Modern Railways – April 2019

Fitted with new diesels: refurbished 1960s electro-diesels Nos 73962

Dick Mabbutt and 73961 Alison stand top’n’tail at Derby on a test

train working to Crewe on 19 December 2017. Steve Donald

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

Informed Sources Roger Ford

There are ways of achieving

this, but it can be hard to fit the

additional technical features

into a locomotive. For example,

Wärtsilä, which makes those

massive ‘cathedral’ engines

for ships and power stations,

is in the Guinness Book of

Records as manufacturing

the most efficient diesel

engine, with a specific fuel

consumption of 165g/kWh.

And while the MTU engine

in the IC125 power cars gives

206g/kWh at rated power, at

the most efficient point on the

fuel consumption curve this

falls to 190g/kWh. This is with

Euro Stage IIIa emissions levels.

FUEL SAVING

While more efficiency could be

squeezed out of the diesel engine,

good housekeeping is likely to

be the most fruitful option. Stop/

start, where engines are shut down

rather than left idling, is already

being applied. Fuel-efficient driving

will benefit from Connected Driver

Advisory Systems (C-DAS). Traffic

Management should make it easier

to keep heavy freight trains rolling,

preserving hard won kinetic energy.

TRACTION

So much for the politics and theory.

What is the reality of the freight

locomotive fleet in the context of

the Johnson Challenge? Table 3

is taken from the report. Table 4

translates this into hardware. Fleets

with modern emissions-compliant

engines are highlighted in green.

I have not bothered with heritage

locomotives such as Class 37

and Class 57. Table 5 shows the

freight electric traction fleets.

For the nominal withdrawal

date I have assumed a

40-year book life. But as we

know, traction equipment

is noted for its longevity.

Table 4 highlights the

dependence of the freight hauliers

on the Class 66, which represents

70% of the total freight diesel fleet.

Table 5 reminds us of the limited

current use of electric traction.

In terms of emissions the Class 66

engine is probably acceptable, but

CO 2 will be relatively high compared

with modern four-stroke engines.

General Motors was paranoid about

fuel consumption and, unlike other

manufacturers, never published

specific fuel consumption figures.

The closest I ever got was a graph

in a British Rail conference paper

in 1987. This included ‘worst new

engine’ at 216g/kWh when the

best new engine (presumably

the Mirrlees) gave 198g/kWh.

Since the freight hauliers are

the most realistic operators on

the network we can rule out

re-engining or re-purposing

Class 66s as an economic

option. Good housekeeping

will see the main reductions.

FUTURE TRACTION

Since the laws of physics and

chemistry rule out pure battery

or hydrogen fuel cell 3 MegaWatt

(4,000hp) freight locomotives,

from around 2035 we are going to

need to start replacing the diesel

locomotives for freight haulage on

the routes yet to be electrified.

Here the good news is that a

modest rolling programme could

have added 2,000 routes miles to

the electrified network by 2040. And

as the Decarbonisation Task Force

notes, new electrification should

be focused on mixed traffic routes

carrying high volumes of freight.

Even if only half the Class 66 fleet

has to be replaced, that represents a

worthwhile investment in research

and development by a locomotive

builder and diesel engine supplier.

The priority would be to produce

a low CO 2 locomotive with the

performance of a 4,000hp diesel.

Why the higher power? On a

congested passenger railway you

are going to have to run faster,

longer and heavier trains. Those

Class 60s grinding up Stormy

Bank at 11mph would not get

on the timing graph today.

HYBRID

Extension of electrification will

reduce the length of the last miles

beyond the end of the wires,

making increased use of electric

traction viable. Here the challenge

will be to provide sufficient diesel

TABLE 1: EUROPEAN DIESEL LOCOMOTIVE EMISSIONS SPECIFICATIONS

ALL G/KWH

CO HC HC+NOx NOx PM

Stage IIIa 3.5 0.5* – 6.0* 0.2

Stage IIIb 3.5 – 4 – 0.025

* HC = 0.4 g/kWh and NOx = 7.4 g/kWh for engines above 2,000kW and 5 litres/cylinder capacity

TABLE 2: DIESEL ENGINE FUEL CONSUMPTION

US Tier 2 195g/kWh

US Tier 3 200g/kWh

Source: MTU

TABLE 3: DIESELS PREDOMINATE FOR FREIGHT

Freight locomotive fleet as

submitted for ETCS fitment

When built/age Number

Pre-privatisation 1957-1993 180

Post-privatisation 1998-2008 567

Third rail diesel bi-mode >50 years old 15

25kV AC diesel bi-mode <5 years old 10

Electric Pre-1996 69

Electric parcel trains 1995 15

TOTA L 856

Source: Decarbonisation Task Force

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