Modelling and dimensioning of circular food production systems fed by geothermal energy: Aquaponics

The ongoing global push for sustainable food production has motivated both the greenhouse horticulture and aquaculture sectors to explore the potential of geothermal energy for heating as an alternative to fossil fuels. Greenhouses and fish farms experience distinct heat demand fluctuations throughout the year and therefore do not make consistent use of geothermal wells. Geothermal wells on the other hand, need to operate close to full capacity year-round to be profitable. An opportunity to improve the economic feasibility of geothermal heating infrastructure is to use circular food production systems, such as aquaponics, which can be operated as a thermal treatment network in order to increase heat extraction from geothermal well installations. The EU funded GEOFOOD project aims to analyze in detail how to optimise the design and operation of geothermal aquaponic facilities. To quantify the potential benefits, a predictive model was developed which simulates the heat balances present throughout the aquaponic-based thermal treatment network. The inputs include the relevant climate parameters of the location, the type of greenhouse/building for both facilities including climate control equipment, as well as crop and fish species. For a scenario considering a 5-ha Dutch tomato greenhouse it is found that geothermal heat extraction can be increased with 31% by combining it with an indoor pike-perch fish farm of 6544 m², without the need of alternative energy sources during peak demands.