index. The next the next poor combustion issue is flame lift that occurs essentially when the flame speed becomes quite low and the speed at which the flame burns is becomes lower and lower and the flame tends to lift off the burner tip and ultimately can extinguish. And generally you see that at low wobby index and the third aspect is sitting and that's generally seen with high density gases which contain higher hydrocarbons. So you get small particles of carbon which give you a sort of yellow tip flame and ultimately you can get deposition of carbon on things like radiant gas fires. Okay next slide please. And so those three poor combustion indicators were tested by Dutton and he carried out testing of their variety of appliances that would demonstrate the three combustion indicators. Okay and so for his incomplete combustion Dutton looked at water heaters, instantaneous water heaters, very common appliance at the time. And for flame lift he looked at cooker hubs and for sitting he looked at gas fires, radiant gas fires. Next slide please and it's the performance of those appliances which really set the basis for which you for the limits in those particular properties. So I mentioned that the Dutton approach uses gas composition and the first step is to simplify the gas composition. Natural gas is quite a complicated mixture it contains up to and more than sometimes 11 components and so in order to get some easier interpretation of the data he converted the gas composition sometimes 11 component gas mixture into an equivalent mixture of methane, propane and nitrogen and in some instances hydrogen. This process of converting to an equivalent mixture is a well-recognized approach and is used quite often particularly in reservoir modeling where you can simplify a composition and you get equivalent properties for that particular mixture and to do this Dutton replaced all of the hydrogens with an equivalent amount of methane and propane. Any inerts were adjusted or converted to a single nitrogen component which preserves the lobby index of the original gas mixture. So once you've carried out this process your 11 component mixture or sometimes more than that is converted to a mixture of methane, propane, nitrogen and possibly hydrogen if there is any in there and so you have a simplified what's called equivalent gas mixture and in carrying out the testing he identified three interchangeabilities that could be related to the composition of the mixture. The first was what's called the incomplete combustion factor and I'll talk a little bit more about that later but that characterizes the formation of carbon monoxide then there's his lift index which characterizes the propensity of the flame to lift from the surface of the burner tip and sooting index which is the the propensity of the gas mixture to form soot and it's possible then to compare all of these three against and develop suitable limiting values in those particular properties and by defining those limiting values you can effectively bound gas composition for normal and in some instances for emergency use only. Next slide please. So Dutton effectively characterized limit values for all of these properties but it's actually quite quite nice to to be able to visualize the region in which normal operation is preferred and he did this by developing a diagram which you plot Wabi index and what's called the P and N number which is the sum of the nitrogen and the propane in this equivalent mixture and that allows you to sort of visualize areas in which gas would be normally deemed to be interchangeable. So this is the simplified version which was adopted into the gas safety management regulations so that central region is where normal operation gases will be considered interchangeable and that's effectively then is bounded by by four surfaces so the surface to the left the the lines to the left are essentially compositions of or that's a feasible so anything to the left of that line would be considered unfeasible unless there was a hydrogen gas in the mixture so in the case of hydrogen free gases then those gases just don't exist outside that region. To the right the sloping line that slopes from top left to bottom right is the setting index line so line gases to the right of that line would generate effectively more so than we would be desirable and then the upper and the lower blue lines are the limits that are formed by incomplete combustion on the top line and that's the incomplete combustion factor which is normally set at a value of 0.58 and that corresponds to a Wabi index of roughly 51.41 so that red line where the blue line intersects the the red line on the left that line there is for a Wabi index of 51.41 so although there is a limit in the gas safety management regulations at the moment of 51.41 for most gases they would be considered not suitable for admittance into grids at the moment because they would hit the 0.48 ICF line before then so although there is a Wabi index limit it's very rarely actually exercised it's usually exercised but the control is exercised by the incomplete combustion factor and on the lower the lower blue line is the lower Wabi index limit which is currently set at 47.2 and doesn't set that not on flame lift considerations actually but on heat service limitations and that's really associated with the instantaneous water heater so Bridget gas corporation at the time would tend to have more and increase in complaints about the water not getting hot enough okay next slide please so based on the open work that we had carried out with SGN what came out was a proposal to to replace the Dutton diagram plot of Wabi index against the PN parameter but to replace that with a Wabi index versus relative density parameter there are two key reasons for that firstly it's consistent with practice elsewhere in Europe Western Australia and the United States and during the developments on the harmonized gas quality standard European harmonized gas quality standard the relative density Wabi index plot emerged as the sort of favorite approach the other reason for changing that is that the propane plus nitrogen the PN is not really an intuitive gas property parameter it's quite difficult to calculate if you don't have a computer program to do that it's not an intuitive property next slide please and you'll see also then that relative density is actually a good proxy for a PN number so there's a direct correlation between that and what that is effectively means then is that you have noticed that the effectively the shape of the Dutton diagram hasn't really changed when you replace the x-axis with relative density okay next slide please so our proposal then is that relative density would be the second parameter and we have set or proposed that the limit value should be set at 0.7 and that corresponds effectively with the European view which developed when they developed the European standard EM12676 which was subsequently adopted as a British standard these footing index limits of 0.6 is not really a safety limited value a safety a safety related parameter it's really to do with discoloration of radiant heaters and that value there of 0.6 intersects with the 0.7 at a round about that value that's indicated there so the drop in the Wobby index is quite small because the relative density constrains that drop quite effectively there are very few gases that in the UK that would have a density relative density greater than 0.7 next slide please so this is the proposed interchangeability diagram that incorporates relative density limits and also incorporates two upper and lower Wobby index limits so in terms of the ICF limits the ICF lines are close to horizontal anyway over the proposed relative density range and so upper limit is quite a terrible simplification and it's also consistent with practice elsewhere next slide please so as I mentioned our first proposal is that the upper limit value will be increased to 52.85 and that corresponds to the current emergency limit value next slide please and the lower limit value we're proposing that the lower limit value would be reduced to 46.5 which is the the current emergency lower limit value next slide please so I'll just briefly cover sort of logic the logic behind setting those upper and lower Wobby limit values so firstly the upper limit why should that be set at 52.85 well the main outcome from the OGM project the opening up the gas markets project was that domestic and small commercial appliances went correctly installed serviced and operated it can safely burn gas with a Wobby index up to 54.7 so that's a quite a wide quite a high high limit value it's consistent with the main findings of the gas qual studies the gas qual study was that carried out the pre normative study carried out by a consortium of European gas appliance testing laboratories and they fed all of their information for consideration by the working group that's developed the European standard on harmonized gas quality so the OGM project produced findings that were consistent with gas qual and equally those findings were consistent with earlier testing that was carried out by DMVGL in support of the UK tripartite gas quality study should also say that that's also consistent with even more recent studies that have been carried out by high deploy which is looking at addition of hydrogen into gas supplies and again there's a major body of work technical work on appliances that are also justifying those limits to the Knex slide please it's also instructive to to look at the origin of Dutton's incomplete combustion factor specification so i'll just talk a little bit about incomplete combustion factor so effectively Dutton defined the incomplete combustion factor as the number of times that the CO2 ratio in the reference gas has to be doubled to give you that that you see in a test gas and Dutton chose the value to characterize incomplete combustion limit as being the instantaneous water heater which is often unflued and typically what he found was that the CO2 ratio doubled every 1.5 megajoules per cubic meter now today's equivalent appliance i guess would be the