What the future brings
Exploring sustainable solutions for greenhouse adaptation and survival
November 17, 2023 By J Lynn Fraser
Greenhouses are ecosystems. They are complicated systems that ‘live’ due to the interaction of lifeforms that include humans (staff), insects (occasionally animals), chemical and technological processes, and energy inputs and outputs all occurring in a niche environment. The greenhouse niche is part of a broader environment comprised of other ecosystems (networks) such as power grids.
A greenhouse needs to adapt and evolve to survive. This has been true since the invention of a rudimentary greenhouse that grew cucumber-like vegetables year-round for Roman emperor Tiberius (AD 14–37) to the first artificially heated greenhouse in Korea in the 1450s to the first ‘modern’ greenhouse — the UK’s Chelsea Physic Garden (1681).1 It will be true when food is grown on Mars.
In the future, lighting, energy sources, control systems, and plants can rely on academic and industry research to anticipate and provide sustainable solutions for future needs.
Strength in diversity and flexibility
“We have to make a sharp turn to reduce our carbon footprint,” comments Dr. Rupp Carriveau, Director of the Environmental Energy Institute, University of Windsor. Carriveau notes that are potential energy sources for Canada and commercial greenhouses that are controversial but energy efficient.
SMR nuclear that refers to small modular nuclear reactors. Proponents of SMRs argue that they offer a low-carbon energy source. SMRs are “smaller, simpler, and cheaper nuclear energy” that can be used in a mixture with other energy sources while offering, for example, an alternative to diesel for remote communities in the North.2 The younger generation of greenhouse growers, Carriveau believes, are more receptive to SMRs with replicable designs that are factory made.
Energy security lies in relying on diverse energy sources. Although Canada is a reluctant adopter, floating solar photovoltaics (FSP) is a viable energy alternative according to Carriveau. This emerging tech involves placing photovoltaic panels on controlled bodies of water like runoff ponds to reduce land use and reliance on rooftops.
Hydrogen is another future energy source states Carriveau. Hydrogen fuel cells can be used to create electricity, water, and limited heat. Hydrogen has the capacity to store energy created from renewable energy to be used at a time when energy demand and/or prices are low.3 Energy sources like these balance out fluctuations in power sources like wind.
Fruit waste, like what most of us find in our refrigerators, is intriguing to a group of researchers at UBC Okanagan. They are studying ways to turn fruit waste, solids and leachate, into a usable form to power fuel cells.4 The future holds promise for this fuel source because Canadians are chronic food wasters. Landfills in B.C., for example, account for 40 per cent of organic waste.4 Every year, 60 per cent of the food Canada produces, approximately 35.5-million metric tonnes, is thrown out.4 Food waste as fuel is not an uncomplicated solution to supplying energy. There are greenhouse gas emissions (GHGs) to contend with, pests, odours, and the risk of local water contamination.5
Biomass gasification takes advantage of emitted GHGs. This process treats food and agricultural waste with oxygen, steam, and heat to create the gases that can become a fuel called syngas.5 This is created from a combination of hydrogen, methane, carbon monoxide, and carbon dioxide.5 Locally made biomass is cost effective.6 In Canada, biomass is largely sourced from industrial and agricultural residues that are easy to store but come with high transportation costs. Some types of biomass are associated with deforestation and use of agricultural land so, fine tuning the sources will need to be addressed for it to be a sustainable alternative fuel.
Learning by light
The use of dynamic LEDs allows for a degree of control over the spectrum of light that reaches greenhouse crops. Dr. Bernard Grodzinski and Telesphore Marie, a PhD student, at the University of Guelph’s Department of Plant Agriculture, are researching controlled environment agriculture in regards to metabolism, photosynthesis, and plant productivity, funded by OMAFRA, OGVG, and Nunhems-BASF.
“Research is focussed on daily lighting programs that deliver lighting cues at specific times of day,” Marie comments. The process is called circadian rhythm entrainment.
“Plants, and all living organisms, have naturally rhythmic inner genetic programming that we can tap into by synchronizing our management practices. The programs can be adapted depending on the species, the plants’ life-cycle stages, and the desired management practices at the commercial operation,” Marie said.
Benefits of the program include savings on both electricity and capital expenses. “LED fixtures supply less light intensity while being spread out over a longer photoperiod. The researchers’ goal is to achieve the same daily light integral as found in more conventional approaches,” Marie says.
Their research is conducted with Calgary-based Genoptics LED where the components for the technology are Canadian made. “This research, in the future, will be scaled-up for greenhouses,” Grodzinski notes.
“AI will be a huge factor in the future. There will be a ‘cool’ integrated system that controls standard environmental variables in addition to the lighting to create robust circadian rhythms,” Marie said.
Something in the air
When plants and fruits mature, they release ethylene. When this occurs in a greenhouse environment baby plants absorb ethylene and ‘age’ before they become ripe. In a greenhouse in a country that is warm year-round removing ethylene is easy and energy efficient. This is not true for northern countries — especially in winter. It will also not be true in space or on the moon or on Mars. Such greenhouses are closed systems. In such an environment, ethylene that harms baby plants has to be removed in an energy efficient manner. As well, air that has to be drawn into a greenhouse has to be heated efficiently. Dr. Jafar Soltan, Associate Dean Research and Partnerships & Professor, Chemical and Biological Engineering, at the University of Saskatchewan, studies how to remove ethylene from closed systems greenhouses.
