Hydroponic Lettuce Research Articles

Seasonal occurrence and abundance of norovirus in pre- and postharvest lettuce samples in Nanjing, China

To assess the contamination of lettuce with norovirus in Nanjing city (China), two hundred and eighty one lettuce samples were collected between 2017 and 2018 from production sites (preharvest) and retail outlets (postharvest) and analyzed. The presence of norovirus was confirmed in 26.9% (71/264) of lettuce samples, with norovirus genogroup I detected more frequently (20.1%) than norovirus genogroup II. Norovirus was detected less frequently in lettuce samples from supermarkets (4.9%) than in samples from greengrocers or farmer markets (36.5%) and was detected both in field-grown (28.9%) and in hydroponic lettuce samples (30%). The norovirus occurrence and levels varied markedly by seasons. The norovirus was more frequently detected in the cold season, with evident correlations between norovirus contamination and ambient temperatures. Interestingly, the norovirus occurrence in loose lettuce was significantly higher (p < 0.05) than in packaged lettuce, highlighting that norovirus contamination might have occurred during lettuce production. The data of this study add to the currently limited body of information on norovirus occurrence in fresh produce in China, highlighting the need for implementation of effective food safety monitoring and management.

Effects of cutter parameters on shearing stress for lettuce harvesting using a specially developed fixture

To investigate the optimal parameters combination of reciprocating cutter for harvesting hydroponic lettuce automatically, a shear fixture was designed for cutting lettuce stems on a universal materials tester. Effects of blade distance, sliding cutting angle, skew cutting angle, and shearing angle on shearing stress were investigated in this study. The orders of the significance of a single factor and double factors were analyzed using the response surface methodology (RSM). A scanning electron microscope was used to observe the microstructure of the lettuce stem to analyze the shearing characteristics at the microscopic level. The RSM results showed that the order of significance for single factors was (i) sliding cutting angle, (ii) shearing angle, (iii) skew cutting angle, and (iv) blade distance. The sliding cutting angle had a highly significant influence on the shearing stress. The order of significance for double factors was (i) blade distance and shearing angle, (ii) sliding cutting angle and skew cutting angle, and (iii) the sliding cutting angle and shearing angle. A quadratic model of the factors and shearing stress was built according to the response-surface results. The optimized combination of factors that gives the minimum shearing stress was observed that it reduced 69.9% of the maximum shearing stress value. This research can provide a reference for designing lettuce-cutting devices. Keywords: Lactuca sativa, hydroponic lettuce, cutting, optimization, response surface method, micro-structure DOI: 10.25165/j.ijabe.20211404.6346 Citation: Cui Y J, Wang W Q, Wang M H, Ma Y D, Fu L S. Effects of cutter parameters on shearing stress for lettuce harvesting using a specially developed fixture. Int J Agric & Biol Eng, 2021; 14(4): 152–158.

Hydroponic Lettuce Cultivation Using Organic Nutrient Solution from Aerobic Digested Aquacultural Sludge

The aim of this study was to demonstrate how aquacultural sludge can be processed and utilized as an organic nutrient solution (ONS) for hydroponic lettuce production. By using a previous developed method, approximately 80% of the processed sludge was reclaimed as a clear, nutrient-rich solution. The performance of the recovered nutrient solution on lettuce growth was assessed in a nutrient film hydroponic system. The results were compared to the results obtained using a conventional nutrient solution (CNS). Yield, fresh weight, water consumption, and nutrient and heavy metal content in leaf tissue were measured. In spite of a 16% lower average fresh weight obtained in ONS compared to the weight obtained in CNS, there was no statistical difference of the yield of lettuce among the two nutrient solutions. After the cultivation period, 90% of the lettuce heads grown in ONS exceeded the marked weight of 150 g. Foliar analysis revealed a similar or higher content of all nutrients, except of magnesium and molybdenum in the leaves of lettuce grown in the ONS compared to lettuce grown in the CNS. This study shows that nutrients recovered from aquacultural sludge can be utilized as fertilizer, thereby reducing the dependency on mineral fertilizer in hydroponic and aquaponic systems.

