The Ethanol Papers - Paperturn manuscript - Flipbook - Page 206
Follow up from TS:
Thanks, but you're still wrong. Yes, engines need to be designed for a specific
fuel in order to run well for it, but a diesel optimized engine will still get more
MPG on diesel than a gasoline optimized engine on gasoline than an ethanol
optimized engine on ethanol and the reason is simply that when using the
proper fuel their relative efficiencies compared to the energy contained in the
fuels are very similar so the energy density of the fuel dominates.
Reply from MARC:
Hi again, TS - Thank you for your recent reply.
I'm not incorrect, and I think you are confusing things a bit.
If you can match a diesel-powered engine to a comparable gasoline or ethanolpowered engine, and the diesel engine gets more MPGs it's because a diesel
engine is a more efficient ICE. This has been known for more than 125 years.
The reason why diesel engines didn't become the primary engines used in automobiles was that they cost more to manufacture and they were much heavier.
On the other hand, gasoline and ethanol-powered engines were never selected
for use as train engines or heavy trucks is because they didn't have the power
of a diesel, and the weight and cost of manufacture was much less relevant. In
modern times, the cost and weight of diesel engines have been mitigated by
new materials and manufacturing techniques/volume; and it's why there are so
many proponents of diesel-powered passenger vehicles. Unfortunately, other
oil industry issues have kept diesel fuel from being readily available, and available at the lower price that it should be. When I was young diesel fuel always
cost less than gasoline, and very recently diesel has been selling in many areas
for less than gasoline, but for 20 years (give or take) diesel was more expensive
However, keep in mind that diesel fuel doesn't need to be produced from petroleum oil. Rudolf Diesel (inventor of the diesel engine) used peanut oil to make
the fuel, and renewable diesel or bio-diesel (made cheaper from ethanol) will
deliver exactly the same mileage in a diesel-powered engine as petroleum diesel fuel.
The reason for my bringing diesel into the discussion that you and I are having
is to show that BTUs (so-called 'energy content') are not relative in the argument