Articles
Exploring the possibility to use energy from solar panels to provide artificial light through LEDs in a vertical hydroponic crop of lettuce
Article number
1296_120
Pages
943 – 950
Language
English
Abstract
One of the biggest challenges of vertical farming is to minimize the energy cost of production while maintaining the quality of the products.
In the current study, a hybrid-solar lighting vertical farming system, powered by photovoltaics during the sunny hours, without using any inverters or converters, that automatically switches to the main power grid during dark hours, named PHOTON RACK (PR), constructed jointly from DEKOULIS LAB and the Agricultural University of Athens, was tested.
To test the efficiency of the system, butterhead lettuce (Lactuca sativa L. Glory) was cultivated by applying the following four treatments: A) high light intensity treatment (HLI) in the upper layer of the PR, consisting of 16 hybrid-solar LED tubes which were powered by two 400 W photovoltaic panels providing 310 μmol m‑2 s‑1 irradiance; B) the PR lower layer, the same as above but powered solely by the main electricity grid; C) the PR intermediate layer, low light intensity treatment (LLI), with 8 LED tubes providing 188 μmol m‑2 s‑1 irradiance.
All PR layers were operated under a 12 h day‑1 photoperiod; D) hydroponic cultivation in recirculating nutrient solution (NFT) in a glasshouse (GH) with an average of 144 μmol m‑2 s‑1 irradiance and a 10 h day‑1 photoperiod.
The upper layer consumed 4.5 times less energy than the lowest layer.
The plants exposed to HLI had a standard morphology whereas those exposed to LLI had a strong shade avoidance-like appearance.
Root and shoot fresh weight, leaf number and area, chlorophyll level, photochemical yield of photosystem II (ΦPSII), photochemical quenching (qP) and real evapotranspiration (ETR) were significantly higher in the HLI treatment.
Leaf nitrates were similar in all PR treatments and significantly lower than in the GH. In conclusion, the HLI hybrid-solar of the PR was capable of minimizing electricity cost while producing safe for consumption lettuce.
In the current study, a hybrid-solar lighting vertical farming system, powered by photovoltaics during the sunny hours, without using any inverters or converters, that automatically switches to the main power grid during dark hours, named PHOTON RACK (PR), constructed jointly from DEKOULIS LAB and the Agricultural University of Athens, was tested.
To test the efficiency of the system, butterhead lettuce (Lactuca sativa L. Glory) was cultivated by applying the following four treatments: A) high light intensity treatment (HLI) in the upper layer of the PR, consisting of 16 hybrid-solar LED tubes which were powered by two 400 W photovoltaic panels providing 310 μmol m‑2 s‑1 irradiance; B) the PR lower layer, the same as above but powered solely by the main electricity grid; C) the PR intermediate layer, low light intensity treatment (LLI), with 8 LED tubes providing 188 μmol m‑2 s‑1 irradiance.
All PR layers were operated under a 12 h day‑1 photoperiod; D) hydroponic cultivation in recirculating nutrient solution (NFT) in a glasshouse (GH) with an average of 144 μmol m‑2 s‑1 irradiance and a 10 h day‑1 photoperiod.
The upper layer consumed 4.5 times less energy than the lowest layer.
The plants exposed to HLI had a standard morphology whereas those exposed to LLI had a strong shade avoidance-like appearance.
Root and shoot fresh weight, leaf number and area, chlorophyll level, photochemical yield of photosystem II (ΦPSII), photochemical quenching (qP) and real evapotranspiration (ETR) were significantly higher in the HLI treatment.
Leaf nitrates were similar in all PR treatments and significantly lower than in the GH. In conclusion, the HLI hybrid-solar of the PR was capable of minimizing electricity cost while producing safe for consumption lettuce.
Publication
Authors
D. Savvas, O. Voutsinos, M. Mastoraki, G. Liakopoulos, K. Dekoulis, G. Ntatsi
Keywords
artificial lighting, hydroponics, plant factories, soil-less culture, vertical farming
Groups involved
- Division Precision Horticulture and Engineering
- Division Greenhouse and Indoor Production Horticulture
- Working Group Organic Greenhouse Horticulture
- Working Group Protected Cultivation, Nettings and Screens for Mild Climates
- Working Group Light in Horticulture
- Working Group Vegetable Grafting
- Working Group Computational Fluid Dynamics in Agriculture
- Working Group Mechanization, Digitization, Sensing and Robotics
- Working Group Modelling Plant Growth, Environmental Control, Greenhouse Environment
- Working Group Greenhouse Environment and Climate Control
- Working Group Design and Automation in Integrated Indoor Production Systems
- Commission Agroecology and Organic Farming Systems
- Division Landscape and Urban Horticulture
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