Epsilon Archive for Student Projects

Abstract

Hydroponic production of vegetables is both resource and land efficient which gives the potential to manage some of the worlds many pressing issues, such as water scarcity, shrinking arable land and a need for sustainable food production (Kumar et al. 2024). Several of the United Nations sustainable development goals (SDG’s), for example 2 “Zero hunger” and 13 “climate action”, can be connected to the development and use of hydroponics. This by potentially enhancing food security, especially in places with high environmental stress and in densely populated areas while reducing crop productions climatic impact (Ngcobo et al. 2024). However, these controlled environment productions use a lot of energy consuming elements (Kumar et al. 2024). This is problematic in a world where energy prices are rising and most energy sources come from non-renewable resources (Ritchie et al. 2024). The main energy consumer in hydroponic greenhouse production is heating and cooling (Liantas et al. 2023). In this experiment two vertical hydroponic systems were set up in a temperature regulated growing chamber. One of the systems was integrated with a localized cooling system and one without. The aim was to improve the hydroponic systems performance in terms of productivity and energy use efficiency. This by providing a more beneficial microclimate enhancing plant growth and regulate the temperature on a smaller scale. The chosen crop was the lettuce, Batavia salad 'Lollo Rossa', Lactuca sativa, the chamber was set to 25℃ and the cooling system 17℃ During eight weeks data was collected on microclimatic variables to evaluate the localized cooling system. Statistical tests in the form of a two-way t-test and Pearson’s correlation test were done at the end of the experiment. A statistical difference in fresh and dry weight was registered at the end of the experiment, where the system without the cooling system had higher values in both categories. This was contradictory to the stated hypothesis that implementing localized air distribution in a vertical system would improve its performance in terms of productivity and energy use efficiency. However, no statistical differences were found between the systems regarding temperature measured with data loggers during the growing period, or of the leaf temperature measured with an Infrared (IR) camera. The similarity in temperature between the systems can be explained by the measurements done on the outflow air in the cooling system, also using the IR camera. This showed a rise in temperature from bottom to top, indicating insufficient cooling. The lower fresh weight in the system with the integrated cooling most likely derived from indirect stress factors induced by the constant airflow. This work highlighted the linkage between different growth variables and even if the temperature regulations systems can be modified to lower energy consumption the other parts must also work together to maximize yield and lower the resource use efficiency necessary to achieve sustainability.