Anyone with chemistry knowledge on the forums?

First off, what kind of chemistry is it? (Organic, Biochemistry, Physical Chemistry, etc)

By energy, the question could be referring to several context-specific things:

1. Metabolism (in general, fats give more energy than carbohydrates, but you would have to do the calculations for butanoic acid and glucose for direct comparison as butanoic acid would be a late-stage product of fat catabolism and would give less energy than a fatty acid)
2. Thermochemistry related energies (Heat of combustion, for example. According to wiki, glucose wins that one).

Sorry, I mastered only nuclear fusion.

Solubility in water is directly related to the amount of polar groups a givem molecule contains.
Butanoic acid contains 1 polar group (the -OH)
Glucose has 5 polar groups (all of them -OH)
Therefore glucose is more soluble in water than butanoic acid

In aerobic respiration, one molecule of glucose gives a net yield of 36 ATP molecules (a total of 38 but 2 are used to recover NADH)
Through fatty acid metabolism, butanoic acid would yield only one ATP as it's too short for more than one cycle (each cycle requires two -CH2- groups and butanoic acid only has 3)
So glucose gives more energy

Source: I'm a biotech student (I admit my organic chemistry is a little rusty so take all this with a grain of salt)

I don't remember much about chemistry, but I know that dropping some water on acid will create a reaction that releases a lot of energy. But nothing of the sort happens if you drop a bit of acid in water. Even so, this alone doesn't answer your question, so... Just ignore this post.