combi water heater the combi central heating boiler and if you do similar tests today then typically what you find is that the CO2 ratio doubles every three megajoules per cubic meter and as a result the correlations that Dutton produced that calculated ICF from composition didn't really correspond to today's appliances. Next slide please so what i've got here is a an example of testing that was carried out by Kiwa during the opening up the gas market project you see some typical results and that again has been replicated in other studies to effectively the bottom line which is a combi boiler you can see that the the doubling of the carbon monoxide concentration occurs over a range of about three megajoules not one and a half and for the back boiler testing it's even more than that it's probably around about six megajoules okay next slide please so Dutton's ICF formula which appears in his paper it's shown here the important thing to look at is the 1.56 on the denominator and effectively that's the essentially what we're saying is that at the time Dutton found instantaneous water heaters the doubling of CO occurred every 1.5 megajoules per cubic meter and what we find is that that formula doesn't really hold for today's appliance so on the graph on the right so the dotted lines corresponding to different ICF values what we're sharing is for those combi boiler and the back boiler what the actual ICF found from the experiment was so if you just look at the top line where the dotted line is ICF equals 2 then the values that you get vary from around about 0.6 up to about 1.1 so again you're getting around about half the value that Dutton's formulation would have given so today's appliance is don't really don't really reflect the Dutton formula so next slide please so in terms of the the ICF limit value itself when Dutton was setting that he was very conscious that traditionally at the time rich gas limit was set to around about five percent over that of the reference gas which is G20 which is pure me saying and it should have been 53.5 53.3 megajoules per cubic meter although there is some confusion in the actual communication as he cites that as the wet gas value of 52.1 but essentially for the dry gas basis it should have been 53.3 but in fact what Dutton adopted at the time was a value of 51.2 and that really came about because of a survey of appliances that was carried out in 1978 which suggested that some appliances might have higher CO2 ratios than than would have been expected it was a very small proportion of appliances but they chose to lower the limit value not set it at 51.2 and not at 53.3 and the paper mentions that there was an expectation that they would review that at time and there was a further survey of appliances but again they chose not to raise the the limit value and that value of 51.2 is effectively close to the ICF equals 0.48 which is currently what's set in the gas safety management regulations and remembering that this was done in the 1970s it almost certainly corresponds to performance of converted town's gas appliances so if you remember conversion from town's gas to natural gas started in 1968 and ended in September 1977 so it's quite a long process of converting and at the time almost most most all of those appliances were converted the churn rate was probably not high enough to get a significant proportion of appliances that were dedicated for natural gas next slide please so the lower limits were proposing setting that at 46.5 and essentially today's testing shows that CO emissions is not really a major issue at the at the lower wobby index concern and it wasn't a concern when Dutton considered his lower limit values the 46.5 megajoules per cubic meter corresponds to Dutton's flame lift limit to a lift index of 1.16 and that's just really when flames started to started to lift off the surface of a gas cooker the existing lower limit value that we have in the GSMR is 47.2 and that was really set as a heat service limit as I mentioned it was set on the basis of instantaneous water heaters and those water heaters would would produce hot water on tap as it were and what British Gas Corporation found was that if the value fell to around 47 then there would be an increase in complaints from consumers. Today's comparable device really I guess is the Combi boiler performance and we have looked at performance of Combi boiler and we don't think that there is a significant change in in temperature of hot water between 46.5 and 47.2 so that's probably not an issue as far as as far as heat service is concerned and so again we'll be setting it on safety considerations associated with flame lift. Next slide please this is just a summary slide and effectively what we're proposing is adoption of limits based solely on the consideration of Wobby index and of relative density. The use of incomplete combustion factor and propane plus nitrogen adds complexity without really any material advantage. The ICF calculated from the original Dutton relationship doesn't really fit with the performance of today's appliances and it also provides us with consistency and practice with other countries which is quite important now because you know we are we are receiving significant quantities of gases through interconnectors and through LNG importation with other countries. The second change is the increase in the upper wobbling limit value to 2.85 which is again more reflective of the performance of today's appliances and it still allows us a safety margin of 1.85 megajoules over the results of in-premises testing in the opening up the gas market project. And finally we're proposing decreasing the lower wobby limit value to 46.5. CO isn't really an issue at this level and it's effectively Dutton flame lift limit and we're proposing that that's the appropriate limit. The existing lower limit value of 47.2 was really set on the basis of heat service and again that's on the performance of instantaneous water heaters again at the time of natural gas change over. Okay I think that's that's my my session I think the next slide will be just a Q&A session. Thank you Dave there's been a few questions and lots of good activity on the chance as well. I think some of you sort of answered as the presentation went on there's been a question about sitting index and the evidence for removing that deep I think you've sort of covered that I just want to just mention reasons behind that. Sorry could you say that again I'm sort of the removal of the sitting index what's the evidence behind that? Yes essentially it's essentially the appliance that was used to indicate sitting or consider sitting index was the radiant gas fire and the sole consideration was really the discoloration that you get when you have a sitting flame. So it's not really a safety related issue obviously if there is sitting going on then there is increase in CO but the main consideration in setting that is the degree of discoloration that you would see on a radiant gas fire radiant and again the proposal is that a density limit of 0.7 would allow reasonable control of additional sitting concerns on such appliances and in fact we often think of the UK as having more stringent regulations but in fact in terms of sitting considerations the current arrangements we would normally permit more dense gases than 0.7 in principle because the sitting limits takes you to a more dense gas although there actually aren't that many examples of UK gases with density grades in the 0.7 so we're actually slightly less stringent in terms of sitting considerations than the rest of the rest of Europe. And just on the point of questions come in from Shane Wilkins about is it not possible for us to block a heat exchanger on an order sale boiler? I think that was studied during the DTI test there were some studies of that. I think it's an order of magnitude different in terms of the propensity to block such heat exchangers. As I stress the current limits are less stringent in sitting index for most of the range of gas quality. The 0.7 relative density limits effectively makes it more stringent for most of the sitting index line and so whilst there are not many UK gases that have a density higher than 0.7 there are some supplies in the in the south related to an onshore natural gas supply and there have been no issues with with such appliances then. Okay thank you Dave I think there are interests of living on in time. I think any other questions that we've not gotten to during this session we will respond to it fully afterwards but thanks for those questions and nobody in this session hands you over to Martin Brown who's going to take us through the widening the lobby for a domestic customer's case. Over to you Martin. Good morning everybody. Dave's provided the framework really with regard to what the current limits are and what the plan changes are for the gas quality ranges that are acceptable in the UK. I'm going to provide you with a bit of a whistle stop tour really in terms of providing an indication of what data was gathered and how that's evolved over the years to enable us to get to the position where we can make these judgments and provide you with background information with regard to what the impacts are with applying those different quality of gases that are different lobby index gases to a range of different appliances. I think some of the key messages that came out of the previous presentation are that the original Dutton work, the original gas safety measurement regulation was built around the converted older style appliances and clearly understanding how more modern appliances behave and what the implications are for those was a gap in the knowledge but I think over the last 20 years we've actually been building that information base and actually extending that knowledge base so that we can actually provide now a very detailed understanding of how the emissions change as a function of the lobby index and the different gas compositions. So can I have the next slide please? So in overview I'm going to touch a little bit about what lobby index is and why it matters. Why we need to think about lobby