INTRODUCTION Geothermal energy is heat that comes from inside Earth It can be used for cooking bathing and heating It can also be converted into electricity Geothermal energy from natural natural pools and hot springs has been used throughout history including by Native Americans and the ancient Greeks and Romans Geothermal energy is available anywhere anywhere on Earth’s surface In some places such as Iceland the heat is so close to the surface it can be easily used as an energy source In Iceland most homes are heated by hot water tapped from volcanic springs Greenhouses heated in the same way provide fresh vegetables vegetables and fruits to this subarctic island In other places holes must be drilled down through rocks to reach the heat The amount of usable energy from geothermal geothermal sources varies considerably Geothermal energy is best found in areas with high thermal 4
This is the Nesjavellir Geothermal Power Plant in Iceland It is used to generate electricity and to supply hot water which is used both for bathing and for heating gradients Those gradients occur in regions affected by recent volcanic activity in areas located along plate boundaries such as along the Pacific Ring of Fire or in areas marked by thin 5
GEOTHERMAL ENERGY Distribution of geothermal resources in the United States Favourability of deep Enhanced Geothermal Systems EGS Most favourable Least favourable Regions not assessed for deep EGS potential No data 2012 Encyclopædia Britannica Inc Source National Renewable Energy Laboratory This map shows geothermal energy resources in the United States As you can see some areas have far more geothermal resources than others do crust hot spots such as Yellowstone National Park and the Hawaiian Islands Areas near volcanic activity often have features that bring heat from deep inside Earth right to the surface such as lava flows geysers geysers or hot springs In other places the extraction
INTRODUCTION of geothermal energy can be more challenging For successful extraction geothermal reservoirs must have adequate permeability or faults that allow fluids to rise close to the surface and an impermeable caprock caprock to prevent the escape of heat In addition such reservoirs must be economically accessible that is within the range of drills The annual heat flow to the surface averages between 50 and 70 milliwatts mW per square meter worldwide In contrast incoming solar radiation striking striking Earth’s surface provides 342 watts per square meter annually The estimated amount of geothermal geothermal energy that can be recovered and utilized on the surface is roughly three times the world’s annual consumption of all types of energy Geothermal energy is an alternative energy source That means that it is one of several renewable renewable power sources that can be used in place of fossil fuels and other traditional sources of energy which are limited in supply and produce pollution and other environmental problems Other alternative alternative energy sources include solar power wind power and waterpower 7
