Building a Growth Model for a Sustainable Vertical Hydroponics that uses the Nutrient Film Technique (NFT)
Co Authored: Arjun Patel, Olya Tkachenko, Lyssa Gagné, Shannon Chakma, and Robert Rinaldi
A Puddleshaker Case Study
Original Date: July 17, 2020
Executive Summary
The purpose of this study is to look at long-term sustainable methods of growing vegetables and fruits for the community using a vertical hydroponic system with nutrient film technique (NFT) in an enclosed 2.59m (height) x 2.44m (width) x 6.1m (length) shipping container. Unable to create a physical prototype, data from secondary research was used to develop the foundation of the growth model. This study uses the data from eight leafy greens and two fruit-bearing plants that grow optimally well in hydroponic systems This is to limit the trial and errors that would normally occur in a physical test and give it the best chance of successfully building a model and harvesting a good yield.
Inspired by the community and a passion for change in the food system, Maison Verte formed in early 2020. Concerned with the high costs of food and the burgeoning impact of the COVID-19 pandemic on urban communities, the non-profit group became interested in exploring the option of growing vegetables and fruits in a cost effective and sustainable vertical hydroponic system. Maison Verte is not only looking at providing affordable produce but running workshops and creating content to build education in communities, uplifting communities and empowering the youth and families to become interested in where their produce comes from, and forming long-term research goals to meet a sustainable society in 2050. Maison Verte is ambitious and has developed valuable partnerships with various non-profit organizations in the community such as the Working Centre, PowershiftWR, Permaculture, Community Programming Reap, and Food System Roundtable.
This case study looks at four different problems that may impact the decision and views on growing foods in a hydroponic system. They include increasing costs to maintain sustainability and source locally, production scalability and overall impact on utilities, accessibility, and finding a unique selling proposition (USP) in a centuries old method.
Key points in this study involve basic plant growth, hydroponic growing systems, sustainability, ecological footprint, locally sourced material, on- and off-grid utilities, scalability, innovative technologies, fertilizers, user experience and user interface design, intellectual property rights, and unique selling proposition.
Findings
INCREASING COSTS TO MAINTAIN SUSTAINABILITY & SOURCE LOCALLY
To ensure healthy plant growth in a hydroponic system, fertilizers are required as they supplement the plant with nutrients to encourage optimal growth. Majority of fertilizers are prepared using, “minerals and products from energy-intensive methods” (DIY Hydroponic Gardens, 2018, p. 16). An example would be the Haber-Bosch process, an artificial nitrogen fixation process and an aid in the production of ammonia currently found on today’s store shelves. This process converts the atmospheric nitrogen gas (N2) into ammonia (NH3) which is then used as a component to make fertilizers like ura and ammonia nitrate. Fertilizer can be natural or synthetically formulated depending on the preference of the gardener, plant, and/or need of the system.
Maison Verte is leaning towards growing produce in a sustainable system with a focus on supporting the local community, this may alter their decision on which fertilizer to use. Not locally sourced, synthetic fertilizers come with a significant impact on the environment and have a large ecological carbon footprint. Aside, synthetic fertilizers work really well in the system by producing the least amount of wastewater resulting in water savings.
PRODUCTION SCALABILITY & OVERALL IMPACT ON UTILITIES
A small hydroponic system does not use the same amount of resources as what a larger scaled system would require. If Maison Verte were to scale their production to meet the growing needs of the community, how would they be able to supply the required utilities necessary to grow their crops sustainability and with the highest yield possible.
Having the hydroponic system on the city grid would be beneficial as it would allow for consistent supply of resources with no large physical infrastructure to take up space. Scalability wouldn’t be as great of an issue but rather the increasing high cost of supply of on- and off-peak times . Going off-grid would have an upfront cost to purchase a solar electric and water reclamation system which would be considered an investment that would be paid over time. Having a solar electric and water reclamation system will help align the hydroponic system towards a more sustainable process of growing crops. However there may be periods of time with no water or potentially no electricity especially if short- to long-term maintenance is ignored. Scalability may be an issue if the solar electric and water reclamation system overexerts itself with the increase in crop production or additional hydroponic modulars.