Root-applied glycinebetaine decreases nitrate accumulation and improves quality in hydroponically grown lettuce

Leafy vegetables like lettuce (Lactuca sativa L.) naturally have high nitrate content and the European Commission has set maximum level for nitrate in lettuce. Glycinebetaine is an organic osmolyte alleviating plant stress, but its role in leaf nitrate accumulation remains unknown. The uptake of glycinebetaine by lettuce roots, and its potential to regulate lettuce nitrate content and improve plant quality were investigated. Two hydroponic lettuce experiments were conducted with different glycinebetaine application rates (Exp1: 0, 1, 7.5, and 15 mM; Exp2: 0, 1 + 1 + 1, 1 + 10, and 4 mM). Plants were analyzed at varying time points. Root application resulted in glycinebetaine uptake and translocation to the leaves. Glycinebetaine concentrations > 7.5 mM reduced leaf nitrate up to 40% and increased leaf dry matter content. Glycinebetaine showed a positive effect on leaf mineral and amino acid composition. Thus, glycinebetaine could be a novel strategy to reduce the nitrate content in hydroponic lettuce.

Root-Associated Bacterial Community Shifts in Hydroponic Lettuce Cultured with Urine-Derived Fertilizer.

Recovery of nutrients from source-separated urine can truncate our dependency on synthetic fertilizers, contributing to more sustainable food production. Urine-derived fertilizers have been successfully applied in soilless cultures. However, little is known about the adaptation of the plant to the nutrient environment. This study investigated the impact of urine-derived fertilizers on plant performance and the root-associated bacterial community of hydroponically grown lettuce (Lactuca sativa L.). Shoot biomass, chlorophyll, phenolic, antioxidant, and mineral content were associated with shifts in the root-associated bacterial community structures. K-struvite, a high-performing urine-derived fertilizer, supported root-associated bacterial communities that overlapped most strongly with control NPK fertilizer. Contrarily, lettuce performed poorly with electrodialysis (ED) concentrate and hydrolyzed urine and hosted distinct root-associated bacterial communities. Comparing the identified operational taxonomic units (OTU) across the fertilizer conditions revealed strong correlations between specific bacterial genera and the plant physiological characteristics, salinity, and NO3−/NH4+ ratio. The root-associated bacterial community networks of K-struvite and NPK control fertilized plants displayed fewer nodes and node edges, suggesting that good plant growth performance does not require highly complex ecological interactions in hydroponic growth conditions.

Comparison of growth characteristics, functional qualities, and texture of hydroponically grown and soil-grown lettuce

Hydroponics has become one of the most popular approaches in today's agricultural production. Yet it is questionable whether hydroponics produce vegetables with comparable quality to soil-grown vegetables. In this study, hydroponically and soil-grown lettuce were compared for morphology, texture, antioxidant capacity, and functional quality. Giant Caesar lettuce was grown in laboratory-constructed hydroponic or soil systems for 35 days. Above-ground plant size, biomass, and leaf size of hydroponic lettuce were not significantly different from soil-grown lettuce. Hydroponic lettuce had significantly (p < 0.05) longer roots, higher moisture and lower ash. No significant difference in ascorbic acid, chlorophyll, β-carotenes, and total phenolics was found in freeze-dried lettuce. However, all compounds analyzed were significantly higher in soil-grown lettuce based on fresh weight. Antioxidant capacity of soil-grown lettuce was significantly higher on both dry- (15.32%) and wet-basis (41.20%). Hydroponic lettuce had softer leaves and firmer midribs; potentially linked to increased lignin (24.18%) in plant cell walls. This represents the first comprehensive side-by-side growth study demonstrating that lettuce grown hydroponically is not the same quality as that grown in soil.

Irriblend-DSW: A decision support tool for the optimal blending of desalinated and conventional irrigation waters in dry regions

Desalinated sea water (DSW) is increasingly being used as an alternative source of irrigation in dry coastal areas. Owing to its high price and singular composition, it is often blended with other water resources to curb costs. Although this is a common practice, limited resources are available to manage the increased agro-economic complexity required to balance several water sources with heterogeneous quality, price, and availability restrictions. To support the management of fertigation with DSW, in this study, we present an open-source decision support tool (DST), Irriblend-DSW. The DST has been designed to identify potentially profitable fertigation options for different water and fertiliser availability scenarios. To demonstrate the key features of the tool, we applied it to two actual case study scenarios in south-eastern Spain, where severe water scarcity led to massive seawater desalination for agricultural supply. The information provided by the DST enabled the assessment of the viability of different water blending options and the selection of an optimal combination of water and fertilisers. The simulation results showed that the fertigation costs of the studied crops, hydroponic lettuce, and greenhouse tomato substantially increased with the integration of DSW. The DST output showed how water price rises, and how additional types and amounts of fertilisers are required when more DSW is used. However, because the salinity of the blend is also reduced with the use of DSW, the yield outcome improves and, thus, to some extent, compensates for the increased cost. In fact, despite higher costs, the studied crops were found to be very profitable when the optimised solutions computed by the DST were selected. Moreover, the optimum fertigation solutions not only reduced costs but also decreased nutrient leaching in areas of severely polluted aquifers.

