Decarbonising Rail: Thinking Beyond Electrification

United Kingdom | November 8, 2023
Reading Time : 7 minutes

As one of the UK’s most energy efficient transportation modes, rail plays an essential role in our transition to a net-zero economy. There are currently many challenges in the industry to attract people back to rail and to ensure fair access across the country to well connected, decarbonised, end-to-end journeys. However, once on a train there is still around 2Mt of carbon emitted every year by rail. With more of our grid being powered by renewable energy – from 43% in 2020 to a target of 100% renewable by 2050 – electrification may seem the ideal solution to decarbonising those remaining parts of our network still operated by diesel trains.

Mega tonnes of carbon emitted by rail annually

2 2

Decrease in CO2 emissions if all trains are electrified

60% 60%

Cost per single track km to electrify

£2 million £2 million

The environmental case for electrified train travel is undeniable; even today it represents 60% fewer CO₂ emissions than its diesel equivalent, which could rise to 80% by 2040 (source RIA). But, at over £2m per single track km, electrification is expensive and around 60% of the network is still not electrified. To electrify requires significant investment commitment from Government, particularly for long-distance, high-speed and freight routes, where overhead electrification is the only viable solution.

The prohibitive cost of electrifying our largely Victorian railway helps explain the staccato nature of an electrification programme. But if electrification is economically unfeasible right now, what practical measures can we take to accelerate progress towards decarbonised traction? How can we help the railway fulfil its greenest potential?

Electrification: no longer a bridge too far?

Those looking for clues as to whether reducing the cost of electrification is achievable need only look north of the border. Here, the Scottish Government’s ambitious electrification programme is demonstrating what’s possible when government and industry work towards one goal: in this case, the decarbonisation of Scotland’s domestic railway passenger services through electric services by 2035.

One of these schemes, the East Kilbride Rail Electrification, is a great example of “efficient electrification” in action. This project is being made affordable by reducing wire heights and electrical clearances under structures utilising voltage-controlled clearances, which effectively means bridges on the route won’t need to be rebuilt to accommodate overhead line electrification.

Demonstrated to be safe and cost-efficient by colleagues, WSP delivered the feasibility studies and designs for the scheme (GRIP2-4). This pragmatic approach has supported a viable and robust business case which has now been embedded into national standards. Through this innovative scheme we can see that boosting capacity and unlocking the environmental benefits of electrification doesn’t have to come with a prohibitively large price tag, and that these benefits can be unlocked sooner than originally thought.

Author

Chris Wood

Technical Director

United Kingdom

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Image 1: WSP collaborated with Highland Spring Group and Network Rail on a facility that will reduce annual carbon emissions by 3,200 tonnes and remove 8,000 lorry movements each year from the roads. Read more .

Charging towards net zero with battery power

In the UK, aside from a handful of minor trials, battery train technology is largely untested on our network. That looks set to change with the Rail Safety and Standards Board (RSSB)’s pioneering development of an operational framework that will pave the way for battery trains to be implemented onto the UK rail network. In doing so, it is supporting Great British Railways Transition Team (GBRTT)’s emergent thinking around battery trains as a key part of its own 30-year strategy for rail. WSP’s work in helping RSSB to identify an optimised operational framework represents a unique opportunity to apply lessons from European neighbours and could become an increasingly popular way for UKPLC to nudge the needle further towards a decarbonised railway.

Plugging the gaps

There are opportunities for battery trains beyond just rural and branch lines. As electrification of the rail network expands along the primary passenger and freight routes – it will bring electrified infrastructure closer together, albeit with gaps along the secondary routes connecting them. Battery could help bridge those gaps, providing a zero-carbon way to support the progressive removal of diesel as electrification continues to roll out. Doing so could also reduce the capital cost of electrification projects as part of an infrastructure-and-rolling-stock solution that reduces the need for total continuous electrification. Clearly, this won’t be suitable everywhere but could certainly help to decarbonise secondary and tertiary routes across our network. Indeed, we recently identified the potential for this approach as part of work supporting Network Rail by undertaking a pre-feasibility assessment of the West of England Line in Wessex. Here we identified the high-level system architecture for electrification of the route and the potential opportunities of combining electrification and battery traction.

Battery propulsion’s utility for tramways and light rail is another innovative avenue that will no doubt grow in the next few years. Perhaps the best example can be found in efforts to power Coventry City Council’s innovative Very Light Rail (VLR) system, a world-leading mass transit project, which I’m excited to be part of. As well as supporting better air quality in the city, the prefabricated track on which it will run will make VLR even more cost-efficient than a traditional tramway, strengthening the business case even further.

Image 2: Rail lines are facing challenges related to increased heavier rain fall.

Freight expectations

As RIA rightly points out, an electrified railway is the decarbonisation technology suitable for mainline freight trains. But with one freight train taking around 70 lorries off the road network, we mustn’t discount the huge potential that even diesel-powered rail freight has to shunt the transport sector as a whole towards a greener future. After all, diesel-powered rail freight produces 76% less CO₂ than an equivalent road journey, whilst simultaneously providing a resilient transportation method for bulks and aggregates. Moving such materials by road is a significantly more complex proposition.

Underlining rail’s essential efficacy, a recent WSP white paper details how rail transportation is already one of the lowest-energy modes of transportation (per person or per ton of freight). Its authors further highlight how this already convincing environmental performance (in the shape of lower CO₂ emissions) “improves greatly” if the electricity for that train comes from renewable sources. Recent research from the Chartered Institute of Logistics and Transport further supports the “low hanging fruit” of electrifying major rail freight flows, effectively shifting more goods from road onto what could be a zero-emissions transport mode.

Rail freight’s potential to reduce costs, mitigate environmental impact and give forward-looking companies an opportunity to be better neighbours within the communities they operate is more than just theoretical. Highland Spring Group Ltd offers a powerful example of how forward-looking companies are unlocking rail’s potential; its new and award-winning rail freight facility in Perth and Kinross, Scotland, means it can now look forward to c.8,000 fewer annual lorry movements and an annual reduction of around 3,200 tonnes of CO₂ emissions by shipping the 450 million litres of natural source water it bottles every year predominantly by rail.

In a broader sense, its unique ability to move vast quantities of materials and commodities safely and efficiently means rail freight also has a role to play in facilitating a greener supply chain. As such, it is set to play an increasingly key role in moving hydrogen and liquified carbon from carbon capture plants around the UK to where they are needed – a carbon efficient transport system supporting the further decarbonisation of our economy. For these reasons, it seems obvious that the electrification of the primary passenger and freight routes should remain the short- to medium-term goal for UK Government.

The bigger picture

Rail should be considered part of a joined-up transport network; one that considers the end-to-end journey of goods and passengers and supports and optimises other modes to maximise sustainability potential, whether that’s public transport and active travel, or freight by water. You don’t have to look far to see evidence that this is happening; Network Rail’s recent introduction of 450 EV charging points at its railway station car parks, and its ongoing research into how it can transition towards a fully electric fleet of maintenance vehicles, great examples of multi-modal thinking.

Only by ‘joining the dots’ can we offer the sort of connectivity that will boost customer demand and reduce our reliance on road.

While fully decarbonised railway traction makes the case for a multi-modal transport solution even more compelling, there is no silver bullet to get us there. However, as the reality of spending restrictions bite while the pressure for progress grows, there are tools – new and proven – that can accelerate our journey to a net zero railway and strengthen the case for a joined-up approach to sustainable transport.