index in the first place from a combustion point of view and this has been a question already on the chat about what the lobby index is and we'll clarify that now. It's equal to the calorific value divided by the square root of the relative density. It's a term that's used widely in gas quality studies and I'll touch upon what it actually means a little bit later on in the presentation. Clearly we need to think about how the different burners might respond to the changes in gas quality so I'll put a couple of quick slides up regarding burner operation and that links in really with the comment that Dave made previously that for domestic appliances without sophisticated adaptive control systems the gas has to fit the burner operation, the appliance operation. The appliances are quite sophisticated compared to what they were several years ago but ultimately they don't necessarily have the capability of actually adapting to extreme changes in gas quality so we need to make sure that the appliances are set up and operating so they can actually manage that gas quality range and burn efficiently and safely. And now I'm going to actually take you on the whistle stop tour really of how the knowledge base is actually extended with regard to the practical tests that we've done and how we've actually ramped up for want of a better phrase the information that we have from the initial DTI work which actually started off with five appliances being tested through subsequent work with the DTI then onto gas quality and then the probably the more significant test programme that's been undertaken which was done by SGN through their opening up the gas market project. So next slide please. So why do we get hung up about what Wobby Index actually is? Well Wobby Index is a key indicator of what is termed gas quality and that's the ability of appliances or different equipment to actually burn gas. One of the nice things is that it's been adopted as a key parameter worldwide so you can talk about Wobby Index and that's understood by a lot of combustion engineers, appliance development people and gas quality people around the world and it's very important for determining interchangeability of these different gases. Why is it important? Well it's an indicator of the actual heat rate going to the burner. This has been discussed in the chat as well and if you've been following that you'll have seen in the discussions. Different gases with the same Wobby Index should give the overall burn performance on the same appliance and one of the aspects that Wobby Index does link to is that it's actually related to the XSA that's available actually within the combustion system. Appliances will be set up for a particular XSA level and that will be done to ensure good performance with the reference gas and enable the other test gases that are used to be burning those appliances but still meet the requirements with regard to the certification standards to get that CE marking. So it's an important parameter and it's linked primarily to safety and performance efficiency and operation. Next slide please. So here's a quick schematic or quick diagram with regard to how a typical partially aerated burner might behave as a function of XSA. On the Y-axis we've got the carbon monoxide content in the emission as a function of the XSA which is labeled on the on the X-axis. Clearly for stoichiometric combustion you don't need any XSA so you'll be down at zero for that. Now that would actually result in quite a high carbon monoxide emission so majority of systems tend to operate with at least 20 possibly even 30 XSA. Now this is for a partially aerated burner. Here we're looking at a typical flame similar to what you would see on a Bunsen burner so it'd be a Bunsen burner type flame where you would actually have sort of a two-stage flame as it were. You have a primary zone and a secondary zone in that flame. The primary zone is often what is termed fuel rich so there's not enough air to actually burn it out and then the secondary zone is where the XSA comes in. And you can see that that type of burner would operate with very low carbon monoxide emission. Four XSA levels in excess of around about 20 percent and it could extend for significant additional levels of XSA and corpus that quite quite admirably. Next slide please. So superimposed on the initial diagram is what would happen if we had a fully pre-mixed burner. So that's where the gas and the air are mixed in a chamber below the burner and then burned to the homogeneous mixture actually above the burner zone. All the air that's required is actually provided through the burner itself. There you can see in the red line that you have different type of performance in terms of what sort of level of XSA would be the optimum for that particular burner. These burners are often used in condensing boilers, the highly efficient, get good control and give good emissions performance or the range from in diagram from about 10 to 45 50 percent XSA. The arrow that you see there, double headed arrow is an indicator of the range of XSA values as a function of the Wobby index range that you might expect to see are from the UK. So if it's been set up correctly with the the G20 reference gas then you can actually get good performance over the whole Wobby index range without any issues in terms of the carbon dioxide performance. Now that's for brand new appliances out of the box. It's not necessarily ones that have been installed and operated for a long period of time. It's not ones that have been misused or damaged in any way. So there's clearly a lot of variability that's required but the safety record of combustion systems and the safety record of the gas industry is good. It's very good in fact. An incidence related to poor combustion although quite prevalent 20 years ago, 30 years ago, the numbers of people that are actually impacted by malfunctioning appliances is actually very few these days. Thank you Pauline. Next slide please. So as I mentioned in the introduction, the level of understanding that's been developed over a number of years has ramped up significantly. It was recognised early on that the impact of different gas qualities on more modern appliances wasn't fully understood and the DTI were looking to evaluate what the impacts would be through changes of the of the gas quality range that could potentially be distributed in the UK and so they've started some studies sometimes called the tripartite studies where they looked at different options with regard to gas quality in the UK and kicked it off in 2004 with a pilot study and then the main study in 2006. The numbers that were involved there were the pilot study was five appliances and main study was 20 appliances. So it wasn't a large number of tests undertaken but there were several and several key factors that came out of that. A few years later the EU gas cost, gas quality ramped it up even further and did a hundred appliances and then with SGNs opening up the gas market study they looked in open at around about 2000 in fact over 2000 appliances and then with the other Scottish independent undertakings that were studied there are even more tests that were undertaken. So it's a good understanding now of what the implication is of different water index gases on a wide range of appliances both ones that are in the laboratory but also installed in a real environment in Scotland. More recently there's additional data that's coming out from high deploy and I think although we've not got a slide on that today the general aspects with regard to that do reinforce the overall trends with regard to the emissions and in addition to what's been going on in the UK and around Europe there's a lot of additional work that's gone on in USA, China, Korea and many other countries. So now what I'd like to do is just take you through some example results and as I say I don't want to dwell too heavily on this but I'll be picking a lot of trends and highlighting what the different studies have actually found as we go through. The format of the of the charts is very similar and I'll just explain that in the first one and then you can see how it cascades through to the others. So for the initial study it says five appliances they looked at a wobbly index range from 46 to 56 so slightly wider than has been considered for the potential changes to to the requirements to regulations that we're proposing now but that gives a bit of a safety margin in terms of the understanding. With regard to the studies it was focusing on the carbon monoxide and nitric oxide emissions and then also looked at efficiency and the efficiency was measured by a flu-loss method. Next slide please. So here's a quick snapshot result of the five appliances. The five appliances are in the key on the right hand side condensing boiler, a water heater, a cooker, a fire and a standard tight boiler. The wobbly index is on the x-axis ranging from 46 up to 56 and the carbon monoxide emission is listed as a percentage on both of the left hand and the right hand y-axis. The left hand one for most of the appliances and the right hand one for the standard boiler. Within the main body of the chart you've got two orange lines and a band. That's actually the current GSMR limit of 47.2 up to 51.4 as Dave highlighted. I just really want to draw your attention to the changes as a function of wobbly index as you go from left to right. For the majority of appliances you can see that the emissions do go up in terms of carbon monoxide although there are some scatter with regard to the ones from the fires. I think reflecting more the difficulty in actually doing those tests rather than any any significant problem. The other aspect there as you can see that when you get gas qualities over a 53 mark they do seem to start to increase quite a lot and that's been taken into account with regard to some of the recommendations that we've come to with regard to the limits. The next slide please that shows the impact of on the NOx emissions again it's on the left hand side the NOx PPM as a function of the wobbly index on the x-axis and you can see that the NOx actually