It doesn’t surprise that the best feedstock for ethanol production is the wheat, along with other grains, like corn and buckwheat. Raisins and prunes work great as they’re dried, and thus contain a lot of sugar per unit mass.

But I was surprised to learn that you can make more ethanol from onions or garlic, than from potatoes. If you have access to significant amounts of garlic or onion waste, you can produce a lot of alcohol fuel from it!

This table was taken from the book “Alcohol can be a gas!” by David Blume, the best alcohol fuel encyclopedia ever!I suggest getting one, though I don’t think that ethanol produced on a large scale can be considered a petroleum alternative.

Therefore, although it is safe to invest money in established alternate energy solutions, especially solar panels, because the government is spending billions to foster their development, one should be careful before spending money and thought on miraculous alternate energy solutions like ethanol. A common notion that has been slowly gaining ground is that biofuels like ethanol can offer a long term solution to America’s fuel crisis and provide substantial returns to investors. This notion, although technically true, yet has several real life obstacles facing it before it turns into a successful alternative to gasoline.

These pumps provide both E85 and E30 ethanol fuels. Photo: ethanolpics.

First, and most important of all, the ethanol produced from corn actually costs more to produce than gasoline. Although, the federal government is presently providing tax cuts to encourage ethanol production and supply, yet there is no guarantee that the tax cuts will be continued in the future. The upswing in the use of ethanol as fuel to be produced from corn has already generated significant impact on the corn farmlands, thereby pushing up the cost of cattle feed and also the price of other animal products.

Although the ethanol manufacturers are making huge profits and ethanol investment is hot on wall street, yet the truth is that ethanol is an extremely costly fuel and even with the tax cuts it actually costs more to produce one gallon of ethanol than one gallon of gasoline. Moreover, transportation and storage of ethanol is also a significant issue. It can not be transported by pipelines as it binds with water. Because of that, storage is also a problem.

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Last, but not least — in most cases, EROEI of ethanol production is very close to unity. It means that if you invest some energy in production of ethanol, you will get only about as much energy in ethanol, as you invested.

Today, ethyl alcohol (ethanol) is not used widely as engine fuel, mostly because of relatively low crude oil prices and low prices of any petroleum-derived fuels. Manufacture of one litre of spirit requires using 8,400 – 11,200 kJ (kilojoules) of energy. Heating value of pure ethanol is only 2/3 of heating value of gasoline, per unit volume.

Anhydrous ethanol (ethanol that contains less than 1% of water) can be easily mixed with gasoline, in any ratio. The mixture of 85% (volumetric) ethanol and 15% gasoline is called E85 and is quite popular ethanol fuel. But most cars run without trouble only on E10 – fuel with only 10% added ethanol.

Why is that? Ethanol has less energy content per unit volume. To release the same amount of energy, you need to use more ethanol than gasoline. Because of that, the engine needs to be altered to give more fuel (carburetor or injection system needs to be tuned). Ethanol contains some oxyden, bound within ethanol particle, so for burning this fuel less air is required than for gasoline. Sometimes it is also needed to alter ignition timing.

Ethanol has also couple of advantages, when compared to gasoline. It has very high knock resistance (measured as Octane Number), so can be used in engines with greater compression than used for gasoline.

Ethanol can be used in diesel engines as well! It is only required that injection nozzles will receive required lubrication. Mixing ethanol with some lubricant (vegetable oil for example) seems enough.

And the most important thing worth noting. Not every ethanol is bioethanol! It is cheaper to produce ethanol by hydration of ethylene than by fermentation of agricultural crops. I must also say, that inputtin of one unit of energy into manufacturing of ethanol from corn in USA gives fuel of only 1.3 unit energy content! For sugar cane this energy balance is more positive, the EROEI is close to 8.