Getting Real About Rail Decarbonisation

There were a couple of important firsts at the IET, Savoy Place, London on Wednesday 10 April (Rail Decarbonisation: Costs, Electrification, London's Future, a joint exercise by the excellent IET London and Railway Networks [2]). The first of these firsts was infamous and we can quickly pass over it: the traditional beer and wine after-session had been de-alcoholised, rendering it short and sullen (at least for me). Let's hope this is a temporary aberration. The second will probably have more impact: a transport professional gave a talk on decarbonisation, setting out an ambitious agenda full of technical excellence, creativity, and management will, to decarbonise a serious transport operation. There was not a scintilla of greenwashing - nothing about increasing recycling or using green photocopying paper, and no blether about biodiesel from canteen chip pans or replacing plastic straws in train buffets. And, glory be, there was not even a whiff of hydrogen! Truly groundbreaking!

The speaker was James Goodger , Engineering Delivery Manager for Net Zero at Transport for London. His is an amazing role, especially since TfL appear serious about helping the Mayor meet his target of net zero carbon by 2030. This is important. With the progressive decarbonisation of the UK's electricity supply, transport has become the UK's highest greenhouse gas emitting sector, and TfL is London's largest electricity user. That said, because TfL's rail operations are already all electric and the UK's electricity supply is rapidly decarbonising, TfL (apart from buses) is already mostly decarbonised and I could make a theoretical argument that (as with all rail authorities) its greatest contribution to global decarbonisation would simply be to get more people onto its electric trains and out of their petrol SUVs.

James and TfL are taking a more adult approach and as he pointed out TfL still do have substantial Scope 1 (direct) GHG emissions from diesel buses and other road vehicles, and gas heating to buildings (some of them substantial such as tube and bus depots), stations etc, as well as Scope 2 (indirect) emissions from traction and bus battery charging electricity. Reducing electricity consumption is good, even if the electricity is green, since it is then free for the decarbonisation of other sectors - for at least 10 more years and possibly indefinitely there will still be a gas component in UK electricity generation to deal with intermittency of solar and wind.

Some of the ideas James explained, such as inverting substations to improve regenerative braking receptivity, have been around for a long time but others are new. What was exciting was their breadth and intelligence. James also evidenced that TfL have tried to think organisationally about how to get schemes instigated, funded and implemented. I remember this challenge from my time on the Underground. We were lucky in that there was, relatively, more money around (before the Olympics and the financial crash) but even so it was hard to make business cases for standalone energy/carbon-saving schemes, unless part of a bigger programme like Cooling the Tube or one of the Line Upgrades. Hard, but not impossible. However, I would say it was impossible on the mainline during my time at Network Rail (and working with TOCs, ROSCOs etc), wherever benefits spanned over entities (which they invariably did). It is probably even harder than impossible at present with the current structural limbo and direct DfT operational control of TOCs.

So I thought I would take TfL's determined, engineering-led approach to 'net zero by 2030' and see what it would mean for the mainline railway: getting real about railway decarbonisation. In my imaginary near-future world GBR have proudly hoisted their double-arrow flag above the former Railway Technical Centre in Derby, and its new leader (me, let's say), the strategic guiding mind of the national railway system, has been given a strong mandate by the incoming Labour Transport Secretary:

Reduce greenhouse gas emissions from the GB mainline railway system by 2040, at minimum cost, to net zero. You are also to minimise overall railway electricity consumption, even if the source is renewable. In making business cases for schemes, you may utilise carbon savings in other sectors if you can facilitate them and assume a carbon price based on international norms [1]. You'll have to use international sources of green funding, because we've got none. Good luck!

I'd snarkily point out that the goal could be achieved very simply, in just a few years, by applying appropriate GHG taxation to road and aviation fuel and that the resultant modal shift to rail might make reinstating HS2 a good idea. However, let's take the more mature business-like TfL approach.

The first step should be to institute rolling electrification, starting with infills. A plan would be developed for a constant rate of installation each year, mirroring the long-standing plea from RIA. The industry would be required to agree standards for cheaper 25kV, and discontinuous electrification in various formats (using 25kV; with a lower DC voltage but still using OLE; and a ground based conductor rail system) for different applications. All purchases of diesel units and diesel hybrids would end - if necessary life-extending Class 15x units to allow battery technology to improve and partial electrification schemes to roll out.

Diesel running under wires would be phased out over several years, with diesel locos taking over only where unavoidable. I would expect the new Transport Minister to tax HGVs appropriately commensurate with their carbon emissions and damage to road infrastructure to ensure rail freight remained competitive. There would be an embargo on scrapping old electric locos like Class 90. A scheme would be instituted to replace diesel packs on Class 8xx hybrid units with batteries (though this could be delayed for some years to allow for battery improvements and electrification extension). Innovative new hybrid electric locos like Class 93 and 99 would be encouraged. This agenda could easily eliminate Scope 1 railway emissions from traction by 2040.

