Why can nutrients be recycled but energy cannot?

Question

Why can nutrients be recycled but energy cannot?

Answer 1

energy exists as potential energy in the bonds of molecules, the things you refer to as nutrients are molecules that have a large amount of potential energy. the energy can be reused if the molecule is rebuilt which sometimes occures in nature and man can do quite well.

Answer 2

Energy can be recycled...or at least reclaimed.

For example, a heat exchanger can be used to reclaim the heat from a dryer and put it back into a house, reducing the need for other heating.