owners of Britain's estimated 17m diesel cars now find that they have a white elephant on their hands? As the price nudges £6 a gallon.
It was sold as the great 'green' fuel. But with prices at a record high, have diesel drivers been taken for a ride?
Spiralling: The cost of diesel has shot up even faster than petrol, as the oil prices soars
industry and agriculture relies on diesel - rising costs will translate into higher prices in the shops
ELMAT: It explains why the connection between Cosan and BP...
Why is diesel becoming so expensive?
Michael Hanlon, Daily Mail
22 May 2008, 10:02am
The Daily Mail's science editor Michael Hanlon explains how diesel is greener and more efficient and why its cost is rising so fast.
Touted as the fuel of the future, it was once condemned as a noxious menace, responsible for belching clouds of carcinogenic particles into the atmosphere and into our lungs.
Now diesel is the acceptable, green face of motoring.
Diesel cars have never been so popular. At the end of the Nineties, only about one in eight cars in Britain used diesel; this year the figure is set to nudge 50%. In France, more than seven in ten cars sold are powered by it.
Modern diesel engines are generally reliable, emit relatively little CO2, and black smoke is largely a thing of the past.
As petrol prices soared, it was not surprising that motorists were eager to switch to diesel; who wouldn't when it meant a 20-30% saving in terms of miles per gallon?
But maybe not for much longer. Diesel may be green and increasingly clean, but it is no longer cheap. The price of diesel recently overtook unleaded petrol by few pence per litre - but now the differential is widening by up to 13p in some filling stations.
As the price nudges £6 a gallon, will the owners of Britain's estimated 17m diesel cars now find that they have a white elephant on their hands?
Why diesel is more efficient and greener
The story of diesel is one of an extraordinary roller-coaster ride in popularity. And looking back, it is clear that whether diesel or petrol wins the automotive beauty contest has little to do with science and engineering and a lot more to do with taxation policies and green fashions.
Diesel (the name comes from German inventor Rudolf Diesel, who built the first diesel-powered engine in 1892) and petrol are spirits derived from the refining of crude oil.
Fuel that can be used in diesel engines can also be derived from vegetable matter, such as used cooking oil, and a whole number of 'biodiesels' made from crops such as oilseed rape and palm oil. Diesel is heavier and 'oilier' than petrol and has a considerably higher 'energy density' - the amount of power that is liberated when a given volume of the fuel is burned.
In scientific terms, diesel produces about 40 megajoules of energy per litre, as opposed to about 35 for petrol. Diesel engines generate 10-20% lower CO2 emissions per mile than an equivalent petrol engine. In addition, diesel is cheaper to make and easier to store, being less prone to evaporation.
Fuel shocks made diesel the motorist's friend
Despite all this, it took several decades for diesel engines to become popular. Old diesel cars were sluggish, rattled like a bag of spanners and spewed enough fumes to suffocate a streetful of pedestrians.
Until the Seventies, diesel cars were virtually unknown in the UK, being confined almost exclusively to the taxi market. Then along came the first oil crisis, when Middle Eastern countries realised they could wield both financial and political clout by reducing supplies.
This was when several car manufacturers, notably in France and Germany, began developing cleaner, more efficient diesel motors as a consequence of rising oil prices. Sales of diesels soared on the Continent, which caused serious problems in the Eighties and Nineties as millions of still relatively unsophisticated diesel cars created smog across cities such as Paris and Lyon.
The French government promoted and subsidised the development of diesel engines, but at one point it got so bad that the Parisian authorities restricted the use of cars to alternate days depending on their numberplate. This was diesel's low point, and by the mid-Nineties the fuel was renowned as one of the worst pollutants. In Britain, the response of government was to push up tax on diesel to make it as expensive as unleaded (it had previously been taxed at a lower rate than petrol).
As a result, investment in diesel technology waned and petrol surged ahead in popularity again, helped also by falling oil prices.
Global warming and the new diesel boom
Have the wheels fallen off for diesel? As the cost of diesel spirals, is it still worth buying one?Then along came global warming. Suddenly, diesel, with its better efficiency, was back in favour. Taxes across Europe were adjusted and moves in Britain to levy lower taxes on cars with lower CO2 emissions meant a huge new surge in the popularity of diesel.
Car manufacturers have responded by developing a new generation of clean and incredibly efficient diesel engines.
BMW makes a small directinjection diesel-powered saloon that is as fast as an E-Type Jaguar yet does more than 45mpg (when I drove one it used less fuel than my borrowed Toyota Prius hybrid).
And Audi has unveiled a diesel version of its new 200 mph R8 sports car which is more economical than an old Volkswagen Beetle.
Why is the cost of diesel rising so fast?
Diesels are still a bit clattery, but the days when they were associated with smoky exhausts and plodding performance are over. So why is diesel getting so expensive?
First, there is the problem of oil-price rises generally. Oil production is static at best, and demand is soaring, especially in the emerging economic giants of India and China.
But there are pressures on diesel that are forcing its price up even faster than that of other petrol products. In Britain and the rest of Europe, spiralling demand for diesel has led to a shortage of refining capacity. Much of the new demand for fuel in China is for diesel, not petrol. And, of course, when supply falls and demand rises, the inevitable result is higher prices.
Should you still buy a diesel car?
So should you buy a diesel car? If you want a large, very powerful vehicle and do a lot of miles annually, the answer is still probably yes. With fuel economies typically around 35mpg for a big diesel, and in the high-teens for a similar petrol version, even £1 or so a gallon more at the pump still means a clear victory for diesel.
But for smaller cars, and particularly for family motorists who do average mileages, the balance is now swinging back in petrol's favour. Diesel cars are more expensive to buy and dearer to service. Some of the newest small petrol engines deliver fuel efficiency on a par with or even greater than that of diesel.
In the United States, where taxes on all fuels are low, diesel has never historically been popular for road cars.
In the end, though, what people choose to power their cars all comes down to tax. And therein lies the problem for the Government. It cannot blame the problem entirely on world oil prices, and hauliers who rely on diesel have in recent years shown how effective they can be in taking action against the Government.
Likewise, industry and agriculture relies on diesel - rising costs will translate into higher prices in the shops, which is not good news for a government already under pressure over the rate of inflation. The fact is that only a small fraction of the cost of what comes out of the pump nozzle has anything to do with oil prices, refining capacity or increased demand in China.
With more than two-thirds of the pump price being accounted for by the Chancellor, what kind of engine you choose is, in essence, down to politics rather than the science of internal combustion. |
