Russell Thomas answers your #BurningQuestions
Every month, we invite experts from across the gas industry to answer your most pressing questions. This month, we’ve explored how the legacy of gasworks, past transitions in gas supply, and future technologies can inform the journey to net zero.
From cleaning up contaminated gasworks sites to planning a nationwide fuel switch, we look at the lessons of the past to guide the future. We’ve looked at how historical infrastructure could be repurposed for hydrogen and biomethane, the role of farming collectives in localised energy production, and what it might take to design a more flexible gas network.
Here's what Prof. Russell Thomas BSc (Hons) PhD CBIOL FRSB MIENVSc CEnv MSCI MIGEM EngTech had to say:
Q: How have old gasworks sites been cleaned up, and what can we learn from that today?
A: A fascinating question and one which relates to many years of my early involvement with the gas industry. The gas manufacturing process produced a number of by-products, such as coal tar and sulphur-rich spent oxide, which contained hazardous substances. Whilst these were usually sold as by-product to the chemical industry, some of them found their way into the ground, leaving a legacy of pollution, which has since needed addressing. This action started after closure where tar tanks would be emptied, however over the passing years the standards for cleaning up such sites have become more stringent.
When the gasworks were no longer needed, the parts of the site where manufacturing was undertaken were often sold to a third party who wanted the land. These sites often found use as car parks or other non-sensitive land use, but others also ended up being used for housing. Most such sites have been investigated to identify if there are any significant risks to those living in the properties and if so remediation work has been undertaken.
A majority of gasworks sites have now been ‘cleaned up’ otherwise known as ‘remediated’ in Great Britain. However, given there were several thousand of these sites, a continued steady flow of these sites will come to light which need remediating. Sometimes this is because the site has been used for a more sensitive land use such as housing rather than a previous land use such as a car park or storage site.
A significant portion of the sites ended up with British Gas Properties, who set off on a long journey over the past 30 years investigating and remediating these sites, a job which was completed this year with the closure of National Grid Commercial Property.
From this you can learn that it is possible to address previous environmental wrongs, remediating pollution and bringing land back into beneficial reuse. Whilst manufactured gas did create potentially hazardous by-products, they found use in the chemical industry, as the feedstock for acids, plastics, dyes, fuels, disinfectants and medications which became important for society. Those industries which just burnt coal directly for steam raising and power generation released these same chemical into the atmosphere, so whilst they were not so obvious on the production site, they produced more widespread pollution. Another lesson is that whatever form of energy you adopt, it will have some environmental impact which may require future mitigation, sometimes these problems are unforeseen at the time.
Q: What are the best lessons that could be learned from the switch over of town gas to natural gas, that could be utilised for possible hydrogen blending, or a full switch to hydrogen?
A: An interesting point. I guess in the case of this question the biggest lesson learnt was that it was possible to plan and organise a switch between gases of different properties. In Great Britain we switched directly from town gas and natural gas, quite a big change in properties between two different gases. It involved splitting the country into small sectors and gradually introducing natural gas into the different sectors and converting the appliances and network over the length of the 10 year conversion programme. In parts of the USA they switched gases in gradual increments, moving from town gas more gradually to natural gas, using larger sectors and more minor adjustments to appliances, it may have similarities to an approach taken with blended hydrogen. I suppose the point here is that conversion can take different forms dependent on what you are trying to achieve.
There are more fundamental lessons that can be learnt, which would be required for any energy transition. The need for extensive planning up front to map out the country into sectors capable of being switched between two energy sources. The need for certainty from the government and regulators that you are going to stick the course of the transition so customers can start to make the investment decisions. The need for effective communications to persuade the public of the need to change. There is also importantly the availability of both of the new energy supply (e.g. hydrogen, biomethane or electricity) and the infrastructure and to get it to where it is needed.
Q: How can historical gas infrastructure be repurposed to support the evolving energy landscape, particularly in the context of net zero?
A: I would have to say it already has. By the introduction of Combined Cycle Gas Turbine power stations being able to switch on and off relatively quickly, it has enabled Great Britain to swing between the intermittent supply of renewables dependent on the sun and wind and back-up power from gas. I’m not sure how else this could have been achieved. Whilst gas has been given some bad press, it has been the enabler of our green electricity energy transition.
The gas network in Great Britain is one of the most far reaching with over 80% of the population with access to a piped gas supply. The success of our previous transition to natural gas means that today so many domestic, commercial and industrial consumers depend heavily on gas. If we are to shift customers away from fossil fuels, we need to ensure that we are not making redundant a valuable and far reaching asset. There will be a need for natural gas for some years to come as it will be a complex process to switch customers to another fuel or energy source.
Dependent on the supply of green gases such as biomethane and hydrogen, our existing gas infrastructure could be repurposed to enable transition to supply these gases. Much of this will depend on investment in research and innovation, as the industry has used innovation in the past to renew itself and find a path forward. Work has been done through projects such as FutureGrid to prove the suitability of the network to hydrogen.
Q: How will gas networks need to change to accommodate energy from renewable sources in the form of hydrogen or biomethane? It seems that they have the opportunity to become more regionally sustainable collectors of energy (from renewable energy production locations) as well as distributors of energy - but they have to have the technology to become 2-way networks not just 1-way distributors. Can farming collectives play a part in this by using poor quality farming land for energy harvesting feed into hydrogen electrolysers and feed into the gas grids?
