Energy is not a substance. It is just a number one can calculate. One does not need to imagine energy as being stored somewhere.

That being said, imagining energy as a substance can help in certain situations, but it is not often obvious "where" the energy is. One might say energy is stored in the field, but I feel this isn't completely satisfactory.

I suspect most practicing physicists don't concern themselves with this question much because it doesn't matter; you know how to calculate it, and you know how to use it. Done.

Energy is not a substance. It is just a number one can calculate. One does not need to imagine energy as being stored somewhere, at least classically.

That being said, imagining energy as a substance can help in certain situations, but it is not often obvious "where" the energy is. One might say energy is stored in the field, but I feel this isn't completely satisfactory.

I suspect most practicing physicists don't concern themselves with this question much because it doesn't matter; you know how to calculate it, and you know how to use it. Done.