Geothermal Power Flashcards
How is the source for geothermal power formed?
Heat is released from the radioactive decay of isotopes of thorium, uranium & potassium in the earth’s mantle
This heat might be moved towards the surface of the crust by molten magma or hot water
What can the heat from radioactvive decay in the earth’s mantle be exploited for?
Space heating
Hot water
Electricity generation
What are the different ways in which geothermal power can be harnessed?
Low temperature schemes: geothermal springs, geothermal aquifers
High temperature schemes: geothermal steam systems, hot dry rock systems
What are geothermal springs and how can we use them?
Ground water that has been heated by hot rocks underground might come to the surface in springs
Can be used for district heating
What are geothermal aquifers and how can we use them?
Hot groundwater may be pumped to the surface from underground aquifers to be used in district heating schemes
How do geothermal steam system works and what can the geothermal power that is harnessed, be used for?
A extraction borehole can be used to bring high temperature groundwater to the surface
This can produce high temperature steam at the surface
Which can be used to generate electricity
Where are hot dry rock systems used?
Where there are hot rocks near the surface but no groundwater
How can the use of hot dry rock systems be maximised?
Fracturing the rocks underground
This increases permeability of the rock and surface area exposed for heat absorption
What locational restraints face the use of geothermal power?
Geothermal power stations using turbines need a source with a temp above 150oC
This means there needs to have been relatively recent volcanic activity in the area so there are hot rocks near the crust
If the rocks are too deep it may be uneconomic to reach them
What environmental impacts can geothermal power have?
If they are developed carefully, they can have few
There are some: infrastructure,gaseous emissions and waste water
How can the infrastructure for geothermal power have environmental impacts?
Steam/hot water pipes can provide obstacles for the movement of large mammals
How can gaseous emissions from harnessing geothermal power have an environmental impact?
The hot water from the ground can release small amounts of gases like carbon dioxide and hydrogen sulphide
Why can the waste water from harnessing geothermal power be a problem?
It can contain salts and heavy metals
Give an example of new geothermal power technology and explain it
Low temperature fluids
New turbine technologies ae being developed that use liquids boiled at lower temperatures
This may allow areas with lower temperature rocks to use them for electricity generation
Including some areas in UK
