Photo of a number of steel reservoirs and pipes in a processing plant, for e1011 Labs' page on methods of cannabis extraction.

A Critical Comparison Between CO2 and BHO in Cannabis Extraction

E1011 explores both methods of cannabis extraction

CO2 versus BHO is a common comparison when it comes to cannabis extraction, and for good reason.  Supercritical carbon dioxide extraction is a method that has gained popularity in the last decade as the “preferred choice” when it comes to solvent-based extractions. With sporadic fatal butane explosions caused by amateur extractors there has been good reason to shun BHO. In this ten-minute read, we extensively explore both methods and unearth the truth of which is superior to the other, if at all this is the case.

For starters, here’s why cannabis extraction is all the rage.

What Happens During Cannabis Extraction?

Cannabis extraction is an essential part of processing cannabis. Without this, one would not be able to maximize on the psychoactive and therapeutic goodies found in the cannabis plant.

If you have had the chance to behold fresh cannabis buds you might have noticed a milky white layer on the surface of the buds. This is made up of tiny crystals which are the trichomes. When touched the feel is sticky. Extraction entails isolating cannabinoids and terpenes which are found in the resin glands (trichomes) of the plant. The extract obtained is used to make different cannabis products that are highly concentrated. This is what makes this step all-too-important both for home and commercial cannabis “manufacturers”.

Depending on the method used for extraction the extract will take different forms. This includes shatter, wax, rosin, and kief among others.

Cannabis extraction can be done with or without a solvent (solventless). Solvent based methods are commonly used due to ease of scalability, among other reasons, though solventless methods have their advantages as well.

Carbon dioxide and butane are common solvents used in cannabis extraction. Below is a breakdown of how both methods work. Further down we will analyze their pros and cons.

What is BHO Extraction?

BHO is the abbreviation for butane hash oil. It follows that this method utilizes butane, which is a hydrocarbon, to extract cannabinoids, terpenes, and other compounds from the cannabis plant material.

Butane removes the trichomes from the plant material while preserving the flavors, scents, and other properties of that strain. If you have come across cannabis shatter this is among the purest forms of BHO; that is why it has a very clear glassy appearance.

How is BHO Extraction Conducted?

In BHO extraction, butane is blasted through the cannabis plant material and washes away the chemical compounds such as cannabinoids, terpenes, and lipids from the plant material. The next step is to separate the solvent (butane) from the extract. The final step is called purging and is very critical since it eliminates butane which is not safe for human consumption.

There are different methods that can be used to purge after BHO extraction, vacuum purge is a common method that is effective.

Amateurs often fail at this step which has led to BHO products being labelled as unsafe, albeit erroneously from our perspective. When purging is done well, a near-pure extract can be obtained.

Butane is a very volatile compound and is consequently explosive in nature. As alluded to earlier, spontaneous fires are always a risk with this method of extraction.

To prevent this, a closed loop system is often used to minimize exposure to the external environment and hence remedy the risk of explosions.

For a home extraction an open loop might be used when necessary precautions are in place. We do not recommend trying this on your own and would hope that anyone who does, uses the outdoors and has a fire-safety system in place.

Pros and Cons of BHO Extraction

BHO extraction was a popular method for a long time, before explosions became all too common. There are several advantages that played part to its stardom back then; one of them being that it is a relatively cheap method. It is also time saving. If you get the process right and are able to exercise caution you will end up with a high-quality flavorful extract.

On the flip side, the open-loop system poses a great danger in the form of explosion risk. A closed loop system can however help to remedy the situation. At the end of the day, BHO is a less safe method as compared to carbon dioxide extraction, all factors considered.

The other concern with BHO has been the amount of residue that remains in the final product. It is difficult to get rid of all the butane even with a vacuum purge. This is a health hazard since butane is unsafe when ingested. That makes it essential to test cannabis products for any residual solvents before they are made available to consumers, regardless of the extraction method used.

BHO is however making a slow comeback for these two reasons. First, it is terpene preserving. Though there are no studies conducted to confirm this, it is believed that BHO will preserve more terpenes as compared to CO2 extraction. Secondly, BHO produces highly concentrated extracts; the cannabinoid content can be as high as 70%-90% depending on how the extraction is carried out.

Enough said of BHO, what does carbon dioxide extraction have to offer?

How is Carbon Dioxide Extraction Conducted?

Carbon dioxide is a natural gas that is not only readily available but it is also eco-friendly and safe. As you may already know, we have lots of carbon dioxide leaving our lungs at any given time.

When carbon dioxide is used during cannabis extraction it can be either used in a supercritical or subcritical state. Supercritical carbon dioxide is commonly used especially on a commercial scale because it is highly effective at extracting cannabinoids.

In this method, carbon dioxide is compressed at extremely high pressures where it turns into a liquid-gaseous phase. When blasted through the cannabis plant material it strips away the trichomes and extracts the cannabinoids. After this, the carbon dioxide is easily evaporated from the extract to leave behind an almost pure extract.

A common misconception with this method is that it does not leave any solvent behind, this is quite impossible with any solvent based extraction method. The case here is that this method does not leave residue which is an obvious advantage. This has contributed largely to the rising popularity of this extraction method.

A closed-loop system uses the naturally-occurring C02, which is odorless, colorless and capable of dissolving cannabis resin from the plant.

At critical pressures, the CO2 is converted into a supercritical state which adopts gas and liquid-like characteristics that is useful for extraction. Unfortunately, the high pressures may degrade terpenes and therefore alter the flavor of the final product.

Pros and Cons of Carbon Dioxide Extraction

Carbon dioxide has several advantages as an extraction solvent. For starters it is readily available and therefore relatively affordable once the startup costs have been provided for.

Carbon dioxide is eco-friendly since it does not pose any environmental risks. It is also safe for the consumer and since it does not leave any residue behind. It is a much better option than BHO in this regard.

It is a popular choice for commercial extraction because it is easily scalable.

On the flip side the start-up costs of this method are prohibitive for small to medium sized cannabis businesses. But perhaps the bigger concern with this method is the loss of terpenes when cannabis is subjected to critical pressures. Terpenes are responsible for the delightful scents, albeit skunky, that we have learnt to associate with cannabis. Additionally, science is now revealing that terpenes have a myriad of therapeutic benefits to offer.

As a result, some extractors are opting for subcritical carbon dioxide extraction. In this method lower pressures and temperatures are utilized. As a result this process takes a longer time and is less efficient as compared to supercritical conditions. However, this method ensures that a significant amount of terpenes are preserved and the result is a much desired full-spectrum product.

Is There A Clear Winner?

As you may have noticed, both methods can quite easily get you to your desired end. This just means that both methods can give you high-quality cannabis concentrates and extracts if carried out optimally. It is no surprise that these are the most common solvent-based cannabis extraction methods. However, there is an alternative to extraction-based methods which delivers a sustainable, full-spectrum product.

E1011 Labs' Revolutionary Alternative

E1011 Labs' method does not use any extraction process. Yet, it is able to deliver a full spectrum of cannabinoids and terpenes in the final product. Our method also focuses on sustainability as it requires less energy and resources and hence efficiency is enhanced. With no chemicals involved, our final product is safe and additionally offers the same ease of use as an oil pen. This is the Elon + Stem method which has recently gained popularity over traditional BHO and CO2 extraction. Read more about e1011 Lab’s revolutionary product line preparation method.