Geothermal energy Flashcards
Advection
A process by which thermal energy is transferred through a medium by a fluid
Convection
The process by which thermal energy is transferred by a substance due to buoyancy difference within the substance
Conduction
The process by which thermal energy is transferred through a substance with no overall movement of that substance. Energy is transferred atom by atom down a thermal gradient
Geothermal gradient
Rate of increasing temperature with respect to increasing depth in the earths interior
Thermal flux
The rate of heat energy transfer through a given surface per unit of time.Measured in watts per square metre.
Hot spot
An area of high heat flow above a mantle plume
Subduction zone
A process where by one section of the lithosphere is forced down beneath another
MOR
mid ocean ridge
Convection cell
A self contained area in a fluid in which upward motion of warmer fluid in the centre is balanced by downward motion cooler fluid at the periphery
What are the three main processes in the formation of the earth which resulted in 1/3 of earth’s geothermal energy?
Formation of the proto- earth
Heat given off due to segregation of core, mantle and crust
Heat given off due to the change in state at the Lehman boundary
Describe how geothermal energy resulted from the formation of proto-earth
Formed by planetoids coming together in collisions. Kinetic energy was transferred to the earth through these collisions which resulted in an increase of thermal energy.
Describe how geothermal energy resulted form segregation within the earth
As mantle, core and crust separated, gravitational potential energy of ‘siderophiles’ was transferred to kinetic energy as they moved down the core. As they fell this energy was transferred to thermal energy. As proto-earth grew, amount of energy gained by fall was enough to melt metals and form molten core
How did the change of state at the Lehman boundary play a role in the earth’s geothermal energy?
The change form solid to liquid transfers heat to the surrounding area
What role does radioactive decay play in the earth’s geothermal energy?
Unstable parent atoms decay to give stable daughter atoms and give off heat energy.
Where does the remaining 2/3 of heat energy come from?
Radioactive decay
