What do you mean by steam heat plants? Are you talking about Geo-thermal plants? And what is a microwave power plant? I have never heard of those before. Solar cells perhaps?
Any of the afore mentioned are not nearly as efficient as coal, oil, or gas power plants. These can increase or decrease output with demand. Wind power is dependent upon nature as is solar. Tidal power plants are extremely expensive to construct. Geo-thermal have a limited output and scientists are a bit afraid of them as they increase the cooling of the earths core. No hot core, no magnetic field to protect us.