Researchers at the University of Windsor are looking to the sun to help solve a challenge for Ontario greenhouse growers – how to expand the sector sustainably while reducing its environmental footprint.
Prof. Rupp Carriveau is heading a project that is looking at the feasibility of a novel solar renewable energy system that would both generate and store energy for Ontario greenhouse growers. The research is receiving funds from the Greenhouse Renewable Energy Technologies (GRET) research and development initiative.
“We’re looking to do two things: reduce the environmental footprint of the greenhouse sector by reducing some of its dependency on fossil fuels in the form of natural gas heating, and enabling better electrical grid capacity by generating and storing power for when it is needed,” Carriveau, director of the Environmental Energy Institute at Windsor, explains.
The system being piloted uses black solar thermal panels that are heated by the sun and the resulting output is used to heat the greenhouse. It also makes use of solar photovoltaic panels and an accompanying electrochemical battery storage system that generates and stores electricity to supplement the amount of power the provincial grid can provide to a greenhouse operation.
Not only will this support future expansion of a sector where electrical infrastructure challenges are limiting growth, but it will also provide extra energy requirements to growers seeking to extend their production seasons by adding additional lighting systems.
“We’re turning the greenhouse from a consumer to a producer of electricity and becoming an asset to the grid,” he says. “And with the new onsite energy generation, we can offload about 20 percent of a greenhouse’s natural gas dependency; that’s enough to handle the pre-heating in the summer.”
Although the feasibility study is still ongoing, results to date indicate that the best performance comes from a combination of 90 percent solar thermal panels, 10 percent photovoltaic panels, and six autonomy hours for the battery bank.
It’s important to note, though, that there may be some variation in this combination across different operations depending on their specific needs, production systems and facilities.
“Our results so far have been encouraging enough that the grower we are working with is going ahead with it – and will use their pond to build the first commercial floating solar installation in Canada,” Carriveau adds.
The ponds offer an ideal solution as most growers don’t have additional land to devote to solar panels – and because the pond will be covered, its water will stay cooler with less environmental contamination such as algae growth, especially in the summer. This will reduce growers’ expenses related to cooling and cleaning up pond water before use in the facility.
“Under Sun Acres is pleased with the findings that have resulted from this project,” says Lucas Semple, General Manager of Under Sun Acres. “The collaboration between the University of Windsor and our facility is a key element to providing accurate energy usage profiles and understanding the complex processes within the greenhouse. Installation of a pilot project is our next step in this endeavour.”
Initial calculations, without considering any cost-sharing or other supplementary funding opportunities that might be available to growers, estimate a return on investment over 10 years.
“The technology will continue to improve and with it the efficiency so the economics can only get better,” says Carriveau.
“Growers are looking for carbon mitigation strategies, lower energy costs and reliable energy supply, and integrating renewable solar energy into a greenhouse’s operations through this type of system will help the sector achieve those results,” he adds.
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