Question

When energy is transformed, some is used, but most is released as unusable heat energy, according to the law of thermodynamics.

Answer 1

According to the second law of thermodynamics entropy of a system always tends to increase it states that none of the process of energy transfer is perfect as part of the energy is always lost as heat during each energy the lost energy serves to increase the entropy of the system this is why only 10% energy of each tropic level is passed to next tropic level and rest is lost as heat