GC: n

CT: Geothermal heating systems utilize the latent heat energy of the earth in order to conserve the energy used to cool and heat residential, commercial, and industrial buildings. With a constant temperature ranging from 50-60˚ F, the upper crust of the earth’s surface provides a perfect environment for harnessing energy. Geothermal designers and technicians utilize specialized ground source heat pumps and a geothermal fluid to transfer this energy from the earth’s crust to the surface. Geothermal fluid is typically formulated from either inhibited propylene glycol or inhibited ethyl alcohol.

S: http://www.houghton.com/heat-transfer-fluids/inhibited-ethanol-solution/geosafe-geothermal-fluid/ (last access: 12 December 2014)

N: 1. geothermal (adj): 1875, from geo- (word-forming element meaning “earth,” ultimately from Greek geo-, comb. form of ge “earth”) + thermal (1756, “having to do with hot springs,” from French thermal (Buffon), from Greek therme “heat, feverish heat,” from PIE gwher- “to heat, warm”. Sense of “having to do with heat” is first recorded 1837. The noun meaning “rising current of relatively warm air” is recorded from 1933).
fluid (n): “substance capable of flowing,” 1660s, from fluid (adj.). Related: Fluidal (1869), fluidic (1821, Marmaduke Tulket).
2. The dry steam, wet steam or hot water, together with dissolved and entrained substances, conveyed or flowing out of the Earth’s crust.
3. Hitherto, apart from various passing references to non-condensable gases, geothermal fluids have been treated in this book simply as H20 – hot water and/or steam. However, these fluids are invariably accompanied by gases and, in the case of wet fluids, by water-soluble substances, some of which can be potentially dangerous to the construction components of a geothermal installation and to the environment.

S: 1. OED – http://www.etymonline.com/index.php?allowed_in_frame=0&search=geothermal&searchmode=none; http://www.etymonline.com/index.php?allowed_in_frame=0&search=fluid&searchmode=none (last access: 12 December 2014). 2. GDT (last access: 12 December 2014). 3. TERMIUM PLUS (last access: 12 December 2014).

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CR: geothermal energy, geothermics.