increases as a function of the wobbly index. Next slide please and the flu efficiencies are reasonably constant actually so there's not that much of a decrease in performance as you go down in terms of wobbly index and not much of an improvement in efficiency as you go up in wobbly index it's reasonably flashed. There was a slight increase as you increase wobbly index but not significant. Next slide please. So the the first DGI study was then extended a couple of years later and increased number of appliances to 20. These are mostly used appliances but there were one or two new ones that were included in that test program. The wobbly index went in just from 45 to 56. Again the focus was on carbon monoxide and NOx emissions primarily from the point of view of safety but also with regard to impact on the environment with regard to NOx not only in the home for any in indoor air quality aspects but also NOx being emitted into the local atmosphere. It was extended to actually include the impact on wobbly index changes on the performance of the safety control systems particularly the flame supervision device or the oxygen depletion sensors that some appliances have. The efficiencies were calculated in the same way as before but they added in an additional test here where the appliances were serviced so that the tests were done and then repeated once they had been the appliances been serviced which could involve some maintenance work or some repair work. The results were then the tests were then repeated with with that serviced appliance. Next slide please. So a quick example of the condensing boiler. Here it's got a premixed burner so it's that the form of combustion that profile that I showed earlier and you can see that from 45 wobbly index value of 45 up to 56 that the CO emissions increase. Again the gas safety management regulation band is shown in the orange bars and the trend is fairly clear from increasing CO across that range. If you prefer the dry air for a CO percentage to be a PPM you're looking at a range there from zero to 400 so it's the values around the GSMR band at the moment range for around about 25 parts per million up to around about 75 parts per million. You may query why there are so many different points at around about 50.7 that's the G20 reference gas it's pure methane and the repeat tests were done with those gases after every other wobbly index gas was tested to ensure that there was no lingering change to performance or impact from dip running those tests so it was it was a cross check that the pipelines were still curving and operating correctly. Next slide please. The NOX profiles you can see it's very similar to the ones that we've seen previously increasing NOX as a function of wobby index. Next slide please. For the open fluid boiler the carbon oxide again very low within the range under lower wobby index and then started doing increases you go to higher but again the fairly modest increases. Next slide please. And again with NOX increasing as a function of wobby index. Next slide please. Gas quality took the testing program to the next level and it was evaluating the impact of gas quality on safe operation efficiency and emissions. 100 appliances were tested a wide range of gas qualities there were 16 companies involved in this from nine companies around the EU and five laboratories actually undertook a lot of the test work. Next slide please. The project was split into several work packets and they're involved for the study of the appliances that were actually installed around Europe and an understanding of the different gas quality regulations and gas specifications that were actually enforced around the different member states. It also looked at certification and how the appliances were tested for for use in those different countries and also look at how the appliances were installed particularly with regard to were they adjusted and altered at the point of installation rather than use factory settings. Based on the the range of appliances that were actually available that sample of 100 were selected tested and then conclusions were drawn and there's a bit of feedback to loop there to ensure that understanding of the results from the different tests that were undertaken were actually used to sort of fine tune the testing program. Next slide please. The appliances were categorized into 29 separate groups. These were based on the different certification standards that we use for different types of appliance so you get a different EN standard that was used for certifying a condensing boiler compared to a cooker and an air heater. Different types of boiler setups and the like so a fairly wide range and the number tested in each segment in each in each of these clusters was actually based in terms of the overall population distribution that was determined in that first work back so there's a lot more boilers so they actually tested more boilers there were far fewer tumble dryers that sort of thing. Next slide please. So you've got the test gases highlighted there with Wobby index against relative density in the sense that a plot that the Atlantis presented ranging from the one on the left hand side being the G20 and then the test gases associated with a range of Wobby index and also exploring the impact of the different gases that might be available close to the 0.7 relative density value. Next slide please. They produced a lot of results out of that project but I think one of the highlights is the impact profile the table on the on the left. Green essentially means that the appliances can cope with a wide range of Wobby index. The Wobby index is listed at the top from 46 to 54 of 55 and you can see that the bulk of the diagram bulk of that table is actually green which means there's no significant increase in the carbon monoxide emission as a function of Wobby index for those particular appliances. There are a few that impact in terms of the amber that give warning that it's starting to increase and then there are as you go to the very high Wobby index values there are a few appliances that would actually give a red which suggests that the CO level was slightly higher than was acceptable. For the eagle-eyed amongst you you'll have already spotted that the top line says one adjusted and followed by a second line being one non-adjusted. These were for premixed condensing bolers and what these tests indicate was that for an appliance that was factory set that's the line two the non-adjusted and that's where it's set at 50.7 for the G20 test gas. That could accommodate the full range of gas qualities without significant impact in terms of operation. The adjusted ones were where the appliance was not adjusted to the 50.7 but one was adjusted to a very high value and then looked across the range and then readjusted to a lower value and adjusted and clearly into those situations the change in Wobby index rather than being 405 megajoules from top to bottom as it were was actually eight or nine and that's actually too great as it were a change for the appliances to actually accommodate hence you would get those the red and the the amber. Next slide please. So you saw that the gas constant ramped up from the DTI work up to 100 appliances. The opening up the gas market study actually went to over 2000 in Auburn and I think this constitutes one of the the most significant data sets understanding what the impact is in terms of the appliances actually installed in people's homes. The testing covered both the high and low Wobby index gases. Key with gas tech undertook a lot of the the the test work here. They did 18 appliances actually in their laboratory with some very detailed work but they also undertook the tests in people's homes as to say by taking a bottle truck round to people's homes and testing with the three reference gases and limit so it was a reference gas and the two limit gases the G20, G21 and G23. These are the test gases that use the certified appliances and they looked at what the impact was in terms of the performance or the missions of sale as with the appliances actually in people's homes and as I say I think it's a there to be applauded it was a extremely good piece of work. There's also in addition to that ongoing spot checks to confirm performance for longer term performance of the of these appliances as well. So not only have they got those one off tests that they've done when they went to people's homes they've also got additional data to understand what the impact is in terms of the longer term performance and again I think these data sets are some of the most significant ones that we've got open to us to understand what the implications are for gas quality. So very quickly the next slide please. The results show here that the variation in sale of those measurements that were made on the different appliances different appliance types as shown in the legend on the right you've got all 400 boilers over 200 boilers with a gas air ratio controller there's a commercial fryer in there, flu, a space heater and then the tumble dryer and the tests were done using these three test gases so you've got three points one at 45.7 one at 50.7 and then the G23 had 54.7 sorry G20 you want to do apologize that's the richer gas. You've got the darker blue current gsmr values you've got the lighter blue box that's actually the proposed easy gas European specification from 47 up to 54 and then you've got the exemption line that's highlighted at 53.25. The CO again is down the left hand side axis on the y-axis and a wobby index on the bottom and you can see that the trends actually are for the most appliances that the CO increases as a function of wobby index across that band or is actually flat and again look at the CO values they're actually quite low in terms of what's actually in the flu so very good performance really across that whole range. Next slide please. For the fluid appliances the trends are very similar there is one group that stands out as not being the same and that's the commercial grill so I'll put that one to one side and just highlight that the general trend is increasing CO as a function of wobby