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/hemp extraction

CO2 versus BHO is a common comparison when it comes to cannabis extraction – both methods having a unique set of pros and cons. 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 find out if one is, in fact, superior to the other.

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

What Happens During Cannabis Extraction?

Cannabis extraction is the process by which the cannabis flower is transformed into a potent extract. If you’re a regular cannabis consumer, you’ve likely encountered the extracts in many forms. They make up the base of infused products like tinctures, topicals, vape cartridges, and many others. 

Have you ever noticed the milky white layer on the surface of cannabis buds? This is made up of tiny crystals that are sticky to the touch called trichomes. Extraction involves isolating the cannabinoids and terpenes which are found in those trichomes to create a concentrated form of the plant. 

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; which 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 potentially toxic butane from the finished product.

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

Amateur extractors often fail at this step which has led to BHO products being labeled as unsafe, albeit erroneously from our perspective. When purging is done correctly, 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 minimize 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 the most popular method before explosions became all too common. There are several advantages that led in part to its past popularity, 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 an explosion risk. Closed-loop systems can, however, help to prevent this risk. 

At the end of the day, BHO is a less safe method as compared to carbon dioxide extraction, all factors considered.

Historically, 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 extremely 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 two reasons. First, it’s great at terpene preservation. 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 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 –  which is impossible with any solvent-based extraction method. What is true is that CO2 extraction doesn’t leave behind any 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 since it does not leave behind any residue. In this regard, CO2 is considered to be a better option that BHO.

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, it does ensure that a significant amount of terpenes are preserved, and the result is a more desired full-spectrum product.

Is There A Clear Winner?

Both BHO and CO2 extraction methods are fully capable of producing potent extracts. With BHO, you increase the risk posed to the consumers and the extractors themselves but can more easily obtain a full-spectrum finished product.

With CO2, you reduce that risk significantly, but it comes at the cost of efficiency and terpene retention. Both methods have advantages and disadvantages, and ultimately the question of which one is better will be answered based on individual extractors’ preferences.

But what if there was another way?

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. The e1011 method prioritizes sustainability as it requires less energy and resources.  With no chemicals involved, our final product is guaranteed to be safe and additionally offers the same ease of use as an oil pen.

By skipping the extraction step entirely and choosing to fill with Stems with premium hemp flower instead of a processed extract, consumers are able to glean a more natural CBD experience using an Elon.

Order an Elon Starter kit to see for yourself how e1011 labs has married the convenience of extracts with the natural goodness of pure unadulterated flower.

Read more about e1011 Lab’s revolutionary product line preparation method.