ACCESSIBILITY TO NECESSARY INFORMATION & EQUIPMENT
In order for the hydroponic system to run, Maison Verte requires an electronic system that will store, track, and maintain information related to health, growth, and optimal crop yield. To cultivate the best yield, the proper settings need to be in place and error-free; otherwise the crop cycle will fail. There are a multitude of components that are interlaced, creating formulas that work when all components are in sync with each other. Essentially if you look at the basic needs of a plant it requires water, light, temperature, and minerals from the soil in order for it to grow. These components together create a growth formula and when tweaked by the user, optimal growth becomes a possibility.
The control interface and physical process of growing crops in the hydroponic system needs to be streamlined in a way that is both accessible and easily understood by all members of the community. At its core hydroponics is a very basic system that has been around since the sixteen century; however the more components that are added to the system, to increase optimal yield, the more complex it becomes.
UNIQUE SELLING PROPOSITION (USP) IN A CENTURIES OLD METHOD
What will make Maison Verte’s hydroponic system different from their competitors? Hydroponics have been around since the sixteenth century with several different methods adding a unique value to the original. Hydroponics have become a popular method of growing produce in urban settings. How can Maison Verte filter out the do it yourself (DIY) hydroponic systems found on the internet and create one with a unique selling proposition? Where do they see themselves among their competitors.
There are several different hydroponic growing systems that have been well explored and are quite popular with the do it yourself (DIY) models such as aeroponics, deepwater culture (DWC), drip system, ebb and flow system, nutrient film technique (NFT), wick system, and vertical gardens. Each type of system is built for different crops whether they are a mixed or just leafy greens, herbs, and flowering plants. Since hydroponics have become popular with urban dwellers it would be hard to sell a model given that they may not have the intellectual rights to the property as opposed to just selling the produce.
Discussion
Ideally Maison Verte would like to devise a vertical hydroponic system in a 20ft shipping container using products and equipment procured sustainability and locally at a reasonable cost. Fertilizers are a key component used in hydroponic systems as they help maintain plant health and yield. They can be obtained as a synthetic by-product created by mined products or developed naturally by animal manure, byproducts from the meat industry, or nutrients from plant sources. Fertilizers come in two different forms liquid and dry. It is easier to add liquid fertilizer in a hydroponic system than measuring and adding dry fertilizer. Liquid fertilizers are expensive to purchase because they are less concentrated, whereas dry fertilizers are cheaper.
In any case there are positive and negative impacts that need to be considered when looking at fertilizers that will be used. Synthetic fertilizers are great since they keep the system clean allowing for the water to be recycled. On the other hand, ingredients used in synthetic fertilizers are not locally mined and they tax the environment. The process of mixing multiple ingredients to make unique fertilizers has improved in the last decade. Nowadays, producers can purchase a few pre-blended fertilizers and mix them together to make what they need.
On the other hand, organic fertilizers can be quite tricky especially to producers who are new to hydroponic systems. If venturing in this direction, it would be best to understand how plants grow under normal conditions first. Unknowingly some producers may take organic fertilizers used in natural gardening and use it in the hydroponic system which then creates a foul smell. Most organic fertilizers are made from animal manure or byproducts from the meat industry. These can easily turn rancid in the system which results in the water being flushed out regularly. The only successful organic fertilizer great for hydroponic systems have nutrients derived from plant sources such as sugarcane. An example of an organic fertilizer with nutrients from plant sources is the molasses-based fertilizer called Pre-Empt.
Overall synthetic and organic fertilizers are beneficial to the overall crop health, growth, and yield. They are very much needed in the system, otherwise the crops will not succeed. Should Maison Verte choose synthetic or organic? Given the direction of the final model it would be interesting to see a mix of both. Each one impacts the environment negatively at some point in their lifecycle with sustainability is almost achieved. Maison Verte is young and looking into hydroponics, so theoretically starting with synthetics would be the best solution and eventually over time using organic fertilizers in their system.