index but the values are actually very low and I think from the test that's here there's significant evidence to demonstrate that extending the range to what was proposed in Dave's presentation down to 46.5 on the lower wobby index up to 52.85 on the upper is actually not going to constitute a significant increase in terms of the overall CO emission. Next slide please. They also did some work when they were doing the urban studies in terms of the impact of NOx the blue line is with the appliance tuned to the G20 reference gas and then the orange line was when it's tuned to 53.0 value gas. If you like what happens there is that the the excess air value is being adjusted and what you can do is just slide the orange line and orange points to the left and that 53 value overlays the 50.7 on the blue and the trend then is the same for both lines so I think the NOx emission is low again from 20 parts million at 45.7 up to around about 65 parts million at the at the wobby index value. So these datasets are actually giving us confidence now in terms of what the performance is in in modern appliances with with several hundred if not several thousand type appliances actually being tested to actually understand what those impacts are. Next slide please. So in summary and just to wrap up the practical tests have highlighted the general trends and the general trends really are of increasing CO and NOx emissions with increasing wobby index with one or two exceptions. However the changes are actually quite modest. The tests on the installed and appliances in people's homes and the laboratory tests as well demonstrated that down to 55 sorry 45.7 megachores meter cubed there's no significant changes in terms of overall performance. Again there's one there's one or two appliances that still book that trend but it's clear for a significant portion of the days it holds. Increasing the wobby index limit to 52.85 will result in increased CO and NOx but these changes are modest I've already highlighted and I think then we come to one of the key aspects I think if appliances have been adjusted from factory settings then this could give rise to more significant changes to emissions and that's been highlighted in work that's been done. But the Gas Hall study there's been all sorts of demonstration of that in Denmark where there's been some work where they found poor performance because the reset appliances actually that are in the field. But within all of this I think it's highlighted with a lot of the test work that's been done. It's appliance servicing and maintenance of all these appliances is extremely important to ensure that performance is maintained across the wobby index range. Clearly any misuse of those appliances or any damage could result in in quite high levels of the mission and servicing and maintenance is then of key importance. That is all I'm going to present to you today with regard to the domestic data sets. I'm sure there'll be lots of questions so I'm happy to take questions now. Thank you Mark, thank you Mark, that's been a good chat on how you're studying chat, on how you're doing work as well. There's been questions with advanced as well which has been around, you mentioned appliance has been correctly set up and maintained and by who. Do you want to just add to that Martin? Sorry, I didn't catch that, can you repeat? You mentioned about appliances being correctly set up and maintained, the question was who by? Well that's a very good point and that's something that I think should be considered in the future. We're not necessarily mandating that it's a legal requirement. We're recommending the appliances really are maintained and gas safe engineers are more than capable to actually do those tests and ensure that that's the case. In terms of initial appliance set up I think the manufacturers do an excellent job in terms of ensuring that the appliances are set for the appropriate gas quality which essentially is a mid-range value and if that's the case then it does give you the ability as it were for the appliance to work right down at the low end but also up to the high end in terms of the limits in terms of what we index. Okay, I just want to touch on some questions about non-oxymissions and in particular. So looking at non-oxymissions if for example non-oxymissions from typical appliances if they reduce the world lobby gases does that mean that sort of hydrogen within blends will reduce the non-oxymissions from the appliances as well? That's a very very interesting question. There's some contradictory evidence in the open literature about what the impact is of hydrogen. Hydrogen blends can actually give a decrease in NOx in some appliances but an increase in others that have been published and I know there's a lot of development going on with regard to NOx with hydrogen and hydrogen natural gas blends. Looking at the basic chemistry and looking at the basic flame phenomena the flame temperatures are slightly higher for an adiabatic flame that could potentially increase the increase the emission of NOx with hydrogen. However combustion is a highly dynamic and influenced by lots of different or the factors that are in the basic chemistry how the heat transfer is done where the combustion actually sits in relation to the burner and burner surface temperatures what the floors are like within the appliance what are the heat transfer they've got. I believe there's potential for actually getting a NOx operation now with both hydrogen natural gas blends and also 400% hydrogen although that's a bit out of scope for what we're discussing with regard to the overall natural gas quantity here at the moment. And just finally on NOx emissions you mentioned about caused by higher water gases there's likely been a modest increase. Is that likely to cause any compliance with eco design issues? I've got to hold my hand up there and I'm not sure I don't think so I think there's enough room between a lot of where the appliances currently operate to the proposed limit although I think with the eco design and the future requirements for meeting limits I think over a lot of our experiences combustion engineers you find that limits get tighter and tighter and tighter. So I imagine that there's lots of opportunity for research to actually develop new systems for NOx operation. I think that's possibly the best approach to take. There's work to do should we say but I think there's a lot of very good work being done at the moment with regard to developing NOx systems. I think the future is bright from a combustion engineering point of view. Okay thank you Martin. I think that'll be it from your section. Now we'll in the interest of time I think we'll move on to the next session. Please keep the chance coming in we will respond to any questions if we don't get round to and we'll now move on to to Sarah Kimpton. Sarah over to you. Thank you Ian. Yeah good morning I'm going to talk about gas quality variations as they are in the gas networks now and the work that we did on industrial and commercial consumers and how they're affected by gas quality. So next slide please. So the gas quality group established quite early on that all the previous evidence had been for domestic consumers and that that's quite correct for as far as the gas safety management regulations are concerned because they are there to protect domestic consumers but there's also a very important group of customers who also use gas and these are the large industrial users and the power generation sector. Now gas quality is very important for this group so it was very it was necessary to establish the current status of this sector and many of these very large users are actually directly connected to the national transmission system and to the gas distribution network so they have their own direct connection and so we engage with all the with a number of trade associations with users and manufacturers of combustion equipment on a one-to-one basis and in groups and also we held a workshop at IGM at which we explored the current and future requirements of this sector. We assessed all the responses we also asked them about hydrogen while we were talking to them although hydrogen is strictly out of scope for today's webinar. Next slide please. So why does gas quality change? Many people think that the gas actually mixes when it's in the gas networks and unfortunately this isn't the case it travels in slugs with very very little mixing except at the interface and then between different gas sources so the gas sort of travels through the gas networks a bit like a train. It enters at a number of different points so we've got St. Fergus, we've got LNG coming in Grain and South Hook, we've got the gas coming in at Bacton in East Anglia and it moves around in the NTS until it is taken out by a customer so it's very once the gas is inside the national transmission system or in the gas networks it's very very difficult to control who's getting what. The only thing is that at all the entry points the gas is GSMR compliant so any gas that you receive from the network will be GSMR compliant. So let's look at this example, the four little pictures you see in front of you so on the top left hand side we have a low-wobby index gas shown as blue and a high-wobby index gas coming up the pipe just past that T and you can see that the red gas or the high-wobby gas starts to spill into the T and there's a little bit of intermediate quality gas in there which is a little bit of blending just so that interface and then after five seconds you can see that the high-wobby gas has started to really spill into that T in a big way and there's a little bit of mixed gas at the interface and it's basically the high-wobby gas is pushing the low-wobby gas through the network as it's been taken out by a customer. After 10 seconds on the bottom left hand side you can really really see that red gas it's got quite well established flow profile and after 25 seconds I mean that plot there is in a slightly different scale but at 25 seconds you can see there's a very well established interface between the red and the blue gases with a sort of