Very shallow geothermal system for energy efficiency in dairy barns

In dairy farms, energy is used in several activities, one of the most energy consuming phase is the milk cooling. This operation, necessary to guarantee the safety of the product, takes place in cooling tanks powered by electric energy. On the other hand, farms must provide large amount of water for cow daily drinking needs. The water is usually supplied by natural wells or aqueduct, in some cases water temperature can be so low that cows are discouraged from drinking, with consequent risks for animal health and production losses. For this reason, a few heat exchangers have been designed to pre-cool milk, taking advantage from cow drinking water and allowing considerable milk temperature reduction and slight water temperature increase. Even though this operation cannot replace cooling tanks, it reduces the energy needs. Recent studies have shown the potentialities of the application of shallow geothermal systems to food processing buildings aimed at energy efficiency. Shallow geo-exchangers configurations can be used to dissipate excessive heat in the ground. Unfortunately, the dissipation potential of the ground is limited, so a large number of geo-exchangers is usually necessary, with related high cost and need of space. A newly developed configuration of spiral geo-exchangers with double circuit could tackle this issue, by dissipating the heat partially to the ground and partially to a secondary fluid. For the specific case of barns, a double advantage should be expected since the waste fluid (water), heated up, can be used as cow drinking water. The aim of this work is to assess the potentialities of the application of the system in a dairy farm. The study uses experimental data from a thermal response test campaign carried on a shallow geothermal system and data for water consumptions of a farm located in Bologna countryside (Italy).