| Abstract |
In another paper presented at this Congress, we have dealt with estimations made by UGI on development of geothermal energy in Italy till 2030. We have stated there that, by only harnessing hydrothermal systems at T>90 °C within 5 km depth, geothermal power generation may reach 1500 MWe and 9.5 TWh/yr in 2030, at most. We have also said that such figures would attain 2000 MWe and 12 TWh/yr by 2030, if unconventional geothermal systems (HDR/HFR/EGS, magmatic systems, geopressurized systems, supercritical fluids, and hot brines) were exploited commercially starting from early 2020. Moreover, in that paper, we have pointed out that unconventional geothermal systems are much more widespread in Italy than high- and moderate-temperature hydrothermal systems, so that their resources within 5 km depth are also notably higher than those harnessable from hydrothermal reservoirs. In consideration of the above, after recalling what unconventional geothermal systems are, and where they can be found in Italy, this paper explains why all of them should be studied at the same time. The priority areas for possible development of these systems extend over 5÷10,000 km2. Their aggregate potential resources for power generation by 2050 are estimated in the range of 200÷500 GWe/yr which, for power plants operating at full load for 50 years and for 6,000 hours/yr, correspond to 4÷10,000 MWe of installed capacity and to 25÷60 TWh/yr of generation. These values include the 500 MWe and the 3 TWh/yr max. indicated in the above-mentioned paper for unconventional geothermal systems by 2030, and add to the capacity and generation which could be obtained from conventional high- and moderate-temperature reservoirs by the same year. The estimation of the extractable resources in the above priority areas emphasizes that, only by harnessing a fraction of the energy stored in unconventional geothermal systems, Italian geothermal generation can take a leap of one order of magnitude higher than the one at Dec. 2010 (882.5 MWe and 5.34 TWh/yr). However, UGI also made the following considerations: i) the technological maturity of the geothermal systems under review requires at least 7-8 additional years of experimental work; ii) some of them overlap or are coalescent with each other at depth in the same area; and iii) some important high-temperature areas are subject to environmental constraints. Consequently, UGI feels that, in Italy, only a large-scale and coordinated R&D Project targeted at unconventional geothermal systems can create the technical pre-requisites to harness their energy potential at industrial scale. The core of the “Project” envisages drilling of 10-20 deep wells (4-5 km) located in geologically different sites, aimed at conducting comparative studies of the geothermal conditions in each area, including (but not limited to) long-term production tests of natural or stimulated reservoirs in order to investigate their behavior under different conditions of fluid extraction |