a plume intermediate to that so if you were an offtake at the end of that pipe in one for one moment in time you could be taking a low-wobby gas and then over a period of say a 10 seconds you would then be receiving the high-wobby gas and there's very little that the gas networks can do about that other than obviously assure you that both the low and the high-wobby gas are GSMR compliant. So that is how it is now and that's how probably how it is going to continue. Next slide please. So another thing to consider is that gas quality means different things to different groups and here we've highlighted about 20 different properties of gas quality that various parties would be interested in. So if you're a producer upstream then gas quality to you means making sure that the gas complies with the gas safety management regulations so you'd be controlling sulfur you'd be controlling hydrogen oxygen you'd be making sure that the hydrocarbon dew points and the water dew points and the wobby index are correct and that will be your main concern if you were a producer putting gas into the national transmission system. If you are the national transmission system then again GSMR is your major concern you want to make sure that all the gas within the network is compliant. However if you're connected to the national transmission system then it depends who you are what you're interested in. So if you're a power generator then the combustion properties are very very important to you so we want you to know about flame lift auto ignition temperatures flashback on all those kind of things and again it'd be similar if you're running a gas engine you'll be very very interested in the methane number. If you were a storage operator you'd be very concerned about hydrating formation and the energy content because that's basically how you run your business and if you are in a operating a gas distribution network then CV is very important because you need to control the CV within the network for to ensure fair billing to customers. Domestic customers at the very end there are actually relatively tolerant to gas quality and then also at the GDN at the gas distribution network level you've got biomethane producers who are also putting gas into the networks and their main concerns will be compliance with gas safety management regulations and CV. So it depends who you are where you are and what you're doing with the with the gas and what gas quality might mean to you. Next slide please. So although Great Britain is an island we're actually very well interconnected with both Europe and Ireland and with the North Sea. So we've got connections with the North Sea. We've got the LNG terminals bringing gas in which will be coming from the Middle East as well and the interconnectors connecting us to Belgium and the Netherlands. We've also got Ireland connected to the NCS via Scotland and indeed Ireland takes about 40 to 50 percent of its gas comes from the UK so we have to be mindful of what we're doing in GB because it impacts on other people and on our neighbours. Next slide please. So what we did we looked at the gas quality data in the national transmission system over the whole of 2019. We took the data from the off-gem directed gas chromatic graphs that are at the NCS off-takes at intervals of about four minutes. Then we used a red amber green system to visualise the range of gas quality that was being received at an individual off-take and also looking at the rate of change of that gas quality. So on the slide following there's each part of the UK has got two circles on it so a big circle indicates the range of the gas quality so if you have a large red circle it means that there's a range of more than three megajoules per cubic metres at that off-take in 2019. If there's a little circle then it means that that indicates the rate of change. Now this was for 2019 and it will be different every year. There is no place on the network where the gas quality is always stable. Note that it also depends what you mean by stable. Are you talking about stable CV or you do want stable Wobby index? They're very very different. As an aside the Federal Energy Regulatory Commission in the US recommends that the maximum rate of change for customers should be 2 per cent per minute in Wobby index and this equates to about one megajoule per cubic metre per minute. I see we've already moved on to the next slide. So for example looking at this slide if you look at southwest England there is a wide range of Wobby index on the image on the left. There's a wide range of Wobby index. We've got a large red circle and we've got high rates of change so we've as we've got a little red circle within that big circle but you can see if you look to the picture on the right that the CV range is not as bad as the Wobby index range and the rates of change in CV are actually pretty low so although the Wobby is changing rapidly and the range is quite big the CV is actually slightly different. And again if you look at northern England where you can see that the Wobby index is quite stable you've got the two green circles in northern but the CV is much more varied so you've got a wide range of CV and sort of medium variability. So this is a good example of what gas quality means to you depends upon what you're actually interested in. If you've got many many different compositions may give you the same Wobby index but they won't necessarily give you the same calorific value so you have to be very very mindful about what it is you're interested in why you're interested in it. And we just reiterate that these images are for 2019 we've also done them for other years and the pattern is very very different so there is no place in Great Britain where you can say the gas quality there is always going to be stable this all depends upon the sources of gas where they're coming from how the gas is moving through the national transmission system so it varies all the time. Next slide please. This one's quite a complicated looking slide but there's just a couple of things would like you to take away from it. The current limits on Wobby index are shown by the dotted black lines so at the top you've got the higher Wobby index and the bottom you've got the lower Wobby index and what I've done here is I plotted the Wobby index against relative density as Dave was explaining a little bit earlier and if you look at all the gases in 2019 you can see that they all fit very nicely within that that proposed diagram. Some of the gases for example in Wales which tend to be the green ones, Wales and southwest England you can see have a very wide range of relative density and there's other gases which have a wide range of Wobby index but within 2019 there was gas was seen almost covering almost the entire Wobby index range that was allowable under GSMR. Next slide please. So here's two power stations just looking at one at the moment so this is the one we're looking at which is information that we receive from National Grid. There are two plots of at the top in orange is the Wobby index and the lower one in blue is the CV. You can see that for power station A the Wobby index and the CV range were about two megajoules per cubic meter over the whole year and if you look at the two plots although they're sort of similar in shape they're not actually identical so this is sort of illustrating again that when the Wobby index goes up for example the CV doesn't necessarily go up as well it might go down so there are a number of instances of that. Just click again please. We'll have a second power station coming on. Yes the second one is another location on the National Transmission System in 2019 and here you can see that the range of Wobby index received by that power station was about four megajoules per cubic meter that's the orange plot at the top and the range of CV was about three megajoules per cubic meter. You can also see some quite scary looking spikes in Wobby index and both CV as well and so there was some very very rapid changes in these properties. That just to emphasise that is the gas quality and how it's varying now so there is a little bit of a myth that the gas quality is relatively constant it isn't it's already varying quite widely but it's all within the GSMR limits. Next slide please and this one's showing a little bit of detail about what was happening in southwest England over a few hours in 2019 so this is results direct from one of the gas chromatographs there so if you look along the bottom we've got the time it's about 11.16 we had gas A and the Wobby index was about 48 megajoules per cubic meter and the CV was about 40. At about 11.45 another gas came along in a slug and the Wobby index increased suddenly and rapidly to about 50 megajoules per cubic meter and the CV dropped and then about 20 minutes later we had another gas came along and the CV dropped again and the Wobby index increased almost up to the maximum limit. If you click again please well should show the gas composition so I'm a little bit concerned here my laptop is just installing some software I don't know why. So you look at the gas compositions you can see that gas A is a natural gas but it's obviously quite a rich gas it's got an awful lot of ethane in it but in order to control the Wobby and the CV there's quite a lot of CO2 and nitrogen's been allowed to be retained in it. Gas B is also a natural gas you will see that there's much less CO2 and nitrogen in that one and the methane content's gone up and gas the last gas is an LNG and you can tell that it's an LNG because there's no carbon dioxide in the gas but you can see that there is about 0.8% of nitrogen in there and if you click yes if you click again on you can see at the top that it's been ballasted with about 0.8% of nitrogen to bring it just under the upper Wobby index limit and if it weren't ballasted it would have been outside of specification it would have been a Wobby index of 51.7. Next slide please So this is a summary of what the information we got back from our assessment and our discussions with the industrial and commercial consumers so on the left hand side you can see how