Volkswagen Is Still Trying To Get Diesel Engines To Burn Cleaner (UPDATED)

The company claims an up to 95 percent reduction in CO2 emissions from paraffinic diesel.

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Photo: VWTDIfan / Wikimedia Commons (Other)

Volkswagen has announced that its latest line of four-cylinder diesel engines are approved to use paraffinic diesel fuel. The automaker says using the fuel can reduce CO2 emissions by up to 95 percent. NOx emissions, on the other hand, may stay the same.

I’m sure when most people think “diesel” and “Volkswagen” the images and headlines of Dieselgate immediately come to mind. The infamous scandal led to a sharp decline in popularity for diesel cars. As the BBC notes, where diesel engines were in about half of the new cars sold in the UK in 2015, now they’re in just 7 percent. It was also a catalyst for a greater push towards electrification.

But Volkswagen isn’t done with diesel just yet.

The company has a plan to reduce its carbon footprint in Europe by 40 percent by 2030. While the focus is on electrification, Volkswagen is also trying to clean up its internal combustion engines, too. For diesel, this means getting the engines to run a cleaner fuel.

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Volkswagen says that all cars with four-cylinder TDI engines delivered since the end of June this year can run paraffinic diesel, which the company explains is:

There are fuels that are produced from biological residual and waste materials such as HVO (hydrotreated vegetable oil), for example. These vegetable oils are converted into hydrocarbons by a reaction with hydrogen and can be added to the diesel fuel in any quantities. They can also be used 100 percent as fuels, however.

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Volkswagen says that running these fuels can cut down diesel CO2 
emissions by 70 to 95 percent.

Missing from Volkswagen’s release is anything about nitrogen-oxide emissions (NOx), which were a huge Dieselgate sticking point. NOx emissions are deadly, and impacted cars were found to be emitting more than 30 times the allowable limit of it. Paraffinic diesel is marketed as lowering NOx emissions, but some may wonder just by how much?

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A couple of recent studies, one for the UK government and another by multiple universities, have found that paraffinic diesel doesn’t make significant reductions in the NOx emissions of unmodified engines.

Image for article titled Volkswagen Is Still Trying To Get Diesel Engines To Burn Cleaner (UPDATED)
Photo: UK Department for Transport
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However, the university researchers found that NOx emissions can be reduced by 20 percent with retarded injection timing.

Still, for those still holding onto diesel engines this is good news, provided the claims actually stack up. Sadly, diesel fans in America like myself are left out as Volkswagen is no longer selling new TDIs here.

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Update: Thanks to a kind reader we actually have some more insight. Testing of paraffinic diesel in other engine shows a reduction of CO2 emissions, but nothing like what VW is claiming. This is from the above study:

Image for article titled Volkswagen Is Still Trying To Get Diesel Engines To Burn Cleaner (UPDATED)
Photo: UK Department for Transport
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That is nowhere near 95 percent. So Volkswagen is likely counting in other factors like the pollution generated in creating paraffinic diesel compared to regular diesel.

I’ve reached out to Volkswagen for clarification.