Abstract: . . .  be carefully managed so that the steam and hot water are produced no faster than they can be naturally replenished or supplemented. Geothermal power plants provide very reliable baseload electricity. Some plants can increase production to supply peaking power. But geothermal plants can’t be used solely as peaking plants; if geothermal wells were turned off and on repeatedly, expansion and contraction (caused by heating and cooling) would damage the well. s s 68 ENERGY FOR KEEPS: ELECTRICITY FROM RENEWABLE ENERGY  . . .
. . .  carefully managed so that the steam and hot water are produced no faster than they can be naturally replenished or supplemented. Geothermal power plants provide very reliable baseload electricity. Some plants can increase production to supply peaking power. But geothermal plants can’t be used solely as peaking plants; if geothermal wells were turned off and on repeatedly, expansion and contraction (caused by heating and cooling) would damage the well. s s 68 ENERGY FOR KEEPS: ELECTRICITY FROM RENEWABLE ENERGY  . . .
. . .  geothermal locations include Iceland, Italy, New Zealand, the Rift Valley of Africa, and Hawaii. Tectonic plate Subducting tectonic plate Magma Magma can reach the surface, or near the surface, where the earth’s crust is “fractured” or thinned, such as at plate boundaries. 60 ENERGY FOR KEEPS: ELECTRICITY FROM RENEWABLE ENERGY Fumarole Fumarole Fault Hot Spring Faul t WATER SOURCE: GEOTHERMAL RESERVOIR: T HO Hot water in hot rock Deep circulation of rainwater and snowmelt HO Very T Hot Ro HEAT SOURCE: Transfer of heat (thermal) energy from cooling magma to surrounding rock and water ks A geothermal reservoir is a large underground area of hot permeable rock saturated with superheated water. c Cold water Hot water Heat The Geothermal Reservoir Rainwater and snowmelt can seep miles underground, where it absorbs heat from the hot rock. This water can get really hot. It can reach temperatures of 500° F (260°C) or higher — way above boiling. Sometimes this hot water will work its way back up . . .
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