Effect of different root lengths for retaining freshness of hydroponic lettuce

Harvesting with roots can help retain the freshness of hydroponic lettuce. And different root lengths may have different effects for freshness. To determine the optimal root length of hydroponic lettuce for retaining freshness, a root cutting and storage experiment was carried out to study some influenced factors of freshness such as changes in weight loss rate, color, and chlorophyll contents. Root lengths of samples were selected as five groups, i.e., 0 cm, 3 cm, 6 cm, 9 cm, and whole root length. Balance, chroma meter, and chlorophyll meter were used to measure the influenced indicators of different root lengths every other day for 15 days. Results showed that the relationship between the loss rate of chlorophyll content and the root length of hydroponic lettuce was not apparent. The chromatic aberration and the root length of hydroponic lettuce maintained a linear relationship. In the group of 0 cm, the chromatic aberration was 8.70 NBS that was maximum in the five groups. In the group of 9 cm, the chromatic aberration was 6.00 NBS that was minimal in the five groups. The relationship between the weight loss rate of hydroponic lettuce and the root length was linear. In the group of the whole root length, the weight loss rate of lettuces was 1.23% that was minimal in the five groups. It can be known that retaining the primary root or whole root of the hydroponic lettuce was beneficial for reducing the change in chromatic aberration, and increasing root length could reduce the weight loss rate of the lettuce. Therefore, considering the influence of the root length on the changes in weight loss rate, color, chlorophyll contents, and the hydroponic characteristics of lettuce, the optimal length of root retention for hydroponic lettuce was selected as 9 cm. • Different root lengths had an effect on retaining freshness of hydroponic lettuce. • Changes in weight loss rate, color, and chlorophyll contents were influenced factors. • Retaining the primary root or whole root could reduce change in chromatic aberration. • Increasing root length could reduce the weight loss rate of the hydroponic lettuce. • Different root lengths had no obvious effect on the loss rate of chlorophyll content.

Comparative Assessment of Hydroponic Lettuce Production Either under Artificial Lighting, or in a Mediterranean Greenhouse during Wintertime

Butterhead lettuce was grown hydroponically in a vertical farm under high (HLI) and low (LLI) light intensity (310, and 188 μmol m−2 s−1, respectively) and compared to hydroponically grown lettuce in a greenhouse (GT) during wintertime in Athens, Greece (144 μmol m−2 s−1). The highest plant biomass was recorded in the HLI treatment, whereas LLI and GT produced similar plant biomass. However, the LLI produced vortex-like plants, which were non-marketable, while the plants in the GT were normal-shaped and saleable. Net photosynthesis was highest in the HLI and higher in the LLI than in the GT, thereby indicating that light intensity was the dominant factor affecting photosynthetic performance. Nevertheless, the unsatisfactory performance of the LLI is ascribed, not only to reduced light intensity, but also to reduced light uniformity as the LED lamps were closer to the plants than in the HLI. Furthermore, the large solar irradiance variability in the GT resulted in substantially higher adaptation to the increased light intensity compared to LLI, as indicated by chlorophyll fluorescence measurements. Light intensity and photoperiod are believed to be the primary reasons for increased nitrate content in the GT than in the vertical farming treatments.

Effects of Hydrogen Peroxide on Organically Fertilized Hydroponic Lettuce (Lactuca sativa L.)

Hydroponic production typically uses conventional fertilizers, but information is lacking on the use of organic hydroponic fertilizers. Development of microbial communities and biofilm that can reduce dissolved oxygen availability is a difficulty with organic hydroponics. One potential solution is the use of hydrogen peroxide (H2O2) which can reduce microbial populations and decompose to form oxygen. However, information is lacking on the impact of hydrogen peroxide on hydroponic crop performance. The aim of this study was to determine the effects of H2O2 concentrations in deep water culture hydroponics by assessing how it affects plant size and yield in lettuce (Lactuca sativa L.) “Rouxai”. In this experiment, three H2O2 treatments, namely the application of 0, 37.5 or 75 mg/L H2O2 to 4 L aerated hydroponic containers with either conventional or organic fertilizer, were compared. The containers had either fish-based organic fertilizer (4-4-1, N-P2O5-K2O) or inorganic mineral based conventional nutrient solution (21-5-20, N-P2O5-K2O), both applied at 150 mg/L N. Three replicates of each H2O2 treatment–fertilizer combination were prepared resulting in a total of eighteen mini hydroponic containers each with one head of lettuce. There were two growth cycles: fall 2018 and spring 2019. When added to conventional fertilizers, both 37.5 mg/L and 75 mg/L of H2O2 led to stunted growth or death of lettuce plants. However, when 37.5 mg/L of H2O2 was applied to organic fertilizers, the lettuce yield nearly matched that of the conventionally fertilized control, demonstrating that the application of H2O2 has the potential to make organic hydroponic fertilization a more viable method in the future.

