CO2 Extraction Process: The Newest Advances, Methods, & Techniques

Starting from the beginning

What is CO2 Extraction and How Does CO2 Extraction Work?

What is the CO2 extraction process?

The plant material is ground up to a coffee-ground consistency (approximately 100 microns). This is the ideal surface size for CO2 – any smaller and there’s a risk of the plant material getting through one of the filters and contaminating the system, and any larger, there’s a risk of channeling, which is exactly how it sounds – the CO2 finds the path of least resistance through the plant material and not all the plant material is exposed to the solvent.

CO2 Extracted Oil

Depending on the parameters used, the extracted oil may require post-processing work to filter out the fats, waxes, and lipids that are pulled along with the cannabinoids. This usually requires additional equipment and some training to get the final product. However, one big advantage of CO2 is that there is no residual solvent left in the extraction – it simply bubbles away after the extraction.

Cannabis Extraction

Once the oil is extracted it will be highly concentrated, so it is much more potent than in smokable form. The extracted oil can be used in a variety of products, from vape pans to tinctures to balms. It is also used in edibles (chocolates, gummies, and drinks), as well as in a very potent extract used for dabbing.

Is CO2 Extraction Safe?

CO2 is not a volatile or explosive solvent. In fact, CO2 is the main component of fire extinguishers! The most safety equipment an operator needs is a CO2 monitor in case of a leak. However, no special safety equipment is needed in a CO2 laboratory, like there is in other forms of extraction.

How much is a CO2 extractor?

Apeks Supercritical systems range from $89,500 to more than half a million! Operated under optimal parameters, the ROI (return on investment) is very quick – a couple of months, if that. The price of concentrated and wholesale oil varies wildly across states, so the ROI depends on which market you’re entering. But don’t just look at the equipment cost, there are several other essential pieces of equipment, or facility requirements needed, and we will get to that a little later in this article.

The Best Cannabis Extraction Equipment

That depends on what you’re trying to create! Some systems are better at creating certain products than others. For example, if you’re looking for terpenes (the flavonoids and taste elements), look at CO2 for your extraction. CO2 is highly tunable and can be set to pull certain components from the plant. If you want to produce live rosin, butane or propane are ideal – this is because live rosin is produced with fresh (wet) plant material and CO2 requires very dry plant material as a source. Distillates are best produced using butane/propane or ethanol. For large quantities, most people turn to ethanol because it is fast, and cheap. However, it is very limited and will pull a lot of undesirable compounds, requiring a lot of post processing after extraction. It isn’t tunable like CO2.

Common Methods of Cannabis Extraction

We talked about a few methods earlier and here is a brief summary of the most common, with the pros and cons of each. Remember, no extraction method is the best – consider what you want to produce, your budget, and your local regulations, before making any decisions. The equipment is all expensive and you want to be successful!

Hydrocarbons

Hydrocarbons are chemical compounds composed of hydrogen and carbon atoms. They are considered highlight flammable and should be handled with care. There are a couple of hydrocarbons in use for cannabis extraction.

Butane:

One of the pros of butane is the lower cost of equipment. However, this needs to be offset by the high facility costs due to the volatility of the solvent. Local fire departments have stringent safety requirements for solvent extraction, and they will require a Class 1, Division 1 facility. The extraction room is, simply put, a bomb shelter. It will need to be completely sealed, with fire suppression systems installed. Gas detectors and an expensive exhaust system need to be part of the build out as well. Regulators will need extensive paperwork and safety certifications before approving a facility.

In addition to high facility costs, butane is susceptible to heat which may cause thermal degradation in the valuable terpenes.

Propane:

Propane has the same safety requirements as butane, so even though the extraction system may be cheaper than a CO2 system, the savings are offset by the high facility build out costs. There could also be a residual taste of propane in the extract.

Alcohol (ethanol):

This is a popular choice of solvent because it extracts very quickly. It’s a common process used by many hemp processors because it’s very fast. However, it does pull an awful lot of unwanted compounds like chlorophyll and it can’t fractionate (separate the terpenes from the cannabinoids), so it’s mostly a one-trick pony. There is also be a slight residue in the final product. However, ethanol is added at the post processing stage anyway, even in CO2 extractions, so as long as the ethanol is food grade, it can be ingested without harm.

