Analysis of Cultivation Days and Yield Efficiency in Plant Factories

6.10 Sensitivity and Risk Analysis for Fund Raising

This section explores how to secure capital funding for plant factories, focusing on the financial metrics essential for persuading investors and financiers to support operations. Below are the critical elements discussed in the text.

1. Capital Funding Strategies:
   • The business planning sheet is utilized to calculate the payback period, which indicates how many years are necessary to recover the initial investment.
   • It is crucial to convince financiers to provide funds for engineering, procurement, construction, and working capital during the start-up period, before the annual cash flow turns positive.
2. Establishing Standards:
   • Standard numbers for efficiency and productivity indexes should be established and utilized in the business planning sheet.
   • These indexes should reflect realistic projections for each year in the planning period.
3. Risk Analysis:
   • An analysis of fluctuations in the set numbers should be conducted, particularly examining a 90% probability for the worst-case scenario.
   • Understanding the worst-case scenario is vital for convincing fund providers about potential risks and ensuring they are satisfied with the proposed terms.
4. Productivity Metrics:
   • Funders may inquire about reducing the number of cultivation days and increasing the daily fresh weightproduced per square meter.
   • Responses should highlight productivity indexes such as lighting PPF consumed per kg of fresh weightand man-hours required for kg of fresh weight.
5. Banker Concerns:
   • Bankers may ask for evidence of efficiency and how other plant factories perform, focusing on the average productivity metrics.
   • They will likely scrutinize the worst-case scenarios and may demand more favorable terms in share allocation or loan conditions.
6. Data Limitations:
   • There is a limited track record and available information on plant factories, making it challenging to convince fund providers of potential risks.
   • The industry requires development of standard numbers for indexes, sensitivity analyses, and risk scenario approaches through cooperation and research.

6.11 Conclusion

The final section emphasizes the interconnectivity of efficiency, productivity, and profitability within the context of plant factory operations. Key points include:

1. Collective Understanding:
   • There is a need for collective understanding among horticultural specialists, operating managers, marketing experts, and financial professionals regarding the value of plant factories.
   • The relationship between money, risk-taking, and return on investment is emphasized.
2. Statistical Confidence:
   • Financial specialists prioritize statistical confidence over scientific data, necessitating robust data and projections to appeal to fund providers.
   • Developing standardized indexes and conducting sensitivity analyses will strengthen funding proposals.
3. Global Cooperation:
   • The necessity for global cooperation is highlighted, as differing standards across countries can hinder progress in controlled environment agriculture.
   • The ultimate goal is to ensure that efficient, productive, and profitable practices in plant factories are analyzed, reviewed, and improved upon.
4. Knowledge Sharing:
   • The communication and sharing of information among operators and financiers are vital for cultivating global wisdom in sustainable agricultural practices.
   • This shared knowledge will enhance understanding of efficiency, productivity, and profitability, ultimately supporting the long-term success of plant factories in addressing global food security challenges.

Implications for Plant Factory Management

1. Optimize Cultivation Practices:
   • By understanding the trade-offs between cultivation days and yield percentages, managers can optimize their practices to achieve desired profitability levels.
   • Utilizing LED dimming systems to regulate growth can be an effective strategy to balance between speed and quality.
2. Focus on Early Growth Stages:
   • The importance of investing in lighting and PPF during the early stages of growth is emphasized. Stronger PPF can set the trajectory for faster overall growth while reducing the risk of tip burn.
3. Continuous Improvement:
   • Emphasizing the need for ongoing research and industry-wide collaboration will lead to better practices and standards within the plant factory sector.

In conclusion, the insights presented outline a framework for plant factory managers to enhance efficiency, productivity, and profitability while navigating the complexities of securing funding and managing operational risks. By focusing on data-driven decision-making and collaborative efforts, the industry can improve practices to better address global agricultural challenges.


Renewable Energy Makes Plant Factory “Smart”

Kaz Uraisami

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Abstract
This chapter discusses the integration of renewable energy, specifically photovoltaic (PV) solar panels, into plant factories. The objective is to explore the feasibility of utilizing solar energy, converting it to electricity, and then using that electricity to power artificial lighting in plant factories. As solar technology becomes more affordable, the potential for off-grid plant factories that rely on solar power is examined, highlighting the benefits of sustainability and reduced operational costs.