All that, along with reinstating HS2, is obvious. What about some of the more radical ideas that TfL are pursuing, or which they probably would if they were running the mainline railway, to give more immediate benefits? Many of James' ideas were rightly focused on improving regenerative receptivity and better utilising the in-house electricity distribution system. On regen and traction power efficiency, TfL are considering increasing the voltage on the Central Line from 750 to 890V DC. We showed back in the halcyon days of the VLU and SSL upgrades that a great deal could be achieved through the systematic use of low-loss conductor rail, increasing voltages, reducing sectionalisation (longer electrical sections during traffic hours to increase the chance of receptive trains being in section), and inverting substations to put power back into the distribution system. Now that all units on the mainline have AC traction motors and traction packages there must be considerable scope for a determined scheme to reduce traction energy use on the mainline DC system in similar ways.

Showing true system thinking, TfL are also considering using their private power distribution system to electrify adjacent bus depots rather than wait forever for DNO grid connections. This should also be possible on the mainline. Wiring up former rail depots and stabling points to recharge trains will surely be easier using railway supplies than DNOs. Maybe the 25kV infrastructure could be used in the same way?

With the prices of PV solar panels dropping to such low levels they are being used as fencing materials the opportunity to apply them to railway land and buildings is huge. The railway has vast amounts of adjacent land with no other sensible use, and buildings with large roofs which are also users of power. There are already successful schemes (famously, Blackfriars station) but the potential is vast and untapped. On the mainline, under the present structure, it is nearly impossible for the proponents of solar schemes to make them pay but this could be changed overnight with a will. There is no technical obstacle.

My friend and IET event co-host Xenophon Christodoulou BEng(Hons) CEng DIC MSc FIRSE FIET , in a question, pointed to yet another possibility: wire up the acres of station car parks all over the country with chargers for EVs. This could predominantly be from solar during the day and topped up where required from traction power (remembering that the railway traction power supply outside peak hours has considerable spare capacity).

Buildings would have gas heating removed and replaced with heat pumps, and since rail facilities are typically large, with copious land (including under tracks), ground-source heat pumps are the appropriate technical solution, with district schemes in railway clusters. Instead of expecting this to happen by magic, a bespoke railway premises heat pump (and solar/battery storage) unit, working with local contractors, could be established. It would then proceed to a long-term rolling programme tackling all railway premises over time.

Remaining non-LED lighting on stations and elsewhere could be changed out within just a few years.

Trains need some focus. Many or most units have powerful electric bodyside heaters. At overhaul insulation could be improved with the heating facility provided by heat pumps, doubling as a/c units in the summer. Proximity (or CO2) detectors could switch off lighting and heating/cooling when units are unoccupied (and possibly lights during the day), and door control could be further improved to reduce heat/cold loss. On-train systems have proliferated in recent years (I think I heard somebody say that a single S-Stock car has 20kW of computers, that can't be right, surely?). Compressors use a lot of power - electric doors and brakes would be better. Traction motors (with local battery storage) on freight vehicles to boost acceleration and recapture braking energy would be progressed. A concerted TfL-like push on train (and station) energy consumption would surely yield considerable savings.

It's not that there aren't great initiatives on the mainline to decarbonise or reduce energy consumption - there are, and some heroes are pursuing them on their local patches (just for example the Class 93, Merseyrail and GWR battery projects, and Cardiff Valleys). But nothing on the mainline replicates the wilful, long-term, system-wide approach that TfL are taking. However, as putative mainline supremo I did have one blistering idea to put to James as a smug question, just to show that TfL haven't thought of everything: there is a fantastic barely used power station, connected to the LU electricity distribution system at Greenwich, beside the Thames for water cooling, currently housing a bunch of old gas-guzzling gas-turbine engines. It is used for emergency power to the tube. Surely an ideal location for Britain's first nuclear Small Modular Reactor?? I raised my hand expectantly, just as Xen brought the Q&A to an end, so there was nothing left but to slink off desultorily for my Guinness 0.0. I'm sticking to decarbonisation.

[1] https://carbonpricingdashboard.worldbank.org/compliance/price. Carbon pricing is complex and varies dramatically around the world. In the UK Emissions Trading Scheme the price is currently USD88/tCO2e. If governments get real about climate change this will rise steadily.

[2] Thanks to the IET for the event, and to the speakers James Goodger and Dr Zhongbei Tian from the University of Birmingham.

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