Geothermal energy is heat that is generated within the Earth. It is a renewable resource that can be harvested for human use.
Explanation:
Geothermal energy is heat that is generated within the Earth. (Geo means “earth,” and thermal means “heat” in Greek.) It is a renewable resource that can be harvested for human use.
About 2,900 kilometers (1,800 miles) below the Earth’s crust, or surface, is the hottest part of our planet: the core. A small portion of the core’s heat comes from the friction and gravitational pull formed when Earth was created more than 4 billion years ago. However, the vast majority of Earth’s heat is constantly generated by the decay of radioactive isotopes, such as potassium-40 and thorium-232.
Isotopes are forms of an element that have a different number of neutrons than regular versions of the element’s atom.
Potassium, for instance, has 20 neutrons in its nucleus. Potassium-40, however, has 21 neutrons. As potassium-40 decays, its nucleus changes, emitting enormous amounts of energy (radiation). Potassium-40 most often decays to isotopes of calcium (calcium-40) and argon (argon-40).
Radioactive decay is a continual process in the core. Temperatures there rise to more than 5,000° Celsius (about 9,000° Fahrenheit). Heat from the core is constantly radiating outward and warming rocks, water, gas, and other geological material.
Earth’s temperature rises with depth from the surface to the core. This gradual change in temperature is known as the geothermal gradient. In most parts of the world, the geothermal gradient is about 25° C per 1 kilometer of depth (1° F per 77 feet of depth).
If underground rock formations are heated to about 700-1,300° C (1,300-2,400° F), they can become magma. Magma is molten (partly melted) rock permeated by gas and gas bubbles. Magma exists in the mantle and lower crust, and sometimes bubbles to the surface as lava.
Magma heats nearby rocks and underground aquifers. Hot water can be released through geysers, hot springs, steam vents, underwater hydrothermal vents, and mud pots.
These are all sources of geothermal energy. Their heat can be captured and used directly for heat, or their steam can be used to generate electricity. Geothermal energy can be used to heat structures such as buildings, parking lots, and sidewalks.
Most of the Earth’s geothermal energy does not bubble out as magma, water, or steam. It remains in the mantle, emanating outward at a slow pace and collecting as pockets of high heat. This dry geothermal heat can be accessed by drilling, and enhanced with injected water to create steam.
Many countries have developed methods of tapping into geothermal energy. Different types of geothermal energy are available in different parts of the world. In Iceland, abundant sources of hot, easily accessible underground water make it possible for most people to rely on geothermal sources as a safe, dependable, and inexpensive source of energy. Other countries, such as the U.S., must drill for geothermal energy at greater cost.
Answers & Comments
Answer:
Geothermal Energy
Geothermal energy is heat that is generated within the Earth. It is a renewable resource that can be harvested for human use.
Explanation:
Geothermal energy is heat that is generated within the Earth. (Geo means “earth,” and thermal means “heat” in Greek.) It is a renewable resource that can be harvested for human use.
About 2,900 kilometers (1,800 miles) below the Earth’s crust, or surface, is the hottest part of our planet: the core. A small portion of the core’s heat comes from the friction and gravitational pull formed when Earth was created more than 4 billion years ago. However, the vast majority of Earth’s heat is constantly generated by the decay of radioactive isotopes, such as potassium-40 and thorium-232.
Isotopes are forms of an element that have a different number of neutrons than regular versions of the element’s atom.
Potassium, for instance, has 20 neutrons in its nucleus. Potassium-40, however, has 21 neutrons. As potassium-40 decays, its nucleus changes, emitting enormous amounts of energy (radiation). Potassium-40 most often decays to isotopes of calcium (calcium-40) and argon (argon-40).
Radioactive decay is a continual process in the core. Temperatures there rise to more than 5,000° Celsius (about 9,000° Fahrenheit). Heat from the core is constantly radiating outward and warming rocks, water, gas, and other geological material.
Earth’s temperature rises with depth from the surface to the core. This gradual change in temperature is known as the geothermal gradient. In most parts of the world, the geothermal gradient is about 25° C per 1 kilometer of depth (1° F per 77 feet of depth).
If underground rock formations are heated to about 700-1,300° C (1,300-2,400° F), they can become magma. Magma is molten (partly melted) rock permeated by gas and gas bubbles. Magma exists in the mantle and lower crust, and sometimes bubbles to the surface as lava.
Magma heats nearby rocks and underground aquifers. Hot water can be released through geysers, hot springs, steam vents, underwater hydrothermal vents, and mud pots.
These are all sources of geothermal energy. Their heat can be captured and used directly for heat, or their steam can be used to generate electricity. Geothermal energy can be used to heat structures such as buildings, parking lots, and sidewalks.
Most of the Earth’s geothermal energy does not bubble out as magma, water, or steam. It remains in the mantle, emanating outward at a slow pace and collecting as pockets of high heat. This dry geothermal heat can be accessed by drilling, and enhanced with injected water to create steam.
Many countries have developed methods of tapping into geothermal energy. Different types of geothermal energy are available in different parts of the world. In Iceland, abundant sources of hot, easily accessible underground water make it possible for most people to rely on geothermal sources as a safe, dependable, and inexpensive source of energy. Other countries, such as the U.S., must drill for geothermal energy at greater cost.