Proof of Stake uses far less electricity than Proof of Work.

Because Proof of Work requires computers to run at maximum speed day and night, it uses as much electricity as entire medium-sized countries. Proof of Stake solves this problem by removing the math race entirely. Since validators are chosen by how many coins they stake rather than how fast their computers are, they do not need massive warehouses full of hot, noisy machines. This makes the whole network incredibly light on energy use.