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7.1 Introduction: Global Price Movement as Commodities

The global price of solar panels has drastically decreased from approximately $10 to $1 over the past 30 years. This significant reduction, primarily driven by Chinese manufacturers, has facilitated the rapid expansion of PV power generation globally. The costs of constructing a solar power system for 1 megawatt have dropped to about $1 million in many regions, thanks to advancements in technology and economies of scale.

Moreover, the price of storage batteries has also begun to decline, influenced largely by the demand from the electric vehicle (EV) market. As the technology behind lithium-ion batteries evolves, it becomes more economically viable for PV plants to integrate storage solutions, allowing for more stable and reliable energy supplies.

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7.2 Smart Energy for Smart Plant Factory

The concept of a “smart” plant factory relies on the use of clean, CO2-free energy sources for its operations. While solar energy generation can be inconsistent, advancements in battery storage technologies allow for energy accumulation during peak generation times, thereby alleviating some of the inherent fluctuations. Off-grid operations eliminate concerns regarding grid limitations and allow for greater independence in energy generation and usage.

To effectively utilize solar energy in plant factories, the energy generated must first be converted into usable electricity, which then powers artificial lighting and other essential systems. This cyclical energy conversion process is key to enhancing the environmental sustainability of plant factories.

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7.3 Experimental Calculation

An experimental model was proposed where a 1,000 square meter plant factory utilizes a photovoltaic system to meet its energy needs. The calculations are as follows:

• Plant Configuration: The plant factory would have 240 cultivation racks, with a total cultivation area of 2,160 square meters.
• Energy Requirements: To achieve a Photosynthetic Photon Flux Density (PPFD) of 200 μmol/m²/s over 16 hours, approximately 5,800 LED fixtures (32W each) are needed, leading to an annual electricity consumption of 3,370 MWh.
• Photovoltaic Requirements: A 3 MW solar power system is required to supply the plant’s energy needs, covering an estimated 30,000 to 45,000 square meters of land.
• Storage Requirements: The battery storage system should have a capacity of about 28 MWh to ensure energy supply during prolonged periods of low sunlight.

The economic justification for this model hinges on the local electricity prices and the cost of implementing such a solar power and storage system, suggesting that investment in renewable energy can be a viable option for plant factories.

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7.4 Conclusion

The viability of plant factories using renewable energy sources highlights a transition towards more sustainable agricultural practices. By minimizing overall social costs and optimizing social value, such as stable food supplies without CO2 emissions, the integration of solar energy into plant factories represents a significant step towards environmentally friendly food production. The ongoing development and cost reductions of solar energy systems make the prospect of smart plant factories increasingly practical and beneficial.

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Chapter 8: Total Indoor Farming Concepts for Large-Scale Production

Marc Kreuger, Lianne Meeuws, and Gertjan Meeuws

Abstract
This chapter discusses indoor farming as a sustainable solution to global food production challenges. It highlights the importance of controlled environments, efficient climate systems, and innovative crop models to maximize yield and quality. The Plant Balance Model is introduced to enhance crop production efficiency across a range of crops, from vine crops to herbs and lettuce.

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8.1 Introduction

As the global population grows, the demand for fresh, healthy, and affordable food increases. Indoor farming offers a solution by reducing water and pesticide use while providing nutritious food. The transition from traditional agricultural practices to more efficient indoor systems is essential to meet future food demands.

By integrating climate control systems that independently regulate light, temperature, and evaporation, indoor farms can optimize plant growth conditions. The use of laminar airflow helps manage evaporation without affecting light levels, further enhancing crop yields.

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This combined excerpt outlines the potential of renewable energy in making plant factories smarter and more efficient while addressing the critical issues of food production and sustainability in the face of a growing global population.

Overview of Indoor Farming Concepts

Indoor farming is a rapidly growing field, leveraging advanced technologies to maximize agricultural productivity in controlled environments. This section delves into the Plant Balance Model and the SAIBAIX Production Process Management System, both of which aim to optimize plant growth and resource efficiency.