Reclaimed water driven lettuce cultivation in a hydroponic system: the need of micropollutant removal by advanced wastewater treatment

For a novel approach of resource-efficient water reuse, a municipal wastewater treatment plant was extended at pilot scale for advanced wastewater treatment, i.e., ozonation and biological activated carbon filtration, and a hydroponic system for reclaimed water driven lettuce cultivation. The treatment specific wastewater lines with the corresponding lettuce plants, differentiated into roots and shoots, were monitored for priority wastewater micropollutants, i.e., acesulfame (sweetener), caffeine (stimulant), carbamazepine, diclofenac, ibuprofen, sulfamethoxazole with acetyl-sulfamethoxazole (human pharmaceuticals), 1H-benzotriazole, and 4/5-methylbenzotriazole (industrial chemicals). As clearly demonstrated, conventional tertiary treatment could not efficiently clean up wastewater. Removal efficiencies ranged from 3% for carbamazepine to 100% for ibuprofen. The resulting pollution of the hydroponic water lines led to the accumulation of acesulfame, carbamazepine, and diclofenac in lettuce root systems at 32.0, 69.5, and 135 μg kg−1 and in the uptake of acesulfame and carbamazepine into lettuce shoots at 23.4 and 120 μg kg−1 dry weight, respectively. In contrast, both advanced treatment technologies when operating under optimized conditions achieved removal efficiencies of > 90% also for persistent micropollutants. Minimizing the pollution of reclaimed water thus met one relevant need for hydroponic lettuce cultivation.Graphical abstract

The effect of different LED light on growth and anthocyanin of hydroponic red oak lettuce in a closed system

The effect of different LED light on growth and anthocyanin of hydroponic red oak lettuce in a closed system

New Aspects of Uptake and Metabolism of Non-organic and Organic Iodine Compounds-The Role of Vanadium and Plant-Derived Thyroid Hormone Analogs in Lettuce.

The process of uptake and translocation of non-organic iodine (I) ions, I– and IO3–, has been relatively well-described in literature. The situation is different for low-molecular-weight organic aromatic I compounds, as data on their uptake or metabolic pathway is only fragmentary. The aim of this study was to determine the process of uptake, transport, and metabolism of I applied to lettuce plants by fertigation as KIO3, KIO3 + salicylic acid (KIO3+SA), and iodosalicylates, 5-iodosalicylic acid (5-ISA) and 3,5-diiodosalicylic acid (3,5-diISA), depending on whether additional fertilization with vanadium (V) was used. Each I compound was applied at a dose of 10 μM, SA at a dose of 10 μM, and V at a dose of 0.1 μM. Three independent 2-year-long experiments were carried out with lettuce; two with pot systems using a peat substrate and mineral soil and one with hydroponic lettuce. The effectiveness of I uptake and translocation from the roots to leaves was as follows: 5-ISA > 3,5-diISA > KIO3. Iodosalicylates, 5-ISA and 3,5-diISA, were naturally synthesized in plants, similarly to other organic iodine metabolites, i.e., iodotyrosine, as well as plant-derived thyroid hormone analogs (PDTHA), triiodothyronine (T3) and thyroxine (T4). T3 and T4 were synthesized in roots with the participation of endogenous and exogenous 5-ISA and 3,5-diISA and then transported to leaves. The level of plant enrichment in I was safe for consumers. Several genes were shown to perform physiological functions, i.e., per64-like, samdmt, msams5, and cipk6.

