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Sustainable Technologies For Cannabis Extraction and Processing

By Alexander Beadle

Published: Jul 28, 2023   
A jar of cannabis extract held by gloves.

Image credit: iStock

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Solventless extraction technologies are growing in popularity these days, among producers and consumers alike. For the consumer, a product that has never come into contact with hydrocarbon or alcohol solvents may seem more organic and therefore bring a certain extra appeal. At the same time, producers are beginning to recognize the benefits of modern solventless extraction technologies when it comes to sustainability.

In a talk at The Science of Cannabis Extraction 2021 online symposium, Thomas Rosengren, chief technical officer at Alchemy 29, highlighted these advantages in addition to explaining how solventless extraction can help producers to maximize their operation’s value.

The environmental impacts of traditional extraction

Extraction operations using hydrocarbon or alcohol solvents offer producers the ability to create high-quality cannabis extracts, as the solvents efficiently dissolve the cannabinoid-containing trichomes in cannabis biomass, yielding a high-purity cannabis oil. However, these methods tend to also require highly-trained labor to operate safely due to the flammability of the solvents, which can cause problems at the commercial scale.

“I see large-scale solventless [methods] having an easier path to ascension in scale, due to the fact that when you’re working with some of these solvent-based systems, as you attempt to scale and move up you have to have ever-increasing volumes of either combustible or high-pressure solvents,” Rosengren said.

“No matter how well you engineer it, there’s just some innate risk – or at least expense – in that. And that risk is mitigated through proper engineering and smart design, but when you get to volumes of a certain size, it’s just inherently a little bit risky.”

Sustainability is increasingly becoming a bigger topic of conversation within the cannabis space. The environmental impact of some cannabis products isn’t lost on producers; there is at least one brand manufacturing its vape products to be more readily biodegradable, as well as refillable and made from hemp-plastic parts.

But beyond these finished products, Rosengren says that cannabis processing and extraction operations should also be looking at ways to become more sustainable with their processes. Indeed, hydrocarbon solvents in particular have been highlighted for their dangerous environmental emissions risks.

“Continued discussion around how we mature the use of the waste that comes from not just hemp but also cannabis flower is going to be imperative. And I think that that’s really where we can one day become a carbon-neutral industry,” Rosengren said. “I would really hope that that’s on every operator’s mind for the long run.”

Solventless methods for sustainable cannabis extraction

In terms of sustainability, solventless extraction comes with the natural advantage of not using such harmful hydrocarbon solvents.

“I think solventless processes offer the easiest method for offloading that product because it contains no trace solvents or chemicals or compounds in it,” said Rosengren. “It’s just the unadulterated biomass.”

Dry shifting has been a traditional form of cannabis processing for thousands of years and requires only manual agitation and no solvents. But in modern commercial operations, solventless often means using ice water extraction.

In this technique, cannabis biomass is loaded into a large drum filled with ice-cold water and agitated in order to remove the cannabinoid-filled trichomes from the cannabis plant material. The cold temperatures prevent these compounds from dissolving into the water before the trichomes can be filtered off and pressed to form hash or rosin.

Maximizing value with solventless extraction

Looking beyond the end extraction product, such a solventless method also allows for biomass to be harnessed in a number of other ways, as Rosengren explained.

“All of the value of the plant is extracted. And that’s something I think that the industry is wizened up to; you really want to be maximizing the value of the plant and pulling everything you possibly can of value out of there,” Rosengren told audiences. “There are some coveted oils, strain-specific full-spectrum oils, that can be produced from a solventless feedstock that can fetch incredible prices.”

“I think that that’s really something that adds substantial value, even if it’s only a small fraction of your byproducts or your derivatives from solving this process, knowing that you can monetize that and still sell that for a healthy retail price is great,” he added.

Solventless methods also have room for other cost-savings. The lack of solvent means there is usually much less remediation and post-processing needed to create a safe final product, which can be a net saving. Additionally, the equipment itself may not require a significant upfront investment, as modern ice water extraction machines do not need specialty fire-safe operation rooms like a hydrocarbon facility might.

Scaling up sustainable extraction

The most traditional methods are very labor-intensive and require constant agitation by hand for hours at a time. But nowadays systems have been developed to suit large-scale operations, meaning that solventless extraction operations are now capable of handling significant amounts of product at very-low running costs.

“The energy cost to run a solventless process, to run a big Whistler Tech 2000, it’s about $10 an hour,” Rosengren said. “Water, we are lucky in that we have well water out here, but we can reuse and recapture that to purify as necessary. And well water is incredibly cheap.”

Solventless can even help operations scale down while they scale up. Large-scale cultivation and processing facilities take up a lot of space, mostly in storing hundreds of kilos of cannabinoid-laden biomass before it can be processed into a variety of products. But a solventless operation can sidestep this issue, as Rosengren explains.

“One of the things that I like about solventless is that you can reduce that biomass to a hash and a live resin that still allows you to derivatize all of your key components while saving an enormous amount of space,” he said. “It’s much, much easier to store 100 kilos of live hash or resin in a proper storage container or an environment than it is to store the amount of biomass that it would take to produce 100 kilos of that flower.”

“There’s nothing in here that’s revolutionary,” Rosengren concluded. “But when you’re looking at sustainability and you’re looking at the cost of building a facility and capitalizing on a facility, knowing that you can consolidate quickly and readily is really exciting.”

This article originally appeared in the Analytical Cannabis - July 2023 Digest.

Alexander Beadle

Science Writer

Alexander Beadle has been working as a freelance science writer since 2017 and has covered the cannabis industry for Analytical Cannabis since 2018. He has also written for our sister publication, Technology Networks, and the cannabis industry consultant firm Prohibition Partners, among others. Alexander holds a Master's in Materials Chemistry from the University of St. Andrews, where he won a Chemistry Purdie scholarship, and conducted research into zeolite crystal growth mechanisms and the action of single-molecule transistors.


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