View source for Geothermal district heating

[[Category:Done 2015-09-05]]
[[File:Under-floor_heating-_in_the_street.jpg|300px|thumb|Figure 1. After circulating through a building, excess low-quality geothermal heat may be directed to sidewalk heaters in order to melt snow.<ref>Wikimedia Commons [Online], Available: https://commons.wikimedia.org/wiki/File:%22Under-floor_heating%22_in_the_street.jpg</ref>]]

''Not to be confused with [[geothermal heat pumps]], which use energy stored under the Earth's surface that originated in the Sun.''

<onlyinclude>'''Geothermal district heating''' is the use of the Earth's natural [[thermal energy]] in order to provide [[heat]] to a group of buildings.</onlyinclude><ref name=geo>GEODH. (August 13, 2015). ''Developing Geothermal District Heating In Europe'' [Online], Available: http://geodh.eu/wp-content/uploads/2012/07/GeoDH-Report-2014_web.pdf</ref> There are locations on Earth that may make better use of this, due to being situated on "geothermal hot spots" (shown in Figure 2) where they have access to higher underground [[temperature]]s. The first use of district heating occurred in the 14<sup>th</sup> century in France.<Ref>J.P Gilbert and F. Jaudin, ''Using Geothermal Waters in France: The District Heating System of Chaudes-Aigues from the Middle Ages'' [PDF], Available: http://pubs.geothermal-library.org/lib/grc/1018282.pdf</ref>

[[Temperature]]s above 40[[Celsius|°C]] and less than 150°C are ideal for these applications, since geothermal temperatures above 150°C are better used for [[geothermal electricity]] generation.<Ref name=ot>Oregon Tech. (August 13, 2015). ''Geo-Heat Center'' [Online], Available: http://www.oit.edu/orec/geo-heat-center</ref> Between 90°C and 150°C is considered a "moderate" temperature range,<ref name=wolf>R. Wolfson, "Energy from Earth and Moon" in ''Energy, Environment, and Climate'', 2nd ed., New York, NY: W.W. Norton & Company, 2012, ch. 8, pp. 204-224</ref> and can be used in certain [[geothermal electricity#Binary cycle plants|low-temperature power plants]], or in more energy-intensive [[geothermal industrial heat|industrial heating]] applications.<ref>Geothermal Education Office 2005. ''Geothermal Energy Uses'' [Graphic]</ref>

[[File:geohotspot.png|800px|thumb|center|Figure 2. Geothermal hot spots around the world.<ref>Adapted from: R. Wolfson, "Energy from Earth and Moon" in ''Energy, Environment, and Climate'', 2nd ed., New York, NY: W.W. Norton & Company, 2012, ch. 8, pp. 204-224</ref>]]

==Use==

The primary uses of this heat is for residential or commercial [[domestic water heating|water heating]] and [[space heating]]. Hot water from surface features or shallow wells circulates through individual buildings or community-wide water systems. Excess heat from these applications may also be sent to sidewalk heaters in order to melt snow (Figure 1).<ref name=wolf/> 

Some countries that are located on geothermal hot spots rely on these methods of heating. In Iceland for example, 9 out of 10 buildings are heated using geothermal energy.<Ref>National Energy Authority. (August 13, 2015). ''Direct Use of Geothermal Resources'' [Online], Available: http://www.nea.is/geothermal/direct-utilization/</ref> Certain places within USA and Turkey also make considerable use of geothermal district heating.<ref>Boise Idaho. (August 13, 2015). ''Geothermal Heating District'' [Online], Available: http://publicworks.cityofboise.org/services/geothermal/</ref><ref>Science Direct. (August 13, 2015) ''Geothermal district heating applications in Turkey: a case study of Izmir–Balcova'' [Online], Available: http://www.sciencedirect.com/science/article/pii/S0196890402001218</ref> The United States' installed capacity of direct use systems totals 470 [[watt|MW]], or enough to heat 40 000 average-sized houses.<ref name=ot/>

==See also==
*[[Geothermal energy]]
*[[Geothermal industrial heat]]
*[[Geothermal electricity]]

==References==
{{Reflist}}[[Category:Uploaded]]