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Although its use is declining, oil heating is still used in areas not covered by the methane grid. Oil heating is becoming more and more expensive, requires frequent tank refill operations, and has high emissions of greenhouse gas (GHG) and air pollutants such as SOx. In addition, spills from oil underground storage tanks (USTs) represent a serious environmental threat to soil and groundwater quality. In this paper, we present a comprehensive analysis on technical alternatives to oil heating with reference to the Aosta Valley (NW Italy), where this fuel is still often used and numerous UST spills have been reported in the last 20 years. We assess operational issues, GHG and pollutant emissions, and unit costs of the heat produced for several techniques: LPG boilers, wood boilers (logs, chips, pellets) and heat pumps (air-source, geothermal closed-loop and open-loop systems). We examine the investment to implement such solutions in two typical cases, a detached house and a block of flats, deriving payback times of about 3–8 years. Wood log boilers turn out to be the most economically convenient solutions; however, heat pumps provide several benefits from the operational and environmental points of view. In addition, including solar thermal panels for domestic hot water or a photovoltaic plant would have payback times of about 6–9 years. The results highlight the economic feasibility and the multiple benefits of a rapid phase-out of oil heating in Italy.

The study is developed through scientific cooperation between the University of Milano-Bicocca and the Regional Agency for Environmental Protection (ARPA) of the Valle d’Aosta Region. Its aim is to produce a decision-support tool to help the Public Administration’manage groundwater and public water supply. The study area is the plain of Aosta, between the cities of Aymavilles and Brissogne; in this area groundwater represents the main source of public water supply. The valley is oriented east-west, along the Baltea for a length of 13.1 km and a width of 4.6 km. The textural and hydrogeological properties of the deposits are strictly connected to glacial deposition and to the subsequent sedimentary processes which took place in glacial, lacustrine and fluvial systems. The study is based on available well information in the Aosta plain - including water wells (133) and piezometers (121) - which have been coded and stored in the well database TANGRAM,. The database facilitates interpretation of the well data, and it allows three-dimensional mapping of subsurface hydrogeological characteristics through database codification and ordinary kriging interpolation. The study is designed to achieve two objectives. The first is to provide the Aosta Public Authorities with a well database in order to simplify groundwater management. The second is to provide Public Authorities with a groundwater flow model of the local aquifer. The model integrates surface and subsurface flows in order to fully account for all important stresses, both natural and anthropogenic, on the groundwater system. It provides a tool for testing hypotheses (such as the impact of new wells) and thereby allows science-based management of the aquifer resource.

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