How Diesel Exhaust Fluid Did Away With Smog and Acid Rain

Internal combustion engines that consume gasoline normally use a spark to start each charge of fuel burning. The reaction that follows does a relatively poor job of converting gasoline into useful energy, with much of it typically being wasted.

The diesel combustion cycle is superior in this respect, as the pressure used to initiate the reaction contributes to the more thorough and even consumption of a specially formulated fuel. That helps make diesel engines more efficient, in general, with a larger proportion of the energy contained within a given amount of fuel being converted into power and work.

Addressing the Major Downside of a More Efficient Combustion Cycle

This allows diesel engines to produce less carbon dioxide than those designed to use gasoline when all else is equal. On the other hand, diesel exhaust is notorious for containing other undesirable substances, as those who have followed large vehicles emitting thick black streams of smoke will have experienced.

In practice, though, the nitrogen oxides that are the most objectionable of these byproducts of the diesel combustion cycle can be virtually eliminated without much trouble. A special substance called diesel exhaust fluid (DEF) is increasingly used to improve the emissions profiles of vehicles and keep air quality high.

Smog: A Serious Problem That Was Once Common and Uncontrolled

Even only forty years ago, many cities in the United States and worldwide suffered from a localized air quality problem dubbed smog. At certain times and under particular conditions, the air around these cities would become weighed down with a foggy, dark vapor that could even make breathing difficult.

In addition to being objectionable in its own right, smog also contributes to a harmful phenomenon called acid rain. With the pH level of precipitation dropping drastically, plants in many smog-plagued areas suffered serious damage.

Breaking Down Nitrogen Oxide in Reliable, Cost-Effective Fashion

Fortunately, such problems have since largely been done away with. Researchers recognized relatively early on that smog could mostly be blamed on the exhaust produced by many diesel engines operating in a relatively small area.

Since then, regulations and laws have increasingly mandated that commercial diesel vehicles use DEF to reduce their emissions of nitrogen oxides. As a result, smog and acid rain have largely been eliminated from the United States and many other countries.