In densely populated countries there is a growing and compelling need to use underground for different and possibly coexisting technologies to produce ‘‘low carbon’’ energy. These technologies include (i) clean coal combustion merged with CO2 Capture and Storage (CCS); (ii) last-generation nuclear power or, in any case, safe nuclear wastes disposal, both ‘‘temporary’’ and ‘‘geological’’ somewhere in Europe (at least in one site): Nuclear wastes are not necessarily associated to nuclear power plants; (iii) safe natural gas (CH4) reserves to allow consumption also when the foreign pipelines are less available or not available for geopolitical reasons and (iv) ‘‘low-space-consuming’’ renewables in terms of Energy Density Potential in Land (EDPL measured in [GW h/ha/year]) as geothermics. When geothermics is exploited as low enthalpy technology, the heat/cool production could be associated, where possible, to increased measures of ‘‘building efficiency’’, low seismic risks building reworking and low-enthalpy heat managing. This is undispensable to build up ‘‘smart cities’’. In any case the underground geological knowledge is prerequisite. All these technologies have been already proposed and defined by the International Energy Agency (IEA) Road Map 2009 as priorities for worldwide security: all need to use underground in a rational and safe manner. The underground is not renewable in most of case histories [10,11]. IEA recently matched and compared different technologies in a unique ‘‘Clean Energy Economy’’ improved document (Paris, November 16–17, 2011), by the contribution of this vision too (see reference). In concert with ‘‘energy efficiency’’ improvement both for plants and buildings, in the frame of the ‘‘smart cities’’ scenarios, and the upstanding use of ‘‘energy savings’’, the energetic planning on regional scale where these cities are located, are strategic for the year 2050: this planning is strongly depending by the underground availability and typology. Therefore, if both literature and European Policy are going fast to improve the concept of ‘‘smart cities’’ this paper stresses the concept of ‘‘smart regions’’, more strategic than ‘‘smart cities’’, passing throughout a discussion on the synergic and conflicting use of underground to produce energy for the ‘‘smart regions’’ as a whole. The paper highlights the research lines which are urgent to plan the soundest energy mix for each region by considering the underground performances case by case: a worldwide mapping, by GIS tools of this kind of information could be strategic for all the ‘‘world energy management’’ authorities, up to ONU, with its Intergovernmental Panel on Climate Change (IPCC), the G20, the Carbon Sequestratio

Soil surveys were performed in Medolla (Italy), a peculiar area characterized by spotty high soil temperature, gas vent, and lack of vegetation, to determine the migration mechanisms and spatial behavior of gas species. Hereby we present soil gas measurements and their isotopic ratios measured between 2008 and 2015, including the 2012 Emilia-Romagna seismic sequence. We found that soil gas concentrations markedly changed during the main shocks of May 20 and 29, 2012 (Mw 6.1 and 6.0, respectively), highlighting the presence of a buried fault intersecting the gas vents. We suggest that crustal dilation associated with seismic activity favored the uprising of geogas towards the surface. Changes in the isotopic signature highlight the contribution of two distinct sources, one deeper, thermogenic and another superficial related to organic-rich layer, whose relative contribution varied before, during and after the earthquake. We suppose an increase of microbial component likely due to the ground shaking of shallower layers linked to seismic sequence, which masks the thermogenic contribution. Although the changes we detect are specific for an alluvial plain, we deduce that analogous processes may be active elsewhere, and that soil gas geochemistry represents an useful tool to discriminate the gas migration related to seismic activity.