Can HGVs ever be weaned off their addiction to diesel? Alternatives such as recycled chip fat, natural gas, electric pantographs or even shire horses (see Commercial Motor 26 November for a trip down memory lane) still seem a long way from the mainstream.

The Committee on Climate Change’s new report, Sectoral scenarios for the Fifth Carbon Budget, sets out possible road maps to decarbonising road transport by 2050. 2050 may seem a long way off but when trucks take 10 years to develop that is only three generations of vehicle design to achieve a huge step change in motive power.

So how does the learned committee envisage this great leap forward to a more environmentally-friendly transport system?

First, they provide a snap shot of where we are today – actually where were in 2013, last year for which figures are available – and a brief history lesson. Transport greenhouse gas (GHG) emissions were 117m tonnes, or 21% of the UK’s total output. Of that 117m tonnes, cars accounted for 62m tonnes (53%), trucks 24m tonnes (20%) and vans 15m tonnes (13%). In comparison domestic and international aviation and shipping emitted 45m tonnes of GHG.

So while road freight transport is clearly a significant GHG emitter, cars, planes and ships remain by far the biggest contributors to global warming.

Emissions from cars fell 13% between 1990 and 2013, a combination of a 15% increase in mileage and a 24% decrease in “CO2 intensity” – mainly fuel consumption.

Efficiency increase

In the same period truck emissions increased by 1.5%, the result of a 1% increase in mileage and a 0.5% increase in CO2 intensity. On the face of it, bad news, but in fact the total tonne-km carried by the UK fleet grew 6%, implying that the efficiency of the fleet increased by 4.5%. This just highlights how hard it will be when the EU starts trying to incentivise the take up of greener trucks by taxing them based on their carbon emissions. How efficiently a vehicle is used has a far greater impact on its GHG emissions per tonne-km than its design.

Emissions from vans shot up 67% - but again the mileage of the fleet rose an even bigger 72%, implying a 5 percentage point improvement in efficiency.

In 2013, biofuels made of 3% of road transport fuel, thanks mainly to the Renewable Transport Fuel Obligation that requires almost 5% of DERV sold in the UK to be renewable biodiesel of one sort or another.

The Committee is of the opinion that “there is scope to significantly reduce transport emissions by 2030 and keep open the option to fully decarbonise surface transport by 2050.”

Fuel prices

However, it does not think this will happen if the government sits on its hands. Fuel prices clearly have an influence on mileage driven – mainly in cars rather than essential freight operators – and at time of writing this report fuel prices were low. So without government action the committee expects GHG emissions from all surface transport to rise from 109m tonnes in 2013 to 126m tonnes in 2030.

What does the committee believe can be done to head off this increase?

Based on a new study by Ricardo, it believes that the fuel efficiency of vans can be improved by 33% between 2010 and 2030 by “aerodynamics, hybridisation and engine downsizing”. This will result in a reduction in “real world” emissions – as oppose the theoretical emissions seen in testing – down to 160 gCO2/km by 2030, and to 117 gCO2/km by 2030.

Turning to HGVs, the committee is of the opinion that “there are significant opportunities to improve the efficiency of conventional HGVs through measures such as heat recovery, low rolling resistance tyres and weight reduction”. Somewhat optimistically, it predicts efficiency will improve by 13% between 2010 and 2030 for rigid trucks and a whopping 33% for artics. This, the report says, is equivalent to a carbon intensity of 580 to 660 gCO2/km – there is no attempt to determine a figure for carbon emissions per tonne-km.

Electric vehicles

The committee accepts that adoption of electric goods vehicles will remain limited until after 2030 due to the limited range offered by current battery technology, it foresees that “hydrogen fuel cells are likely to become a feasible zero-emissions solution for longer range and heavier vehicles”. But it concedes that problems developing a hydrogen refuelling infrastructure will hold back their adoption until at least 2030.

The committee dismisses natural gas due to its relatively low reductions in carbon emissions over diesel, wireless recharging of HGVs through coils under the road due to its £5m/km installation cost and biofuels because of their low availability.

As well as reducing the carbon intensity of road freight transport vehicles, the committee believes greater savings could be achieved by changes made by operators. A report by the Centre for Sustainable Road Freight estimates that measures such as driver training and fitting aerodynamic aids could improve efficiency of rigids by 13% and artics by 22% by 2030, with driver training yielding two thirds of these improvements.

It also found that improved logistics and shifting more freight to rail could reduce emissions by 9% for rigids and 11% for artics, also by 2030. If longer, heavier vehicles were allowed, these savings could increase to 11% for rigids and 25% for artics.