Geothermal Energy has been used for thosands of years. Ancient Humans used to use natural hotsprings to bath, cook, and for heating. This form of Geothermal energy would be considered "direct use". This type is still used today through direct heating systems to heat buildings and homes. Another form of geothermal is hydrothermal power plants, which basically use steam vents from the earth to power a turbine. Really its like a steam engine. These power plants are 97% cleaner than traditional power plants and have little effect on the ground they operate on. Once the water from the steam has been brought up from underground it is injected right back into the earth.
Geothermal Energy has been used for thosands of years. Ancient Humans used to use natural hotsprings to bath, cook, and for heating. This form of Geothermal energy would be considered "direct use". This type is still used today through direct heating systems to heat buildings and homes. Another form of geothermal is hydrothermal power plants, which basically use steam vents from the earth to power a turbine. Really its like a steam engine. These power plants are 97% cleaner than traditional power plants and have little effect on the ground they operate on. Once the water from the steam has been brought up from underground it is injected right back into the earth. 
