Modern Railways – April 2019

Last mile loco: No 88001 heads a Doncaster Decoy to Millerhill

train of rails at Thirsk on 24 May 2018. David Andrews

Informed Sources Roger Ford

24 Modern Railways April 2019 http://www.modern-railways.com

TECHNOLOGY

This report’s conclusions highlight

the problem facing the railway

industry in various of its current

dealings with a Government

ruled by policy-based evidence.

I can’t better the observation of a

perceptive chum who explained

that ‘if you press too hard for

reality of thinking, you lose the

argument politically just n o w ’.

Personally, I have always believed

that there is no point in being

obliging with Government because

it can’t and won’t reciprocate.

That said, since the industry made

electrification unaffordable without

outside assistance, it has been

hard to counter the Government’s

enthusiasm for bi-modes, batteries

and hydrogen. Hopefully the

McNaughton (p24, last month)

and Railway Industry Association

reports will have turned the tide.

But when it comes to the need

to decarbonise freight traction in

response to the Johnson Doctrine

(see box), I would have liked to have

seen a more robust defence of the

industry. Emissions statistics make

variable track access charges look

simple. However, I calculate that

while rail freight is responsible for

roughly 10% of the UK’s total freight

tonne kilometres (rail and heavy

goods vehicles) it generates 3% of

the total CO 2 emissions generated.

Put another way, for each tonne of

CO 2 produced, HGV traffic generated

8,000 tonne kilometres, compared

with 28,500 for rail. But that’s the

steel wheel on steel rail for you.

To its credit, the report does

remind Government that ‘there is

currently no low or zero carbon

alternative to diesel for road haulage,

other than for local delivery vans’.

It adds: ‘this presents rail with a

unique opportunity to offer low

carbon freight transportation if

greater use can be made of existing

and future electrification. It follows

that priority ought to be given to

future electrification schemes for

those mixed traffic lines that carry

a significant volume of freight’.

ALTERNATIVES

JoJo’s challenge is characteristically

vague. Note that it refers only to

petrol and diesel cars, not HGVs.

And ‘diesel-only trains’ provides

fertile ground for unintended

consequences. Far better to

have set targets, sorry ‘ambitious

targets’, for CO 2 reduction and

left the rail freight industry to

work out how to achieve them.

Meanwhile, it is time to examine

the final two paragraphs in the

challenge: the technical vision

of bi-modes leading into battery

storage and ultimately hydrogen

fuel cell power. Despite reiterating

that there is no alternative

independent power source

available for diesel-only freight

and maintenance (yellow) trains,

the Decarbonisation Task Force

report still buys into the credo that

bi-mode and battery technology,

‘while a challenge, could deliver

significant improvements’.

As C. M. Joad would have said, ‘it

all depends on what you mean by

“significant”’. Let’s start with batteries.

HARD

Time for some hard numbers.

Lithium ion batteries currently have a

maximum energy density at cell-level

of 250Wh/kg. In practice, to maintain

service life these batteries must not

be fully charged or discharged.

Various ranges are quoted. The

most optimistic limits I have seen

are between 10% and 90% charge,

with 20%-80% also given. The

Decarbonisation Task Force report

is the most pessimistic at 30%-70%.

Then you have to put the battery

cells in a housing that includes the

supporting auxiliary equipment.

This raft also has to absorb heavy

shunt shock loads, which adds

further weight. This is known as

‘pack-level’ energy density.

In one current aviation

application, the pack-level energy

density of Li Ion batteries is

quoted at 143Wh/kg. However,

my analysis of the battery packs

in the three UK battery hybrids

(‘Informed Sources’, May 2018)

showed a real life pack-level

energy density of 50Wh/kg.

But let’s stick with 250Wh/kg

because it is almost exactly one-third

of a horsepower hour (hph).

Sorry, electrical engineers.

STORMY

Back in 1991, I footplated British

Rail’s ultimate heavy-haul

locomotive, the Brush Class 60,

taking on the ultimate heavy

THE JOHNSON CHALLENGE

‘I would like to see us take all

diesel-only trains off the track

by 2040. If that seems like an

ambitious goal – it should be and I

make no apology for that. After all,

we’re committed to ending sales of

petrol and diesel cars by 2040. If we

can achieve that, then why can’t the

railway aspire to a similar objective?

‘Rail may be less carbon intensive

than road transport. That’s why

modal shift’s so important. Getting

freight and passenger vehicles off

the roads onto greener forms of

transport. But that does not absolve

the rail industry from cleaning up

its own act.

‘New bi-mode trains are a great

bridging technology to other low

emission futures. And as battery

technologies improve we expect to

see the diesel engines in bi-modes

replaced altogether. With batteries

powering the train between the

electrified sections of the network.

‘Or maybe in the future we could

see those batteries and diesel

engines replaced with hydrogen

units? Alternative-fuel trains

powered entirely by hydrogen are a

prize on the horizon.’

Jo Johnson, Transport Minister,

12 February 2018

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