Geothermal energy Flashcards
What is geothermal energy
Energy from the earths interior
why is geothermal energy renewable
(kinda weird definition)
it is a renewable energy source because heat is continuously transferred from within the earth to the water recycled by rainfall
What are the 3 layers of the earth
core, mantle, crust
What is the core of the earth composed of
inner core - iron center
outer core - magma - radioactive decay generates heat
What is the mantle composed of
magma and rock
how thick is the crust on continents vs under the ocean
25-55 km thick on continents
5-8 km thick under oceans
How are geothermal hot spots created
volcanic activity - magma near tectonic plates
What are the classifications of geothermal resources
hydrothermal
magma
enhanced
geopressurized
describe hydrothermal
high temperature water in steam, liquid or mixed phase
describe geopressurized
hot-water 150-180 °C under very high pressure, with methane and dissolved solids
describe magma
molten rock under volcanoes at temperatures > 650 °C
describe enhanced
water injected into hot rocks, generating steam
What is the process for enhanced geothermal systems
1) water is injected at high pressure into hot rock formations
2) The heated water returns to the surface as steam
3) Steam powers turbines for electricity generation
What is the depth and temperature of the rock formation for a enhanced geothermal system
3-5 km
hot rock formations can reach to 250 °C
What are the resource temperature categories and their range
low temperature T < 90 °C
medium temperature
90 °C < T < 150 °C
high temperature T > 150 °C
What are the reservoir states
steam dominated and liquid dominated
What is the difference between the reservoir states
steam-dominated has a higher quality with high enthalpy and energy
liquid dominated is more used worldwide and often produced as brine or brine-steam mixture
Geothermal energy involves the ________ use of geothermal water for space, water, and process _________
direct
heating
carrying geothermal water over long distances is not ____-effective
cost
heating requires geothermal resource temperatures above ___ °C
50
Which 5 countries lead in geothermal heating
china, sweden, iceland, turkey, and USA
in iceland, what percent of buildings are heated using geothermal energy
90%
What is the total annual global space heating using geothermal energy in joules
360,000TJ
geothermal brine is not directly circulated due to undesirable _________ properties
chemical
heat exchangers are used to transfer the heat of _________ water to __________ water and this heated _________ water is sent to the district
geothermal
fresh
fresh
Geothermal heat can be used in _____________ refrigeration systems.
* These systems are feasible for ________ cooling with sufficient annual cooling load.
* ______ initial costs limit the widespread use of geothermal cooling systems.
absorption
district
high
What temperature does the absorption cooling system operate in
100-200 °C.
What are the typical refrigerants
NH3 and H2O or water-lithium bromide
Refrigerant absorption occurs with the help of a _______ _______
transport medium
The most widley used absorption refrigeration system is
ammonia-water system
What are other absorption refrigerant system and what is there refrigerant and how is it limiting
Water-lithium bromide and water-lithium chloride both have water as a refrigerant and these systems must remain above the freezing point of water. Therefore they are limited to applications such as air conditioning.
What are the advantages of geothermal energy sources
low operational cost
easy integration with other renewable energy systems
widespread availability
stability and reliability
wide-range operational capacity
fossil fuel-free operation
environmentally friendly
no complicated systems or components
What are the disadvantages of GES
effects of earthquakes
surface instability
environmental impact due to some harmful emissions
high initial costs
What are the classification of geothermal energy applications
power generation
heat pumps
other
What are the types of power generation for geothermal
dry-steam geothermal power production
flash geothermal power production
binary geothermal power production
combined flash/binary geothermal power generation
What are the two types of heat pumps
heat pump applications
reversible heat pump applications
What does the other applications category include. For geothermal
absorption cooling applications
hydrogen production
industrial chemical production
drying processes
List the 5 steps for geothermal power generation
- Geothermal energy sources
- Steam generation/heat extraction from production well
- Power generation cycle
- Electricity generation
- Water discharge to injection/ reinjection well
Can a heat pump be used to heat a house in the winter and cool it in the summer?
yes
What are the 3 types of ground-source heat pumps
- Horizontal loop ground-source heat pump
- vertical loop ground-source heat pump
- ground water wells ground-source heat pump
Fill in the blanks:
Overview of horizontal loop ground-source heat pump
* Horizontal piping is buried underground at depths of 1.2 to _____ meters.
* This system is ideal for areas with sufficient _______ for pipe installation.
* Commonly used in homes with ______ backyards.
2.0
space
large
Do i need a big backyard for vertical loop ground-source heat pump
no, it is suitable for areas with limited space
What depths does vertical piping range from
10 to 250 m
Advantages of vertical loop
minimal maintenance and operates safely
year-round heating and cooling
challenges of vertical loop
higher installation costs than horizontal systems
limited capacity per borehole, with lower ground temperatures impacting performance
Fill in the blanks:
Overview of ground water wells ground-source heat pump
* Underground water circulates through
the _________ of the heat pump.
* Heat is transferred from the water to the
refrigerant, and ________ water is returned
to the ground.
evaporator’
cooler
Fill in the blanks:
Overview of ground water wells ground-source heat pump
* Water wells are typically __ to __ meters
deep, offering high _________ at
relatively low cost.
* These systems require ________ for
sufficient water yield, and regular
maintenance
and ______
quality
monitoring are essential.
5 to 50
capacities
aquifers
water
