Freightliner Inspiration Truck self-driving truck conceptEnlarge Photo
When a major lobbying group issues a statement replying to an academic study the same day that study first hits the media, you know it's major.
On Monday, the Diesel Technology Forum responded to an article in Nature with a statement that supported "improved real-world testing" of diesel emissions.
Those more stringent tests, the group's executive director Allen Schaeffer said, would "play a major role in helping to reduce nitrogen oxide (NOx) emissions."
The group also, naturally, recommends adoption of newer diesel technology with improved exhaust-cleaning and aftertreatment systems.
The study it responded to, Impacts and mitigation of excess diesel-related NOx emissions in 11 major vehicle markets, is a lengthy analysis that summarized the nitrogen oxide emissions of diesel vehicles from roughly 80 percent of the world's diesel vehicles in 11 markets.
The product of years of work, and with no fewer than 11 authors listed, it concludes that more than half of light-duty diesel vehicles on the world's roads today emit more NOx than the legal limits.
Emissions Analytics EQUA Air Quality Index showing diesel testing results, April 2017Enlarge Photo
The same applies to roughly one-third of heavy commercial vehicles, which have often been certified under far more lenient standards despite the far higher annual mileage each one covers compared to a passenger vehicle.
The summary that opens the Nature article contains the following points:
On-road diesel vehicles produce approximately 20 percent of global anthropogenic emissions of nitrogen oxides (NOx).
Regulated NOx emission limits in leading markets have been progressively tightened, but current diesel vehicles emit far more NOx under real-world operating conditions than during laboratory certification testing
Across 11 markets ... nearly one-third of on-road heavy-duty diesel vehicle emissions and over half of on-road light-duty diesel vehicle emissions are in excess of certification limits.
Volkswagen TDI diesel vehicles owned by Phil Grate and family, Seattle, WashingtonEnlarge Photo
These excess emissions (totaling 4.6 million tons) are associated with about 38,000 ... premature deaths globally in 2015, including about 10 percent of all ozone-related premature deaths in the 28 European Union member states.
Heavy-duty vehicles are the dominant contributor to excess diesel NOx emissions and associated health impacts in almost all regions.
Adopting and enforcing next-generation standards (more stringent than Euro 6/VI) could nearly eliminate real-world diesel-related NOx emissions in these markets, avoiding approximately 174,000 global premature deaths in 2040.
Nitrogen oxides, the study notes, are key precursors to the formation of both ozone and specific types of particulate matter (known as PM2.5).
The final set of Euro 6 standards are roughly equivalent to those in effect in the U.S. for passenger vehicles since January 2008, known as "Tier 2 Bin 5."
Significantly, the study concludes that all but eliminating real-world NOx emissions from diesels, hence averting 174,000 premature deaths, "can be achieved by implementing Euro VI standards" for all vehicles not yet covered by them.
Selective Catalytic Reduction (SCR) process for diesel exhaust aftertreatment [Diesel Tech Forum]Enlarge Photo
Those are now predominantly heavy-duty trucks.
In other words, bring new heavy-duty trucks to the same emission standards as cars must now meet in Europe and North America, and replace older trucks with newer ones, and by 2040, NOx emissions from diesel engines will largely have been eliminated as a public-health menace.
That was, arguably, the point of many earlier limits on diesel emissions.
Which two-thirds of diesel passenger vehicles didn't actually meet when used in the real world.
EDITOR'S NOTE: An earlier version of this story said the Diesel Technology Forum replied to the study described before it hit the media. In fact, the lobbying group issued its statement more than five hours after the study was released—and after it had been covered by The New York Times. The story has been updated; we apologize for the error.