Professor Toby Peters, Professor in Cold Economy at the University of Birmingham, writes a guest blog for Global Action Plan about the subsidised refrigeration vehicles contributing to the air pollution in our cities.

I am sure today “National Clean Air Day”, many will be calling for a comprehensive diesel scrappage scheme. If so, not a moment too soon. Air pollution in Britain kills around 40,000 people per year, and in cities diesel is the biggest culprit.

The scheme would reportedly provide financial incentives to scrap the oldest vehicles in the areas where pollution is worst – meaning Britain’s cities. This also makes perfect sense; by one measure, London reached its annual pollution limit on 5 January.

Any move to reduce the number of diesels on the road should be welcomed, but a conventional scrappage scheme would do nothing to tackle the heaviest polluters; and, worse still, its purpose would be undermined by existing subsidies that perversely support continued pollution. Before we start spending taxpayer’s money to take diesel cars off the road the government should consider a minor reform that would cost nothing (in fact save more than £100M in getting rid of a tax subsidising pollution) and target the vehicles that emit the most.

Subsidising the biggest polluters

Analysis has shown that the independent transport refrigeration units – TRUs, the secondary diesel engines used to provide cooling on refrigerated trucks and trailers delivering food to our shops and restaurants – emit up to 93 times more nitrogen oxides (NOx) and 165 times more particulate matter (PM) than the emissions limits of a Euro 6 diesel car.

But worse, independent TRUs are entitled to run on half price ‘red’ diesel, meaning we not only tolerate their grossly disproportionate emissions but also subsidise them. TRUs are allowed to run on red diesel because they are classed – bizarrely – as ‘Non Road Mobile Machinery’, even though they operate on a truck or trailer.

It makes sense to tackle TRU emissions because they grossly disproportionate emitters, the number of vehicles affected would be small – 84,000 in the entire country - and market-ready zero-emission alternatives are available. We must though scrap red diesel now for TRUs not just because it is morally wrong to subside diesel, but because it also prevents new clean cold technologies from taking off. Analysis of zero emission TRU technologies show that they would have lower lifecycle costs than TRUs running on unsubsidised road diesel, but that they cannot compete with red diesel and its 50% subsidy. This loophole has to go.

Finding a solution

The last Government announced in March a call for evidence around red diesel. But rather than delay, there is no conceivable economic justification for continuing to subsidise such a mature and highly polluting technology against new zero-emission competitors. Britain is one of only a handful of countries in the EU that still permits this.

Two key measures to reduce vehicle emissions quickly are to ban all diesel TRUs from Britain’s cities by 2022, giving five years for supermarkets and the food industry to find zero-emission replacements, and with immediate effect, scrap the red diesel subsidy for TRUs everywhere. Removing red diesel subsidy would show the right direction of travel; a complete ban on diesel is obviously the real change needed.

The government has already wisely invested tens of millions of pounds to support early stage clean cold technologies. Scrapping red diesel would help make those technologies fully commercial not undermined by a perverse subsidy, creating a platform for future exports and jobs. It is also exactly the kind of technology-neutral, sector support proposed under the government’s new industrial strategy.