The cost of procuring and maintaining a consistent flow of resources need to be addressed prior to considering and building the prototype. Resources can be obtained sustainability off-grid with a large overhead investment cost or using reliable on-grid access with no large physical structures taking up space. The cost associated with either depends on potential current and future scalability of the vertical hydroponic system.
Let’s look at the pros and cons of scalability when factoring in on- and off-grid utilities that the vertical hydroponic system will need. Hydroponic crops need to have a consistent flow of water and electricity, so naturally being on-grid seems like the most reasonable choice. On-grid doesn’t require too much space or an investment into large expensive infrastructure equipment. However, the current projected use of electricity would be expensive on-grid especially with on- and off-peak times. This would include a constant water circulation, grow lights, filtration, and ventilation.
Since sustainability is one of the core focuses of Maison Verte, off-grid utilities is potentially a viable solution. The model would be able to use solar electric and water reclamation systems to draw required resources from the surrounding environment. Essentially, Maison Verte would take what they needed and not have to tap in for extra resources. On the other side, scalability might be an issue depending on how much Maison Verte will increase their production. There is the large upfront investment that Maison Verte will need in order to purchase the solar electric and water reclamation systems and the location of placement. Although modern solar electric systems have been upgraded, Maison Verte needs to consider reliability that water and sunlight from the environment will be. If sustainability is the factor then Maison Verte should look into purchasing, or potentially renting if available, a solar electric and water reclamation system. However, if Maison Verte is looking to save money then they can save up for the initial investment of these systems.
To ensure that all members of the community have access to the community hydroponics garden, the system will need to be compliant with Accessibility for Ontarians with Disabilities Act (AODA), implemented in 2005, and with consideration of universal design. Accessibility of the design should factor in diverse sensory abilities and preferences such such as eyesight, hearing, and multi-modality. As well, cognitive conditions that may affect the ability to process, understand, and communicate information. To maximize the accessibility of design, cognitive load should be considered as it factors in the amount of new information that can be processed, memorized, and recalled at any given time. There are a lot of factors that need to be considered when finalizing the model especially using the 20ft shipping container. It may be impossible to factor in every consideration, but aiming for high accessibility standards would open the door for more users and increase the quality of design.
When designing the electronic interface it would be best to consider the language, colour, typography selection, and typesetting. If Maison Verte wants to consider the experience aspect of the interface then wireframing, prototyping, and user testing is vital. This will help refining the usage needed and understand the true process that is required by the projected users. Placing the model in a 20ft shipping container could potentially be tight and modular units may need to be removed to allow for wheelchair accessibility and height restrictions.
Creating a growth model that outlines what plants to use, track growth cycles, nutrient release times and amounts, and correlate information with environmental conditions. This growth model can be created through spreadsheets and using coding filtered through a clean interface. Conducting user testing will allow for refinement of this interface filtering out information to help with cognitive load.
There are many different types of hydroponic growing systems that can be found on the internet, research papers, magazines, and books. It has been around for several centuries and has become quite popular in recent years. How can Maison verte create a model with a unique selling proposition? Since there are many systems the focus will be on the most beneficial and relevant systems such as aeroponics, DWC, drip, ebb and flow, NFT, and wick.
Aeroponic systems are great for creating a fully sustainable system using fish to generate nutrients for crops. Growth and yield rates are the best out of all the other systems, however they are quite complex given that they need regular monitorization of pumps to avoid any failure. If Maison Verte is interested in expanding the variety of their crops then DWC could be a potential consideration. However, plants are subjected to root rot if oxygen levels aren’t closely monitored. The drip system has plants grown separately and receiving nutrients through a drip. Any extra solution is then recycled or drained out. This system required high maintenance especially if the water is recycled making it lean towards being expensive. The ebb and flow systems require a higher level of expertise in hydroponics and since the system requires a certain level of knowledge to set up the automation process. The NFT is a popular system that allows for nutrients to be recycled with the plant roots not being completely submerged. This method allows users to adjust inputs for optimal growth although it requires more time, money, and some expertise to set up. A simple and easy method of hydroponics is the wick system. Nutrients are stored in a separate reservoir and are moved to the root system using capillary action. Out of all the methods mentioned, this system is the least expensive when it comes to set-up and maintenance. There are some major flaws to the system such as lack of oxygen to plant roots and higher volume of nutrient solution to reach plant roots. This system is great for small systems, at home systems, and it’s not really suitable for large plants that require more nutrients.
