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AbstractThe efficiency of Geothermal Heat Pumps (GHPs) strongly depends on the site-specific parameters of the ground, which should therefore be mapped for the rational planning of shallow geothermal installations. In this paper, a case study is presented for the potentiality assessment of low enthalpy geothermal energy in the Province of Cuneo, a district of 6900 km2 in Piedmont, NW Italy. The available information on the geology, stratigraphy, hydrogeology, climate etc. were processed and mapped, and conclusions were drawn on the geothermal suitability and productivity of different areas of the territory surveyed.

AbstractThe possibility of recovering the heat ejected with the exhaust air arising from the aerobic conversion of organic waste for feeding a micro organic Rankine cycle (ORC) was investigated. This heat was upgraded by the combustion of a given amount of solid recovered fuel (SRF). The exhaust air rate ejected by the aerobic process ranged from 40 to 95kg/day per each tonne/day of waste processed and the temperature ranged, respectively, from 340K to 330K. Calculations refer to a typical aerobic treatment facility able to process 20,000 tonnes of organic waste per year. Maximum efficiency in the utilization of the heat produced by the combustion of SRF, ranging from 14% to 22%, was achieved for ORC operating at a compression ratio from 1.5 to 2.5 and exhaust air temperatures from about 340 to 350K. Operating the ORC with compression ratios higher than 3.5 and exhaust air temperatures of about 510K, the power output ranged from about 9 to 12kW. In these conditions, for the size of the facility investigated, the efficiency of the utilization of the heat generated by the combustion of SRF was from 4% to 7% higher than the ORC thermodynamic efficiency.

AbstractHydrological uncertainty due to daily flow variability and to the effect of climate change on water resources is a critical topic in the feasibility evaluations of hydro-power projects, especially for run-of-river power plant.The effect produced by these factors on the annual energy output of such type of plant was investigated. Empirical methods to improve the performance of the plant are proposed, which enable the choice of the most suitable design flow (Qd) according to the hydrological features of the river, to the frequency of dry and wet years in the basin and to the target energy production.

AbstractResidual sludge coming from dimension stones working plants represents a problem for Stone Industries (cost connected to their landfilling); sludge as such can be used for environmental restoration of derelict land or in cement plants, according to Italian regulation. However it is also possible to think about their systematic treatment for the production of Secondary Raw Materials or “New Products”. To individuate possible different applications a geotechnical characterization was conducted on sludge as such and on different mixes. In detail the possibility of using them as products for dumps waterproofing and for land rehabilitation and reclamation is discussed.

Abstract The siting and design of a Tidal Energy Converter (TEC) require the characterization of the flow velocity field acting in terms of space and time, in order to assess the hydrodynamic forces, to calculate the structural loading and power capacity, also helping investment strategy and project financing. In this framework, the selection of the emplacement site is of paramount importance for optimizing efficiency of TEC. In this study, we propose site assessment procedures for emplacement of TEC machines, comparing a sea tidal site with two rivers ones. Sites differ each other from geomorphological characteristics. The Cook Inlet (South-Central Alaska) is a large subarctic estuary, which extends about 250 km from Anchorage bay to the Pacific Ocean. Tidally dominated currents control the hydrographic regime, with water levels and currents periodically influenced by tides from the Gulf of Alaska, which are significantly amplified as approaching Anchorage bay. The Chang Jiāng river (also named Yangtze, China) is the longest in Asia and the third in the world, with a huge flow rate. The Pearl River Estuary (China) has a length of about 70 km, a width of about 15 km and an average depth of about 4.8 m. It is deeper than 20 m in its eastern part, and discharges into a microtidal environment along the northern shelf of the South China Sea. The TEC performances have been compared in the three different geomorphological environments. Results show how TEC in rivers can perform up to 5.47 kW/m2, a huge value compared to the wide sea turbines, able to perform up to 10.76 kW/m2.

Abstract CH4 hydrates could represent a sustainable energy source by coupling their extraction to a CO2 replacement process. This permits a permanent CO2 storage in a solid phase and the reduction of the seabed modification due to the CH4 extraction. Promising methodologies for CO2 replacement are depressurization, thermal stimulation (or a combination of both), or the use of chemical inhibitors. We have taken into account thermal stimulation. The CH4 hydrates were formed with a pore saturation of 10%, whereas different concentration of gaseous CO2 were fluxed inside the reactor. In a first set of experiments, the CO2 concentration was fixed at values never higher than 15%, while in a second set the gaseous CO2/CH4 ratio was inverted. Two tests for each condition were performed. In all tests, the temperature was increased at the end, to improve the replacement process. Results demonstrated that the CO2 fluxed leads to hydrates formation and, at the same time, hinder the CH4 hydrates dissociation. Two parameters were evaluated: i) the ratio between the stored CO2 and the amount of CO2 injected (ηcapture), ii) the ratio between both CO2 and CH4 hydrates moles after the replacement process, and the CH4 hydrates moles before the replacement (ηentrapped). The assumed ηcapture value are 0.42 and 0.44 in the first conditions, and 0.27 and 0.28 in the second one. By contrast, the second parameter shows an opposite behavior, being the two values 0.13 for the first conditions and 0.27 and 0.74 respectively for the second ones. This could be explained by the fact that injection of higher quantity of CO2 produces a greater thickness of CO2 hydrates in the external parts of pores, which prevent the CH4 to flowing