Plant Balance Model

The Plant Balance Model was developed through a comprehensive data collection effort involving over 500 measuring fields and millions of data points over five years. This model serves as a vital tool in predicting biomass production, understanding plant growth dynamics, and adapting to climate changes.

Key Components of the Plant Balance Model:

1. Yield: Represents the maximum biomass production, expressed as dry matter per square meter per year. It considers the efficiency of photosynthesis and the harvest index—the percentage of produced biomass that is harvested.
2. Specs: These are the desired specifications for the produce, including target weight and dry matter content.
3. Speed: This factor relates to the temperature and the time required to complete growth cycles for plants, quantified in Growing Degree Units (GDUs). This metric indicates that an increase in temperature can accelerate growth.
4. Sinks: Refers to the necessary number of sinks (e.g., fruits, leaves) to achieve the desired product yield. It aids in determining plant density and predicting yields based on climate parameters like temperature and light intensity.

Calculations and Assumptions:

• The theoretical maximum dry matter production is pegged at 30 kg/m²/year under ideal light conditions (300 μmol/m²/s of blue and red light).
• Real-world conditions lead to a more practical yield of 15 kg/m²/year, influenced by various factors, including light interception, daylength, harvest index, and planting events.

This model not only assists in yield prediction but also guides the design of large-scale indoor farms, like the one established by 80 Acres Urban Agriculture LLC in Cincinnati, which utilizes advanced growing techniques and air treatment systems.

SAIBAIX: Production Process Management System

The SAIBAIX Production Process Management System aims to enhance the profitability and efficiency of Plant Factories with Artificial Lighting (PFAL). It addresses the challenges faced by PFALs, where only 25% are profitable due to insufficient control over cultivation environments and productivity metrics.

Core Functions of SAIBAIX:

1. Management of Plant Growth: This involves the quantitative assessment of various environmental and growth factors, including:
   • Air temperature
   • Water vapor pressure deficit (VPD)
   • CO2 concentration
   • Nutrient solution ion concentration
2. Management of Production Process: SAIBAIX focuses on reducing lead times and labor costs while increasing plant growth rates. Efficient automation is key to maintaining cost performance without sacrificing quality.
3. Sales Management: Unlike traditional factories, PFALs cannot halt production mid-cycle, necessitating a robust system to manage production outputs in response to market demand. This prevents product shortages and waste, which can lead to losses.

Conclusion and Future Developments

Both the Plant Balance Model and the SAIBAIX system showcase the synergy of technology, climate control, and plant science in modern indoor farming. With continuous advancements in LED technology and plant genetics, the potential for increased yields and enhanced food quality is promising. Future developments will likely focus on optimizing production efficiency, improving nutritional profiles of crops, and ensuring the sustainability of indoor farming practices, ultimately contributing to global food security.

This excerpt presents a comprehensive overview of the management and monitoring of plant growth in Plant Factory with Artificial Lighting (PFAL) systems. Here are the main points and themes from the text:

Key Themes and Points:

