Accelerating The Sustainability In Agricultural Sector Using Geothermal Water: The Utilization of Treated Geothermal Water For Lettuce Cultivation

The Agri-food industry consumes roughly one-third of all global energy production, with an estimated 12% used for crop production and nearly 80% for processing, distribution, retail, preparation, and cooking (FAO, 2010). Moreover, the agri-food chain accounts for 80-90% of total global freshwater use, where 70% alone is for irrigation. In this regard, the rational management of water, energy, and food security should be secured (availability, accessibility, and quality) and achieved sustainably. Therefore, this project aims to introduce a novel approach that integrates low-enthalpy geothermal resources as a source of energy and irrigated water for the agricultural sector. The study is part of a bilateral research project funded by NCBiR (Poland) and Tübitak (Turkey). The experiment on lettuce cultivation using soil and hydroponic systems were realized at the greenhouses of the geothermal laboratory of PAS MEERI in Bańska Niżna, Poland. Geothermal water used in the experiment characterize as SO4-Cl-Na-Ca and have mineralization of about 2.3 g/L, which needs to be treated before its utilization for irrigated water. Therefore the UF/RO water treatment facility fitted with a typical industrial plant component is used to desalinate the geothermal water. In this experiment, we used five types of lettuce, namely: Lactuca sativa var. crispa (lollo rosa), Lactuca sativa var. capitata (butterhead Michalina), Lactuca sativa var. capitata (iceberg), Lactuca sativa var. capitata (butterhead bona), Lactuca sativa var. capitata (butterhead Justyna). To study the influence of the percentage of treated geothermal water in lettuce cultivation, we proposed three different variants of water: (1) a mix of 100% treated geothermal water with nutrients, (2) a mix of 30% of tap water and 70% treated water with nutrients, and (3) a mix of 10% of raw geothermal water with 90% of treated water and nutrients. The experiment lasted for a month, and the pH, humidity, EC, and temperature were constantly controlled and measured. Moreover, the physical-chemical analysis of irrigation water, lettuce leaves and soil will be presented. Comparing the acquired physical-chemical data with the US Department of Agriculture data revealed that the number of microelements (Cr, Fe, Mn, Ni, Pb, Zn) and macroelements (Ca, K, Mg, P) in the plants is within the recommended value. Moreover, the analysis of other elements such as Hg, As, B, and Cd is also in the permissible value. The result highlights the beneficial effect of using geothermal water for lettuce cultivation in geothermal greenhouse plants. For a comprehensive study, an analysis of energy, environmental and economic aspects will be presented as well. The study validated that the untapped source of geothermal brine utilization will significantly accelerate the sustainable, clean, and renewable energy transition, especially for the sustainability of the agri-food chain in the world.

Acknowledgements These studies are realized by an international research project funded by NCBR (Project POLTUR3/Geo4Food/4/2019) and TÜBITAK (118Y490), 2019-2022.