For about 12,000 years, Native American tribes built steambaths at the Geysers and used the steam and hot water for healing purposes and cooking.
The Geysers is the world's largest geothermal field, containing a complex of 22 geothermal power plants, drawing steam from more than 350 wells, located in the Mayacamas Mountains approximately 72 miles (116 km) north of San Francisco, California.
The first geothermal wells drilled in Geyser Canyon were the first in the Western Hemisphere.[1] The first power plant at the Geysers was privately developed by the owner of The Geysers Resort[1] and opened in 1921, producing 250 kilowatts of energy to light the resort.[2] In 1960, Pacific Gas and Electric began operation of their 11-megawatt plant at the Geysers.[9] The original turbine lasted for more than 30 years and produced 11 MW net power.[10]
By 1999 the steam to power extraction had begun to deplete the Geysers steam field and production began to drop.[2] However, since October 16, 1997, the Geysers steam field has been recharged by injection of treated sewage effluent, producing approximately 77 megawatts of capacity in 2004.
In general, the Geysers has 1517 MW of active installed capacity/ 22 Plants
In fact, The Geysers satisfies nearly 60 percent of the average electricity demand in the
North Coast region from the Golden Gate Bridge to the Oregon border.
1.517 GW / 22 = 68.9 MW
1.517 GW / 350 = 4.334 MW
https://en.wikipedia.org/wiki/Enhanced_geothermal_system
An enhanced geothermal system (EGS) generates geothermal electricity without the need for natural convective hydrothermal resources. Until recently, geothermal power systems have exploited only resources where naturally occurring heat, water, and rock permeability are sufficient to allow energy extraction.[1] However, by far most of geothermal energy within reach of conventional techniques is in dry and impermeable rock.[2] EGS technologies enhance and/or create geothermal resources in this hot dry rock (HDR) through 'hydraulic stimulation'.
When natural cracks and pores do not allow economic flow rates, the permeability can be enhanced by pumping high-pressure cold water down an injection well into the rock. The injection increases the fluid pressure in the naturally fractured rock, triggering shear events that enhance the system's permeability. As long as the injection pressure is maintained, a high matrix permeability is not required, nor are hydraulic fracturing proppants required to maintain the fractures in an open state. This process is termed hydro-shearing,[3] perhaps to differentiate it from hydraulic tensile fracturing, used in the oil and gas industry, which can create new fractures through the rock in addition to expanding the existing fractures.[4]
Water travels through fractures in the rock, capturing the rock's heat until forced out of a second borehole as very hot water. The water's heat is converted into electricity using either a steam turbine or a binary power plant system.[5] All of the water, now cooled, is injected back into the ground to heat up again in a closed loop.
EGS technologies, like hydrothermal, geothermal can function as baseload resources that produce power 24 hours a day, like a fossil fuel plant. Unlike hydrothermal, EGS may be feasible anywhere in the world, depending on the economic limits of drill depth. Good locations are over deep granite covered by a 3–5 kilometres (1.9–3.1 mi) layer of insulating sediments that slow heat loss.[6] EGS wells are expected to have a useful life of 20 to 30 years before the outflow temperature drops and the well becomes uneconomic.
http://c03.apogee.net/contentplayer/?coursetype=geo&utilityid=oge&id=6991
Energy calculations can be done using one of three basic methods:
- Degree-day procedure, which is the simplest but gives the poorest results.
- Bin method, which is relatively simple and accounts for the changing outdoor temperature and partial load conditions. This method is often used on single family residential applications.
- Hour-by-hour method using one of the many software programs available for these calculations. This method is often used for large commercial and institutional systems where considerable detail is required to make a good analysis.
Three key points are:
- The heating load should be calculated at the specified winter design outdoor temperature.
- The cooling load should be calculated at the specified summer design outdoor temperature.
- The assumption that neither heating nor cooling is required for a certain range of outdoor temperatures, typically from 62°F to 67°F.
GEOTHERMAL RESOURCES IN THE DIFFERENT REGIONS OF CANADAPotential geothermal applications in Canada
The USGS has defined moderate-temperature resources as those between 90°C and 150°C (194 to 302°F), and high-temperature geothermal systems as those greater than 150°C.
In 1981 at a project in Imperial Valley, California, Ormat Technologies established the technical feasibility of the third conventional type of large-scale commercial geothermal power plant: binary. The project was so successful that Ormat repaid its loan to the Department of Energy (DOE) within a year. Binary geothermal plants have made it possible to produce electricity from geothermal resources lower than 302°F (150°C). This has expanded the U.S. industry’s geographical footprint, especially in the last decade.
Binary plants use an Organic Rankine Cycle system, which uses geothermal water to heat a second liquid that boils at a lower temperature than water, such as isobutane or pentafluoropropane. This is called a working fluid (or “motive fluid” in Figure 7). A heat exchanger separates the water from the working fluid while transferring the heat energy. When the working fluid vaporizes, the force of the expanding vapor, like steam, turns the turbines that power the generators. The geothermal water is then reinjected in a closed loop, separating it from groundwater sources and lowering emission rates further (see section 5). Most new geothermal plants under development in the U.S. are binary.
United States Government energy agency estimates that the total energy available from global geothermal resources is approximately 15,000 times the energy contained in all the known oil and gas reserves in the world. ???
The U.S. has about 3 GW of geothermal electricity installed, out of the worldwide total of 10 GW. Surprising to me, Iceland has just 0.6 GW installed, but this is 30% of their national electricity production. Another surprise to me was that the Philippines also derive about 30% of their electricity from geothermal sources, amounting to 1.9 GW - See more at: http://physics.ucsd.edu/do-the-math/2012/01/warm-and-fuzzy-on-geothermal/#sthash.Vpd33DSD.dpuf