1. Monitoring and Detection:
   • Continuous monitoring of plant growth variables, like net photosynthetic rates and ion uptake, is crucial for early detection of growth abnormalities in PFALs.
   • The text emphasizes that traditional monitoring methods focusing solely on state variables (like temperature and light) may miss critical, unforeseen changes, such as toxic outbreaks or equipment failures.
2. Ion Uptake Management:
   • Managing the ion uptake rate of nutrient solutions is essential, especially for cultivating mineral-rich and medicinal plants.
   • Even if electrical conductivity (EC) remains uniform, the balance of ion concentrations can fluctuate, affecting plant health and component quality.
3. Resource Use Efficiency (RUE) and Cost Performance (CP):
   • A focus on accurately assessing productivity and CP is vital for profitability in PFALs. This includes monitoring resource costs (seeds, CO2, water, fertilizer) and energy costs.
   • The text highlights the relationship between electricity consumption, operational ratios, and improvements in environmental factors beyond lighting that can enhance yield without additional costs.
4. Water Use Efficiency (WUE):
   • PFALs achieve significantly higher WUE compared to traditional greenhouses, often maintaining levels above 80-90%, thus minimizing water loss.
5. Noninvasive Measurement Techniques:
   • The text discusses the potential of using camera image analysis for evaluating plant conditions (growth state, physiological disorders, etc.) to enhance quality control.
   • There’s a noted need for quantitative evaluation methods as traditional visual assessments can be subjective and impractical in large-scale operations.
6. Process Management and Optimization:
   • Efficient production in PFALs involves streamlining human-involved processes like transplanting, harvesting, and packaging, which account for about 25% of production costs.
   • The Decision-Based Process Design (DPD) method is recommended to standardize and optimize work processes to ensure consistent quality and efficiency.
7. Data Utilization through Modeling and Big Data:
   • The increasing datasets available from PFAL operations can be analyzed using sophisticated techniques, including multivariate analysis and machine learning, to optimize growth and resource use.
   • The text illustrates how environmental factors can influence harvest weight predictions through data-driven estimates.
8. Commercial Applications of SAIBAIX:
   • The SAIBAIX system has been implemented in both commercial and educational PFALs in Japan, resulting in significant improvements in yield and understanding of plant growth processes.
   • Examples include the optimization of air-conditioning systems for better environment management and improved yield outcomes within a short operational period.
9. Educational Impact:
   • The introduction of SAIBAIX in educational settings allows students to engage with plant science and technology, fostering interest in multiple scientific disciplines.

Conclusion:

Overall, the text outlines a modern approach to agricultural production within controlled environments, emphasizing the importance of precise monitoring, efficient resource use, data analysis, and educational outreach. The implementation of innovative systems like SAIBAIX is shown to significantly enhance productivity and understanding in both commercial and educational contexts.

This passage from the text discusses various aspects of productivity improvement in plant factories with artificial lighting (PFALs) and highlights the importance of air distribution systems. Here’s a summary of the key points:

Productivity Improvement in PFALs

• Cultivation Conditions: Different cultivation conditions can significantly affect the yield of crops. For example, Frill Lettuce shows a more than twofold increase in harvest weight under optimized conditions.
• Role of Production Management Systems: Effective production management systems are crucial for maximizing profitability in commercial PFALs. They should include functions for monitoring:
  • Cultivation Environment: Air temperature, light, CO2 levels, and airflow patterns.
  • Productivity Metrics: Resource Use Efficiency (RUE) and harvest predictions.
  • Production Optimization: Enhancements in production processes and ordering management.

Air Distribution Systems

• Significance: Proper air distribution is essential for creating uniform growing conditions in PFALs. The design of air distribution systems impacts the overall environmental uniformity, energy efficiency, and crop quality.
• Design Challenges:
  • Non-uniform Environment: The combination of multiple tiers, heat from lighting, and improper air conditioning can lead to environmental nonuniformity.
  • Key Variables: Essential factors include airflow patterns, boundary layer thickness, and air current speed, which are critical for optimal heat and gas exchanges.

Theoretical Concepts

• Leaf Boundary Layer (LBL):
  • Defined as a thin layer of still air around the leaf, influenced by air friction.
  • Airflow Types: Can be laminar, turbulent, or transitional, affecting heat and gas transfer.
• Resistances to Gas Exchange:
  • Heat and gas exchange involves various resistances at the leaf surface, including:
    • Boundary Layer Resistance (ra): Resistance due to the still air around the leaf.
    • Stomatal Resistance (rs): Resistance posed by the stomata during gas exchange.
    • Cuticular Resistance (rc): Resistance due to the leaf cuticle.
    • Mesophyll Resistance (rm): Internal resistance in leaf tissue.

Conclusion

• Future of PFALs: With advancements in genetic engineering, phenomics research, and AI technology, production management systems in PFALs are expected to evolve further, making them indispensable for cultivating plants with desired characteristics.

The text emphasizes the need for detailed engineering analysis in the design of PFALs to ensure efficient resource use, improve air circulation, and achieve better crop yields.

