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Why is Earth interior hot?• Heat from
rocks & atmosphere slow heat loss
≈ 4.6 b.y. ago
• gravitational collapse
• radioactive decay
• Circulate hot water or stream thru buildings
• Generate electricity– Hot water or steam to turn turbines – convert secondary fluid to vapor to turn
turbines
The Geysers, CA - largest single source of geothermal power
Dry Steam Power Plant• fluids are primarily steam• oldest type of geothermal power plant• gases can include H2S• very noisy
Air emissions• radon gas • H2S• CO2
• methane• ammonia
Thermal pollution (low thermal efficiency (20%); low steam temperatures
Noise
Potential pollution Problems – depends on type of geothermal
http://www1.eere.energy.gov/geothermal/gpp_animation.html
Hot, Dry Rock Animation
Animations of Geothermal Electric Power Plants
http://www.youtube.com/watch?v=kjpp2MQffnw&feature=related
http://www.youtube.com/watch?v=vSZ1dIBdOIs&feature=related
Noisy Steam Release
Wells and Power Plant – longer animation
http://uk.youtube.com/watch?v=ehRgYs9qOvk
Wells and Power Plant
Geothermal Heat Pumps
• Earth T nearly constant 50-60 oF near surface
www.daviddarling.info
www.igshpa.okstate.edu
http://swgeothermal.com/Images/GeoAnimation.gif
Summer, cooling almost free
Winter, heating cheaper than standard heat
pump
20o
20o
50o
20o
homeimprovement.resourcesforattorneys.com
System costs are returned in energy savings in 5–10 years. System life is estimated at 25 years for the inside components and 50+ years for the ground loop. There are approximately 50,000 geothermal heat pumps installed in the United States each year.
The initial cost of installing a geothermal heat pump system can be 2-3 times that of a conventional heating system in most residential applications.
• Ocean thermal energy conversion (OTEC) – exploits T difference between warm
surface water and deep cold water
A geothermal heat pump (also called GeoExchange, earth-coupled, ground source or water-source heat pump [1]) system is a heating and/or cooling system that uses the earth´s ability to store heat in the shallow ground or water thermal masses.Geothermal heat pumps are known also as "GeoExchange" systems, or "ground source heat pumps", to clearly distinguish them from air source heat pumps. It is important to understand that ground source heat pumps draw energy from shallow ground. The energy originates from the sun: none of the energy originates from the centre of the Earth, in spite of the name "geothermal heat pump". Genuine geothermal energy from the centre of Earth is available only in places where volcanic activity comes close to the surface.These systems operate based on the stability of underground temperatures: the shallow ground, this is the upper 10 feet (3.0 m) of Earth´s surface, has a very stable temperature throughout the year - between 10 and 16 °C (50 and 61 °F), depending upon location's annual climate [2]. Like a cave, the shallow ground temperature is warmer than the air above during the winter and cooler than the air in the summer [3]. A geothermal heat pump uses that available heat in the winter (heating) and puts heat back into the ground in the summer (cooling).The system cost are returned in energy savings in 5–10 years. System life is estimated at 25 years for the inside components and 50+ years for the ground loop. There are approximately 50,000 geothermal heat pumps installed in the United States each year [4].
The heat pump itself, explained more fully in the article on heat pumps, consists of a loop containing refrigerant. The refrigerant is pumped through a vapor-compression refrigeration cycle that moves heat from a cooler area to a warmer one.
The initial cost of installing a geothermal heat pump system can be two to three times that of a conventional heating system in most residential applications
Hydrogen (H2) as fuel
2H2 + O2 = 2H2O Why is this a nearly ideal fuel!
Pure water is the only waste!
How do we make it?
H2 is explosive – engineering challenges
2H2O = 2H2 + O2
energy
What kinds don’t make CO2?
solarnuclearhydropower