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Cake day: June 13th, 2023
  • grue@lemmy.worldtoNews@lemmy.world•New Jersey man pleads guilty to nationwide conspiracy to violate the Clean Air Act by remotely disabling pollution control devices on diesel trucksEnglish
    41·
    8 hours ago

    The EGR and DPF systems used in diesel trucks cause (or caused, it’s been a while since I last looked it up) a big reduction in fuel mileage. I think it was a 2 or 3 MPG reduction.Doesn’t sound like much, but it adds up when you are running 200,000+ miles a year per truck. With the system running I believe the average fuel mileage for the trucks in our company is around 6 to 8 MPG depending on the route.

    I think it’s worth noting that this is an environmental benefit, not only an economic one. In other words, it’s not that people defeating the emissions control devices are making their trucks purely worse for the environment for their own selfish benefit; it’s that they’re making a trade off between increased ‘regular’ (for lack of a better term) pollutant emissions like NOx/SOx/particulates, and decreased greenhouse gas emissions (CO2).

    I’m not saying they’re altruistic – obviously they do it to save money (at least until they get caught and fined) – but I am saying that we can’t just assume it’s bad without first doing the math and making a value judgement about what sorts of emissions we care about.

    Geeking out about an edge case where not having the fancy emissions controls is better: using biodiesel

    There are also more complicated considerations, such as how getting rid of these emissions controls and retuning the engine may also allow it to run on higher percentages of biodiesel. The trade-offs associated with that are not only the fact that the fuel becomes carbon-neutral (net CO2 emissions go to zero, at least for the percentage of the fuel that is bio- instead of dino-), but also that biodiesel naturally has zero sulfur in it (which means zero SOx) and burns cleaner (fewer particulates) and hotter (more NOx) than dino-diesel. On top of that, more NOx could be a bad thing or a good thing, depending on whether you’re driving in a NOx-limited or VOC-limited regime.

    In other words, using 100% biodiesel in an urban environment (VOC-limited) is IMO enough to actually justify preferring not to have the fancy emissions controls for legit environmentalist reasons: the better efficiency in general (as the parent comment mentioned), zero net greenhouse gas emissions, zero SOx, irrelevant NOx, and all at the cost of only moderate particulates (more than would be emitted from a vehicle with a DPF, but less than would be emitted if the same car were burning dino-diesel).

    Of course, none of those benefits occur unless you actually seek out B100 (or at least, significantly higher percentages than the B5 that normal diesel can be blended up to), and that’s a motivation much more associated with the hippie types that drive VW TDIs and old Mercs, not truckers.