Reader Question: Any Benefit to Using Alcohol as a Fuel?

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Here’s the latest reader question, along with my reply!

John asks: Can you explain what benefit is actually gained with alcohol and lay out the economic factors that are also involved? I used alcohol for racing, back in the late sixties and seventies, because it burns cooler, and doesn’t detonate, but has half the BTU’s per gallon, so we used jets in the carbs for twice as much fuel, still running cool, but able to put more BTU’s to work. As a mechanic, I can only see alcohol as a loss of efficiency, a cost factor, well hidden, and problematic because of “denaturing it”, and the methanol destroying seals and o-rings in the fuel control systems. Semper Fidelis!

My reply: You’ve already answered much of your own question!

Alcohol contains less energy per gallon on a BTU basis than gasoline; this means it takes more alcohol to make “x” power – which translates (in street cars) as lower miles-per-gallon. It’s ironic that – given all the government baying about fuel efficiency – it mandates a fuel that is inherently fuel-inefficient.

Alcohol (ethanol) does have octane enhancing properties and is used for that purpose – and high-octane fuel is needed by high-compression engines, which engines do make more power (all else being equal).

This is one of the reasons why high-ethanol-content fuels (15) are being pushed by the car industry as well as the government. They want to build – are building – very high CR (and turbocharged/DI) engines for cars generally – not just high-performance cars -in order to achieve power/MPG gains for purposes of compliance with CAFE – the federal fuel efficiency fatwa.

So, it’s being done not for market but regulatory compliance reasons. And it costs car buyers money – in the form of more expensive vehicles, both up front and down the road when they need service.

It’s also probable that the power/efficiency gains are negated by the energy-inefficiency of the fuel itself. It would be interesting to see what the mileage-vs-mileage would be for say a 3 liter V6 with 9.5:1 compression on regular (E0, no ethanol or very little of it) unleaded vs. a 2.0 liter four with 11.5:1 running E15 (15 percent ethanol). If there is any difference in MPGs, I’d be willing to bet a steak dinner it’s negligible. Meanwhile the 2.0 four with the high CR is a harder-working/more stressed engine than the larger V6; it will likely not last as long – and require more in the way of service over time.

Ethanol/alcohol is also very corrosive to fuel system parts not designed to handle it. This is primarily an issue for older cars made before the mid-1990s, but it’s a real issue nonetheless.

It also is moisture-attractive (condensation, inside the fuel system) and that is a problem for power equipment, which is why many manufacturers of such strongly warn about using any fuel with an alcohol concentration above E10.

The bottom line is that alcohol as a fuel is like EVs as cars. Both “work” – but not as well as the things they’re trying to replace – which they are trying to replace using government force, as there’s little market demand for either thing.

Thanks for the kind words!

Got a question about cars – or anything else? Click on the “ask Eric” link and send ’em in!

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  1. Alcohol does burn CLEANER, but that’s only because it has the hydroxide (OH) molecule as part of its makeup; it has oxygen in it to promote combustion. Other than that though, it’s hard to see any benefit to alcohol based fuels.


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