Answer:
caffeine.
Explanation:
When Xi consumed several cups of coffee to stay wake for another hour.Coffee contains caffeine.Since caffeine is psychoactive drug and it is legal also unlike other psychoactive drugs.You feel more energetic.It acts as a central nervous system stimulant and when it reaches the brain it causes alertness and you will feel more awake.But Xi consumed more than he needed hence he was not able to go to sleep.
The natural resource enables the operation of most of China's power plants is coal.