Air Distribution and Its Uniformity

10.1 Leaf Boundary Layer and Air Currents

The leaf boundary layer (LBL) affects both heat and mass transfer in crops. The primary resistances to water vapor diffusion include cuticular resistance, stomatal resistance, and the leaf boundary layer resistance (LBLR). LBLR significantly influences heat transfer, while air movement alters boundary layer thickness, impacting crop growth positively or negatively.

Leaf Boundary Layer Thickness (LBLT) is the distance from the leaf surface to the point where flow velocity approaches the free stream value. It is determined by leaf characteristics (size, shape, roughness) and air movement. The average LBLT near a flat leaf is given by:δbl=4.0lvδbl​=4.0vl​​

where ll is the mean leaf length in the downwind direction (m), vv is the ambient wind speed (m/s), and δblδbl​ is in mm.

Effects of Air Current Speed and Direction

Insufficient air circulation reduces photosynthesis (Pn) and transpiration (Tr) by limiting gas and water diffusion. Kitaya (2005) found that increasing air current speed from 0.02 to 1.3 m/s raised Pn and Tr by 1.2 and 2.8 times for a canopy of cucumber seedlings, respectively. Similarly, single leaves saw increases of 1.7 and 2.1 times at speeds from 0.005 to 0.8 m/s. Wind enhances transpiration by lowering LBLT and replacing moist air with drier air, creating a favorable water potential gradient.

Air current direction also impacts transpiration rates. Kitaya et al. (2000) showed that vertical air currents increased evaporation rates significantly compared to horizontal currents, emphasizing the importance of forced vertical air movement in high-density cropping systems.

Tipburn Prevention

To maintain high-quality crops, proper air circulation is critical. Poor circulation can lead to temperature deviations and crop disorders, such as calcium deficiency-induced tipburn in lettuce. Vertical airflow has been shown to prevent tipburn effectively, with air speeds of at least 0.3 m/s recommended near the canopy.

Studies (Goto and Takakura, 1992; Kitaya et al., 2000) highlight the importance of vertical airflow in reducing tipburn incidence, which can occur due to stagnant air limiting transpiration, even with adequate calcium supply.

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10.2 Air Ventilation/Distribution System in Plant Factories

10.2.1 Air Movement

Air movement in plant factories (PFALs) arises from wind pressure, buoyancy, and mechanical force. Air infiltration (unintentional inward air movement) is generally negligible in high airtightness buildings (0.01–0.02 air changes/hour). Buoyancy generates airflow due to temperature differences; cooler, denser air falls while warm air rises, creating spatial temperature gradients.

Mechanical ventilation, using fans and ducts, is essential for creating a uniform climate within PFALs. Proper design of the air distribution system (inlet and outlet placement) is crucial for maintaining temperature, humidity, CO2 levels, and airflow.

10.2.2 Air Distribution System

Overall Control (OC): Mixing ventilation systems are widely used to achieve overall air distribution. High-velocity air supply mixes room air for uniformity. Outlets should avoid short-circuiting supply air. Airflow patterns significantly influence temperature gradients.

Localized Control (LC): Despite OC, localized control enhances air circulation at the crop canopy. Simple methods, such as airflow/cooling fans or perforated air tubes, improve air movement and climate uniformity, particularly in dense cropping environments.

Airflow/Cooling Fan: Positioned strategically, these fans can improve air speed and distribution within shelves. However, air temperature can increase due to mixing with warm air from lighting.

Perforated Air Tubes: They deliver conditioned air to the canopy, promoting uniform airflow and helping to maintain temperature and humidity.

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10.3 Assessment of Air Distribution System

10.3.1 Air Exchange Effectiveness: Measures ventilation efficiency by comparing real and ideal air changes.

10.3.2 Local Mean Age of Air (MAA): Indicates how long it takes fresh air to reach a designated point in a room.

10.3.3 Efficiency of Heat Removal: Evaluates ventilation’s effectiveness in removing heat from the growing area.

10.3.4 Coefficient of Variation (CV): Assesses climate uniformity in PFALs, providing insight into air temperature, humidity, and CO2 concentration variations. A low CV indicates higher uniformity, though it should be interpreted cautiously when means are low.

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This concise overview encapsulates the essential aspects of air distribution and its critical role in optimizing plant factory environments for crop production. Let me know if you need any modifications or further details!

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