Abstract: . . .  different types of such processes as mentioned in point b) of previous chapter, generally speaking we can say that: • conduction-dominated systems (HDR, for instance) may become in the future a sustainable energy source, but do not meet the requirements of a renewable resource; • convection-dominated systems are a sustainable energy source (at a sustainability level, though, different from case to case), but in few places only represent a renewable resource; • hydrothermal systems in areas where active igneous processes occur at shallow depth meet the requirements of being both a sustainable and a renewable resource; • magma systems may become in the future a sustainable and renewable . . .
. . .  Peccei (1972). (Italian version, 2nd edition). Edizioni Scientiche e Tecniche Mondadori, Milan (Italy). [5] International Geothermal Association (IGA), (2001). Clean Power from the Heart of the Earth. Paper presented at the IX Session of the UN Commission on Sustainable Development (16-27 April, 2001); New York (USA). In press. [6] Muffler P. and Cataldi R. (1978). Methods for Regional Assessment of Geothermal Resources. Geothermics, Vol. 7, pp. 53-89; Pisa (Italy).  . . .
. . .  may differ notably from case to case. 2. Renewability (natural resupply of heat), solely depends on deep geological processes, which are beyond any human control. 3. Sustainability and renewability thus reflect different concepts; nonetheless, they are interdependent from each other in that the level of sustainability may affect the rate of renewability, and viceversa, especially when massive quantities of heat are tapped in high-temperature areas. 4. Heat-extraction rate in a given area is in most cases much higher than heat-resupply rate. As a consequence, a notable deficit generally occurs in the total input-output heat balance. 5. On the other hand, since exploitation times of . . .
. . .  Scientiche e Tecniche Mondadori, Milan (Italy). [5] International Geothermal Association (IGA), (2001). Clean Power from the Heart of the Earth. Paper presented at the IX Session of the UN Commission on Sustainable Development (16-27 April, 2001); New York (USA). In press. [6] Muffler P. and Cataldi R. (1978). Methods for Regional Assessment of Geothermal Resources. Geothermics, Vol. 7, pp. 53-89; Pisa (Italy).  . . .
--2752,4,344,2555,13758