UK rail sector on track to diesel-free trains by 2040
29 per cent of the UK train fleet still runs on diesel
Passengers board a Eurostar train at St Pancras International station in London. About 29% of the UK train fleet still runs on diesel and freight trains run almost entirely on it. Photo: Tolga Akmen / AFPAs host of the recent COP26 climate summit, Britain’s drive to help slash global carbon emissions will involve keeping to its own target of phasing out diesel trains over the next two decades, industry bodies and observers say.
According to the latest government data, about 29 per cent of the UK train fleet still runs on diesel and freight trains run almost entirely on it.
The government has unveiled plans to electrify an additional 180 miles (288 kilometres) of track in a new rail strategy. This would help “to meet the ambition of removing all diesel-only trains from the network by 2040”, the Department for Transport said.
Diesel dependence
While electric trains emit 60 per cent less carbon than their diesel counterparts, only 42 per cent of the UK rail network is currently electrified, according to official data. That places the UK far behind European neighbours, such as the Netherlands, where 76 per cent of the network is electrified.
Only 42% of the UK rail network is currently electrified, That places the UK far behind European neighbours, such as the Netherlands, where 76% of the network is electrified
With the current surge in electricity prices, some electric-run operators have recently been forced to revert to diesel locomotives, trade body Rail Freight Group (RFG) observed last month. While the RFG described the switch back to diesel as “regrettable”, it insisted it was only temporary.
Its director general, Maggie Simpson, highlighted a need for “more electric wires to support the investment in newer locomotives”. Britain’s rail freight is presently 90 per cent hauled by diesel engines.“Of course, in the long term, we need to move to a decarbonised economy, so more use of electric traction is going to be a huge part of that,” Simpson told AFP.
Last month saw the launch of a new fully-electric passenger train in the UK – Lumo’s London-Edinburgh service carries no auxiliary diesel engine.
Train operators are taking the opportunity to transition also via hybrid models in much the same way as carmakers. Chiltern Railways, which runs passenger services between London in southeast England and the country’s Midlands, recently announced investment in a hybrid battery-diesel train, developed by rolling stock owner Porterbrook and Rolls-Royce, the maker of aircraft engines.
Hydrogen future
As well as increasing electrification of its rail tracks, Britain is in the early stages of producing trains that can run on the renewable energy hydrogen. French train manufacturer Alstom has announced plans to deliver the UK’s first-ever fleet of new hydrogen trains, as opposed to rolling stock that has been remodelled.
“Rail is already the lowest emission transport mode, but we can do even more,” Nick Crossfield, Alstom’s managing director UK and Ireland, said as the group this month unveiled its hydrogen project in collaboration with British trains owner Eversholt Rail.
The COP26 event in Glasgow – attended by Britain’s Prince Charles who is a committed environmental campaigner – showcased a hydrogen-powered train. HydroFLEX, developed by Porterbrook and the University of Birmingham with the help of UK government funding, is a remodelled train that its designers claim can carry sufficient hydrogen to match the performance of a diesel engine.
While Glasgow Central train station displayed HydroFLEX to the general public, the nearby COP26 summit focused on ending sales of road vehicles that run on fossil fuels.
Battery-electric trains can deliver environmental justice, cost savings and resilience to the U.S.
Trains have been on the sidelines of electrification efforts for a long time in the U.S. because they account for only 2% of transportation sector emissions, but diesel freight trains emit 35 million metric tons of carbon dioxide annually and produce air pollution that leads to $6.5 billion in health costs, resulting in an estimated 1,000 premature deaths each year. What's more, these deaths and adverse health impacts disproportionately affect disadvantaged and low-income communities, which are more likely to be located near freight rail yards and railways.
The recent dramatic decline in battery prices has created a new possibility for electrification of freight trains. Researchers from the U.S. Department of Energy's Lawrence Berkeley National Laboratory (Berkeley Lab), collaborating with UCLA and UC Berkeley researchers, make the case that the U.S. can retrofit diesel-electric trains with batteries in a way that is cost-competitive with diesel. Doing so would avoid these unnecessary deaths and health impacts and save the U.S. freight rail sector $94 billion over 20 years from reduced air pollution and carbon dioxide emissions. Their study was recently published in the journal Nature Energy.
"A rapid conversion of the freight-rail sector is not only technically feasible and cost-effective, it would bring immediate and lasting health and economic benefits to lower income communities," said Natalie Popovich, Berkeley Lab scientist and lead author of the study. "And it would provide a boost to our nation's efforts to curb climate change, especially considering that U.S. freight rail capacity is expected to double by 2050."
Trains play a significant role in moving goods throughout the U.S., particularly heavy freight such as coal, lumber, and ore. According to the Federal Railroad Administration, 28% of U.S. freight is moved around the country by rail, and that percentage is expected to grow substantially in the next couple of decades. At the recent 2021 United Nations Climate Change Conference, the U.S. joined a dozen other countries in signing onto new agreements to curtail shipping emissions, and zero-emissions solutions for freight rail transport will be part of that commitment.
