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Beginning in 2013, a team of researchers from West Virginia University (WVU), funded by the International Council on Clean Transportation (ICCT)1, began their study assessing the nitrogen oxide (NOx) emissions released from light-duty diesel vehicles, in the United States. A light-duty diesel-powered vehicle is one that has a gross weight of less than 8,500 pounds2.
After conducting a series of road tests comparing three different vehicles, two of which were Volkswagens, the study found that these vehicles release alarmingly high concentrations of nitrogen oxides that not only exceeded the limits set by the United States Environmental Protection Agency’s (EPA) Clean Air Act (CAA), but also differed greatly than the levels previously presented by Volkswagens during their emission tests.
Since this discovery, the United States has already taken action against the illegal activity conducted by a group of Volkswagen Engineers to construct this “defeat device” software that allowed for pollution controls to rise only during times in which emission tests were conducted, which has cost the company a staggering $4.3 billion fine1.
As information continues to emerge around this emissions scandal, European antitrust authorities have begun to look further into the allegations that have been made against Volkswagen, as well as the Daimler and BMW automotive companies. Until recently, more than half of the cars that were sold in Europe relied on diesel fuel, which is a stark contrast to the United States and Asian countries where diesel fuel accounts for only a small percentage of their vehicle usage.
As the fuel of choice for nearly all heavy-duty trucks and vehicles such as buses, trains, ships, boats, military vehicles and diesel engines present in equipment, diesel fuel increases the energy potential per gallon by 12%, thereby prolonging engine life for such vehicles that require heavy-duty demands3. In addition to increasing a vehicle’s fuel efficiency, diesel-powered vehicles are also associated with reduced regular maintenance and lowered carbon monoxide emissions4 however; the ability of this fuel to produce more nitrogen oxides as compared to gasoline engines is the source of the diesel scandal.
In gasoline-fueled vehicles, a majority of the greenhouse gas emissions that are released following the combustion of gasoline is carbon dioxide (CO2), however, trace amounts of methane (CH4), hydrofluorocarbon (HFC) and nitrous oxide (N2O) are emitted during this process5. While diesel-fueled vehicles are associated with producing less amounts of CO2, the recent awareness of the possible harmful effects associated with the emission of diesel fumes, particularly the high levels of nitrogen oxide found in these emissions, have prompted several European cities to consider a complete ban of these vehicles for consumer use.
When inhaled, NOx is capable of penetrating deep into the lungs and causing a series of deleterious respiratory effects including decreased lung function, aggravation of respiratory diseases such as asthma, as well as an increased susceptibility to obtaining infections within the respiratory tract6.
With the overwhelming amount of news arising around the world regarding the safety of diesel fuel, the question remains: What is the reality of a clean diesel alternative? The high amounts of sulfur present in traditional diesel fuels poses a worrisome threat to the environment and human health; however, industry leaders continue to release new and improved versions of clean diesels that contain 97% less sulfur than the previously used blends.
This type of diesel fuel, otherwise referred to as ultra-low sulfur diesel (ULSD), reduces soot emissions from diesel vehicles by 10% while simultaneously offering up to 730 miles per tank in some diesel-fueled trucks7. As the automotive industry continues to center their efforts on maintaining a sustainable environment, the development of biodiesel as an alternative to fuel combines the technologies of the traditional diesel engine with a renewable and clean-burning fuel replacement.
As the use of biodiesel, which is composed of a variety of natural animal fats and recycled cooking and soybean oil, has already been incorporated into 5-20% of diesel blends, the rapid interest in expanding this diesel component is evident.
In conclusion, despite the adulterations that have been made to a number of diesel vehicle emission detectors, diesel fuel remains a highly sustainable and energy efficient fuel that is necessary in powering some of our most important automotive needs.
References and Further Reading
- “Engineering a Deception: What Led to Volkswagen’s Diesel Scandal” – The New York Times
- “What are Light-Duty Diesel Vehicles?” – WyoTech
- “Diesel Fuel Data, Facts, and Statistics” – California Energy Commission
- “Buying Diesel: What You Should Know” – CarsDirect
- “Sources of Greenhouse Gas Emissions” – United States Environmental Protection Agency
- “Basic Information About NO2” – United States Environmental Protection Agency
- “What is Clean Diesel?” – Diesel Technology Forum
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