Synergic and conflicting issues in planning underground use to produce energy in densely populated countries, as Italy Geological storage of CO2, natural gas, geothermics and nuclear waste disposal

AbstractIn 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 [GWh/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 Sequestration Leadership Forum (CSLF) and the European Platforms such as the “Zero Emissions Fossil Fuel Power Plants” (EU-ZEP Platform), the Steel Platform, the Biomass Platform too. All of these organizations agree on the need for synergistic and coexistent uses of underground for geological storage of CO2, CH4, nuclear waste and geothermic exploitation.The paper is therefore a discussion of the tools, methods and approaches to these underground affecting technologies, after a gross view of the different uses of underground to produce energy for each use, with their main critical issues (i.e. public acceptance in different cases).The paper gives some gross evaluation for the Lazio Region and some hints from the Campania Region, located in Central Italy. Energy Density Potential in Land (EDPL), is calculated for each renewable energy technology (solar, wind, geothermal) highlighting the potentiality of the last.Why the Italian case history among the densely populated countries? on the Italian territory is hard to find suitable areas (mostly if greenfields) to use the own underground, with respect to other European countries, due to the presence of seismotectonic activity and many faulted areas characterized by Diffuse Degassing Structures (DDSs, which are rich in CO2 and CH4). In this cases, public acceptance must be facilitated by the concerted efforts of researchers, universities, NGOs and policy-makers

Geothermal Potential Evaluation for Northern Chile and Suggestions for New Energy Plans

Chile is a country rich in natural resources, and it is the world’s largest producer and exporter of copper. Mining is the main industry and is an essential part of the Chilean economy, but the country has limited indigenous fossil fuels—over 90% of the country’s fossil fuels must be imported. The electricity market in Chile comprises two main independent systems: the Northern Interconnected Power Grid (SING) and the Central Interconnected Power Grid (SIC). Currently, the primary Chilean energy source is imported fossil fuels, whereas hydropower represents the main indigenous source. Other renewables such as wind, solar, biomass and geothermics are as yet poorly developed. Specifically, geothermal energy has not been exploited in Chile, but among all renewables it has the greatest potential. The transition from thermal power plants to renewable energy power plants is an important target for the Chilean Government in order to reduce dependence on imported fossil fuels. In this framework, the proposed study presents an evaluation of the geothermal potential for northern Chile in terms of power generation. The El Tatio, Surire, Puchuldiza, Orriputunco-Olca and Apacheta geothermal fields are considered for the analysis. The estimated electrical power is approximately 1300 MWe, and the energy supply is 10,200 GWh/year. This means that more than 30% of the SING energy could be provided from geothermal energy, reducing the dependence on imported fossil fuels, saving 8 Mton/year of CO2 and supplying the mining industry, which is Chile’s primary energy user

Biogeochemical and microbial community structure differently modulates CO2 and CH4 dynamics in two adjacent volcanic lakes (Monticchio, Italy)

By hosting significant amounts of extra-atmospheric dissolved gases, including geogenic CO2 and CH4, volcanic lakes provide relevant ecosystem services through the key role the aquatic microbial community in mediating freshwater carbon fluxes. In view of elucidating the mechanisms governing the microbial spatial distribution and the possible implications for ecosystem functioning, we compared the hydrogeochemical features and the microbial community structure of two adjacent stratified volcanic lakes (Lake Grande - LG and Lake Piccolo - LP). Water chemistry, gases and their isotopic composition were coupled with microbial pigment profiling, cell counting, and phylogenetic analyses. LP showed transparent waters with low concentrations of chlorophyll-a and the occurrence of phycoerytrin-rich cyanobacteria. LG was relatively more eutrophic with a higher occurrence of diatoms and phycocyanine-rich cyanobacteria. Considering the higher concentrations of CO2 and CH4 in bottom waters, the oligotrophic LP was likely a more efficient sink of geogenic CO2 in comparison to the adjacent eutrophic LG. The prokaryotic community was dominated by the mixothrophic hgcI clade (family Sporichthyaceae) in the LG surface waters, while in LP this taxon was dominant down to -15 m. Moreover, in LP, the bottom dark waters harbored a unique strictly anaerobic bacterial assemblage associated with methanogenic Archaea (i.e. Methanomicrobiales), resulting in a high biogenic methane concentration. Water layering and light penetration were confirmed as major factors affecting the microbial distribution patterns. The observed differences in the geochemical and trophic conditions reflected the structure of the aquatic microbial community, with direct consequences on the dynamics of dissolved greenhouse gases