Diesel-electric, but not battery-electric
Unlike several other regions in the world, all freight trains in the US are still diesel electric, largely because the typical electrification strategy of building electrified lines over tracks is harder to implement in the U.S. with its vast distances. In diesel-electric trains, a diesel engine is connected to an alternator that then supplies electricity to electric motors connected to the locomotive axles. Retrofitting the trains to be powered by batteries is therefore feasible because diesel-electric trains already have an electric motor.
"Dramatic improvements in battery technology, coupled with the existing electric drivetrain in predominantly diesel-electric freight trains in the U.S., pave the way for a rapid conversion to battery-electric freight rail and with substantial cost savings," said Berkeley Lab scientist Amol Phadke, corresponding author of the study. "Also, the weight of batteries is less of a constraint than it would be for electric vehicles or trucks. We can add a car to a freight train built out with batteries, and the weight of that battery car is not an issue with trains."
Diesel-electric trains have been around since the 1920s, and they started to replace steam trains in the 1930s since they performed better and were less polluting. At that time, using diesel engines to generate power for the motors on trains was cheaper than trying to develop fully electric trains due to high electricity costs. Now, a century later, we are at a point where the price of electricity is competitive with diesel, and the environmental and health costs of continuing to rely on diesel to power freight trains are too devastating to ignore.
"Our analysis shows that a switch to battery-electric freight will cut the industry's annual carbon dioxide emission by more than half, eliminating more than 400 million metric tons of carbon dioxide in 20 years," said Popovich.
The study highlights that additional pathways to electrifying U.S. freight trains exist, such as electrifying trains via overhead power lines or using hydrogen fuel cells in conjunction with battery-powered trains. However, based on the fact that freight trains are already diesel-electric, and considering recent advances in battery technology, the researchers show that the battery-electric pathway offers the most cost-effective, long-term solution with multiple added benefits.
Their analysis shows that existing battery technology could power a freight train for 150 miles (the average daily distance traveled). A battery-powered freight train would use half the energy required by a diesel-electric train, and taking into account falling battery prices and environmental costs of diesel, battery-electric trains are on track to be more cost-competitive than diesel-electric trains. Since freight rail planning is centralized, the study suggests that railroads could achieve high volume use of fast-charging infrastructure, which would further reduce costs.
One major benefit of retrofitting existing diesel-electric freight trains with battery cars—otherwise known as battery tender cars—is that the battery-electric trains can always fall back on the diesel engine as a backup fuel source. This dual-fuel capability, allowing for either battery or diesel usage, is a unique advantage compared to fully electrifying the freight rail system or using hydrogen fuel cells.
Modular batteries offer resilience benefits
Another major benefit is that battery-electric trains can be deployed as clean backup power, thus bolstering the electric grid's resilience. Historically, diesel-electric trains have been used as power generators during emergencies. In early 1998, a series of ice storms left over a million without power in the northeastern U.S. and in parts of Canada. In one suburb of Montreal, the mayor moved an entire diesel-electric locomotive close to City Hall to supply power for their emergency response operations.
With the rise of extreme weather events and power outages, battery-electric trains have the potential to be deployed nationwide to avoid blackouts. These modular, battery tender cars can be transported to where they are needed and charged in locations where the electricity prices are low, thus offering significant advantages over grid-scale storage. Moreover, the battery tender cars could work as modular shipping containers, capable of exchange between freight rail and maritime shipping vessels, with positive benefits to decarbonizing both sectors and expanding the resilience reach.
"Conversion of the U.S. freight rail sector to battery-electric would generate about 220 gigawatt-hours of mobile storage," said Phadke. "Furthermore, these battery tender cars could be deployed during extreme events, such as during the recent catastrophic wildfires in California or the 2021 winter storm in Texas that left millions without access to electricity. This mobile energy storage capability would also create a potential new revenue stream for freight rail operators."
From a technical perspective, the researchers demonstrated that there should not be any constraints in moving to fully battery-electric freight trains, but further research and large-scale demonstration projects are needed to optimize charging infrastructure. "Berkeley Lab's systems and markets analyses shed light on this overlooked area and demonstrated that we can decarbonize some sectors with existing technology, which will help us reach our climate goals that much faster while also advancing environmental justice and grid resilience. It's a win-win-win," said Berkeley Lab Energy Storage Center Director Noel Bakhtian. "The techno-economic analysis of battery-electric freight trains shows that we have viable solutions available to enable the transition to a clean, affordable, and resilient energy future."
UK rail sector on track to diesel-free trains
More information: Natalie D. Popovich et al, Economic, environmental and grid-resilience benefits of converting diesel trains to battery-electric, Nature Energy (2021). DOI: 10.1038/s41560-021-00915-5
Journal information: Nature Energy
