Why are generators in thermal power plants cooled with hydrogen instead of air?

Why are generators in thermal power plants cooled with hydrogen instead of air?

When the generator is running, the stator and rotor coils will generate heat. This heat is absorbed by the hydrogen inside the generator. The hot hydrogen is pumped into the pipeline of the hydrogen cooler to exchange heat with the cold water in the water pipe, and the heat is released into cold hydrogen, which is then pressed. This cycle is repeated inside the generator, and the hot water is pumped away and replaced with cold water. The hydrogen cooler is where their heat is exchanged, in the same way as the condensing chamber of a refrigerator. As for why hydrogen? Because hydrogen absorbs heat better than air, high-power generators are cooled by hydrogen or water, and low-power generators are fully air-cooled.

The following is the hydrogen cooler that VRcooler has provided to customers recently: