Answer the following question given this paragraph: 

At a geothermal power plant, engineers drill wells into the hot rocks. Hot water or steam may come up through the wells. Alternatively, water may be put down into the well to be heated. It then comes up. The hot water or steam makes a turbine spin. This makes electricity. Pictured below is an example of a geothermal power plant ( Figure below ).


Q: Drilling wells into hot rocks to release hot water or steam is an example of what kind of power plant?


A:
geothermal