The Geothermal Energy Association estimates that projects now under development around the country could provide up to 2, megawatts of new capacity [ 3 ]. Since there are more hot water resources than pure steam or high-temperature water sources, there is more growth potential in the binary cycle, heat exchanger design.
These "hot spots" occur at tectonic plate boundaries or at places where the crust is thin enough to let the heat through.
One cause for careful consideration with EGS is the possibility of induced seismic activity that might occur from hot dry rock drilling and development.
In addition, GHPs have a very minimal effect on the environment, because they make use of shallow geothermal resources within metres about feet of the surface. In addition, such reservoirs must be economically accessible that is, within the range of drills.
Environmental concerns also taint the issue of geothermal energy. International Market Overview Report. The largest geothermal system now in operation is a steam-driven plant in an area called the Geysers, north of San Francisco, California.
There is a very large geothermal resource base in the U. For example, despite their long-term savings, geothermal heat pumps have higher up-front costs.
Such cascaded uses can be found in the United States, Iceland, and Germany.
Once this heated water is forced to the surface, it is a relatively simple matter to capture that steam and use it to drive electric generators. Drilling near this depth is now possible in the petroleum industry, although it is an expensive process. Several factors have influenced the growth of geothermal generating capacity: More complicated, but more effective, systems use compressors and pumps—as in electric air conditioning systems—to maximize the heat transfer.
The Italian and American plants were dry steam facilities, where low-permeability reservoirs produced only steam. Binary plants have the capability to ramp production up and down multiple times each day, from percent of nominal power down to a minimum of 10 percent [ 1 ].
Most of those effects, however, can be mitigated with current technology so that geothermal uses have no more than a minimal impact on the environment.
In fact, Iceland gets more than 50 percent of its primary energy from geothermal sources [ 9 ]. In thousands of homes and buildings across the United States, geothermal heat pumps also use the steady temperatures just underground to heat and cool buildings, cleanly and inexpensively.
However, ground-source heat pumps are catching on in some areas. The project came online inand in provided enough additional electricity for approximatelyhomes [ 7 ]. Isobutane boils at a lower temperature than water, so it is more easily converted into steam to run the turbine. Appropriate site selection, assessment and monitoring of rock fracturing and seismic activity during and after construction, and open, transparent communication with local communities are also critical.
The hot rock reservoirs, typically at greater depths below the surface than conventional sources, are first broken up by pumping high-pressure water through them. This causes the secondary fluid to flash vaporize, which then drives the turbines. Heat is continually produced in this layer, mostly from the decay of naturally radioactive materials such as uranium and potassium.
Early industrial direct-use applications included the extraction of borate compounds from geothermal fluids at Larderello, Italyduring the early 19th century. An EGS project in Basel, Switzerland, was cancelled in because of a number of induced seismic events. Trends in the top five geothermal electricity-generating countries, — US EIA Global geothermal electric capacity.
In Klamath Falls, Oregon, and Boise, Idaho, geothermal water has been used to heat homes and buildings for more than a century. The plants then pump more water through the broken hot rocks, where it heats up, returns to the surface as steam, and powers turbines to generate electricity.
Even in well-characterized resource areas, there is significant exploration and production risk, which can result in high development costs. Electricity generation requires high-temperature resources that can only come from deep underground.Annual U.S. & Global Geothermal Power Production Report April 4 Executive Summary The international geothermal power market is booming, growing at a sustained rate of 4% to 5%.
Please Note: The findings, interpretations, and conclusions expressed in this report are entirely those of the author and should not be attributed in any manner to the Geothermal Energy Association, to its affiliated organizations, or to members of its. The concentration of geothermal energy at any given location must be quite high in order to make heat extraction feasible, and not all geothermal sites are created equally.
Regions that have well-developed geothermal systems are located in geologically active areas. These regions have continuous, concentrated heat flow to the surface.
In the United States, most geothermal reservoirs of hot water are located in the western states, Alaska, and Hawaii. Wells can be drilled into underground reservoirs for the generation of electricity. The Geothermal TCP provides a flexible and effective framework for international collaboration on R&D concerning the sustainable use of geothermal energy.
Energy Information Administration - EIA - Official Energy Statistics from the U.S. Government.Download