On a kilogram-for-kilogram basis, how does the chemical potential energy in butter compare to that in coal, oil, or gasoline?

The comparison of chemical potential energy in butter to that in coal, oil, or gasoline illustrates a fascinating aspect of energy sources. Butter, which is primarily composed of fats, stores energy through the chemical bonds of triglycerides. The energy contained in fats is typically around 37 kilojoules per gram or approximately 37,000 kilojoules per kilogram.

Coal, oil, and gasoline, which are fossil fuels, also store energy through their hydrocarbon structures. The energy content in these fuels can vary, but it generally falls within a similar range—often around 30 to 50 kilojoules per gram, depending on the specific type of fuel.

When comparing the energy densities of these substances on a kilogram-for-kilogram basis, butter's energy content does not vastly exceed that of coal, oil, or gasoline, nor does it fall drastically short. Instead, they reside in a comparable range, leading to the conclusion that butter's energy content is about the same as that of these fossil fuels, falling within a factor of 2. This emphasizes that while butter is a biological energy source and fossil fuels are geological, they are both efficient energy carriers within a similar order of magnitude.