The Unconventional Geothermal Resources: Features and Current Uses

The geotliernml systems can be distinguished as conventional and unconventional resources. The conventional geothermal systems are composed o essential elements, such as a heat source, a reservoi with a geotherrrial fluid and a caprock. The heat source can be a magmatic chamber or volcanic bodies which are both generally located in areas north crustal thinning and mantle uprising phenomena. In the last two decades, non-conventional geothermal systems, such as enhanced geothermal systems, magma systems with supercritical fluids and geopressured systems have been also explored. This chapter provides a description of the above mentioned unconventional geothermal systems. The chapter is divided in three main paragraphs, starting from the enhanced geothermal systems to conclude with the geopressures systems. Geological features, case studies and current uses of each one are highlighted.rth the resumed systems. The final part of the chapter has been dedicated to a special case study relative to production of geothermal energy with co-produced resources.Published1TR. Studi per le Georisors

Geothermal favourability mapping by advanced geospatial overlay analysis: Tuscany case study (Italy)

The geothermal resource exploration generally requires a combined analysis of various geo-information datasets. In this framework the geospatial analysis as the weighted overlay, performed under GIS (Geographic Information Systems) environment, represent a strong tool to solve problems such as the site selection. This technique is applied on not homogeneous input data to perform an integrated analysis and producing favourability maps. This work is based on the development of a new weighted overlay scheme, that combines favourable geological factors, which allow the identification of hydrothermal geothermal resources, and geological hazards (seismicity and volcanism), which can potentially limit the exploitation of a geothermal resource. The technique was tested on Tuscany Region (Italy), where two geothermal fields, Larderello-Travale/Radicondoli and Monte Amiata, are in operation. Results show that the most promising areas mostly coincide with the exploited geothermal fields. Moreover, new areas with a high geothermal favourability are identified. Low-cost and rapid resource evaluation approaches like this could play a key role during the early stages of a geothermal exploration plan. Moreover, this methodology could be extensively used in other geothermal areas not only by the scientific community but also by stakeholders, as first concrete tool to explore a potential resource suitable for exploitation.Published1377-13871TR. Studi per le GeorisorseJCR Journa

Evaluation of the Theoretical Geothermal Potential of Inferred Geothermal Reservoirs within the Vicano–Cimino and the Sabatini Volcanic Districts (Central Italy) by the Application of the Volume Method

The evaluation of the theoretical geothermal potential of identified unexploited hydrothermal reservoirs within the Vicano–Cimino and Sabatini volcanic districts (Latium region, Italy) has been made on the basis of a revised version of the classical volume method. This method is based on the distribution of the partial pressure of CO2 (pCO2) in shallow and deep aquifers to delimit areas of geothermal interest, according to the hypothesis that zones of high CO2 flux, either from soil degassing and dissolved into aquifers, are spatially related to deep hydrothermal reservoirs. On the whole, 664 fluid discharges (cold waters, thermal waters, and bubbling pools) have been collected from shallow and deep aquifers in the Vicano–Cimino Volcanic District and the Sabatini Volcanic District for chemical and isotopic composition, in an area of approximately 2800 km2. From this large hydro-geochemical dataset the pCO2 values have been computed and then processed to obtain a contour map of its spatial distribution by using geostatistical techniques (kriging). The map of pCO2 has been used to draw up the boundaries of potentially exploitable geothermal systems within the two volcanic districts, corresponding to the areas where endogenous CO2 raise up to the surface from the deep hydrothermal reservoirs. The overall estimated potential productivities and theoretical minimum and maximum thermal power of the two volcanic districts are of about 45 103 t/h and 3681–5594 MWt, respectively. This makes the Vicano–Cimino Volcanic District and the Sabatini Volcanic District very suitable for both direct and indirect exploitation of the geothermal resources, in view of the target to reduce electricity generation from conventional and poorly sustainable energy sourcesPublished1421TR. Studi per le GeorisorseJCR Journa

Preliminary chemical characterization of groundwater in the Rome municipality.