we group them so we've got power generation gas engines industrial applications boilers storage NTS compressors because they're also gas turbines there's some folk using natural gases feedstock and then there's also the industry the supply industry who are manufacturing control and measurement systems if the other what if the you can see at the moment the under current gsmr limits the fluctuations of about up to about three megajoules per cubic meters and sometimes a little bit more and you can see for the power generation and the gas engine sector that would cause some problems if they didn't have control systems fitted and once control systems are fitted then they are able to manage this this range of Wobby and CV for industrial consumers like with very large burners they're okay at the moment if their burners are set up in the mid range of Wobby that they're likely to see so I would probably recommend something like pure methane if they happen to be setting up their burner in the field as there's a gas passing at that point with one of the either at the upper or upper or the lower limit they would have a problem so this sector it would be quite it would be very very important for them to actually understand what the gas quality is when they're setting the burners up there's a couple of ways to do that it will be really great if we could have a handheld CV or Wobby index device or some service maybe provided by the gas networks to that someone could call and then find out what the gas quality is likely to be passing at that point at that time the same is also true for for large boilers if they're not set up in the mid range then they could also be a little bit inefficient or producing more emissions than perhaps they should be for the storage sector chemical feedstock at the moment they seem to be operating quite happily with it with the current gsmr limits if we were to increase the upper limit to 52.85 you can see the power generation and the gas gas engine sector would have a would have problems coping with that without control systems but with control systems then they are perfectly able to cope with that again a similar problem with the industrial large industrial burners it's they they need some measure some way of understanding what the gas quality is when they're setting it up to make sure that they're not setting it up what when the gas passing that point is either at the upper or the lower limit so I mean the main message to take away from this is that there is mitigation available or could be available for all these sectors which would make it possible for these these this group of customers to use however we do acknowledge that for some sectors this could be expensive especially for gas turbines and they all there might also be limits on the allowable gas quality as far as their insurance cover from the original equipment manufacturers is concerned so we do acknowledge that that is an issue however these are the factors that the hsc will be taking into account when they're looking at all the evidence when that before they're making their decision so if you want to contribute to the consultation process or you want to raise a particular subject then please do respond to the to the consultation document that's currently out there and issued by igem I think that's what I'm going to say now thank you very much thank you Sarah some chats have been around looking at so by methane and potentially looking at fluid and average cv in the fact of not hosting and in june with with nitrogen would be useful to maybe look at that as a potential modeling exercise to put your thoughts on that Sarah as far as flowy to average cv is concerned there is currently a network innovation project and being undertaken by cadent where we're looking at better ways of billing customers so that is the bills that they receive is much more close to the the gas that they're actually receiving so we are addressing that and if we can do that then that would negate the need for by methane to be proponated it would also mean that if you had a very very high cv gas or whatever you would be able to get that in as long as it was within the gsmr limits i'm not also suggesting that cv is one of the gsmr limits but yeah thank you so yeah we're looking at that great thank you well we'll move on to the final session now and i'd like to invite Dave Landau back to talk about the network safety impacts and we'll have a cuny session then that as well Dave over to you okay thank you Ian um could you have the next slide please okay um just for a way of an overview i'm really just kind of answered two questions which came up at an early stage during the during the activities of the working group first question is really about flammability limits so would the hazardous area limits and procedures for gas escapes for instance need to be revisited if the wobby index limits were changed secondly we had a query over pipeline fracture propagation and essentially the really question is would increase in the wobby index limits result in an increased risk of fracture propagation increase okay next slide please so as far as flammability limits are concerned essentially flammability limits would the hazardous areas limits and and gas escape procedures need to be revisited well essentially these things are principally governed by the flammability and the explosion limits of natural gas that you convey and for many igem standards the lower and the upper flammability limits are just taken to be 5% and 15% gas in air in practice the flammability limits do vary considerably and they've probably never been these values next slide please so here i'm just going to illustrate the the variation that you see in UK gas quality so taking the lower flammability limits that varies typically from around 4.5 to 4.9 so next slide please and you'll see that this traditional value that we take for LFL of 5% is actually quite way outside what what we actually see next slide please and many of you will be familiar with the mean backed in gas composition which is a sort of taken to be a sort of representative of the early natural gases that came from the southern North Sea and those mean that mean backed in gas composition has lower flammability limit of 4.9 4.9 percent next slide please the current LNG that arrives at GB that has a lower flammability limit that varies from around 4.64 to 4.9 but typically it's sort of quite a narrow band and you can see that causes that's what causes the spike in in overall gas quality in that area next slide please in fact current worldwide LNG varies quite wide widely you get some that centers around about 4.8 percent and some of the richer LNGs tend to have a flammability limit that's that sits around 4.6 percent and so when you look at the UK gas quality what's happened is that it's it's been shifted slightly by the ballasting that's that we see in order to admit the gas with an appropriate WB index so if you go to the next slide what we've got here are typical sources of LNG and what you find is that the ballasting does tend to affect the lower flammability limit but there's not a great amount so if you look at the grain and the grain ballasted composition so typical compositions from grain then you would see ballasting the gas so that its WB index goes from 52.19 to 51.25 gives a change of around 0.07 percent gas in air in the flammability limit so it's not a great amount but that causes the shift from the value for worldwide LNG to sort of a central value within the UK range. Next slide please so with the IGEM gas safety standards then most often you consider the impacts at 20 percent of the lower flammability limit as I say based on traditionally you would think of that as being 1 percent gas in air and also many of the IGEM standards use mean-backed in gas as the basis for setting their standards and the flammability limit of that is 4.9 percent gas in air. Next slide please so what that actually means then is in practice our safety margin isn't really 80 percent which is 100 minus 20 percent so if we have current UK gas quality we're currently enjoying a safety margin of around 78 to 79 percent 79.6 if we only considered mean-backed in gas but as we've seen mean-backed in gas is not really representative of UK gas nowadays and for the LNGs with a quite a wider range of flammability limits then the safety margin will decrease slightly from 77 to 78 so there's still quite a lot of overlap in what we currently enjoy in terms of safety margin but in practice the safety margin is not is not 80 percent and not that much different to what we are currently seeing so we don't anticipate the being an immediate need to change criteria. Okay next slide please next question really then is pipeline fracture propagation and the question really is would the risk of fracture propagation increase if the or the index limits are changed? Okay so the key thing to understand here is that generally gas transmission pipelines tend to be constructed from high strength steel they're generally preferred because the reduced construction costs and the higher capacity because you can construct them at higher pressure and higher sizes offsets the higher materials cost however you do have to consider the ability of such steels to arrest a propagating ductile fracture they need to be tough enough in order to to arrest the a fracture that would be generally caused by outside forces so if you had mechanical damage to a pipeline causing a fracture then you don't want that fracture to sort of propagate indefinitely and so your concern is to have steels that are tough enough in order to withstand that. Next slide please so essentially pipeline operators tend to use a Patel 2 curve what's called a Patel 2 curve approach and they show they can use that to show that fractures will not propagate beyond a small number of pipe joints and in order to do that you compare the fluid decompression wave velocity talk a little bit about that and the crack propagation velocity so essentially when gas escapes from the pipeline the fluid will drop in pressure as it escapes and the pressure will fall within the pipeline