Renewable Energy - Geothermal Energy Flashcards
Tempearture is variable…
With deapth thus a thermal gradient develops within the Earth.
Lithospheres steep temperature gradient…
Due to solid rock conductivitiy.
Sources of energy in Earth…
Radioactive Decay…
Internal energy store from formation of Earth.
Phase changes
Energy from Earth formation…
High gravitational pull with release of gravitational energy heated the planet…
Four sources of decay…
U235/U238, K40 and Thorium232
Concentrations of radioactive decay depends on…
Rock concentration and location
What is rock thermal energy(containining radioisotopes) described by?
Fouriers law
Heat Flow Rate is equal to…
Heat transfer of coefficient multiplied by body area, multiplied by temperature change and material length.
Why does the oceanic crust contain less radioactive materal?
More recenetly formed
Disadvantages of Geothermal Energy?
Variability of the resource, alternates per location
Weibull distribution
A scale parameter probability distribution.
What does geothermal energy vary with?
Depth and Rock type above/surrounding resource
Ground Source Heat Pumps
The exploitation of ambient temperatures a few meteres below the surface to heat a building
Majority of accessbile geothermal resoruce…
Naturually heated water to 150 degrees
Where is heated water found?
Magma intrusions or hot spots below the surface, rock fractures bringing in meteroic water.
Meteoric Water
Water derived from precipitation
Binary Cycle
Plants with the transfer of geothermal fluid heat to a secondary working fluid.
Highest potential geothermal resource…
Waters above 150 degrees only present in tectonic or volcanically active areas
Why is magam hard to utilise?
High temperatures are beyond what is feasible with current technologies and are located in hard to access regions
How can magam inaccesiblity be bypass?
Nearby superheated water bodies
Superheated
This means a liquid under pressure above its boiling point without vaporisation.
