Ethanol vs. Hydrocarbon vs. Co2 vs. Solventless Extraction Processes: What’s the Difference?
Cannabis concentrates are the fastest growing segment in the market and if you’re reading this, we’re guessing that you can understand why! There are many extraction techniques involved in creating these products. Some methods use organic solvents, while others use pressure or even water.
In commercial sized facilities, hydrocarbon, ethanol, Co2 and solventless are the most typical extraction processes utilized at scale. Curious about the difference between these extraction types? Read on!
The cannabis plant produces trichomes, which contain a myriad of compounds that can be extracted and used in different ways. It’s important to point out that not all of these compounds are beneficial, and the type of solvent and extraction method chosen will have a significant effect on the final set of compounds contained within the cannabis extract. In order to extract these compounds, the cellular membrane must be dissolved or agitated – this releases the active compounds into the solvent. Non-polar solvents such as ethanol and hydrocarbons are particularly advantageous to this process, disrupting the lipid-bilayer which contains the desired compounds, but they are not the only way.
Any extraction method involving solvents should only be performed by qualified, experienced individuals using rated and inspected equipment. When a cannabis lab is determining which extraction method to use, there are a number of factors they need to take into account such as cost, scale, safety, desired end products and legal availability in their particular region. Each method has different benefits, depending on what factors are important to the end goal of the operation.
Ethanol Extraction
Alcohol extraction is a widely available method of extraction that may have been used as early as 2000 BCE. For cannabis, it involves soaking the flowers in alcohol (preferably ethanol) to extract the trichomes into the solvent. The raw cannabis is then removed, the liquid is filtered, and the alcohol is distilled from the remaining oil. The advantage of ethanol extraction is that it doesn’t necessarily require high-end equipment and the process can be quite simple at a small scale. It also has the added benefit of the lowest price point, in terms of entry costs. The downside of ethanol extraction is that an operator is extremely limited in the final form factors of products that ethanol can produce. This production method generally produces a crude oil that then goes into large scale distillation to remove the remaining undesirable compounds such as chlorophyll. Ethanol extraction generally yields tinctures and products that are infused with cannabis oil through distillation. A drawback here is that the distilled oil is devoid of terpenes and other phytochemicals that imbue cannabis oil with enhanced physical and psychoactive benefits.
Another drawback of ethanol distillation is that it is a relatively inefficient process, since evaporation and recovery take large amounts of heating and cooling energy, physical space, and time. Over time ethanol purity will go down, meaning that it will require purification or replacement.
Hydrocarbon Extraction
Hydrocarbon extraction is one of the most popular methods of extraction, and for good reason. This form of cannabis extraction uses a hydrocarbon-based solvent (such as butane and propane) to extract compounds from the plant material. The polarity of the solvents is highly advantageous in that it allows the operator to be selective in what compounds are extracted, which allows the less desirable compounds such as chlorophyll and water-soluble compounds to be left behind. New advances in hydrocarbon extraction technology have also been able to utilize practices similar to chromatography in separating the myriad of compounds available in the cannabis plant during the extraction process. Since hydrocarbon solvents are extremely volatile, they easily evaporate making extractions relatively quick. Similarly, removing residual solvents from the oil is significantly easier. Hydrocarbon extraction also has the most options in terms of final form factors for consumer products, making everything from the highest quality dabable product to basic crude depending on operator experience, setup, SOP’s and equipment choice.
However, hydrocarbon extraction also has some major drawbacks which limits its viability for many operators. To begin, some local jurisdictions have deemed the process too dangerous and have outlawed the license types all together. The volatile nature of hydrocarbon solvents requires significant facility infrastructure and engineering including rated extraction rooms, sophisticated gas detection systems, fire suppression, and certified and peer reviewed extraction equipment. Most states will also require significant inspection and sign off from state and local authorities making the licensing aspect far more difficult, expensive, and time consuming. To top it off, a simple operator error can pose a significant liability for any production facility and its personnel. Despite these risk factors, some of the most successful cannabis companies in the country who produce the highest quality oil products are doing it using hydrocarbon extraction, so there is a proven track record.
Co2 Extraction
Co2 extraction, also known as supercritical extraction, uses carbon dioxide “solvent” and requires the use of high-end, industrial-grade equipment for precise measurements, temperature control, and separation of the finished product. The supercritical Co2 extracts and isolates the terpenes and cannabinoids from the flower. The fluid is then separated from the flower. Supercritical Co2 extraction was considered to be one of the best methods of extraction at scale in the early days of the recreational cannabis market. Most of the first concentrate products, including most pen cartridges at the time, were produced using Co2 oil. Co2 also enjoys a perception from some consumers that it is a “cleaner” technology than other solvent based extraction methods.
Recent improvements in Co2 technology also allow more specific ability to target and extract very specific cannabinoids such as cannabigerol (CBG), cannabichromene (CBC), cannabinol (CBN), and cannabicitran (CBT) (in addition to THC and CBD), and terpenes separately. These processes are still being tested at scale, and the lack of availability of appropriate biomass to effectively extract these compounds effectively at an economy of scale poses a significant limitation. Over time, Co2 has fallen into less favor due to operational and economic considerations. As the market developed, other equipment and technologies advanced and consumer demand for different products evolved. One of the main drawbacks of CO2 extractions is that the process almost always produces a viscous oil that is typically delivered in an oral syringe or cartridge unless significant post processing expertise and equipment is also available. This presents a serious limitation to the products that can result from Co2 extraction – thus limiting the product SKUs that a facility can distribute to the market.This method requires a major investment in expensive, high-end, often industrial-grade equipment. Co2 is inherently a poison at high concentrations, and rapid off-gassing from an equipment malfunction could cause suffocation for an operator. Final form factors are limited and extractions take a very long time, making the production schedule inefficient.
Solventless Extraction
Solventless extraction encompasses many types of processing including ice water hash, dry sift hash, and Rosin. Whether separated mechanically, by temperature, or by pressure these types of concentrates have their roots founded in the traditional varieties of hashish. Solventless is a small batch process, but when properly done it can produce high end concentrates. Solventless hash is generally predicated by a very high-end input material because the ability to manipulate the process through extraction is limited. Equipment, specialized buildout, and energy demands are generally minimal.The drawbacks are that the ability to scale these production facilities are limited as the processes cannot be automated or be processed in large quantities – thus requiring significant physical labor. Desirable solventless concentrate can rarely be made from anything less than high end flower or whole plant fresh frozen material. There’s also an increased risk of having issues with water soluble compounds such as mold.
How do Businesses Determine the Best Extraction Methods for their Products?
To determine the best extraction method for their facility, a cannabis business will take into consideration their facility capabilities, desired product types, business model, scalability, and budget. At this point in the industry, the economic viability of Co2 is questionable and the idea that it is cleaner than any other method is a misnomer. We believe that in general, Co2 is no longer an advantageous extraction method at scale mostly due to long extraction process times, potency, yields, and limited product form factors compared to hydrocarbon extraction.
Now to answer the question that you’re probably all wondering – we use both hydrocarbon and ethanol extraction methods at the Dabstract labs.
Hopefully this provided an interesting look at what goes on behind the finished product you find on store shelves! Did you learn something new? Tell us in the comments!