CO2

CO2 is considered safer and purer than other forms of extraction. No safety equipment or facility build out is needed. Vent lines are small, and the only additional piece of safety equipment needed is a CO2 monitor in case of a leak. The cost of the system is usually higher than hydrocarbon or ethanol systems, so the initial investment is higher.

What extraction method is the best?

There isn’t one! Instead, there is a best method to create a specific product. Let’s explore that concept: all extraction methods are good for vape pen oil. CO2 is not good for live resin because the plant needs to be as fresh as possible and CO2 doesn’t like the water content. CO2 is okay for dabbing products, but it’s labor intensive to produce the right consistency (it can be done but might not be worth it if that’s all you’re planning to produce). The same goes for distillates – hydrocarbons and ethanol are best for this product. CO2 is first in class for terpenes though – it is a highly tunable solvent, which allows you to separate various compounds, and terpenes are one of them. Oils used for edibles are also best produced with CO2, but for infused products, look at ethanol.  

Watch the short video to learn more:

How Do You Extract CBD with CO2?

CBD (Cannabidiol) is one compound found in the hemp and cannabis plant (and other plants too – say hello to echinacea!). Both hemp and cannabis have CBD in higher concentrations than other plants though, so for the purposes of this conversation, we’ll focus on those two. Hemp is related to cannabis but they are not the same plant. They’re like cousins, so cousin hemp is renowned for having a high CBD content, while cousin cannabis is known for higher concentrations of THC (tetrahydrocannabinol). THC is the compound that gets you high. CBD doesn’t contain any properties that makes you high though, which is partly why it’s so popular.

To extract CBD successfully, you need source material with a high percentage of CBD, so hemp is a good candidate. The plant is harvested at the end of the growing cycle (usually around four months) and dried completely. As mentioned above, CO2 does not do well with water – it simply separates out of the extract and reduces your yield. The plant is hung up to dry, or placed in an oven to completely dry it. Some customers who live in humid regions use a freeze dryer to get all the moisture out. 

Once fully dried, the plant is ground up to coffee-ground consistency. This is then poured into the extraction chamber of a CO2 extraction system. The vessel is then sealed and the operator enters the parameters they would like to use (time and pressure). Apeks Supercritical systems are fully automated, so once the parameters are entered, the system will ask the operator to check a few things, and then off it goes!

The pressure in the system rises, and the temperature goes up to whatever it’s set to. The CO2 flows through the extraction vessels and through the plant material. Because of the pressure, the CO2 converts from a gas to a liquid, which is a fabulous solvent. It picks up the oil in the plant material as it flows through before it goes to the separation chamber,

where it goes through an orifice, which de-pressurizes it, converting it back to a gas. The oil contained in the flow drops out of the gas stream, into a collection cup. The CO2 continues in a loop, going through the material until it gets to the selected time, at which point it ends the run. Depending on parameters, the operator may have to pause the extraction run to harvest the extracted oil.

This short video below will outline the concept of CBD extraction with an Apeks Supercritical machine.

CO2 systems are excellent at fractionation which is when the extraction is chunked into different components: terpenes, subcritical extractions, and supercritical extractions. The advantage of this is that the post processing time is cut down and the terpenes are not degraded by high pressure and temperatures. This quick video outlines the principles of fractionation:

Terpene extraction

Terpenes are the smell and flavor of a plant. They are fragile by comparison to the rest of the compounds, so need special care! They are also sought after in the oil industry so it’s important to preserve them. In a typical Apeks Supercritical CO2 run, they are extracted in about 20-45 minutes (depending on the system). No further processing work is required, and they are simply set aside.

Subcritical extractions

Subcritical means low pressure/low temperature, specifically under 1083psi and 83F. This extraction pulls more out of the plant than the terpene run did, but not as much as a supercritical. This extraction does require some post processing, but not a huge amount. Look at the CO2 phase diagram for details of the pressures/temperature and the accompanying phase changes

Supercritical extractions

This the final extraction and it will pull the remaining oil from the plant. It will also pull fats, waxes and lipids so the extract will be crude oil and will require post processing distillation to remove those components. However, the waxes can also be used in lotions so don’t discard it!

Once all three extractions are complete, and the crude oil has been refined, the terpenes can be added back in, for a full spectrum oil. This is the highly sought-after CBD oil that’s fetching top dollar and generating so much interest in the market!

The Entourage Effect

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