·         As of 2007, geothermal power supplies less than 1% of the world's energy, but could be much more.

·         Geothermal is presently a $1.3 billion per year business.

·         Geothermal resources supply about six percent of the energy produced in California.

·         There are 8,000 megawatts (MW) of geothermal electricity are currently produced around the world (2,800 MW of capacity in the United States).

·         MIT has found that for a maximum investment of $1 billion, United States could produce 100 GWe (gigawatts of electricity) or more by 2050.

·         Today geothermal energy is limited to hydrothermal (hot water/steam) resources. In the future, we will be able to use the heat of the deep, hot rock of Earth's crust and possibly magma!

·         Geothermal energy right now costs about 4-6 cents per kWh.

·         The condensed steam and extra fluid is put back into the ground so the plant does not run "dry". [1]

  

Types of Geothermal Plants

1.       Dry Steam

2.        Flash- Uses water well above boiling point at normal sea level pressure. As the water is pumped from the reservoir to the power plant, the drop in pressure causes the water to convert, or "flash", into steam to power the turbine.

3.        Binary-The water used in binary-cycle power plants is cooler than that of flash steam plants. The hot water transfers heat to fluids with a lower boiling point. Costs less, and doesn’t need to be so hot

4.        Enhanced Geothermal Systems (EGS)-EGS involves pumping water into hot rocks (at least 10 km) down in the earth, rather than using water.


Geothermal Heat Pumps (For Homes)


  1. Even though the installation price of a geothermal system can be several times that of other systems, the additional costs are returned to you in energy savings in 5–10 years.
  2. System life is estimated at 25 years for the inside components and 50+ years for the ground loop.
  3. There are approximately 40,000 geothermal heat pumps installed in the United States each year.

 

Pros

Cons

  • Energy harnessed is clean and safe for the surrounding environment.
  • It is also sustainable because the hot water used in the geothermal process can be re-injected into the ground to produce more steam.
  • Unaffected by changing weather conditions.
  • Works continually, day and night, providing baseload power.
  • It also offers a degree of scalability: a large geothermal plant can power entire cities while smaller power plants can supply more remote sites such as rural villages 

 
  • Affect land stability
    • EGS: where water is injected into hot dry rock where no water was before.
  • Dry steam and flash steam power plants also emit low levels of carbon dioxide, nitric oxide, and sulfur,
    • at roughly 5% of the levels emitted by fossil fuel power plants.
    • can be injected back to earth reducing to 0.1% emissions.
  • Eventually specific locations may cool down=loss $
  • Not strictly renewable in the same sense as the hydro resource.

 

[[Note to Igor: Insert Companies that deal in Geothermal services (check out Ormat)]]