WHAT IS GEOTHERMAL ENERGY The drill operators watch their equipment bit is almost 2 miles 3 2 km below Earth’s surface It spins and churns cutting through rock Its Their rig has been running for 40 days Its drill target is an underground steam field There are sensors on the end of the drill They detect heat Suddenly the temperature spikes The drill operators get ready Deep underground the drill Drilling for geothermal exploration requires heavy equipment and several workers 5 CHAPTER ONE
The Calistoga plant in the Geysers is one of the largest US geothermal power plants breaks through to a pocket of superheated steam A thick white blast of steam shoots into the air It roars like a jet engine The drillers rush over to seal the wellhead The superheated steam from this well is 575 degrees Fahrenheit 300 C It will be sent through a turbine As the turbine spins it generates electricity The well is in California in an area called the Geysers Heat is stored below the ground in this 6
region The heat from the Geysers supplies enough energy to run more than 20 power plants Earth’s Hot Core Heat stored underground is called geothermal energy Geo and therme are the Greek words for Earth and heat Earth’s core can reach 10,800 degrees Fahrenheit 6,000 C This is about the same temperature as the surface of the sun Some of the Earth’s inner heat is left over from when the planet formed This happened more than 4 5 billion years ago Some of it comes from radioactive elements naturally found in rock The elements release heat as they decay Heat from Earth’s core flows out toward the surface Some becomes trapped in cracks and pores filled with water The water warms up It becomes a reservoir of geothermal energy Some geothermal reservoirs are close to the surface People can drill into them and use the heat 7
