South Western Railway says it’s committed to becoming a net zero railway by 2040, 10 years ahead of the UK target. Part of its plan is a rolling stock replacement programme switching all remaining diesel trains to electric/ battery power. It hopes to finalise this plan by 2032.
The company runs a fleet of 30 year old class 158 and 159 diesel units on services on the West of England line to Exeter and Salisbury using unelectrified track from the west of Basingstoke. They emit around 20 times as much carbon dioxide per mile compared to third rail electric trains and even without the carbon reduction targets would need replacing in the next 5 to 10 years.
South Western says it’s been trialling numerous promising technologies, but it claims “retrofitting our diesel fleet with lower carbon technologies at this stage of their lives is not deemed economically viable”.
Although there are longer-term plans to electrify some non-electrified routes, the implementation timetable is such that SWR is likely to have to replace the diesel fleet with a self-power solution, such as battery and/or hydrogen. There is also doubt about whether the Office for Rail and Road would approve further third rail electrification. It considers that the weight of safety evidence creates a presumption against new-build or extended third rail being reasonably practicable.
In the short term, SWR says it’s already reducing its carbon emissions by maintaining and refurbishing components such as traction motors rather than directly replacing them.
In the longer term it says it’s exploring several options but “the technology that replaces the diesel fleet is dependent on what becomes commercially viable for use on the UK network”.
Battery powered trains are the most likely option for the replacement of the current class 158/9 fleet, as the technology is already available, and SWR says it appears to be the most economically viable solution. There are still some infrastructure challenges associated with this. For example, batteries need recharging after 60 – 80Km. This figure could be reduced if there are service delays (and there are plenty of those on the single-track sections). Infrastructure will have to be installed so that trains can be rapidly charged, possibly at stations.
An alternative option to batteries is the use of hydrogen. This can be made using electricity generated by wind, sun or tide and would therefore produce no greenhouse gas emissions. A prototype hydrogen powered train ran last year to the COP26 conference in Glasgow.
Amy Dickinson, Head of Sustainability at South Western Railway, commented: “Tackling climate change is one of the greatest challenges facing the railway, and indeed the whole country. Taking the train is already one of the most sustainable ways to travel, and we are proud of the progress we have made so far, but we know that more needs to be done. We are leading the way as the first train operating company to publish a robust, transparent, and cost-effective roadmap to net zero by 2040, ten years ahead of the UK’s overall 2050 legal deadline".
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