Transcript Energy Resources Alternative Sources

Low-CO2 Energy
http://www.sciencecartoonsplus.com
Geothermal Energy in Perspective
6% of 8%
Most People’s Idea of Geothermal Energy
Lone Star Geyser,
Yellowstone
Mammoth Terraces,
Yellowstone
Why is Earth interior hot?
• Heat from
≈ 4.6 b.y. ago
• gravitational collapse
• radioactive decay
rocks & atmosphere slow heat loss
Geothermal Gradient
Plate Tectonics & Geothermal power plants worldwide
• Circulate hot water or stream thru buildings
• Generate electricity
– Hot water or steam to turn turbines
– convert secondary fluid to vapor to turn turbines
Heat is an energy transfer from hot (higher T) objects
to cold (lower T) objects
Dry Steam Power Plant
• fluids are primarily steam
• oldest type of geothermal
power plant
• gases can include H2S
• very noisy
The Geysers, CA - largest single source of geothermal power
• The Nesjavellir Geothermal Power
Plant in Iceland
wikipedia.org/wiki/Geothermal_power
Potential pollution Problems – depends on type of geothermal
Air emissions
• radon gas
• H2S
• CO2
• methane
• ammonia
Thermal pollution (low thermal efficiency (20%);
low steam temperatures
Noise
Animations of Geothermal
Electric Power Plants
Hot, Dry Rock Animation
http://www1.eere.energy.gov/geothermal/gpp_animation.html
Wells and Power Plant
http://www.youtube.com/watch?v=vSZ1dIBdOIs&feature=related
Noisy Steam Release
http://uk.youtube.com/watch?v=ehRgYs9qOvk
Wells and Power Plant – longer animation
http://www.youtube.com/watch?v=kjpp2MQffnw&feature=related
Few areas with hot rocks near the surface
thefraserdomain.typepad.com/
Geothermal Heat Pumps
• Earth T nearly constant 50-60 oF near surface
www.igshpa.okstate.edu
www.daviddarling.info
Summer, cooling
almost free
Winter, heating cheaper
than standard heat pump
D 20o
D 50o
D 20o
D 20o
http://swgeothermal.com/Images/GeoAnimation.gif
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.
homeimprovement.resourcesforattorneys.com
Horizontal ground loops
Thermal energy from lakes, abandoned mines
http://www.oscette.com/Tunnel.jpg
• Ocean thermal energy conversion
(OTEC)
– exploits T difference between warm
surface water and deep cold water
Ocean thermal energy conversion
alternateformsofenergy.com/Geothermal
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 syste
Hydrogen (H2) as fuel
2H2 + O2 = 2H2O
Why is this a nearly ideal fuel!
Pure water is the only waste!
H2 is explosive – engineering challenges
How do we make it?
2H2O
energy
=
What kinds don’t make CO2?
2H2 + O2
solar
nuclear
hydropower
Fig. 15.32a