Geothermal Energy Flashcards
What is Geothermal Energy
Heat Generated in the core of the earth
What is typically the thermal gradient in Iceland
500C/Km
What 3 things are needed for extraction of geothermal heat
Heat source
Permeable Rock
Wells to extract heat
Why is permeable rock important for geothermal heat extraction
Because it absorbs water to absorb and transport heat
Why is a heat exchanger needed if geothermal energy is to be used as heat
To transfer the energy from saline geothermal water to fresh water, Less corrosion and can be used in boilers etc
What Is needed to produce electricity from geothermal energy
Separator, Re-injection well and Steam Turbine
What are some challenges of geothermal energy
High cost of wells
Hard to find reservoir
Chemically aggressive geo fluids can cause corrosion and scaling
What are some benefits of Geothermal energy
Low carbon emissions
24/7
Technology similar to hydrocarbon industry
What are the purposes of reinjection
Prevent disposal of saline groundwater (Can be ecologically damaging)
Maintain reservoir pressure at depth
What are the problems with reinjection
Can lead to short circuiting
Rate of cooling can effect life time of geothermal system
Will a rock with high permeability and high porosity be a good reservoir rock (such as sandstone)
Yes- High permeability
Would a rock with high porosity but low permeability be a good reservoir rock
No
What are the 2 types of permeability
Intergranular (Sand stone)
Fracture (Granite)
What countries have a high Geothermal potential
US New Zealand Turkey Philippines Indonesia
What effects the efficiency of a geothermal turbine
Ambient Temperature at surface
Reservoir depth
