Dynamic Lighting in Controlled Environment Agriculture (CEA)
Dynamic lighting control in Controlled Environment Agriculture (CEA), often termed smart, intelligent, dual, or multi-channel horticultural lighting, involves adjusting both light intensity and spectral composition to meet the specific needs of various crops throughout their growth stages. This technology can be managed through manual inputs, such as commands or schedules, or via autonomous algorithms, facilitating highly customised lighting solutions in smart greenhouses and vertical farming applications. The adoption of dynamic lighting is primarily driven by two objectives: optimising energy consumption and steering biological growth. However, these objectives can sometimes conflict with one another. This article will discuss the advantages and disadvantages of both approaches.
Biology Focused Dynamic Lighting
Biology-led dynamic lighting focuses on optimising plant growth and yield by tailoring light intensity and spectra to the specific biological needs of plants at various growth stages. This approach leverages the influence of specific wavelengths on plant responses to enhance photosynthetic efficiency, accelerate growth cycles, and influence morphological traits such as plant height, leaf expansion, and flowering time. Research suggests that adjusting artificial lighting to align with the growth stages of specific plants can boost net photosynthetic activity and reduce time to harvest.
Beyond growth optimisation, biology-led dynamic lighting can enhance production quality by improving nutritional content and sensory attributes. For example, targeted lighting recipes can increase concentrations of vitamins, antioxidants, or cannabinoids in their respective plants, while also enhancing aesthetic qualities like colour, flavour, and aroma in vegetables, herbs, or flowers. This level of control could be beneficial for high-value crops where quality and appearance are critical, allowing for a quicker return on investment.
Dynamic lighting offers operational advantages for growers by enabling the creation of zones with specific light recipes tailored to cultivars or their growth stages. This zoning flexibility supports plant diversity and experimentation, allowing growers to adapt lighting strategies to seasonal demands or rotating crops, thereby facilitating continuous environmental adaptation. By adjusting both artificial photon flux and spectral composition from LED technology in response to fluctuating solar radiation within greenhouses, dynamic lighting can more effectively maintain a consistent growth environment throughout the year compared to traditional static control methods.
However, biology-led lighting systems present several challenges. Advanced LED fixtures required for spectrum customisation are more costly to produce and implement than standard systems. They also utilise various combinations of components that vary depending on the active light recipe, leading to underutilisation of other components and diminishing the cost-to-efficiency ratio. Maintenance can be complicated, as sensors used for precise control need regular calibration, and environmental factors such as dust or humidity can impact their reliability. Some systems rely on stable wireless connectivity, which can be challenging in agricultural environments, and integration with the internet introduces potential cybersecurity risks.
Additionally, not all crops respond similarly to spectral adjustments, necessitating fine-tuning for specific cultivars. This requires extensive research and thorough in-application trials before widespread implementation. While the ability to adjust spectra offers flexibility, it also introduces risks to cultivation. It is crucial to ensure that control over the lighting remains with the most qualified and experienced growers, with careful consideration given to the parameters within which any automated algorithms adjust the lighting.
Energy Focused Dynamic Lighting
Energy consumption-led dynamic lighting control aims to reduce operational costs and enhance energy efficiency by adjusting light output in response to energy availability and market pricing. This approach seeks to minimise electricity expenses while striving to maintain suitable crop growth conditions. For instance, growers might consider decreasing the use of high energy wavelengths, such as blue and green light, and increasing red light during peak energy pricing periods, then reversing this during off-peak hours when energy is more affordable.
Integrating renewable energy sources such as solar and wind into dynamic lighting systems offers several advantages. By aligning lighting schedules with renewable energy production, growers can reduce grid dependence, enhance sustainability, and benefit from lower tariffs through load-shifting strategies. This approach is particularly appealing for large-scale operations due to its scalability and adaptability to real-time energy market fluctuations, potentially providing additional financial resilience. However, despite these benefits, the energy demands of dynamic LED lighting systems remain significant.
This consumption-led approach can present significant biological production challenges. Reducing certain light wavelengths to save energy compromises plant growth and morphology, particularly in seasons or regions with lower solar radiation or in sole-source applications such as vertical farming. Essential wavelengths, such as blue light critical for vegetative growth, might be reduced, resulting in unsatisfactory and uneven plant development. Energy driven systems are also highly dependent on market conditions; price volatility and sudden changes in energy availability could disrupt lighting schedules, making it challenging to maintain consistency. Additionally, frequent adjustments to light spectra can stress the plants, adversely affecting yields, quality, and desirability, particularly in higher-value crops.
Closing Thoughts
Both biology-driven and energy-driven dynamic lighting systems share considerations of cost, complexity, and flexibility. The level of control, its granularity, and integration directly influence capital expenditure. Advanced systems with sophisticated adaptability require higher upfront investments but offer precise control and scalability. Assessing system compatibility with existing climate controls is essential, as is determining whether the lighting system will function as a standalone unit or as part of an integrated solution. Capturing and analysing data across these advanced systems can provide insights that continually refine lighting strategies to maximise efficiency and productivity.
Dynamic lighting control is a powerful tool for CEA, balancing biological optimisation and energy efficiency. Some systems aim to enhance crop growth and quality, while others prioritise energy reduction. Selecting the appropriate approach or integrating elements from each depends on specific growth objectives, crops in production, and the facility in which they are being adopted. Thorough evaluation on a smaller scale is advisable before widespread adoption. As implementation costs decrease, dynamic lighting holds potential for innovation, scalability, and resilience in modern agriculture. By optimising resource use and improving crop yields, it can contribute to global food security, addressing the increasing demand for sustainable food production.