Antimicrobial Mitigation via Saponin Intervention on Escherichia coli and Growth and Development of Hydroponic Lettuce

Various saponins have demonstrated allelochemical effects such as bactericidal impacts as well as antimycotic activity against some plant pathogenic fungi, thereby acting to benefit plant growth and development. A commercial saponin solution was evaluated for bactericidal effects against Escherichia coli and growth of lettuce (Lactuca sativa) in a hydroponic system. E. coli (P4, P13, and P68) inoculum at final concentration of 108 colony-forming units (cfu)/mL was added to 130 L of a fertilized solution recirculating in a nutrient film technique (NFT) system used to grow ‘Rex’ lettuce. After 5 weeks in the NFT system, E. coli populations were lowest in the inoculated treatment that did not contain any saponin addition (0.89 log cfu/mL) when compared with all other inoculated treatments (P &lt; 0.001). The treatment containing 100 µg·mL−1 saponin extract had an E. coli population of 4.61 log cfu/mL after 5 weeks that was higher than treatments containing 25 µg·mL−1 or less (P &lt; 0.0001). Thus, higher E. coli populations were observed at higher saponin concentrations. Plant growth was also inhibited by increasing saponin concentrations. Fresh and dry shoot weight were both higher in the inoculated and uninoculated treatments without the saponin addition after 5 weeks in the NFT system (P &lt; 0.0001). Lettuce head diameter was smaller when exposed to saponin treatments with concentrations of 50 and 100 µg·mL−1 (P &lt; 0.0001). Lettuce leaves were also tested for the potential of E. coli to travel systemically to the edible portions of the plant. No E. coli was found to travel in this manner. It was concluded that steroidal saponins extracted from mojave yucca (Yucca schidigera) are not an acceptable compound for use in mitigation of E. coli in hydroponic fertilizer solution due to its ineffectiveness as a bactericide and its negative impact on lettuce growth.

The applicability of anaerobically treated domestic wastewater as a nutrient medium in hydroponic lettuce cultivation: Nitrogen toxicity and health risk assessment.

The applicability of anaerobic effluent (AE) from an anaerobic membrane bioreactor (AnMBR) treating domestic wastewater as a nutrient medium was evaluated through hydroponic cultivation of lettuce. The growth of lettuce plants on AE media was significantly inhibited to 31-40% in height and 36-48% in number of leaves compared to that on half-strength Hoagland solution (HHS) as a control. The primary cause of inhibition was nitrite toxicity as induced by partial nitrification. Therefore, the nitrification of AE as a pre-treatment step was adopted to prevent the toxicity of nitrite. The heights of lettuce grown on nitrified anaerobic effluent (NAE) and nitrified anaerobic effluent with 96mg/L sulfate (NAES) were in the range of 11.4-11.5cm and was comparable to that on control solution (11.4cm). The potential health risk for heavy metals was insignificant based on health risk index (HRI<1) and targeted hazardous quotient (THQ<1). These results show that efficient crop production can be achieved with AE, but suitable pre-treatment steps should be followed.

Adjustment Pattern of pH Using Random Forest Regressor for Crop Modelling of NFT Hydroponic Lettuce

IoT makes it possible to automatically adjust pH based on sensor numerical data for NFT hydroponic lettuce. In this research, we use sensors of light intensity, farm temperature, farm humid, reservoir level, reservoir temperature, humid on the outside farm, outside farm temperature at Kartika Farm and Turus Asri. Data were taken for five cropping periods. We got different adjustment pattern of pH based on these sensors and Total Dissolved Solids (TDS) control. Furthermore, Kartika Farm’s cropping was different from Turus Asri. In a kilogram of Kartika Farm cropping ingredient seven holes of hydroponic lettuces while Turus Asri cropping ingredient ten holes of hydroponic lettuces. Economically, Kartika Farm harvests more benefits than Turus Asri. In this research, we modeling the pattern of pH adjustment at Kartika Farm using random forest regression. The result showed that the important variable for pH adjustment modeling is water level, TDS and green house humidity. We got an accurate value for the model is 78,37% with MAE and MSE consecutively 0.19 and 0.15.

The effect of hydroponics systems on the growth of lettuce

Shifting patterns of consumption in urban communities to consume pesticide-free and clean vegetables encourage the development of hydroponic cultivation in urban areas. In hydroponic lettuce cultivation, resource efficiency in the production stage is vital to be implemented so that the profits of hydroponic farmer increase. This study aims to provide recommendations for a more efficient hydroponic system to increase the growth of lettuce plants. The research method used in this study was a complete randomized design consisting of five treatments that were replicated five times. The treatment consists of five types of hydroponic installation systems, namely: A = Nutrient Film Technique System (NFT), B = Deep Film Technique System (DFT), C = EBB and FLOW Systems (EFS), D = Aeroponic Systems (AS), and E = Floating Raft System (RFS). The parameters observed to measure the effectiveness of each system in increasing the growth of lettuce plants are plant height, leaf number, fresh weight, and shoot-root ratio. The observational data were then analyzed using analysis of variance at 5% significance level and Duncan’s test at 5% level. The results showed that the NFT hydroponic system of lettuce plants was 6%-10% more efficient compared to the floating raft system and DFT system in increasing yields.

