Facts Sheet 5. Fuel and emissions: Trains compared with replacement express coaches and lorries November 2013

This paper expresses the fuel consumption of the UK’s passenger rail and rail freight in miles per equivalent UK gallon of diesel and in km per litre along with carbon emissions in gms of CO2 per passenger-km and per tonne-km.

Also provided are the percentage savings in fuel and emissions if the rail function were carried out by replacement express coaches and lorries operating on the railway alignments.

In summary we find that, subject to carbon capture etc., the rubber tyred option would reduce overall energy consumption and emissions by significant amounts given the UK generating industries characteristics.

Caveat

The abstract of a paper by Mikhail V Chester and Arpad Horvath illustrates how vital it is to have dust to dust estimates of energy consumptions and emissions.  There we see the estimates of life cycle energy inputs and emissions in the USA add 63% to the tailpipe values for road vehicles, 31% for air and 155% for rail.

Instead of that, nearly all UK emission studies (including this one) deal with tail pipe emissions alone.  Consequently the conclusions drawn from those studies may be far from the truth. 

However, our conclusion would be greatly strengthened if dust to dust calculations, using the Chester and Horvath parameters, were included.

Further if large scale electrification extends the life of coal fired power stations then, subject to carbon capture, the emission from electrical generation allocated to rail should increased to circa 1050gms per KWh , more than double the present industry average.  That would greatly increase the savings in emissions from replacement coaches and lorries.

The sources and assumptions

The source for passenger-km, tonne-km fuel usage and emissions is the Office of the Rail Regulator’s data set.

Source for the efficiency of power stations, used to estimate the primary burn is the Digest of UK Energy Statistics.

10% of the energy content of the crude delivered to refineries is deemed lost in the refineries and in transporting diesel to filling stations and to the fuel tanks.

That express coaches on railway alignments would return 12 miles per gallon, or 10.8 after allowing for refinery losses, and would carry an average of 25 passengers.

Lorries picking up from or delivering to rail freight terminals would carry 24 tonnes, return 8 miles per gallon, or 7.2 after allowing for refinery losses.  The drag in and out at each end of the rail journey would be 10 miles, and the lorries would find no return loads.

lorries replacing trains would carry an average of 12 tonnes (24 tonnes out, back empty) and return 10 miles per gallon, or 9 after refiner losses.

Two sets of results are available, namely (A) ignoring the drag in and out by lorry from rail freight terminals, and (B) including the latter but assuming it is avoided if the line haul is by lorry.

Summary results

The following tables summarise:

Comment: Passenger rail fuel consumptions have improved considerably, but the coach performs far better than does rail.  The reverse is the case if lorries replace rail freight on the line haul.

The ratios in table 2 show that if the national rail function were discharged by express coaches and lorries there would be a reduction in energy consumption in the range 30% to 34% and a reduction in carbon emissions in the range 7% to 15 %.

Calculations and detail

These are in the attached spread sheet where sensitivity tests can be carried out and where data is available for the assumption that the CO2 emissions from the generating industry should be doubled to represent the marginal effect of keeping the coal fired stations operating so as to sustain rail.  According to Network Rail, rail is the biggest single user of electricity in the UK.