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IMechE & COP26

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As well as being an official observer to COP26, the Institution of Mechanical Engineers (IMechE) is keen to raise awareness of the role engineers play in tackling climate change and advocate for positive policy change. To do so, the Institution focused on three key themes: energy transition; clean transport; and cities and the built environment. It has published policy papers for each theme and held a two-day hybrid event to consider them on 28-29 October. In addition, the IMechE’s Railway Division held a half-day event on 20 October: “Refocusing the railway in a post-pandemic world.” I was asked to speak at both of these events.


The first presentation on the agenda was my own on catenary-free electric trains. This considered the benefits and disadvantages of hydrogen and battery trains. It also stressed that, in a net-zero world, hydrogen trains had to be seen as part of a hydrogen economy as the gas is likely to be the optimum zero-carbon solution for high-powered applications such as HGVs, especially when infrastructure costs are considered.

The following speaker, Professor David Cebon, disagreed and presented a plan to erect a double catenary electric road system (ERS) on 15,000km of main roads and motorways. This system was presented as proven technology as rail uses overhead line and the system has been demonstrated by projects in Sweden and Germany. Many in the rail industry would dispute this. A particular issue is these pilot projects have a 670 V DC system. If this was to power HGVs on a busy motorway, this would require about 5MW per kilometre. Rail OLE uses 25kV AC to supply such power. Furthermore, the Climate Change Committee’s Net Zero report considers that, for HGVs, hydrogen may offer the lowest whole system cost.

Orion’s class 319 EMU converted for express cargo deliveries.

Railway recovery

Mark Gaynor, the Rail Delivery Group’s Head of Rail Strategy, explained how the railway was recovering from Covid with changing travel patterns which included a significant reduction in five-day-a-week commuters. As of 7 October, rail passenger journeys and services run were respectively 69% and 88% of pre-pandemic levels.

Other presentations considered how the railway should respond to this to meet customer expectations and improve efficiency. TfL’s Anjay Ray spoke on the 4LM project to improve services on its sub surface lines. Daniel Fredriksson, Network Rail’s Express Freight Development Lead, considered the opportunities and challenges of using converted passenger trains to deliver parcels into city centres or distribution hubs. He explained that there were opportunities to co-locate such hubs alongside heavy freight facilities.

GBR transition

Michael Clark, Programme Director of the Great British Railways Transition Team, explained how GBR is to be set up and the challenges it faces. The team now has a website, though currently it only shows its seven members who are led by Andrew Haines. Michael advised that next year he expected to see the required legislation which would merge Network Rail, the Rail Delivery Group, and parts of the DfT, though in the meantime there was much that could be done and that a particular challenge was reduced revenue. He felt that GBR offered significant advantages and, from an engineering perspective, would see rolling stock and infrastructure considered as part of a whole system.

The safety implications of creating GBR were considered by John Abbott, Deputy Chair of the Parliamentary Advisory Council for Transport Safety (PACTS). John has experience of safety being compromised with the creation of Railtrack and felt that introducing the new GBR organisation was a similar fundamental change. Hence, clarity of safety responsibilities was essential. John also explained how PACTS considered that GBR was an opportunity to re-engineer the rail to support a 24/7 365-day economy and modern logistics. He also noted PACT’s wider concerns which included HGV’s safety record of 66 vehicle occupants and 450 other road users killed each year.


The IMechE’s two-day COP26 event on 28-29 October was introduced by its President, Peter Flinn. He considered how engineers had contributed to economic progress that, each year, has resulted in 93 million cars and 50,000 aircraft being produced, with 25,000 TWh of electricity generated. Since 1847, extreme poverty among the global population has been reduced from 90% to less than 10%, despite that population increasing from 1.2 to 7.8 billion. Yet the downside is the climate emergency, as atmospheric CO2 concentration has risen from 284 to 412 ppm.

Energy transition

Guy Newey of the Energy Systems Catapult (ESC) stressed the need for whole systems thinking. This required breaking down silos between electricity, heat, and transport and joining up the physical requirements of the system with policy, market, and digital arrangements. The ESC’s modelling indicated that, to achieve net zero, unabated annual fossil fuel consumption had to be reduced from 1,500 to less than 300 TWh and electricity consumption increased from 300 to 700TWh whilst energy consumption from district heating and hydrogen would be respectively 150 and 250TWh.