itself and the rate at which the decompression occurs is a property of the fluid and the key thing is that if the fluid decompression velocity is larger than the crack velocity then the crack tip stress the stress at the tip will decrease and the crack will arrest and vice versa so if the fluid decompression velocity is a lot lower than the crack velocity then the pressure is maintained at the tip of the crack and that will then make the crack propagate further. Okay next slide please and so you can visualise that on a curve and so first of all there's the gas decompression curve so we're plotting velocity in this case it's the velocity of the wave front the decompression wave front against pressure and that's the gray curve the gray solid curve and then what I've got illustrated here is the fracture curve so there's the fracture propagation rates and the pressure and the red line is the red and the green lines are for two different steels with differing toughness and next slide please and in this slide you can see for the red material then the crack can propagate indefinitely because it sits below that gas decompression curve so you have a situation in which crack can propagate and next slide please and if you have a tougher steel then you'll see that a tougher steel will prevent propagation so you don't get into this situation where the stress at the tip of the crack is too high. Okay next slide please so for this assessment what we did was to compare the relative risk that it would be posed by differing gases so essentially what we did was to examine gas decompression curves for various gas compositions so the gas decompression curve will be dependent on the thermodynamic properties of the fluid as well as the starting pressure and the temperature in the pipeline at the time of fracture. Next slide please so the gases that we looked at a set of pipeline gases from GB import terminals so we had access to compositions that were characterized in quite fine detail by a consortium that was looking at hydrocarbon due temperature measurements and calculations and so that provided us with a set of gas compositions that were typical of that being imported into the UK in 2009. We also have compositions of LNGs which characterized by the the NIC projects opening up gas markets and we can use those when they're ballasted and unballasted so those are all those compositions that are available in the report that forms part of the technical pack for the gas quality working group. Next slide please okay so so for the pipeline gases this is the sort of behavior that you get and the first thing I need to sort of point out is that the the fracture curve the dotted line is illustrative only with an exclamation mark because it's not intended to be a particular section of piping any particular gas transporters network but it's just illustrative to show the principle that's involved in the Betel method. So you can see here for these pipeline gases the red line is is the one that shows the greater risk of propensity and the gray line is the the lower risk of propensity to propagate cracks and you see that the red line is has a wobby index of 49.54 and the gray line has a wobby index of 49.45 and yes make it pardon intermediate between that it is the green the green gas gas E which has the highest wobby index of them all which is 50.23 so there isn't really a clear pattern in terms of wobby index and propensity for pipeline fracture propagation. So next slide please and in this slide these are for the LNGs that we looked at and what I've got here are the purple the purple line the lower of the lines you can see that's an LNG from grain and it's also an LNG from grain that's ballasted and if you look extremely closely you'll see that there is a slight difference that you can see a slight suggestion of a dotted line but essentially the points are the same and the decompression curve is the same and yet they've got differing wobby index and if you look at another LNG which is the Qatar LNG that's shown illustrated by the green arrow and you'll see that that has a shift which swings to the left shifts the velocities to lower velocities and you can see that it comes much closer to the fracture line and so what you can see from this and you can see with other compositions is that ballasting doesn't actually change the risk of a particular gas if a gas shows some propensity for increased risk then ballasting doesn't in fact affect things at all. So it's not really a wobby index issue it's as usual with a lot of gas quality parameters they tend to be correlated with each other and it's not necessarily a sign of causation it's just the fact that they're associated with some of these gases that are associated with high wobby index. So if we leave the limit as it is and say admitted Qatar gas in adding a nitrogen to it to ballast it to bring it down it's wobby index down would in fact not change the risk at all. A next slide please. I'll just try and summarize these two questions then. The flammability limits vary widely for existing UK gas anyway it was never as high the lower flammability limit was never as high as 5% and as a result our safety factor was never really 80% it was around 78% in the early days for mean black tin gas and for most unballasted LNGs then it would change from around 78% to 78% sorry 77 to 78%. So there's not a significant change in our safety factor that we would enjoy with a different unballasted LNG. As far as pipeline fracture is concerned then it's not really a wobby index issue it generally tends to be high density gases which can be exacerbated by hydrocarbon liquid formation. So on those LNGs where you sort of shift in the curve what's actually happening is the gas is entering a two-phase region a hydrocarbon liquids are dropping out a little bit which increases the density increases the the decompression wave or decreases the decompression wave velocity and ballasting doesn't really alter that risk and so it's not an obvious parameter to specify that would control that risk so certainly wobby index isn't an appropriate thing it wouldn't it wouldn't prevent that risk from occurring. Existing compliant gases show varying risk and the risk really is dependent on the pipeline properties and the operating conditions as well as the gas fluid and our recommendation from this is that gas transporters should continue to assess their assets for future supplies they do that now and so there's not a suggestion that the pipelines are currently at risk and it's just something that they would continue to do but what you can't do is rely on wobby index limits as a control measure for that and as I say there's not really an obvious parameter that would control that so you would have to just carry out that assessment when you foresee different gases entering okay I think that's that's the end of that so I'm not sure whether any questions have emerged on the chat. Thank you thank you Dave on that one I think you've got a very kind of comprehensive presentation there on the network safety implication so in the middle of this maybe some the first time that people have seen the the study that you've done here we would welcome any comments you've got on that please please fire them them into as well we'll get around to questions that we haven't answered at the end of the session and we'll set them to feed them back out as well if you'd like to go on to the next slide we'll close out this particular session the consultation is open now until the end of of July and where we welcome any of your comments please go on to the website please have a look at it in terms of timescale is what will then happen is that we will then collate all the comments that we've got we'll bring them back in to the group where necessary to respond to take into anything we've maybe missed and appreciate all your comments that you've fed in today now that can take depending on the number of comments we get can take maybe a month two months and by the end of that period we'll then have a body of evidence from the industry comment period as well as all the studies that we've now collated and we'll bring that to the health and safety executive in the form of a bundle of safety advice and safety case information to support any of the changes that we've made now that can take us maybe up to something right one in October where potentially depending on how things go with timescales that could be a time when we could be looking at publishing the item standard at the same time what's happening just now is the health and safety executive are we'll be consulting and they're already beginning to do a round of interviews looking at the impact of the changes that were being produced and from that they will then carry out their impact assessment with a view to looking at then changing GSMR which could take into hinting to another sort of 12 months afterwards until that period is completed but we will similar to complete this work as soon as we can certainly after the consultation period has ended so please go onto the website please have a look at the comments and please fire those comments into into IGM through the through the website and we'll take them into account in order liberations and thank you thank you to the presenters to Martin, to Sarah and to Dave in particular for the time today as well I'll hand you back to Tom to close out. Thanks Ian just a few final remarks from me to again note that the recording and responses to the questions raised during the chat will be will be shared and to reiterate Ian's request to respond and share your comments via the consultation process to repeat the data that's open until the end of July and finally from energy networks association in the gas goes green team I'd also like to thank our speakers Ian McCluskey Dave Lander, Martin Brown and Sarah Kimpton and finally a big thank you to all of you for joining today and for your engagement it's been a really interesting discussion and great to see all the engagement via the chat and we look forward to seeing you at future gas goes green and IGM events coming up so many thanks all and have a good day