At the Vignoble du Ruisseau in Dunham, in the Eastern Townships, rows of vines take their long winter siesta under cocoons of insulating geotextile, covered with a layer of snow.
But these vines benefit from an additional source of heat to ensure their comfort during the harsh cold of the Quebec winter: geothermal energy.
The family that owns the vineyard believe they are the first in the world to use this technology to protect the vines from the cold.
“The thinking here is, go big or go home,” said Sara Gaston, general manager of Vignoble du Ruisseau.
The system, patented by the vineyard, distributes heat over 7.5 hectares of fields, thanks to 15 kilometers of surface and underground pipes, maintaining the soil temperature above -10 C all year round.
WATCH | How the vineyard’s geothermal system keeps the grapes warm:
In addition, the cellars, vats and cellars of the vineyard are all heated and cooled thanks to geothermal energy.
“Two meters underground, it remains between 5 and 8 degrees, summer and winter”, specifies Gaston. “Whether you’re in Hawaii or France, it’s about the same temperature.”
The system works by transporting this underground heat to the surface using a glycol solution circulating through the tubes.
Gaston specifies, in winter, that the redirected heat protects the sensitive buds and makes it possible to limit the loss of grapes during extreme cold.
“We wanted to make sure the vines didn’t die and that there was a full, quality harvest, year after year,” she said. “This allows us to have vines over ten years old… which are imbued with the land of our region.”
She says the idea of using geothermal heating came from the family’s desire to plant grape varieties such as Cabernet Sauvignon, Merlot and Riesling, which tend to prefer the warmer climates of the French regions of Burgundy and from Alsace.
“These grape varieties resist up to -18 [degrees]”, she said. “That’s why we have to heat them to be sure that when we get minus 30… the vine will be fine.”
They turned to geothermal energy as an ecological option and developed their own system to exploit it. On particularly cold days, says Gaston, the vineyard generates additional heat from electricity or wood chips.
While the system is primarily used in the winter, she says the vineyard also uses geothermal heat to “wake up” the vines a few weeks earlier in the spring, to give the grapes a longer growing season.
“An original idea”
While other vineyards and agricultural projects have adopted geothermal systems to heat buildings, using geothermal energy to directly heat the ground to protect plants is “a novel idea” according to Fuzhan Nasiri, PhD in Environmental Systems Engineering. and associate professor at Concordia University.
Nasiri said systems like the one used at the vineyard are considered shallow systems because they rely on temperature differences between the surface and a few meters underground to act as a heat source in winter or a heat sink in winter. summer.
Shallow geothermal energy is ideal for agricultural land, Nasiri said, because over a large area, energy “can be tapped continuously from multiple points below the earth’s surface.”
In contrast, deep geothermal systems rely on vertical wells, or boreholes, that range from 500 meters to several kilometers deep, and can produce heat to generate enough steam to run a power plant.
Nasiri said that although Quebec’s geological and soil characteristics generally make deep geothermal systems too expensive, there is “great potential” for more shallow geothermal projects in the province.
He said that after the initial investment, the systems could “provide a clean, renewable, continuous source of heat that is almost free” and if used to heat entire buildings could “reduce a considerable amount of load on our networks.
“A major opportunity exists in [the] the use of geothermal energy for district heating systems for neighborhoods in cities or remote communities in Quebec, which are off-grid and solely dependent on diesel,” Nasiri said in an email.
The geothermal model used at Vignoble du Ruisseau is one that the vineyard has developed itself and which Gaston says she is willing to share with other growers as they refine the technical specifications of the system.
“Eventually, we want to export this technology, whether to our neighbors in Ontario, outside Quebec or even outside Canada,” she says.