Ontario’s greenhouses are critical for supplying food, cannabis and flowers – all big economic generators for the province. At the same time, these operations consume a lot of electricity, so finding ways to become more energy efficient is increasingly important as Ontario continues to grow.
Along with existing energy-saving technologies greenhouse operators can get started with, several next-generation innovations hold promise for making greenhouses even more energy efficient in the years to come.
Here’s what growers should keep in mind for optimizing their energy use now, and what they should keep an eye on as they plan for the future.
For most greenhouses, lighting presents the biggest opportunity for energy savings. Many greenhouses today use high-pressure sodium (HPS) lights but LED grow lights can save between 35 and 55 per cent more energy. They also last longer, reducing maintenance costs.
LEDs can also offer growers more control over how much light they use and when. “Automated control systems can help to change the intensity of lights and allow growers to use different colours to induce specific plant responses,” says Mike Dixon, a University of Guelph professor and researcher on controlled environments. “For example, during the reproductive stage, fruits and seeds react to different spectral quality and have different metabolic requirements.”
Integrating lighting sensors into a greenhouse can help growers optimize their LED lighting levels depending on sunlight levels. For example, some cannabis growers can use ambient sensors to meet their daily light interval targets.
The technology isn’t widely used in Ontario yet, but researchers around the world are looking at ways to integrate solar photovoltaics into roof and shade screens. Along with using the sun for electricity, these panels could potentially harvest light to create the right light spectrum for crop production, doing double duty for greenhouse operators. Research into using solar technology to store more energy for ground-source heat pumps is also underway.
Variable frequency drives (VFDs) help motor-driven equipment – such as fans and pumps – run more efficiently. These drives adjust the motor equipment’s speed based on the load required. In other words, they can slow down or speed up – so depending on the task at hand, they use only the energy needed, rather than running at full capacity all the time.
For example, if exhaust fans in a greenhouse don’t need to be running at full speed all day, VFDs can accommodate their varying needs to reduce overall energy consumption.
VFDs can be used in all kinds of greenhouses and can help reduce energy by 12 per cent when they’re used on pumps and fans. Remember to consider choosing high-efficiency fans when upgrading your equipment.1
As battery systems continue to develop, growers may soon have more opportunities to store the energy they harvest through solar technology, making their greenhouses more self-sustaining.
Researchers in Ontario and elsewhere in North America are also exploring interconnected microgrids, particularly for areas using a large amount of grid-supplied electricity (such as Essex County in Ontario). These renewable energy-focused microgrids combine technology such as solar photovoltaics, generators, storage units and microturbines, giving nearby greenhouse operations another reliable, long-term power option.1
Managing lighting, heating, cooling and ventilation appropriately is crucial for growing quality plants. Integrated environmental control systems can help. An integrated controller can include VFDs, exhaust fan speeds, shade and thermal curtain operations, and heating and ventilation equipment. Growers can also use them to control zone pumps, mixing valves and irrigation systems.
Research and development into better sensors, artificial intelligence (AI) and machine-learning technology is continuing to ramp up. These technologies have the potential to save growers more energy and help them monitor and control pests and diseases, according to the University of Guelph’s Mike Dixon.
Researchers in Ontario are currently developing smart, wireless irrigation technologies and sensors to detect and monitor moisture levels in the soil and air. “Soon sophisticated imaging systems will be more routinely deployed in controlled environment applications where even slight nutrient imbalances and pathogen activity can be detected and responded to by automated environment control,” Dixon says.
As data and automation capabilities continue to evolve, growers will be able to use their lighting, heating and ventilation technology more effectively to produce better crops and use less energy in the process.
As these technologies continue to develop, greenhouse operators will have even more opportunities to design flexible, energy-efficient operations that will keep Ontario growing for years to come.