New technologies and the latest research in new book vertical farming

10-11-2023 | |
Purdue University researchers have been working on LED lighting strategies to increase yield and reduce energy costs for the vertical farming sector of indoor agriculture. - Photo: Purdue University
Purdue University researchers have been working on LED lighting strategies to increase yield and reduce energy costs for the vertical farming sector of indoor agriculture. - Photo: Purdue University

Professor Toyoki Kozai and Dr Eri Hayashi have had a major influence on the advancement and global understanding of vertical farming. Future Farming asked them four questions about their new book ’Advances in plant factories: New technologies in indoor vertical farming’, published by Burleigh Dodds.

The book provides a review of the latest research in the development and application of plant factories with artificial lighting (PFALs). It assesses the environmental impact of urban vertical farms and how the use of energy and other resources can be optimised to minimise this impact.

The book also considers the application of machine vision, plant phenotyping and spectral imaging in plant factories to monitor plant health and growth. There are several case studies of businesses from North America, Europe, and Asia, with different business models and technical features for commercial production of multiple crops.

What are examples of important advances in these indoor vertical farms or PFALs?

One example is the drastic improvement of electricity-photon conversion efficacy and cost performance of white LED covering a wide range of wavebands. Using W-LEDs, the electricity consumption of the cultivation room was almost halved compared to fluorescent lamps, and the spectral distribution (ultraviolet, blue, green, red, and far-red) of light sources could be adjusted to meet the purpose of plant production.

Another example is interdisciplinary research on plant factories with artificial lighting (PFALs). This research has started in several countries by natural and social scientists, economists, engineers, administrators, business people, and policymakers. Articles on PFALs are included in some supplemental readers used for educational purposes in schools. The number of papers published in related journals has been increasing exponentially since 2017.

And public acceptance of PFAL-grown (pesticide- and herbicide-free, and ultra-water saving) vegetables locally produced for local consumption has been slowly but steadily prevailing in Japan and limited regions in Europe, America, and Asia.

What do you consider to be the biggest challenges of vertical farming?

We have described several methods and strategies for challenges in the book. Some examples are:

  • Automatic spacing of plants to maximise the percent of light energy received by leaves over the light energy emitted by lamps, which reduces the cultivation area, electricity consumption, and working hours for transplanting and harvesting in PFALs.
  • Optimisation of the growth-stage and cultivar-dependent light intensity, its optimal spectral distribution, lighting cycle, and lighting direction (upward and sideward).
  • Breeding, environment control, and management for maximising harvest index (ratio of marketable produce to total plant weight).
  • Spatially (three-dimensionally) uniform control of aerial and rootzone environment factors in the plant community to maximise the photosynthesis and growth rates of a plant community (The aerial and rootzone environments are considerably ununiform in the densely populated plant community if uncontrolled).
  • Generation of all the electricity required for operating PFALs by solar energy or its equivalent to minimise the CO2 emissions per kilowatt hour (kWh) of electricity and per kg of produce.
  • LCA (life cycle assessment)-based and circular-economy-based design and management of autonomous PFALs with respect to energy, water, fertilizer, CO2, and other resource inputs such as cultivation area, and working hours and time for cultivation.
  • Implementation of phenotyping (plant trait measurements) and generative AI.

To what extent will vertical farming compete with open cultivation, for example with fruit and vegetables and perhaps bulk crops such as grain, soy or corn?

Infarm announced last year to have successfully produced wheat in an indoor farm, using no soil, no chemical pesticides and much less water than open field farming. - Photo: InfarmThe PFALs using white LEDs (W-LEDs) were probably first built for commercial production in 2016. So, the W-LED PFAL technology has a history of 7 years, and is at an infant stage.

The production of berries such as strawberries and blueberries in PFALs will be widely commercialised after their breeding is suitable for production in PFALs (probably by around 2030). PFAL berries do not compete with the open-field berries because they belong to different classes/kinds of produce for different markets.

Some portion of medicinal plants (herbs), head vegetables (e.g., cabbage) and root vegetables (e.g., carrots), and ornamentals (e.g., dwarf orchids, bedding, and interior plants) will be also be commercialised after their breeding is suitable for PFALs.

Bulk crops such as grain, soy, and corn for open cultivation can be efficiently bred in PFALs by cultivating them under various environmental conditions 3-4 times a year. On the other hand, the cultivation of bulk crops as food and feed mainly for taking calories is not justified. Not only because of commercial unprofitability but also because of huge amounts of heat energy generated during the cultivation. Such bulk crops will be commercialised if they are sold as healthcare products with some medical functions (not as staple foods for calories).

What are some important lessons we have learned so far from operational and shuttered vertical plant farms?

In many cases, shuttered PFALs could have been better designed and managed with respect of sanitation control, emergency control for partial and total power failure and malfunction of main environment control units, and risk management for sudden changes in demands due to social and weather issues.

Operational PFALs tend to be well designed and managed with respect to marketing and risk management tools, resource supply and waste processing, and monitoring and control of produce quality for food safety, consumer demands, and sustainable plant production.

The Future Farming Newsletter

Sign up for our newsletter and receive all our need-to-know content three times a week.

René Groeneveld Correspondent for Australia