A: Biomethane certainly represents an opportunity for farmers to benefit from green energy as some have with wind and solar power, but perhaps with less visual changes on the landscape. Much progress has been made in this area, and it is quite feasible that some rural areas could develop networks for biomethane and possibly hydrogen. Moving back to a model of smaller independent networks, this would require additional local gas storage and with it, you lose some of the flexibility of the wider gas network. However, it is important for the gas industry to keep innovating to ensure no opportunities are ignored.
Q: How could a pilot along these lines be set up and funded? At our trial site location in North Yorkshire we have a collective of 200 farms around us all very interested in reducing their dependency on diesel and potentially also able to use hydrogen in localised fertiliser production.
A: It sounds like you have the ideal set up for developing at least in the first instance an extensive biomethane capacity and possibly hydrogen production depending on the resources available. Certainly worth speaking to your local gas network and the likes of Future Energy Networks (FEN), who would be able to advise on innovation opportunities.
Q: The calorific value of Hydrogen is around one third of that of natural gas. To deliver the national thermal demand, will the grid be operated at three times today's pressure 70 bar (i.e. 210 bar) or will the number of transmission mains be increased by a factor of three? Or will low pressure hydrogen production plants be located around the country like the town gas works before natural gas was distributed nationwide?
A: Yes, hydrogen has a calorific value around one third of natural gas. At current demand you would need to make changes to the grid to enable this additional supply to be met including increased storage. Regional production of gas in the form of hydrogen is possible as is for biomethane. There is still a long way to go to work out what role gas will play in the future. Maybe a new game changing innovation will be developed, which we have not yet accounted for.
It is likely that we will see a continued drop in gas demand as customers switch to heat pumps or possibly hybrid systems. However, the uptake of alternatives to gas will have to rise very rapidly to make any substantial inroads into the current dominance of gas.
The role of gas in the future may change to meet niche demands, or it may continue backing-up power generation, but using hydrogen instead of natural gas.
Q: The explosive range of hydrogen in air is greater than that of natural gas. What safety considerations have been given to the transmission/distribution of this gas? One of the reasons given for conversion to natural gas was that it is a much safer fuel than town gas, which contained 50% hydrogen?
A: An important question and thanks for raising. Town gas was indeed regarded as a hazardous gas but not for its hydrogen content, but the carbon monoxide content which was about 7%. When we switched from coal based town gas with a hydrogen content of about 52% and carbon monoxide content of 7% to reformed gas from oil by-products in the 1960’s, which had about a 68% hydrogen and 2% carbon monoxide concentration, fatalities dropped. Obviously the move to natural gas removed the carbon monoxide content altogether which removed the risk of carbon monoxide poisoning from the gas altogether.
The safety of hydrogen is one which the Health and Safety Executive have been addressing, so you will get an answer on that from them soon. From a historical perspective the opposite was a problem, switching to natural gas, they found it much harder to ignite and this created equally concerning safety issue as the gas could build up and create an explosion risk. A lot of work was done on ignition systems to improve their performance and minimise risks.
I will leave the last words to Harold Lipscombe of Scottish gas from 1977 “Yes, gas is a very safe fuel, at least as safe as any other— but, like all sources of heat and power, it must be treated with due respect.”
NEXT UP: May's education panel
(Submit your questions by 15 May)
Dave Williams, Design Co-ordinator at National Gas, is a passionate advocate for apprenticeships and skills development in the gas industry. Starting as an apprentice in 2007, he has built a career spanning technical, supervisory, and engineering roles, gaining expertise in asset management, integrity engineering, and workforce development.
With experience mentoring apprentices, assessing NVQ candidates, and leading professional development initiatives, Dave has played a key role in supporting new talent in the industry. His insight into training and career progression makes him a valuable expert for our May Q&A on education and apprenticeships.
Richard Harper started his career as an apprentice service engineer with the West Midlands Gas Board and has over 45 years’ experience within the gas utilisation industry. He has carried out a range of roles, including installation and maintenance work, heating breakdowns, and gas emergency call-outs.
The latter part of Richard’s career has focused on technical safety and compliance. He is currently responsible for managing the Standard Setting Body, which sets the training and assessment requirements for Gas Safe registered engineers.
Richard supports Energy & Utility Skills in identifying the skills gap for net zero and helped develop a hydrogen training and assessment programme for utilisation engineers. He is also involved in the review of apprenticeships and is keen to ensure that the industry attracts the talent required for the future.
Rob Anderson has worked in the plumbing, heating, and domestic gas industry for over 26 years.
He began his career as an Apprentice Technical Engineer at British Gas, later becoming a Safety Assurance Engineer. In this role, he conducted carbon monoxide (CO) incident investigations for the Health and Safety Executive and energy suppliers, and prepared expert witness reports for Coroners’ Courts.
Rob has also mentored and trained engineers—a role he particularly enjoyed. His passion for developing talent led him to join Crowcon Gas Detection Instruments in 2019, where he managed key national accounts and offered technical support. He also built relationships with training centres and represented the company at industry events.
In 2022, Rob became a lecturer at Abingdon & Witney College, designing and delivering a gas curriculum for Level 3 apprentices, with a focus on practical skills and Gas Safe registration.
He joined Ideal Heating’s Expert Academy in October 2024 as Technical Training Manager. Rob says, “This role allows me to stay at the forefront of industry developments while giving back to the trade.”
He is a registered engineering professional with the Engineering Council and an active IGEM ambassador, promoting carbon monoxide safety across the industry.