Dear CARB personnel,
I recently submitted comments for the off-road diesel
regulations. The crux of my comments there were issues with
regulatory language that would exclude biodiesel blends and instead
legislate the use of R99/100. In fact my prior comments had
mentioned the benefits of biodiesel lubricity potentially being
more important for larger and more powerful marine diesel engines
than for many of the smaller off-road engines affected by the
pending off-road legislation. I had not realized at the time this
parallel track of harbor craft legislation was already underway and
much further along than for off-road diesel. I came across all this
quite by chance tonight during a random internet search looking at
biodiesel blends to potentially reduce CII scores under IMO
legislation, which is obviously an entirely different topic.
I have nothing new to add here aside from again not
understanding the rationale to exlude biodiesel blends in the
regulatory language. From my layman's viewpoint, a B20/R80 blend
would seem to offer significant reductions in both PM and NOx
emissions versus petroleum diesel. As I noted in my off-road diesel
comments, the issue of potential increased NOx emissions with BD/RD
blends with greater proportions of biodiesel is not an area where I
think you can make conclusive statements about NOx emissions
increasing with biodiesel. Amongst the research articles I have
read attempting to answer this NOx/BD question, there are simply
too many variable in experiment setup as well as the data itself to
state with any certainty that BD results in more NOx versus
petroleum or renewable diesel. While there is a growing supply of
RD coming on the market, there is still quite a bit of BD
production that seems most appropriate for heavier-duty engine use
such as in larger marine craft and locomotives, etc. I fail to see
how CARB legislating against a use of a B20/80 blend will benefit
the citizens of California. My understanding from what I have read
is that the particulate matter emissions of larger engines under
various workloads is harder to manage with DPF devices than with
smaller diesel engines. Given the importance of PM emissions from
both a human toxicity standpoint, as well as their GHG potential,
it seems logical to allow the use of at least a B20/R80 blend given
the known advantages of BD in reducing PM emissions. As stated
earlier, the lubricity of biodiesel also has the potential added
benefit of reducing engine wear-and-tear in these larger,
harder-working engines, which should also have at least a
theoretical advantage in reducing emissions simply through engines
being in better condition over time. Clearly I could be
overthinking this last point. Given the maritime and rail industry
interest in BD blends both nationally and internationally, I would
have to think that if there were major concerns with biodiesel that
these would have become apparent through commerical disinterest in
using these fuels. As I stated in my off-road comments, in the US
at least, it may be the economic forces and competition for
feedstock create market forces that reduce biodiesel production
over time in favor of renewable diesel (and sustainable aviation
fuel).
As always, thank you for providing a forum through which I can
voice my thoughts and opinions as a California citizen. For the
record, I do have a small investment in a private, potential future
renewable diesel project, but otherwise have no commercial or other
connections to any corporation or lobbying group, etc.
Sincerely,
Josh Kehoe
|