Peter Jones: Petrolheads can save the planet

London recently suffered a nasty smog, due in part to the huge increase in diesel engines. Picture: Getty Images

I CONFESS. I have got something badly wrong. I bought diesel cars thinking that they were better for the environment than cars fuelled by petrol. Wrong. It turns out that diesel engines are far less green and may be doing more damage than everybody thought. But this is also a perfect example of where politics can stymie any prospect of sensible and increasingly urgently needed action.

I am comforted by the fact that lots of others have made the same mistake. A few days ago, I heard a 5 Live news presenter confessing that he had acquired a diesel car under the impression that it was, relative to a petrol engine, green.

Why did we think that? Generally, it is because vehicle engines, cc for cc, consume about 10 per cent less fuel than a petrol engine and, therefore, put less carbon dioxide into the atmosphere. Since burning fewer hydrocarbons would help slow global warming, then switching from petrol to diesel seems like a good thing to do.

I did know that diesel exhaust contains particulates – tiny bits of soot, metals, sulfates, silicates, and all sorts of other stuff, some carcinogenic – which are so small that they can be easily breathed in. I was under the impression that filters collecting these particulates, and catalytic converters, had largely solved the problem, but apparently not.

Filters and converters do cut particulate emission by about 80 per cent, which some might consider not enough. It also seems that filters can clog, especially in stop-start town driving. Since replacing these can cost a four-figure sum, quite a lot of drivers sneakily simply have them taken out, a practice that from this month will lead to a vehicle failing its MoT test.

Another problem is nitrogen dioxide in the exhaust, which is injurious to health. Apparently, it was assumed some time ago that advances in technology and engine design would deal with the problem. Not only has that not happened, the process has also gone into reverse, with nitrogen dioxide emissions having increased.

All this means, according to recent medical research, that the pollution from diesel exhausts causes much greater health problems than has been supposed. The effects on children may be particularly profound, stunting their intelligence.

This is why lead in petrol was banned, so something must be done. But what? The proportion of vehicles with diesel engines has gradually risen. Nearly all vans, taxis, lorries and buses have diesel engines, and a third of private cars are diesel-powered.

They became more popular, not because of virtuous belief that they are greener, but because of fuel costs. Since, by and large, more miles can be travelled per £1 of diesel than per £1 of petrol, it made economic sense to have a diesel vehicle, especially for those who do a lot of miles.

But now it is clear that all these diesel vehicles are causing serious atmospheric harm. This became particularly obvious in southern Britain recently when the usual pollution in the air, some of it but by no means all stemming from diesel fumes, combined with Saharan dust to create a nasty smog.

In France, where diesel is cheaper than petrol and so diesel vehicles are much more prevalent, air conditions in traffic-choked Paris have become so endemically poor that the authorities have resorted to periodic rationing of private car access to the city, with bans on cars with odd, or even-numbered, registration plates on certain days.

Back in Britain, the scientists who have been advising the UK government on the diesel pollution issues have concluded that expecting technology and vehicle manufacturers to solve the problem is not going to work.

Neither does setting a rigorous emissions-testing regime, with cost penalties imposed through vehicle licensing, appear to work. This, according to the government’s air quality expert group, has been a “complete failure”. Many vehicles pass under the test conditions, but under normal road conditions their emissions can be four to five times worse than when tested.

Reducing private car usage is the perfect solution, but it is not going to happen to any significant extent. Encouraging people to switch from diesel to petrol is another option.

This would also help solve another problem. Because use of petrol has fallen by about 10 per cent in the past 15 years, Britain’s refineries have excess petrol-producing capacity despite refinery closures. They are also unable to produce enough diesel, demand for which has risen. Imports make up the balance.

Refineries are currently on the edge of unprofitability, and face a big increase in costs caused by legislation aimed at cutting their environmental impact and increasing their safety. A switch to petrol use would help ease their problems. As we know from recent problems at Grangemouth, this is a serious matter, with many thousands of jobs at stake.

So it seems pretty obvious that there are a lot of economic, environmental and public health reasons to take action.

Unfortunately, it is also obvious that the simplest and most effective policy response is to make diesel more expensive compared to petrol. But this is where sensible policy runs into political problems. Diesel is already about 5p/litre (about 3.5 per cent at current prices) more expensive than petrol, a differential which is due to refining costs and not to any tax difference. In terms of miles covered per litre of fuel, to wipe out the motoring cost advantage, another 10p/litre would have to be added. Or you could subtract the same amount from petrol.

The political problems are, however, huge. Raise the price of diesel and there will be huge protests from taxi drivers, haulage firms, bus companies, van drivers. This is not a lobby that any government wants to take on.

Reduce the price of petrol, and there will be a great outcry from those concerned about environmental issues. In political terms, it would probably be out-balanced by the gratitude of private motorists.

But in fiscal terms, the loss of tax revenues would be too much for any government to bear in these straitened times.

If we are serious about improving the environment and public health, especially the health of children, and serious about safeguarding the thousands of jobs at installation such as Grangemouth, then something should be done. But it doesn’t look like we can rely on any government to do it.

It will be down to people like you and me, if we have diesel cars, becoming petrolheads.