Wi | dvswia - 8/12/2014 07:27
yeah, I am so wrong. I figured I would be told that.
the physical properties of these fuels will n o t change, and your mit guys will tell you the same thing if you nail them down on it.
They won't but what matters is how much of that energy can be used and at what cost. I don't like the current corn ethanol e85 concept any more than you do, but that doesn't mean it's all bad.
The energy content of the fuel as expressed in btu/gasoline gallon equivalent is only one part of the equation. We aren't burning these fuels for heating homes, they are being used to cause an explosion inside a cylinder, this creates inefficiencies.
Methanol is similar to ethanol and used in many racing engines because you can create more power due to the characteristics of the fuel, providing you set that engine up to run that fuel. Look at tractor pulling. Guys went away from diesel because it was too hard on parts and easier to make more power with alcohol motors. The actual BTUs per gallon of methanol are less than half that of gasoline. Then there's nitromethane which many have seen in top fuel drag racers. The btus per gasoline gallon equivalent are even lower yet. But somehow they can get 8000hp out of a 500 cubic inch engine. Hopefully this illustrates that the BTU per GGE is not everything.
Part of the equation iis the oxygen content of these fuels. Ethanol and methanol are both alcohols which contain oxygen. Gasoline is a hydrocarbon and therefore contains no oxygen. Big whoop right? Depends what you want to do. You need oxygen for any of these fuels to combust, there's only so much oxygen that can fit inside a given space (aka cylinder). You can increase the density in multiple ways, but there are still limits. A fuel with its own oxygen can aid in more complete combustion and obviously more power with less air. This is partially why alcohol fuels have such low emissions. Additional oxygen is why nitrous is used as well. Some think it just magically adds power, it doesn't, it allows more fuel to be burned.
These engines can run very rich as well, since they provide their own oxygen. As many know stoich for gasoline is 14.7:1. Diesel is nearly the same also. Stoich for ethanol is 9:1. Stoich for methanol is 6.5:1. Stoich for nitromethane is only 1.7:1. Of course engines run outside of these numbers often. Top fuel motors will run as low as 0.5:1.
There's a lot of things that go into efficiency and comparing fuels. You can't make a direct comparison with only one factor.
One other simple thing to understand as well is that miles per gallon is largely irrelevant too. The goal is your cost per mile. If you burn 40% more of fuel "a" to save 50% over the cost of fuel "b" then you've reduced your costs. There are other things to consider as well though.
Everything about is talking about E100. Many people associate ethanol with e85 which leads to confusion.
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Breaking OPEC ; Ethanol Optimized Engine Project
