Energy is released during the oxidation of compounds in respiration. How is this energy stored and released as and when it is needed?

The energy which gets released during the oxidation of compounds in respiration is stored as Adenosine Triphosphate i.e., ATP. The ATP is stored in the form of chemical bonds.
ADP + IP + energy → ATP (ADP = Adenosine Diphosphate and IP = Inorganic phosphorous)
When energy is required then, this bond energy is broken and utilised
ATP → ADP + IP + energy.