A high-precision detection method of hydroponic lettuce seedlings status based on improved Faster RCNN

In order to improve the efficiency and reduce high cost for seedlings sorting in the raising process of hydroponic lettuce seedlings, we propose an automatic detection method for hydroponic lettuce seedlings based on improved Faster RCNN framework, taking the dead and double-planting status of seedlings growing in a single hole as our research objects. Since the characteristics of hydroponic lettuce seedlings are dense and small in the images, our model uses High Resolution Network (HRNet) as the backbone network for image feature extraction so as to obtain reliable and high- resolution feature expressions. Besides, we adopt focal loss as the classification loss in the Region Proposal Network (RPN) stage to address the imbalance between difficult and easy samples in seedlings classification. We also employ the Region of Interest (RoI) Align instead of the RoI Pooling layer to improve the detection accuracy of seedlings in the different status. The results show that the mean average precision of our method for the hydroponic lettuce seedlings is 86.2%, which is higher than RetinaNet, SSD, Cascade RCNN, FCOS and other detectors. Compared with different feature extraction networks, the detection accuracy of adopting HRNet performs nicely. Therefore, our method presented for the detection of hydroponic lettuce seedlings status can achieve high accuracy and identify seedlings in a problematic status well, which will provide technical support for automatic seedlings detection of hydroponic lettuce.

LED Light Quality of Continuous Light before Harvest Affects Growth and AsA Metabolism of Hydroponic Lettuce Grown under Increasing Doses of Nitrogen.

To study the effects of light quality of continuous light before harvest on the growth and ascorbic acid (AsA) metabolism of lettuce (Lactuca sativa L.) grown under relative high nitrogen level, lettuce plants grown under different nitrogen levels (8, 10 and 12 mmol·L−1) were subjected to continuous light with different red: blue light ratios (2R:1B and 4R:1B) before harvest. The results showed that the shoot fresh weight of lettuce under 12 mmol·L−1 nitrogen level was significantly higher than that under other treatments. There were no significant differences in shoot dry weight, root fresh weight, root dry weight, soluble sugar content, nitrate content and AsA content in leaves among the treatments at different nitrogen levels. The content of AsA in leaves was significantly higher than that in petioles before and after continuous light. Under the same nitrogen level, the fresh weight of lettuce under continuous light quality 4R:1B was significantly higher than that under other treatments. The content of AsA in lettuce leaves increased in different degrees after continuous light before harvest. High yield and AsA content could be obtained by 72 h continuous light with red and blue light 4R:1B at 12 mmol·L−1 nitrogen level. After continuous light, the content of AsA increased significantly due to the increase of the ratio of red light and nitrogen level, which increased the activities of L-galactono-1,4-lactone dehydrogenase (GalLDH) and dehydroascorbic acid reductase (DHAR) involved in AsA synthesis and in the recycling of DHAR to AsA respectively.

Framework for design and optimization of a retrofitted light industrial space with a renewable energy-assisted hydroponics facility in a rural northern canadian community

The purpose of this study is to develop a design framework for retrofitting a light industrial building with a hybrid renewable energy-assisted hydroponics farming system for production of fresh food in rural north Canadian communities. This design protocol is targeted at facilities in rural areas of northern Canada, which could benefit from better access to fresh food, especially given the harsh climate as well as the long and limited transport routes. The process includes 1) a review of the existing building; 2) estimation of design loads for system sizing, such as temperature and humidity control, adequate lighting, airborne carbon, and water; 3) multi-objective genetic algorithm optimization of the hybrid renewable energy system for minimal operating cost and emissions; and 4) comparison of costs and greenhouse (GHG) emissions of the proposed farming operation with the traditional food supply chain. To demonstrate the proposed methodology, a case study building in a rural community in Alberta, Canada was evaluated for retrofit. The results showed that the GHG emissions generated from local hydroponic lettuce production, aided by a hybrid renewable energy system (HRES), are three times greater than those emitted by transporting an equivalent quantity of food from southern California, USA. On the other hand, the life cycle cost showed that the cost to produce lettuce from the case study facility is comparable to the price of lettuce available from traditional import, which shows a promising potential to provide fresh and cost-competitive food in the community, among other qualitative benefits gained from this empowering opportunity.