Supercritical CO2 Extraction

supecritical C02 ExtractionThere’s no denying that the most potent and flavorful concentrates are made via butane extraction— butane is a nearly perfect solvent given its affinity for cannabinoids, ease of removal and non-toxicity. Unfortunately, as the media and opponents of legal cannabis are quick to point out, the flammability of butane poses a serious safety hazard; especially with so many untrained clandestine chemists making dangerous attempts in their garages, bathrooms and kitchens (such environments are dangerous even with proper equipment and experienced personnel). With many medical states like Colorado and Washington cracking down on BHO producers, forward looking extractors have become more interested in supercritical CO2 as a much safer, cheaper, less explosive alternative to butane.

Supercritical CO2

CO2 is cheap, non-toxic, odorless/tasteless, and readily available with excellent purity for use across a broad range of industries. Because of its relative safety and widespread use, it’s particularly easy for just about anyone to purchase large volumes of pure, compressed liquid CO2 without any anyone else batting an eye (just ask anyone who home-brews beer or soda). The catch? One cannot simply blow CO2 over marijuana leaves and extract the THC; the CO2 must be in a supercritical state.

Supercriticalphasediagram
We all know about the solid, liquid and gas states of matter— “supercritical” is a special state that exhibits the traits of both a liquid and a gas. At pressures above 1100 PSI and temperatures higher than 88ºF, CO2 enters the supercritical state and its solubility (ability to extract different compounds) becomes a function of temperature and pressure. This is what makes supercritical CO2 extraction so desirable in the commercial natural extraction industry: its selectability can be fine tuned in real time to pick up lighter molecules (terpenes) or heavier molecules (cannabinoids) while minimizing the pickup of heavier plant fats and waxes.

Why You Haven’t Been Impressed

CO2 extracts certainly aren’t anything new but the costs to obtain the technology and expertise required to run a proper extraction are hundreds if not thousands of times greater than the costs involved in making BHO (an automated system can cost anywhere between $50K-$100K). While temperature and pressure have relatively little effect on the solubility of butane in a closed-loop BHO extraction, a few degrees can mean drastic changes in the final product of the CO2 extraction (often resulting in that dark, bitter CO2 oil most people are familiar with). In many cases, uneducated extract makers subject their raw CO2 concentrate to additional seperation methods like ethanol “winterization” or thin film distillation completely destroying any terpenes that may have been present (or not, many CO2 extractors use trim with low terpene content in an effort to generate higher margins and pay off their heavy initial investment). This is why they add artificial flavors to products like “the clear”— there’s very little good, natural taste left after all the processing and its entirely possible there’s not even an effort to separate different strains before extraction.

That being said, it won’t be long before you are impressed with CO2 extracts. The technology has evolved quite a bit even in the last two years with now multiple companies offering comprehensive extraction systems and some of the more scientific, state-licensed extraction labs in Colorado and Washington creating some truly impressive raw products with purity and terpene profiles that rival live resin.

The Future of Concentrates

humminbirdco2As marijuana legalization continues to sweep across the US, the safe production of concentrates will become a bigger and bigger issue with states looking to one another about how to handle it. There is absolutely no doubt that state governments will favor CO2 extraction over butane— it wouldn’t be surprising to see BHO gradually phased out as governments put a regulatory squeeze on butane extraction and CO2 technology becomes better and more affordable. So next time you come across some good looking CO2 concentrate, keep an open mind! You might be surprised.

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