8  Truck

Adapted from Cullen, Allwood, and Borgstein (2011)

The way energy is used for transporting goods by truck is mostly similar to cars (Chapter 7).

8.1 Characterisation

The thrust force provided by the truck’s drive train is resisted by mechanical rolling resistance and aerodynamic drag. In addition, for practical driving, additional thrust is required to accelerate the truck.

8.2 Key issues that affect efficiency

  • Lower rolling resistance in the tyres leads to reduced mechanical drag. Rolling resistance is mostly due to dissipation of energy in the tyre material as it deforms, which is primarily affected by the vehicle mass.

  • The aerodynamic drag on the truck is determined by the truck velocity, its projected frontal area and the drag coefficient based on its shape.

  • Lower vehicle mass means less energy must be used to drive up gradients, and to accelerate the truck. The energy used for acceleration dominates during urban driving.

8.3 Efficiency limits

Cullen, Allwood, and Borgstein (2011) estimated the current efficiency and efficiency limits for European average trucks are:

Current 4500 kJ/km
Practical limit 2400 kJ/km

This estimate considers:

  • Some reduction in mass from 14.1 t to 12.7 t (including goods).
  • Modest reductions in rolling resistance coefficient of friction and drag coefficient, based on design values from the US.

This does not consider:

  • Reductions in frontal area (because all the volume in the truck is needed for goods).
  • Energy recovery in the braking system.
  • Turning off the engine during idling.
  • Reducing energy use by accessories (e.g. air conditioning).
  • Reducing maximum speed and acceleration.
  • Putting more goods in the same truck.

See section S.4.2 of the Supplementary Information from Cullen, Allwood, and Borgstein (2011) for more details.

8.4 Final Energy used for trucks

This table shows the quantity of final energy \(F\) used in the UK in one year, for all road transport, both cars and trucks:

      Energy [PJ/year]
Fuel Device EndUse  
Electricity Electric Motor Mechanical 13.3
Liquid fuel Diesel Engine Mechanical 977.9
Spark Ignition Engine Mechanical 572.6

You will need to use this figure to estimate how much of the energy in the table above (which is for all road transport) is relevant to trucks. The fractions for each fuel type are [ref ECUK, 2013 values]:

  • Petrol: 2% is used for trucks
  • Diesel: 49% is used for trucks
  • Electricity: a negigible amount is used for trucks