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Retrofit: cleaning up dirty engines

HGV trucks delivering goods

The COVID-19 lockdown has led to a decrease in air pollution in our towns and cities thanks to the reduction in traffic.

HGVs are one of the heaviest polluters on the roads. The humble bin lorry could become an unlikely symbol in the fight for cleaner air.

HGVs and bin lorries

There are around 500,000 HGVs registered in the UK, just over 1% of the country’s 38.9million road vehicles. 

Yet HGVs make up 13% of all of the UK’s road transport emissions with their diesel engines – a mighty 3% of the UK’s ENTIRE greenhouse gas emissions.

Of the half a million HGVs, approximately 13,400 are bin lorries. Around 80 of those have already been retrofitted and the UK Government estimates that around 7,500 bin lorries are ripe for retrofit

What is retrofitting?

A retrofit means altering a vehicle’s engine to reduce its emissions. Most retrofit systems fit to the existing “dirty” engine and clean it up. Adding a filter and catalyst to the engine’s exhaust reduces particulate matter (PM) and Oxides of Nitrogen (NOx), made up of Nitrogen Monoxide, or nitric oxide (NO) and Nitrogen dioxide (NO2). 

You can also re-engine a vehicle i.e. take the old engine out and put a new, cleaner engine in. 

Particulate Matter (PM) includes soot and wind-blown dust. A diesel particulate filter (DPF) is fitted to remove 98-99% of tailpipe particles.

Nitrogen Oxide (NOx) comprises nitric oxide (NO) and nitrogen dioxide (NO2). By fitting a Selective Catalytic Reduction (SCR) NOx is reduced 80-90%.Urea (ammonia solution) is injected into the exhaust and passes over the catalyst and at high temperatures (above 200deg C) the NOx is reduced to Nitrogen and water.

Changes coming

New HGVs comply with tighter Euro VI emission standards but the majority of bin lorries and other HGVs on the road are Euro V compliant, which currently allows them to emit more polluting particulates. Upcoming legislation will soon demand all HGVs comply to the stricter Euro VI standard, which will mean they need to substantially reduce tailpipe emissions of particulate matter (PM) and Oxides of Nitrogen (NOx).

Euro VI-compliant vehicles can circulate freely in ultra-low emission areas, or Clear Air Zones (CAZ), such as inner London. There are hefty fines for any non-compliant vehicles entering the zone.

Substantially more clean air zones are on the way. Birmingham and Leeds are rolling out a chargeable clean air zone, with Derby, Nottingham, and Southampton aiming to become clean air zone compliant. Manchester is working on a solution to cover all its boroughs, too. There will then be a second wave of 32 more clean air zone areas in the UK.

This legislation will radically alter the vehicles on our roads right across the UK – we can’t simply move non-compliant HGVs to other areas of the country. Bin lorries will be particularly affected.

Why retrofit?

Bin lorry collecting refuse

Colin Smith is the Programme Manager for Freight and Clean Vehicle Retrofit at Energy Saving Trust.

He said: “HGVs and bin lorries are a big investment.

It costs about £15,000-25,000 to retrofit an HGV, and around £150-200,000 to convert it to electric. A brand new electric HGV can cost £350-400k.”

The UK is in a transition phase, moving towards cleaner, lower carbon transport, but given the costs involved, it’s not practical to expect councils or other HGV operators to immediately scrap their existing fleet. As Colin explained:

“This is about cleaning up what is already out there and you either need to replace or retrofit. If you retrofit a Euro V, relatively young vehicle then there is a better chance of the system giving a payback over more miles. That’s why retrofit is a good option and can lengthen the clean air zone compliant life of the vehicle.”

The technology around electric HGVs is progressing but it has some way to go. Currently electric HGVs are expensive to buy as well as needing very large batteries, potentially reducing their payload. They also have limited driving ranges although this could well change in the near future.

Finland trip

Before the current lockdown, Colin travelled to Finland to oversee tests carried out on a retrofitted bin lorry at the VTT Technical Research Centre of Finland vehicle test facility.

Energy Saving Trust monitors retrofits and assures the testing process on behalf of the Department of the Environment, Fisheries and Rural Affairs (DEFRA), to ensure vehicles and suppliers are complying with set criteria.

The results and market potential for the retrofit technology were encouraging.

Colin explained: “Bin lorries are a great test case because they operate to a great extent in urban areas that suffer poor air quality and in ultra-low emission zones such as in London. With bin lorries, there is a unique driving pattern with a lot of stopping and starting in urban areas, slightly longer runs with fewer stops in more rural areas and then a final, longer run when the lorries return to base or the waste transfer station.

They tested a refuse collection vehicle to this representative cycle on a ‘rolling road’ in laboratory conditions, including how a Volvo-powered bin lorry engine performed on the Clean Vehicle Retrofit Accreditation Scheme (CVRAS) HGV representative drive cycle.”

Future possibilities

Part of the requirements of the Clean Vehicle Retrofit Accreditation Scheme (CVRAS) is the ability to conduct in-service monitoring. This means taking the engine out and checking tailpipe NOx sensor data to make sure systems are performing properly. All this can be viewed in real-time and remotely over the cloud, showing if the engine is filtering properly.

Colin added: “People need to look at their fleets now.

Retrofitting is a great option for vehicles with long term life potential. They need to change soon. Retrofitting can extend the compliant life of vehicles.”

Other ideas include putting HGVs onto truck trains for long-distances or mountainous areas, something that’s already used in the Italian Alps. This reduces the amount of road travel and reduces emissions.

Bin lorries are highly visible on our streets and could help provide a clearer answer to the question facing all HGV operators:

  • Replace with cleaner Euro VI diesel vehicle;
  • Retrofit current vehicle to bring it to Euro VI equivalence; or
  • Electrification?

Whichever option freight operators choose – there’s no getting away from the need to clean up the UK's dirty vehicles.

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Tom Shearman's picture
Tom Shearman brings 25 years' of journalism experience to the Energy Saving Trust blogging team. He loves writing about renewables and energy efficiency, plus how policy can change people and the environment. His articles have been published internationally, he has co-written trekking guide books, responsible travel articles and short stories.