Soltan has created a process to oxidize ethylene and convert it to CO2. His lab’s research has created a catalyst that speeds up oxidation. The catalyst can be customized to the environment it is placed in and can take into consideration temperature, humidity, and size of the ‘landscape’.
“Different plants release different levels of ethylene and also have different tolerances,” Soltan said. His technology is roughly the size of a shoe box with the catalyst inside and it runs on electricity.
“It can check how much ethylene to remove and how much is safe. The catalyst facilitates reaction of ozone with ethylene,” Soltan notes.
Installation, the control system, the controller that can open and close valves, and a blower for air are all part of the equipment needed to run the catalyst. Soltan’s technology saves on energy needed to heat and cool air in a closed system greenhouse and it saves money that would have been lost on pre-maturely ‘aged’ young plants by removing ethylene from closed system greenhouses.
In the near future, intelligent power electronic interface design will benefit commercial greenhouses’ energy efficiency.
“Power electronic interfaces (power converters) convert energy from one form to another to suit the application (e.g., AC (alternating current) power from a wall outlet to DC (direct current) power to charge a cell phone). During the conversion process there is power loss due to the semiconductor components of the power electronic interface. Power loss, through various circuit design, component selection and control techniques, can be minimized,” said John Lam, Associate Professor & Vice Chair, Department of Electrical Engineering & Computer Science, York University.
“Currently in the field of power electronic interface design, researchers are exploring the use of emerging wide bandgap semiconductor devices (such as Silicon Carbide (SiC) and Gallium Nitride (GaN) devices). These devices exhibit very low power loss and allow for the design of more power-efficient and reliable power converters,” Lam notes. “My research laboratory has developed a new adaptive SiC-based power electronic interface for renewable energy applications that allows the achieved power efficiency to remain between 98–99 per cent throughout its operating range.”
The practical application of this, for greenhouse owners, is an increased power efficiency. “In the long run, smart and highly power-efficient power electronic interface will be the key to enable more energy efficient applications,” Lam believes.
“’Live’ high-fidelity representations of real-life systems, that is digital twins do what humans cannot as they continuously process the real-time data stream from the sensors of the physical twin and use it in complex analysis and simulation mechanisms for decision-making purposes,” said Dr. Istvan David of the Department of Computing and Software at McMaster University.
“I expect in the next five-to-10 years, digital twin-driven smart agronomy will become available for end-users,” David said.
“Digital twins are key enablers to more sustainable growing practices and I foresee grower companies in the near future adopting this mindset and supporting it with digital twins,” David observes. “Digital twins help you with precise automated control to keep environmental variables always at values that are most appropriate for the specific lifecycle phase of plants while also being able to minimize energy footprint,” David notes.
The digital twins’ software was applied to managing 50,000 strawberries and bumblebees in a Quebec greenhouse.
“The same simulators and most of the hardware can be used for basically any plant as long as good enough models of the given plant are available,” David said.
Costs involved in implementing digital twins range from low, such as hardware (sensors and actuators) and software costs (cloud technologies), to the high involving, for example, “Smart agronomy systems, such as HVAC systems, and irrigation systems…often in the tens- to hundreds-of-thousands of dollars,” according to David.
“As a former head of innovation at a multinational company, I can wholeheartedly recommend academic collaborations for piloting digitalization projects. Collaborations between academia and industry are particularly important in fostering sustainable agronomy practices. I would encourage greenhouse companies out there to reach out to potential academic partners and see what they can achieve together.
“Developing and operating digital twins needs technical expertise.” For this reason, David advises working with a company that can consult with greenhouse operators that will facilitate “gradual learning.” He also suggests starting small then scaling up.
Artificial intelligence (AI) may be, for some, a natural evolutionary next step for greenhouse ecosystems. They are, however, not completely without a few missteps. In his study of the use of AI in smart greenhouses, Dr. Chrysanthos Maraveas, Agricultural University of Athens, commented on possible missteps. These include cost, variations in the algorithm’s performance in the real world, aging, and a “lack of experience with the technology.”7 The advantages, Maraveas found, include increased crop yields in addition to efficiently used water and fertilizer. Energy efficiency also improved because photovoltaics, pricing, and autonomous communication between the greenhouse system and external power grid supply were integrated.8
Climate change, COVID-19 today, and future pandemics, wars both physical and cyber, and power black outs are examples of threats to food, energy, and physical security. A flexible greenhouse ecosystem that can adapt and evolve as an independent ecosystem or functioning as part of a larger secure ecosystem can survive a variety of threats.
1 Growlink, ‘The History of Greenhouses’
2 Canadian Small Modular Reactor (SMR) Roadmap Steering Committee, ‘A Call to Action: A Canadian Roadmap for Small Modular Reactors’
3 U.S. Energy Information Administration, Hydrogen explained.
4 UBC Okaganan News, ‘UBCO researchers aim to energize fruit waste.’
5 Salvador Escobedo Salas, ‘The Conversation, Here’s how food waste can generate clean energy.’
6 Daniel Ciolkosz, ‘Things a greenhouse owner can do to improve energy efficiency.’
7 Chrysanthos Maraveas, MDPI, ‘Incorporating artificial intelligence technology in smart greenhouses: Current state of the art.’
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