At the moment, Maison Verte will be using a 20ft shipping container. This study needs to consider available space and potentially the idea that the model will be used in other locations. Creating a system with modular components that can be added and removed is beneficial making the model unique. Vertical gardens are another growing system that would be great to integrate into the model. It is a popular system, but it will help maximize the available growing area in a given footprint (DIY Hydroponic Gardens, 2018, p. 115). It should be noted that it lacks upper support for plants that are top heavy, so not all plants can grow in using this system.
Maison Verte should use a combination of a NFT paired with vertical gardening in the model. This will create a system that is sustainable since it recycles the nutrients, allows for adjustment of inputs, and maximizes available growing area.
Conclusion
To conclude, Maison Verte will need to take into consideration several different factors when building the prototype and eventually the final model. Given that they are a startup with limited capital with an interest in locally grown foods and sustainability, Maison Verte would be best to work with a vertical hydroponics system using the nutrient film technique. Tapping into the city grid would be cost effective, however making an investment into an electric solar and water reclamation system is a good direction towards a sustainable system. When purchasing these systems Maison Verte needs to consider potential scalability in crop numbers and yield. The system will need to be able to sustain the increase without exerting itself, otherwise they will need to add another system or additional components.
When it comes to the nutrients required to feed the crops using both synthetic and organic-based fertilizers would be beneficial. However, take note in avoiding manure and byproducts from meat processing plants. Using plant-based fertilizers such as sugarcane will help keep the system clean and limit the amount of wastewater expelled.
Creating a growth model will form a database in which information can be filtered based on what the user will need to know such as what plants to use, track growth cycles, when to release nutrients and how much, and pair it with the environmental conditions. The interface and space will need to be designed using AODA and universal design methods. It may be hard to design for all accessibility needs but aiming for high accessibility standards will open the door for more users and increase the quality of the model. Once the interface has been designed it would be beneficial for user testing to be conducted to help refine the design and make the model easier to use.
Recommendations
Maison Verte needs to create a hydroponic prototype using vertical gardening and nutrient film technique (NFT). Once equipment has been refined it can be taken to the final stages of building a model. Designing the system to have single modular components that can be added and removed to accommodate space and location is key, and adds to the unique selling proposition.
Since a physical test has not been conducted, take the proposed plants found in the growth model and run a couple growth cycles. This will help fine tune the growth model, fix any errors that may occur, and pinpoint the exact fertilizer formulation for optimal health, growth, and yield.
When designing the operating system for the model, make sure to conduct user testing for optimal usage. This will also determine how much control is needed and whether settings can be automated. It’s important that the interface informs the user but also allows the user to track changes if needed.
NFT is determined to be the most applicable hydroponic delivery method for use in the Hydroponic Shipping Container (HSC). This type of system works well because the roots of a plant absorb more oxygen from the air than from the nutrient solution itself. Since only the tips of the roots come in contact with the nutrient solution, the plant is able to get more oxygen which facilitates a faster rate of growth. Also, these recirculating systems offer high water efficiency and ample oxygenation to root systems. Besides, NFT systems can be applied to a variety of different crops, such as lettuce, strawberries, and peppers, and the nutrient solution can be customized for each crop. Furthermore, NFT troughs can be constructed with relatively inexpensive building materials, such as PVC pipe.
So, the NFT hydroponic unit design increases crop yields and improves uniformity between systems leading to a sustainable and effective method of food production and reduction in the overall energy consumption in the full-scale hydroponic shipping container.
