EXCLUSIVE: Dartmouth Engineering Students Conduct First-Ever Study On Energy Efficiency In Cannabis Cultivation

Dartmouth's Thayer School of Engineering and Arthur L. Irving Institute for Energy and Society announced the results of a first-of-its-kind independent study on energy efficiency in the cannabis industry.

The study was sponsored by the Sustainable Cannabis Coalition and supported by Rocky Mountain Institute and seasoned building science engineers.

These results were based on data collected from MariMed Inc. MRMD, an MA-based multi-state cannabis operator and Maryland-based Culta, a  seed-to-sale company that provides indoor and outdoor-grown marijuana & accessories.

A team of six senior engineering students conducted research through the Cook Engineering Design Center at Thayer over a six-month period during the 2021-22 academic year, adopting a whole system approach to meet plant and grower needs by focusing on yield per unit of energy, cost and carbon emission.

"This research provides an independent, fact-based analysis of the enormous potential for the cannabis industry to reduce both capital and operating costs while improving key metrics like grams of product per kilowatt hour of energy and grams of product per grams of CO2 emission,” said Dr. Stephen Doig, Senior Research and Strategy Advisor at the Irving Institute.

Research: Analysis and Methodology

The research provided regulators and industry operators with key insights into how the cannabis industry can meet climate, grid and energy goals while improving business operations and cost targets. Research analysis also showed an additional 50%+ energy and greenhouse gas (GHG) reduction potential after installing LED lighting, reducing the impact on the grid and emerging standards for “green” Cannabis.

“The students found that operators using LED lights can reduce energy use by 50% with even greater savings for those using HPS systems. Even larger savings are likely available to the indoor cannabis industry overall since the scant data available suggests that industry-wide energy use intensity is 2-3X higher than the optimal minimum conditions needed for robust product production," Doig said.

The students adapted a methodology developed at the Rocky Mountain Institute (RMI) by understanding the key needs of the plants (light, temperature, VPD, water) for optimal production. They also took into consideration that plant needs change over the growth cycle and that heating and humidity loads can vary 10-fold across the day-night cycle.

The team explored active and passive options to meet those needs dynamically and grounded their analysis by fully metering grow lights, humidity and temperature control systems.

The study yielded significant results, including:

• Under “optimal minimum” conditions, HVAC systems can reduce fan energy by 50% during the light cycle and 90% during the dark cycle especially if a displacement ventilation approach to humidity control is adopted.
• Using the best-LED lights can reduce cooling needs by 10% compared to average LEDs and by 30+% compared to HPS.
• The students also demonstrated that using air-side economizers (free outdoor air cooling) could further reduce mechanical cooling needs by an additional 40+% depending on facility location. Free cooling is a standard practice in the building industry today (and code in many states).

Findings:

In an exclusive interview with Benzinga, Dr. Doig said, “It was exciting to see that there is still substantial room for efficiency improvement even after the switch to LED lights (...) Large energy reductions are possible in both new construction and existing facilities. There are substantial additional energy and cost reduction opportunities beyond the scope of this initial study.

“Regulators and Grid operators should applaud the results since widespread industry adoption will lower the peak demand on the grid and provide guidance on key metrics to compare operators across the industry.” 

To allay fears of outdoor contamination, the students pointed out that industries highly sensitive to contamination like pharmaceuticals and semiconductors use filtration to manage contamination levels.

While the study did not address capital costs in detail the results suggest that growers who adopt an optimal minimum approach will save capital as well as operating costs since HVAC systems will be smaller and/or there will be fewer of them for the same yields.

Low Carbon Electricity System

“The industry will be able to dramatically reduce its carbon footprint and be a “good citizen” in the broader effort to ensure a reliable and low-carbon electricity system,” Doig told Benzinga when asked about the future of the cannabis industry.

“The study provides fundamental insights on how to regulate the industry with respect to energy, climate, and environmental goals and how to compare performance across facilities, states, and regions,” Dr. Doig noted. “Our experience is that the industry has been incredibly supportive and open to finding ways to reduce its energy use and carbon footprint.”

It Is All About Sustainability

Tim Shaw, COO of MariMed said he and his company were impressed. 

“We were incredibly impressed by the knowledge, passion, and commitment of the Dartmouth students and faculty involved in the study, and thankful for the opportunity to participate. As a company committed to improving people’s lives every day, we take our responsibility to help create a cleaner environment very seriously,” Shaw said.

“Implementing Dartmouth’s recommendation to redesign cooling and dehumidification implementation and to install even higher-efficiency LED lighting in our facilities is just one of many initiatives we are considering as part of our sustainability efforts at MariMed.”

The Sustainable Cannabis Coalition in partnership with RMI, Dartmouth and other key industry players intend to conduct further research in the 2022-23 academic year.

“Based on the success of this initiative, we are looking forward to extending the work with Dartmouth into additional new-build opportunities, retrofits, and developing consistent industry metrics for energy efficiency and GHG,” said Shawn Cooney, co-founder of the Sustainable Cannabis Coalition (SCC). “Our members are eager to participate in the process of standardizing the way our industry approaches its use of resources. We need to measure our usage of scarce resources across all phases of our product's life cycles.”

SCC members and partners, Culta, Byers Scientific, Anderson Porter Design, Valiant, Sustain Life, Fluence and Inspire also participated in the research, providing additional information to the Dartmouth team.
Photo: Courtesy Of Dartmouth Student Sustainable Cannabis Team