Geothermal heat pumps for sustainable farm climatization and field irrigation

In intensive breeding farms, maintaining an adequate indoor thermal environment and air quality is cru-cial in order to establish healthy conditions and increase productivity. In the EU, fossil fuels and electricityare the main energy sources adopted for this purpose, yet introducing renewable energy sources andefficient Heating Ventilating Air Conditioning systems would reduce energy consumption and improvesustainability.Another environmental concern in agricultural production is related to the intensive use of fertilizers,causing nitrate contamination in surface water and groundwater. Therefore, innovative strategies toreduce fertilizers and simultaneously reduce primary energy consumption are worthy of investigation.This paper addresses both issues, studying the application of geothermal heat pumps in the agro-zootechnical sector, where they are rarely applied and thus their potential needs to be verified. The studyconsiders systems based on the closed loop configuration, i.e. Ground Source Heat Pumps (GSHP), andon the open loop configuration, i.e. Groundwater Heat Pumps (GWHP).Firstly, a pilot GSHP system for a piglet stable in Northern Italy is presented. Thanks to the use of bothground source and thermal recovery of air ventilation, the system achieves an appreciable reduction inboth primary energy consumption and running costs, compared with a more traditional system typicallyadopted in this kind of farm.Secondly, the feasibility of an innovative concept of a GWHP combined with the irrigation system isstudied through numerical modelling. The area of the piglet stable is represented in a flow and heat trans-port model; groundwater used by the heat pump is re-injected up-gradient during the cold season, whileit is used for irrigation during the warm season. The system would provide energy-efficient climatizationto the farm stables and, at the same time, promote the reuse of nitrogen in cultivated fields as a result ofgroundwater recirculation through irrigation.