Improvements to the current proposed solution can be made in several areas. First, there are several components of the NFT design that should be studied further in order to increase crop yields. Customizing the nutrient solution for optimal crop growth, improving both the solution delivery and drainage, and optimizing lighting in terms of uniformity and total illuminance are some actions that could be taken into consideration.
Moreover, further iterations in the growth model parameters, layout and function of hydroponic trays in the full HSC could take advantage of the three-dimensional space to increase crop yields without increasing the production land footprint. Stacking trays vertically in the shipping container would maximize the use of the total volume of the space. Regarding the energy model, improvements can be made in prediction of lighting and pumping electricity consumption. Additionally, further testing and data collection of system air temperature and humidity in a fully assembled version of the HSC is required in order to optimize air flow, ventilation, heating, and cooling methods.
Designing the HSC involves considering practical, useful approaches to hydroponic growing in small spaces as well as trial and error with various components in the NFT Test Unit. Additionally, growing crops hydroponically requires knowledge of agronomy and chemistry, as well as skills in operating mechanical systems.
More broadly, hydroponic vertical farming in refurbished indoor spaces is certainly an innovative concept. With the current situation, there is a growing need for local food production and alternative sources of nutritious foods as more people find themselves living in urban areas and as the negative effects of industrial agriculture are realized.
Since the HSC and other commercial shipping container farms, such as Freight Farms, The Growcer, True North Produce, and Growtainer, are high density, mobile systems, they have the potential to reduce the impact of geographic barriers to fresh foods. Mobility has been an important factor in the success of programs such as the Mobile Good Food Market, a travelling community food market truck that brings fresh produce to low income neighbourhoods in Toronto. Similar to a mobile market concept, shipping container farms have the potential to not only deliver but also grow fresh produce in a variety of neighbourhoods.
In essence, the HSC design demonstrates possibilities in vertical hydroponic growing for mobile applications, and with further improvements to design components and reduction of system energy consumption, the HSC can become one of many solutions improving the way food is grown and consumed. Practical iterations in the growth model will undoubtedly make it possible for food production and consumption systems to become accessible, affordable, and sustainable for communities in the local neighbourhood.
Implementations
In order to take Maison Verte from concept to prototype and eventually to the final model. The following steps should be implemented.
Step 1
Maison Verte must purchase supplies for the hydroponic system. The startup costs documents at the end of the case study should provide some guidance into the equipment required and a budget.
Step 2
Construct the system using the nutrient film technique (NFT) model. Some general areas to look at:
● sources of electricity; an electric solar and water reclamation system would be a sustainable investment
● ventilation
● fertilizers, with an emphasis on plant-based products
● safety and ease of use for the public within the shipping container ● ability to diagnose and fix troubleshooting
Consider designing the system based on having a single modular component that can have units added or removed for versatility based on space and yield needs. In this case, the space needs would need to support a shipping container. For example, using a smaller plastic reservoir and a small square footage of grow lights would be a good start. If wishing to expand the system, the components should be able to “interlock” with another module. The modular system would provide a unique selling proposition for Maison Verte.
Step 3
Next, run a few grow cycles to streamline and collect data about the growth process. This will be used to fine-tune the growth model and make any changes to the physical components of the system. This purpose of this step is also to confirm the initial research from the original theoretical growth model.
Step 4
The growth model is taken to the next level at this stage. Use a UX/UI process to develop the growth model into an interface that is understandable and intuitive to navigate for all types of users. It should follow the accessibility standards (AODA) and present information in such a way that the user is not overwhelmed.Some features of the growth model include being able to filter and track for information like environmental conditions,what plants to use, the correct amount of fertilizer, or how much light is needed.
Some recommended design methods and processes for a mobile or web app:
1. Discover: User interviews and market research
2. Define: Personas, use case scenarios, journey maps
3. Ideate: sketches
4. Prototype: wireframes, visual designs, site maps, information architecture
5. Test: user testing
User testing should be emphasized to ensure that problems are detected early and the final growth model actually aligns with user needs.
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