How many energy sources can the body use

[Wesley Clark]

I know about protein, fats and carbohydrates. However a few months ago i learned ethanol is converted to acetate and used by the body. I dont know if acetate fits into any of the above 3 categories.

Another energy source is ketones. I think these qualify as fats though.

So aside from the four listed (fats, carbohydrates, acetate and protein) does the body have any other energy sources?