Can We Electrify Road-Haulage?

Having confirmed that the answer to the question Can We Electrify Shipping? is a big "no", I decided to check the feasibility of electrifying long-distance trucking.

Suppose we want to truck some fruit and vegetables from Spain to the UK, a journey of about 2,000km.

https://mwtruckparts.co.uk/what-fuel-economy-mpg-does-a-lorry-get reports Department for Transport findings that for "an artic weighing over 33t ... in 2015 ... fuel consumption figure jumped to 7.9mpg" and "a modern lorry consumes 29.774 litres of fuel per 100km".

So, our 2,000km journey requires 600 litres of diesel.

https://www.volvotrucks.com/content/dam/volvo/volvo-trucks/masters/euro-6/pdf/trucks/volvo-fm/specifications/Volvo%20FM-Specifications-UK.pdf specifies Volvo's HGVs as having "aluminium or steel tanks in volumes from 150 to 900 litres. Maximum fuel volume is 1,480 litres for a 4x2 tractor". Good: this is consistent with the fuel requirement above.

The energy density of diesel is 45MJ/kg - https://energyeducation.ca/encyclopedia/Energy_density.

Diesel density is 900 kg/m³ - https://www2.mst.dk/udgiv/Publications/1998/87-7909-173-3/html/kap04_eng.htm.

So 600 litres of diesel has mass 540kg and contains 25GJ of chemical energy.

https://en.wikipedia.org/wiki/Fuel_efficiency says "Passenger car diesel engines have energy efficiency of up to 41%". Let's assume a large diesel engine has fuel efficiency of 45%.

That means the fuel load above can produce total kinetic energy of 11GJ.

https://cleantechnica.com/2018/03/10/electric-car-myth-buster-efficiency/ says "An electric motor typically is between 85% and 90% efficient". Let's assume a large electric engine has fuel efficiency of 90%.

So we'll need to store 12GJ of energy in batteries to generate the same kinetic energy as the diesel.

https://en.wikipedia.org/wiki/Tesla_Model_3 says that Tesla's lithium-ion batteries store 150Wh/kg. That's 0.54 MJ/kg.

So for 12GJ of battery energy, we need 22t of batteries.

Oh dear: 22t of batteries aren't feasible for a lorry carrying 20t of cargo.

What Distance Is Feasible?

Turning this result around, and supposing we install 2,000kg of batteries in a 38t truck, our truck would have a range of 200km at the cost of losing 10% of the cargo capacity. We might consider installing 4,000kg of batteries for a range of 400km and a reduction in cargo capacity of 20%.

Suppose we let the ferry take most of the strain: a 400km range would probably get our truck from the ferry to the distribution hub, but the 200km range might not.

It's likely that increases in range will be possible by design improvements to reduce air friction; by the use of regenerative braking; by improvements in battery technology. Those improvements will be incremental rather than game-changing.

Conclusion

Road-haulage could probably be electrified to fulfil medium-length journeys eg within the UK.

For longer, trans-continental journeys, the freight could travel most of the way by ferry or electric train. Or the journey by lorry could be split into multiple stages with the tractor or batteries switched at each staging point.



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