As clamor grows over the emissions from diesel engines, the future of this workhorse power plant could be in real jeopardy. With international bans on coming into place in Paris, Madrid, Athens and Mexico City by 2025, and several more cities seriously considering the future of diesel vehicles, it seems that this could be the beginning of the end for these engine types.

Diesel engines are renowned for being an economical alternative to petrol engines on long steady journeys, and are the engine of choice for road haulage, but increasing concerns about exhaust emissions and the effect that they have on the environment are becoming more strident, and may finally remove these vehicles from the roads.

Breathing in diesel exhaust fumes


The main issue with diesel is the fumes from the exhaust, which differ from petrol engines in composition. Diesel engines operate in a different way to petrol engines and are controlled by fuel supply rather than the mixture of fuel and air that is the main factor on petrol engines.  Therefore, the waste products are subtly different and are characterized by being rich in nitrogen oxides rather than being a major producer of carbon monoxide that is the main concern with petrol engines. Indeed, diesels produce only one/twenty-eighth the carbon monoxide that petrol engines do, but the huge increase in NOx emissions is a distinct worry to an increasing number of governments and environmentalists.

Even in the short term, diesel fumes are dangerous, and high level exposures to diesel exhaust fumes can irritate the eyes and lungs. Continuous exposure to diesel exhaust fumes can cause long term, or even chronic, respiratory ill health with symptoms including sustained coughing and difficult to shake feeling of breathless. At the worst levels of exposure, if people are exposed to diesel engine exhaust fumes regularly and over a long period – typically several years - there is an increased risk of contracting lung cancer, emphysema, or other serious chest complaints.

Painting the town… black

But harmful gases aren’t the only issue with diesel engines and the sooty deposits that they create are not only a risk to the health of people, but contaminate buildings as well.  This has become a characteristic of many cities and the buildup of dirt and dark-colored deposits that contaminate paintwork, windows, and build up on iconic statues and monuments that grace them. These become more of a problem with diesel engines as the low level of air in the system doesn’t allow carbon deposits to form combinations of carbon/oxygen gases which may be carried away in the air, and are heavy enough to form thick layers on surfaces.

Banning diesel vehicles

Plainly there are many issues with diesel engines and it seems that an increasing number of cities will now issue bans on diesel engines introducing diesel scrappage schemes. It is estimated that in the European Union that air pollution is responsible for around 467,000 premature deaths, and while it would be difficult to attribute all of those to diesel emissions, they are a significant producer of the world’s environmental issues.  But to ban them is a huge move, since diesels power many of the taxis, delivery vehicles, and even trains that service out cities, and these too could be affected in Europe unless they comply to new stringent legislation.

With four future bans confirmed, many other cities are now in a position where they are considering the implications of such a ban. In the UK the Supreme Court has ruled that the Government must do more to protect the environment and citizens from the effects of diesel fumes. While there is no outright ban planned, it may not be too far off. Recently, Norway has announced that it will ban the sale of all fossil-fuel based cars within the next decade, and this is a move that is likely to be popular with many forward thinking countries. Going much further than the diesel bans being imposed by other countries, Norway will see the gradual demise of all petrol and diesel cars on the road as, with no new models available, older cars would gradually disappear.

Paving the way for electric cars


However, Norway is already high up the list of countries that run large numbers of electric cars, with an estimated 24% of cars being fossil-fuel free. The electric car alternative is an interesting point of view, since these cars are effectively fueled by fossil fuel using power plants, but the essential difference is that energy generation tends not to take place in areas away from centers of population so don’t contribute to the poor air quality being experienced in many cities.

Fake facts and figures

However, there is a particular issue in the UK, in which during the Labour Government control of  2001 promoted the use of diesel cars and offered concessions in the budget of that year, encouraging many motorists to buy them.  Now, with potential bans coming in, many of those who were urged to buy the cars on the basis that they were cleaner and would ultimately be cheaper for owners to run.  At the time, there was concern about the carbon monoxide that petrol engines produced and diesel car ownership was encouraged through tax concessions including lowering the price of diesel fuel at pumps by government tax reductions.

Unfortunately, the government proposals were partly based on exhaust data produced by the car manufacturers themselves and subsequently it has been shown that several factors in these tests, including fuel consumption figures and missions analysis were being manipulated by software fixes, and showed the cars in much better light that they really were. This faked data essentially drove sales in diesel cars, and helped keep polluting models on the road.

You may find some interesting true car statistics here.

Fair criticism

The diesel bans that are coming into place are likely to be the start of an eventual downturn in diesel engine vehicles, but the criticism being levelled at them, may not be completely warranted. Analysis has shown contamination by NOx comes from a series of sources, with car engines being quite low down the list. The largest source is from electricity generation, with home and commercial heating not too far behind. The third largest source is from non-road transport – such as diesel trains – leaving diesel cars at a significantly lower level.   While there are plans being considered for those sources too, the thought of outright banning them is unthinkable without a suitable alternative in place.

The future of diesel

So the intended blanket bans on diesel cars removes only one source of NOx from our cities roads and not, by any means, the largest one.  The world’s cities will continue to run diesel engine busses, and allow diesel engine delivery vehicles and heavy goods vehicles (HGV’s), provided that they are new enough to meet the EU’s Euro 6 standard.  Of course, this would also apply to cars and bans would effectively remove the oldest and most polluting from our cities roads first, but with the world taking a more environmental view, legislation is unlikely to end there. The future is likely to see allowable limits that continue to reduce until any fossil-fueled vehicle becomes illegal, firstly in cities and then become scarce in the wider world.

With our increasing knowledge of the effects of fossil fuel on the environment and our health, it was always likely that vehicles using them would face some kind of sanction, but the truth is that it is happening much sooner than many suspected.