Which is better for the environment – diesel or unleaded petrol?
IN the past, diesel fuel was always considered dirtier than petrol. But newer standards regulating sulphur content and improved technology in diesel engines have made diesel somewhat kinder to the environment. Many eco-advocates now tout diesel as a viable and preferable alternative to regular unleaded petrol.
Where diesel fuel really shines over petrol is improved fuel economy, thanks to its higher “energy density”: diesel contains more power per litre than petrol. Today’s diesel engines have 20% to 40% better fuel economy than their petrol counterpart, which some say more than makes up for the fact that they also produce about 15% more greenhouse gases. This greater efficiency means that diesel engines emit less carbon monoxide and carbon dioxide and fewer hydrocarbons than gasoline engines.
Diesel’s downside is that it emits larger amounts of nitrogen compounds and particulate matter (soot) that can cause respiratory problems and even cancer. The California Air Resources Board attributes 70% of that state’s cancer risk from airborne toxins to soot from diesel cars and trucks. Nationwide, studies have shown a 26% mortality increase for those living in soot-polluted areas.
But diesel’s dark side is getting a little brighter, thanks to new technologies such as Mercedes-Benz’ BlueTEC system (now used in many VW, Audi and Chrysler diesel models) that filters particulates while improving overall engine performance. The Diesel Technology Forum (DTF), a trade association of car-makers, engine builders and petroleum distributors, reports that technologies now commonplace in new diesel engines reduce the tailpipe output of particulate matter by as much as 90% and nitrogen oxides by some 50% compared to diesel engines on the road just a decade ago.
“Thanks to state-of-the-art engines, cleaner-burning fuels, effective emissions-control systems, and advancements in the fuel injection system, it would take 60 trucks sold today to equal the soot emissions of one 1988 truck,” reports DTF.
Meanwhile, continually improving fuel efficiency standards in the European Union (where the majority of new cars purchased in many member countries use diesel fuel) are forcing car-makers to design more fuel efficient, less polluting vehicles around the world. Another green benefit of diesel-powered engines is their ability to run on plant-derived biodiesel instead of petroleum-based diesel. And in the near future consumers may be able to shop for new diesel-electric hybrid cars now on the drawing boards of major automakers around the world. – EarthTalk/EThe Environmental Magazine
Cleaner now: Today’s diesel is somewhat kinder to the environment, thanks to newer standards regulating sulphur content.