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Not surprisingly the then transport secretary, Chris Grayling, lost faith in the industry’s ability to deliver electrification and cancelled future schemes. He also concluded that electrification was the wrong technology and that innovative self-powered traction was the future.
This was unfortunate as electric trains are more powerful and efficient than self-powered trains. They do not have to store energy nor do they have mini-power plants with a space-constrained power output and unavoidable energy conversion losses. Electric trains are unique in offering high-power, high-speed transport with net-zero emissions as they are directly powered by electricity which can be produced from renewables.
Decarbonisation was on rail minister Jo Johnson’s agenda when, in 2018, he called for diesel-only trains to be removed by 2040 and required the industry to “provide a vision for how it will decarbonise”. However the rail industry decarbonisation task force set up to respond to this call did not have a free hand. As one of its research reports noted, “UK government has made clear its intention to decarbonise rail where possible and to use innovative solutions rather than relying on full electrification”.
Prospects for hydrogen
Yet, if electric trains are not the answer, the alternative is on-board storage of zero-carbon electricity, for example by batteries. The range of such a train would be about 100km. An alternative is to use electricity to produce hydrogen by electrolysis. Although this adds complexity and inefficiency, hydrogen compressed at 350bar has a greater energy density than batteries. Hence it can give a medium-speed (140km/h) passenger train a range of about 1,000km.
So battery and hydrogen traction are only suitable for a small percentage of rail passenger traffic and not for freight. Hence, if diesels are to be eliminated, the only alternative is a large-scale electrification programme. If this is not the government’s view, proposing it as a solution could have been counter-productive.
The rail decarbonisation task force published its final report in July 2019. This called for a balanced mix of electrification and hydrogen and battery traction. Yet it stated that a large-scale electrification programme may be required. A further report published by Network Rail, Traction Decarbonisation Network Strategy (TDNS), concluded that rail decarbonisation required 13,000 single-track kilometres (stk) of electrification with hydrogen and battery train deployment on respectively 1,300 and 800 stk of infrastructure.
Much work has also been done to learn lessons from the Great Western electrification debacle and recent schemes have been delivered in a cost-effective manner.
Green ambitions
Hence it seems that the case for rail electrification is starting to be accepted, with the government’s plan for a green industrial revolution including a commitment to electrify more railway lines. However, no new electrification schemes have been authorised.
Selling electrification is not a problem north of the border where Transport Scotland takes the view that the country’s railway can best serve the people with electric trains that encourage modal shift through improved journey times and better reliability as well as being greener, more efficient and cheaper to operate. Hence when one Scottish electrification scheme had a substantial cost overun, the response was not to cancel electrification, but to ensure that lessons were learned so that future schemes were delivered in a cost-effective manner. Last July, the Scottish government published its rail decarbonisation plan which commits to electrifying almost all of the country’s railways by 2035.
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