In many ways, rail is seen as the ultimate form of decarbonised transport. It is efficient, relatively fast and not always as dependent on fossil fuels as most of its competitors.

Yet it still has a way to go on its journey to net zero carbon. Diesel trains continue to generate polluting emissions, and a network largely built in Victorian times clearly can’t be expected to fully align with 21st century environmental standards.

Scotland has huge ambition when it comes to greening rail travel. It has set a target date of 2035 for eliminating diesel across its 2820 kilometres of track, though it is clear that meeting that deadline is going to be a challenge.

At present, only 25% of the network north of the border is electrified, compared to 42% across the UK as a whole. This means that some 1800 kilometres of track in all have been identified as needing electrification.

However, other novel solutions are going to be required to decarbonise in the required timescale, including hydrogen and battery power as well as the more traditional overhead wires.

Siemens Mobility is working to help shape the future of the railway in Scotland, developing innovative technology that will create a network ready for the low carbon age.

Justin Moss, the company’s Head of Sales for Electrification, concedes that a timescale of just 14 years before diesel is taken out of the picture presents a challenge – but is not impossible. 

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“It’s not very long away. But we have some real experts when it comes to modelling, looking at areas such as power requirements. We are examining how we can electrify further and faster, while being aware that we may not have everything completed by 2035.

“We are looking at the rolling stock we can use and if we can bring in hydrogen and battery power as a kind of sticking plaster to get the biggest reduction in carbon as quickly as possible, with electrification rolled out after that.”

It is easy to see why expanding the existing electrified network is so daunting: it needs considerable infrastructure including overhead wires and existing structures such as bridges could have to be altered to accommodate these.

“Also, Scotland is a country with hills and mountains and there is a challenge in getting power to those areas in the most cost efficient way possible. It may be better to use hydrogen power, for example on the west coast.

“We are working with Transport Scotland and Network Rail to model the routes, look at the best solution to get to net zero as quickly as possible.”

As a large and specialised global company, Siemens has a recognised capability in areas such as signalling and rolling stock “It’s a case of working together very closely as a team to come up with the most efficient solutions. We want to go as quickly as possible”, Justin Moss explains.

Routes need to be examined, identifying which ones are the easiest and most cost effective to electrify quickly. At the same time, low or zero carbon alternatives need to be considered for the more difficult ones, including those in remote areas.

“You’re not going to demolish or fundamentally change things like historic bridges, so it’s about how you solve the problem of how you put power there.”

Equipping a new generation of trains with hydrogen technology could offer an answer, but Mr Moss points out that it is a new and emerging low carbon offering for which there will be huge parallel demand from cars, heavy goods vehicles and heating. 

“At the moment, the infrastructure just isn’t there to fill the trains up with hydrogen. However Siemens Mobility is partnering with Siemens Energy to provide the full hydrogen rail system including refuelling and green hydrogen supply and currently has two hydrogen rail projects underway in Germany. 

“Electrification currently offers the best solution as it provides the biggest carbon reduction, so that will always be our starting point. But if you can’t use that technology, hydrogen could be a good route to take.”

It is likely that some of the trains of the future will be able to operate using different power sources – or in bi-mode, as the industry calls it.

As well as working in the traditional electrified way – picking up power from overhead wires through a pantograph on the top of the train – they may also have an alternative technology using a battery or hydrogen. This would mean their operation could be similar to a current hybrid car, running on one fuel source and then switching seamlessly to the other when necessary.

As an example, the trains might run on battery power through stations, avoiding the need for the complex new infrastructure needed for electrification and cutting down on noise.

A feasibility study is ongoing and development work currently taking place with Transport Scotland. Other parts of the rail network will also need to be upgraded, including the signalling infrastructure. Smart technologies can not only reduce emissions on their own, but also help to replace a lot of the existing physical trackside infrastructure.

Replacing this with on-train and in-cab technology will help in a number of ways by driving cost efficiencies, providing better information for drivers and allowing for a greater frequency of trains, meaning that they can run closer together and consequently that capacity can be increased.

“I see signalling as an enabler for decarbonisation”, says Campbell Braid, Siemens Mobility’s Signal and Programme Director. “But it’s expensive and we have to deliver more efficiencies to make it an affordable part of the process.

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“We need to convert a lot of the existing mechanical infrastructure such as signal boxes, which means upgrading the technology to make it electrification ready. This will also bring benefits for passengers and freight.”

There is no single solution, Mr Braid says. “We need to find a way to deliver more efficiently in order to allow more trains to run to a timetable that allows passengers to move quickly. That’s where in-cab technology and train detection systems come in.”
Can Scotland’s railway really be decarbonised as early as 2035, though? “I think the answer to that is yes. We do need to go faster and we need to be different, but through a mix and match of technology and rolling stock, we’ll have a joined up system.”


‘E-highways’ look set to be the direction of travel

THERE is no question about it: transport belches out carbon. As a sector, it is responsible for 24 per cent of global emissions. This means that radical thinking is needed to develop innovative solutions.

One promising answer to the problem of pollution caused by road traffic is to build e-highways. These will cut emissions from HGVs, and a number of companies including Siemens have extensively tested them in Germany, Sweden and the United States.

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In some ways, this proposed technology harks back to the days of trolley buses some 60 years ago, though it is clearly more sophisticated. 

E-highways will use powered overhead wires, with lorries having pantographs fitted to draw the electricity.

The power supplied would power an electric motor on the vehicle. At the same time, it would charge an onboard battery, allowing the lorry to use this when it drove off the directly electrified route.

A consortium including Siemens Mobility, is to undertake a pilot e-Highway project in Yorkshire. This is part of the £20m put aside for zero emission road freight 
feasibility studies and aims to electrify some of the major UK freight roads by 2050.

“Effectively, we are taking rail technology and putting it on the motorway, but we now need to see how it will work in terms of logistics”, says Siemens Mobility’s Justin Moss. 

“It will be a way of reducing carbon output from HGVs, using the sort of overhead line you would find on a light rail system. This would be installed above the slow lane of the motorway for vehicles to attach themselves to.

“We’ve identified that the road link between Glasgow and Edinburgh, for instance, would work very well for this sort of technology. It complements the need for getting more freight on the railway. 

“You’re not going to get rid of HGVs completely, but this solution would work in terms of agility. It’s potentially quite expensive, but not necessarily as complicated as it would be for rail.”