In summer 2015 a geochemical survey on groundwater was carried out at 31 sampling points (wells and piezometers) belonging to the new “Official monitoring groundwater network of Rome Municipality” (GMNR). The following parameters were measured: temperature, pH, electrical conductivity (i.e. salinity) and alkalinity; these data were used to compute partial pressure of CO2 (pCO2). Furthermore, samples were collected to characterise waters from a chemical point of view (major elements). To implement our data - base, chemical analyses of 6 CO2 - rich mineral waters of Rome were considered. Hydrochemical survey was mainly devoted to: i) classify waters in chemical facies; ii) investigate the main water-rock interaction processes governing the water’s chemical evolution, also affected by variable amounts of dissolved CO2 and iii) define the pCO2 level in groundwater in the frame of the knowledge so far acquired in the Tyrrhenian sector of central Italy.. Groundwater shows a dominant Ca-HCO3 chemistry; some samples belong to Na-HCO3, Na-Cl and CaCl2 hydrochemical facies. In the dominant facies waters show a large variability in the abundance of chemical elements, in their salinity (ranging between 0.46 e 3.83 g/l) and pH (in the interval 5.87-7.22); these features are mainly due to different water-rock interaction processes together with the presence of variable CO2 contents. Na-HCO3 waters show the lowest salinity values (TDS up to 0.32 g/l) and strongly alkaline pH; cation exchange processes with clays, causing Na enrichment and Ca and Mg removal from solution, can be invoked to justify the observed chemistry. Waters of the Castel Fusano Natural Reserve (CFNR) belong to the Na-Cl and Ca-Cl2 facies; the different chemistry reflects the geochemical processes going on in the considered coastal aquifers such as: i) mixing between freshwater and saline waters of marine origin (fossil waters, seawater intrusion) and ii) cationic exchanges with clays that make up the less permeable sediments of the area. Two samples of the CFNR group have Ca-HCO3 chemistry and represent aquifers not affected by salinization processes. Calculated pCO2 distribution is highly variable, from low (0.03 bar) to high values (0.72 bar), implying different CO2 input (and origin) in the studied aquifers. Highest levels of carbon dioxide are linked to the degassing processes going on in the Tyrrhenian sector of Central Italy.Published47-576A. Geochimica per l'ambiente e geologia medicaN/A or not JC

The 220Rn/222Rn ratio to characterize the post-earthquake near-surface crustal deformation within the framework of probabilistic plant risk assessment

Earthquake-induced permanent ground deformation can significantly impact the safety of industrial plants. In particular, the frequency of occurrence of secondary faults, especially far from the primary structures, should be considered in order to not underestimate the true distribution of faulting after a major earthquake. During April 2009, a Mw 6.3 earthquake occurred in the Abruzzo region (Central Italy), close to the city of L’Aquila. Soon after the main shock, a soil gas survey was carried out performing 222Rn and 220Rn, soil and flux gas measurements. Results highlighted the spatial influence of active tectonic on gas migration toward the surface. Anomalous soil gas values were found at major faults and even where there were no faults known in literature. During summer 2015, the soil gas survey was repeated in order to both assess the natural degassing in absence of seismic events and quantify the spatial domain of tectonic discontinuities inferred during the previous campaign. The comparison of results from the two surveys highlights that soil permeability strictly depends on seismic stress variations. The changes in the 220Rn/222Rn ratio observed during the two surveys suggest a higher gas flow rate induced by the changes in the vertical permeability of soil and, presumably, in the structural assessment. This would indicate that the crustal deformation fields that result from large earthquake may cause post-seismic fault displacement especially on secondary tectonic structures contributing significantly to the seismic hazard of probabilistic nuclear, geothermal, CO2 storage or, in wider terms, industrial plants.UnpublishedBarcelona - Spain4T. Sismicità dell'Itali

Influence of tectonics on global scale distribution of geological methane emissions

Earth's hydrocarbon degassing through gas-oil seeps, mud volcanoes and diffuse microseepage is a major natural source of methane (CH4) to the atmosphere. While carbon dioxide degassing is typically associated with extensional tectonics, volcanoes, and geothermal areas, CH4 seepage mostly occurs in petroleum-bearing sedimentary basins, but the role of tectonics in degassing is known only for some case studies at local scale. Here, we perform a global scale geospatial analysis to assess how the presence of hydrocarbon fields, basin geodynamics and the type of faults control CH4 seepage. Combining georeferenced data of global inventories of onshore seeps, faults, sedimentary basins, petroleum fields and heat flow, we find that hydrocarbon seeps prevail in petroleum fields within convergent basins with heat flow ≤ 98 mW m-2, and along any type of brittle tectonic structure, mostly in reverse fault settings. Areas potentially hosting additional seeps and microseepage are identified through a global seepage favourability model.Published23056A. Geochimica per l'ambiente e geologia medicaJCR Journa