Kirsty Gogan of LucidCatalyst focused on the challenges of energy transition. She felt this needed the equivalent of the impossible burger, a vegetarian substitute with the same taste and texture of the real thing. Such drop-in substitutes are needed to make best use of existing assets. She considered that there was the potential to develop low-cost nuclear power to provide advanced heat sources that could replace boilers in conventional power stations.

The benefits of nuclear power were also stressed by consultant David Ross as it provides the stable base load required by the electricity grid. He contrasted this with electricity generation from natural gas with carbon capture and storage (CCS) which is the only other way of net zero-carbon base load generation. The generation of 1GWh of electricity by nuclear power produces 5kg of spent fuel whereas gas with CCS produces 400,000kg of CO2 which requires permanent storage. His presentation also showed how more nuclear power could significantly reduce the required renewable generating capacity for a net-zero grid.

Jamie Burrows of the Global CCS Institute explained how carbon capture was needed for deep decarbonisation of hard-to-abate industries, for the production of low-carbon hydrogen at scale, and zero-carbon bio energy production. He advised that there are currently 27 worldwide operational CCS facilities capturing 40 million tonnes of CO2- equivalent per annum (MtCO2e), but to deliver on climate commitments a hundredfold increase in CCS capacity is needed by 2050.

The reactor dome of the nuclear power station at Sizewell in the UK.

The development of wind power technology was the subject of a presentation by Matthew Laskaj of Project Engineering Management. He explained how the average turbine size had doubled from 5MW to 10MW over the past ten years. He also noted how many of the skills needed by the wind industry were similar to those in the oil industry.

Built environment

Carbon emissions from buildings represent a quarter of total UK emissions. Options to decarbonise buildings include heat pumps, replacing gas with hydrogen, district heating schemes, better insulation and connecting houses that produce electricity into networks to share energy. There were no presentations on these topics which were discussed by a panel of experts. For those without prior knowledge, it was difficult to understand the advantages and problems of these technologies although it was made clear that there was no one silver bullet.

Issues discussed included the use of ground, air, and borehole heat pumps, which don’t supply hot water and are not suitable for densely populated areas for which electrically powered district heating schemes may be more appropriate. It was felt that heating had to be considered as part of an overall heat and building strategy. Moreover, new financial models were needed to support domestic consumers with refit costs and incentivise sustainable house building.

Energy Minister Anne-Marie Trevelyan opens the first Hydrogen demonstrator homes in July 2021.

The panel all thought that the use of hydrogen to heat domestic premises was an extremely dangerous move due to its propensity to leak and its explosive properties. Yet no reference was made to the Hy4Heat initiative set up by the Department for Business, Energy & Industrial Strategy. This has produced a report, reviewed by the Health and Safety Executive, that concluded that hydrogen is as safe as natural gas.

The domestic heating discussion was followed by a sobering presentation from Dr Tim Fox who chairs the Institution’s Climate Change Adaptation Working Group. He referred to the Independent Assessment of UK Climate Risk which predicted hotter, drier summers with wetter, warmer winters and increased frequency and intensity of heavy rainfall, heatwaves and droughts. By 2100, sea levels could rise to between 0.7 and 1.15 metres in London. The UN’s Intergovernmental Panel on Climate Change makes a similar projection but does not rule out a two-metre rise due to uncertainty around ice sheet processes. Tim noted that, with buildings typically having a 100-year life, engineers need to design for these sea level rises now.

Sarah Hayes is currently working with the Centre for Digital Built Britain, Britain’s National Digital Twin programme, as the project lead for the Climate Resilience Demonstrator project. She explained how this initiative enables resilience planners to take a cross-sector level view to make decisions to maximise resilience.

Clean transport

In 2017, transport accounted for 167 of the UK’s 503 MtCO2e. Of these, the emissions from various modes of transport were: Cars – 70; HGVs – 21; Vans – 19; Air – 36; Ships – 14; and Rail – 2. IMechE’s Clean Transportation Lead, Amol Gulve of the Volvo Group, advised that the Institution had published a cross-modal strategy which had three priorities: i) reducing demand; ii) modal shift to public transport and rail; and iii) improved efficiency and use of renewable fuels.

