4 Ways Modern CO2 Extraction Has Evolved

Cannabis extraction is a rapidly evolving science. Innovation has exploded in the past two decades, driven by the growing demand for diverse and potent cannabis products and market pressures forcing cannabis extractors to leverage increasingly efficient processes.

In recent years, innovative techniques have emerged to harness the full potential of carbon dioxide (CO₂) extraction, including leveraging subcritical CO₂ and integrating ethanol as a co-solvent. This combination has brought about a spectrum of possibilities, especially to large-scale commercial operators.

1. Consumer Safety

In a recent appearance on the Cannabis Unraveled podcast, Jason Laronde, head of sales at Vitalis, shed light on the numerous advantages of integrating subcritical CO₂ with a co-solvent.

While the podcast host, Jessie Kater, SVP of Innovation and R&D at multistate operator (MSO) Curaleaf, mentioned that the non-flammable qualities of CO₂ extraction made it attractive (and sometimes mandated) in certain markets, Laronde expounded on the consumer safety benefits that come with extracting with CO₂ (with or without a co-solvent).

While some regulations translate to obstacles in the cannabis industry, extraction compliance comes from a place of public safety, he said. Substances like residual solvents or heavy metals present in biomass that remain after extraction can create serious negative business outcomes for product manufacturers, including loss of consumer trust, regulator fines, or even a license suspension.

Residual solvents, especially, can create health hazards for consumers when present above legally allowable levels. In the interview, Laronde shared how some extraction systems used in the fragrance industry that leverage hydrofluorocarbons like R134a (a refrigerant used in certain air conditioning systems) are crossing into the cannabis industry. These systems are “totally fine for the fragrance industry, but people don’t smoke their cologne or perfume,” Laronde said. “When you heat these products, that residual solvent can convert into some very, very dangerous things.”

When using high-purity CO₂, the residual solvent risk in cannabis extraction is near non-existent. “The majority of the solvent used in the entire process is CO₂, the same CO₂ that is in your soda pop. So … it’s a very clean, effective, and safe process,” he said.

“There is something to be said about making sure that … we’re using as little solvent as possible, that we’re using as benign a solvent as possible, that we are adulterating and manipulating the product as little as possible to ensure … that there isn’t a whole lot of other things that are along for the ride that could potentially be harmful to the consumer,” Laronde noted.

2. Environmental Impact

In addition to being potentially harmful to consumers when not properly purged, certain solvents can be much more damaging to the environment than CO₂. For example, R134a is a hydrofluorocarbon (HFC) with a global warming potential (GWP) rating of more than 1,400, meaning it is 1,400 times more efficient at trapping heat within the atmosphere than CO₂, which has a GWP rating of one.

R134a, like many other HFCs released to the atmosphere, also partially break down into potentially toxic compounds like trifluoroacetic acid (TFA) that ultimately end up in soil, groundwater, and even our bodies. Once in the environment, TFA and other “forever chemicals” can be difficult or impossible to remove.

That isn’t to say that CO₂ extraction processes have always been eco-conscious. Laronde explained how in the earliest days of CO₂ extraction, “you’d fill a pressure vessel full of your cannabis and you’d basically just push liquid CO₂ through it. And out the other end, the CO₂ would blow off as a gas in the atmosphere, and you’d end up with an extract in your separator,” a process he likened to an open-blasting butane process, an extraction method where hydrocarbon is just vented into the atmosphere, which can cause explosions.

Modern CO₂ extraction systems recapture the solvent that has been passed through cannabis biomass. By filtering the terpenes and particulates to return the CO₂’s purity to its original levels, operators increase their environmental sustainability and decrease operating costs by reducing the frequency at which the CO₂ needs to be replaced.

3. Product Diversity

The commercial success of any extraction system should be graded on two metrics, according to Laronde: “Can you make products economically at scale? And can you make a product that consumers want to buy repeatedly?”

Historically, operators looking to meet the wide variety of consumer preferences would have to run several extraction systems, whether CO₂, hydrocarbon, ethanol, or solventless. However, Vitalis’ patented subcritical CO₂ extraction process allows operators to make a wider variety of consumer extracts using a single machine.

“We developed a process at Vitalis to use subcritical [CO₂], ... a sub-zero liquid CO₂, as a solvent,” Laronde said. He noted that in the past, cold extraction was the domain of hydrocarbons, which allowed those processors to better extract flavor and aroma compounds.

“One of the unique features of Vitalis’ equipment is, if the customer so chooses, … they can actually go the other way: Go extremely low pressure and very low temperature, [and] put in live, fresh frozen product … [to] create those live products using CO₂,” he explained. This subcritical CO₂ extraction method relieves the manufacturer from having to worry about residual solvents and to completely skip the purging step of the extraction process.

“Manufacturers are now at a point where they can potentially choose one extraction methodology and make the vast majority of the catalog that they want to bring to market,” Laronde said. “And then maybe they have a small hydrocarbon system sitting in the corner for making diamonds, or they have a small water-hash process for making hash because people are seeking out that particular SKU.”

4. Scalability

One of the main drawbacks of CO₂ extraction is that it is a much longer process; traditionally, CO₂ extraction can take up to eight hours to complete. However, the other innovation Vitalis has developed with its extraction systems is the integration of ethanol as a co-solvent to bring that compound’s scale and speed into the CO₂ extraction process.

“The addition of very tiny amounts of another solvent—say 1% or 2% injection of ethanol into the CO₂ stream—allows it to take what otherwise would have been a six- or eight-hour process … to a 40-minute extraction, increasing the throughput of the machine,” Laronde says. This co-solvent injection also allows operators to avoid certain co-extracted products like fats and waxes, in turn requiring less filtration and refinement downstream.

“[This] speaks to that [less-]adulterated, use [of fewer] solvents, do [fewer] things, give respect to the plant so that when it comes to the consumer, it’s a better and more true-to-the-plant product” goal that Vitalis has with its units.

In a rapidly advancing industry, the integration of subcritical CO₂ with an ethanol co-solvent is already redefining the way large-scale processors operate, enabling them to better meet consumer demands and regulatory standards alike.