Indoor marijuana cultivation is surprisingly energy intensive—production facilities consume about 10 times as much energy as an office building per square foot.
It’s not just the lighting used to help the plants grow, although that makes up between 30% and 40% of the energy use. The largest energy use, often making up between 50% and 60% of the demand, is for cooling and dehumidification to prevent sensitive cannabis plants from growing mildew.
The high energy demand for dehumidification can send energy costs soaring for marijuana-growing facilities, even requiring expensive and time-consuming electrical infrastructure upgrades. That’s why some growers are turning to an innovative, cost-saving alternative technology: chillers driven by propane or gas.
What is a gas-driven chiller?
Gas chillers are really a form of combined heat and power, or CHP, says Steve Lafaille, vice president of business development for the Waltham, Mass.–based energy production company Tecogen, manufacturer of the Tecochill gas chiller. The system uses a propane- or gas-powered engine to drive the compressor in a chiller machine to create chilled water, while the waste heat from the engine is recovered to create hot water.
Powering these energy-intensive chillers with more affordable propane or natural gas instead of electricity can reduce utility costs by 50%, Lafaille says. Perhaps just as importantly, these systems can help growers quickly and affordably retrofit industrial buildings for growing marijuana when the existing electrical infrastructure is insufficient.
That was the case for a marijuana grower in Douglas, Mass., that converted an old envelope factory building to a more lucrative cannabis cultivation facility. Like many older buildings, the former factory was electrically constrained and at the mercy of the electrical utility to upgrade. But growers don’t have time to wait.
“These people have been told 18 months, 24 months, 36 months to upgrade the power,” Lafaille says. “If you look at what’s happening in cannabis, in three years, the price is going to be cut in half on the market. So time is money in the business.”
Instead, the Douglas grower brought in a Tecochill unit that eliminates the need for additional power from the utility. With natural gas lines eight miles away, the facility used the existing 30,000-gallon propane tank to fuel the unit.
Gas-driven chilling has applications in other agriculture and commercial markets. Growers of lettuce, leafy greens, and herbs are also using these systems, although their plants are less dependent on dehumidification.Gas chillers have long played a role at buildings such as universities and hospitals for comfort cooling, Lafaille notes. But he foresees the technology playing a larger role in facilities that use process cooling all the time, such as food and beverage manufacturers. “We’ve really proven that the product can run 24/7, 365 days a year and have a really high degree of uptime and reliability,” Lafaille says. “And that’s what those other process-cooling customers really want to see.”
Visit propane.com to learn more about how facilities are enhancing resilience and reducing their carbon footprints with gas-driven chilling.