Amol then considered the electrification of road transport with battery electric vehicles and noted that HGVs, which typically travel 400km per day, are the hardest to decarbonise and may require the use of hydrogen fuel cells.

Climate Central’s projection of land below annual flood level in 2050.

Decarbonising the rail sector was considered by Network Rail’s Iain Flynn who noted that the rolling resistance of a car tyre on an asphalt road was 12 to 30 times more than steel wheel on steel rail. His presentation explained the advantages of electrification and considered hydrogen and battery trains for lightly used lines.

Alex Best, an aero gas turbine consultant, presented options for decarbonising air transport which accounts for 2.6% of all greenhouse gas (GHG) emissions. He noted that since 1990 aircraft efficiency has improved by 1% per year. However, despite these efficiency improvements, increased demand is predicted to increase GHG emissions by a further 19% by 2050.

Although battery energy density is expected to increase to 400Wh/kg, this is still 30 times less than conventional fuels. Alex advised that all-electric planes are likely to be limited to planes with less than 20 seats having a range of less than 300 miles. Liquid hydrogen is being considered as a net-zero option for planes of up to 200 passengers with a range of 2,000 miles. However, such planes present significant problems.

Sustainable aviation fuels (SAF) are advanced biofuels produced primarily from waste oils and blended with conventional fuels in concentrations of up to 50%. Power to liquid fuels can be produced by synthesising carbon from CO2 with hydrogen. This requires a significant amount of energy which makes them much more expensive than conventional fuels.

SAF can reduce emissions by 80% but are currently three to five times more expensive than conventional fuels and were only 1% of the aviation fuels used in 2019. They are, however, the quickest route to aviation emission reduction but require extensive investment to produce the required amounts at an acceptable cost.

Professor Reza Ziarati, who is currently leading the Greenship project, noted that the marine sector had also improved its fuel efficiency. He considered that Ammonia was a possible net-zero solution for shipping and advised that an Ammonia powered Suezmax ship had been ordered. With a worldwide fleet of 56,000 merchant ships averaging 37,000 tonnes, it was important that the lifecycle of ships was considered. Ammonia is promising in this respect as, with modification, it can be used by existing diesel engines.

A panel of four experts, including your writer then answered questions about their sector. These brought out further issues including the need to consider embodied carbon, the cost of supporting infrastructure for net-zero road vehicles, and that a likely 2050 fuel scenario showed that 75% of transport energy could be supplied by sustainable liquid or gaseous fuels. My contribution was to emphasise the importance of rail capacity to accommodate modal shift. Unfortunately, in this respect, the need for HS2’s eastern leg has not been heeded by Government.

Transport, energy, and buildings are sectors that depend on fossils fuels and account for 84% of UK CO2e emissions. The IMechE’s COP26 conference was a thought-provoking two days which emphasised the role of engineers in implementing solutions to achieve net-zero emissions in these sectors. It also highlighted the need for effective policies that only Government can provide if these sectors are to be weaned off relatively cheap and easy to use fossil fuels.

David Shirres BSc CEng MIMechE DEM
David Shirres BSc CEng MIMechE DEMhttp://therailengineer.com

Rolling stock, depots, Scottish and Russian railways

David Shirres joined British Rail in 1968 as a scholarship student and graduated in Mechanical Engineering from Sussex University. He has also been awarded a Diploma in Engineering Management by the Institution of Mechanical Engineers.

His roles in British Rail included Maintenance Assistant at Slade Green, Depot Engineer at Haymarket, Scottish DM&EE Training Engineer and ScotRail Safety Systems Manager.

In 1975, he took a three-year break as a volunteer to manage an irrigation project in Bangladesh.

He retired from Network Rail in 2009 after a 37-year railway career. At that time, he was working on the Airdrie to Bathgate project in a role that included the management of utilities and consents. Prior to that, his roles in the privatised railway included various quality, safety and environmental management posts.

David was appointed Editor of Rail Engineer in January 2017 and, since 2010, has written many articles for the magazine on a wide variety of topics including events in Scotland, rail innovation and Russian Railways. In 2013, the latter gave him an award for being its international journalist of the year.

He is also an active member of the IMechE’s Railway Division, having been Chair and Secretary of its Scottish Centre.


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