Solvents like hydrocarbons, supercritical CO2, and ethanol are routinely used to produce a wide range of cannabis extracts. In all three cases, the solvent is mixed with the cannabis plant material to dissolve the active compounds. The residual solvent is then separated from the cannabis oil.
Which is the best extraction method? These three approaches to extracting cannabinoids (and terpenes) differ in terms of their cost, efficiency, yield, safety, use cases, and the quality of the extracts produced. The best cannabis extraction method will depend on your budget and goals.
Hydrocarbon Extraction
Hydrocarbon extraction is the most flexible cannabis extraction method in terms of input material and output SKUs. It is most frequently used for cannabis classed as “marijuana” rather than hemp.
To perform hydrocarbon extraction:
- Any type of raw cannabis material (trim, sift, fresh frozen, or dried flower) is packed into an extraction column.
- One or more light hydrocarbons such as butane or propane are passed through the plant material to dissolve the active compounds. BHO extraction, by definition, is performed with butane. BHO stands for “butane hash oil.” PHO (“propane hash oil”) is made with propane.
- The residual solvent is vacuum-purged from the cannabis oil. Some folks may perform an optional color remediation process (CRC) before vacuum purging for really low-quality trim or old biomass.
Use Cases
Different purging parameters and additional post-processing techniques are used to produce a wide range of SKUs from hydrocarbon cannabis oils, including live resin (when fresh frozen flower is used), wax, crumble, badder and budder, high terpene extract, THCA, diamonds and sauce, and THC distillate.
Advantages of Hydrocarbon Extraction
- Hydrocarbon extraction makes the most lucrative end product with live material, which is live resin.
- Hydrocarbon extraction can be applied to any kind of starting material.
- Hydrocarbon extraction equipment is the most cost-effective to install by far. You will still want to ensure you invest in a top-quality closed-loop extraction system such as those offered by Illuminated Extractors.
Disadvantages of Hydrocarbon Extraction
- Technically even with a very thorough purge process there will still be minuscule butane PPMs, but it’s less than when you smoke flower with a lighter. Proper purging is essential.
- Hydrocarbon solvents are highly flammable. It’s essential to perform this process in a licensed C1D1 room and ensure thorough safety training and best-practice procedures.
How to Improve Hydrocarbon Extraction Efficiency
Hydrocarbon extraction is made significantly more efficient by performing biomass reduction before packing the plant material into the extraction column.
Biomass reduction involves chilling dried or fresh frozen biomass with liquid nitrogen and rotating it inside a drum fitted with a 200µm or 400µm mesh screen. The trichomes fall through the mesh while the bulk of the plant material remains inside the drum.
The trichomes can be packed into the hydrocarbon extraction column for more efficient extraction while the remaining plant material is run through an ethanol system and then further refined to make distillate.
Our side-by-side runs have shown that biomass reduction with The Original Resinator XLS Pro and liquid nitrogen reduces the amount of solvent needed by at least 80% along with an 85% reduction in labor hours and an average 7.48% increase in yields compared to running whole-plant material (see the details in our biomass reduction and hydrocarbon extraction white paper).
The cost savings for hydrocarbon extraction businesses over time are significant.
Main Takeaways about Hydrocarbon Extraction
Hydrocarbon extraction is one of the most popular cannabis extraction methods used today thanks to its cost-effectiveness, high throughput, and versatility in terms of inputs and outputs. It is also popular with extractors thanks to the ability to make high-ticket “live” extracts like live resin.
Performing biomass reduction prior to the hydrocarbon extraction process significantly improves the efficiency of the process for reduced hydrocarbon use (and hence reduced costs of hydrocarbon replacement) and only a fraction of the labor costs for improved profitability.
CO2 Extraction
Carbon dioxide extraction was very popular at the dawn of the legal cannabis industry but has become less common as better technology has come along.
Carbon dioxide extraction (CO2 extraction) involves the use of supercritical carbon dioxide to dissolve the active compounds in cannabis. In its supercritical state (between a liquid and a gas), carbon dioxide that is run through cannabis plant material acts similarly to a chemical solvent. Water is often added to facilitate extraction. The CO2 is then evaporated cleanly off the extract for a solvent-free final product.
Use Cases
CO2 extraction is primarily used to process dry marijuana or hemp trim to make THC or CBD oil for vaporizers.
Advantages of CO2 Extraction
- Supercritical carbon dioxide extraction facilitates high throughput and scale.
- CO2 extraction results in a clean end product with no chance of a chemical solvent remaining in the material after extraction.
- Extractors can “tune” the temperature and pressure to target specific compounds in the cannabis extraction process.
- Very little post-processing is required after CO2 extraction.
Disadvantages of CO2 Extraction
- CO2 extraction only works with dry material, typically marijuana or hemp trim, meaning that its uses are more limited than hydrocarbon or solventless extraction.
- CO2 extraction systems are very expensive to purchase and also to run due to their high energy consumption.
- CO2 extraction systems use very high pressure. This makes it essential to follow the relevant safety protocols to protect operators. Just as with hydrocarbon extraction, the process is safe when done properly.
Main Takeaways about CO2 Extraction
CO2 extraction is prized for its ability to produce a very clean final product without the risk of residual solvents that comes with solvent-based extractions. It was very popular at the beginning of the legal cannabis industry but has fallen out of favor due to the high costs of installation and energy use and its limited flexibility with material compared to other extraction methods.
Ethanol Extraction
Ethanol extraction remains popular for its high throughput and relatively low impact on human and environmental health. Ethanol (an alcohol solvent) has been granted a “green circle” designation by the Environmental Protection Agency, which means that the chemical “has been verified to be of low concern based on experimental and modeled data.”
By way of comparison, butane also has a green circle designation and propane has a green half-circle, which means that “additional data would strengthen [the EPA’s] confidence in the chemical’s safer status.”
Ethanol extraction can be performed in several ways:
- The traditional maceration method
- The hot Soxhlet Extraction method
- Cold ethanol extraction
- Cold ethanol extraction with a centrifuge
Cold ethanol extraction with a centrifuge is the most commonly used ethanol extraction method today. The plant material is ground and then soaked in cold ethanol in a centrifuge. The mixture is then spun in the centrifuge and the extracted solution is pumped into a collection vessel. From there, the ethanol is removed, generally via falling film evaporation.
Use Cases
Ethanol extraction is mainly used for bulk hemp extraction or bulk THC oil processing. The lowest quality material of all three types is generally pushed through ethanol systems. The primary SKU ethanol systems make is bulk crude oil that then requires further refinement for use in vapes, edibles, gel caps, tinctures, and topicals.
Advantages of Ethanol Extraction
- The ethanol extraction process has by far the highest throughput of the methods listed.
- Ethanol extraction uses less electricity than CO2 extraction, making it cheaper to run and also to scale once the equipment has been purchased and set up.
- Ethanol extraction can be used to turn low-quality cannabis plant material into marketable SKUs.
- Cold and warm ethanol extraction can be used to extract different kinds of compounds from the plant material. Warm ethanol extraction dissolves a higher range of compounds than cold ethanol extraction.
Disadvantages of Ethanol Extraction
- Ethanol extraction equipment is very costly in most cases.
- Ethanol dissolves a wider range of compounds compared to other extraction methods. It also dissolves polar compounds like chlorophyll because it is a polar solvent. This can be an advantage or disadvantage depending on the products the extractor wants to make.
Main Takeaways about Ethanol Extraction
Ethanol extraction is very effective and useful for making revenue-generating products from low-quality cannabis plant material. However, the solvent’s low selectivity when dissolving compounds in cannabis means that significant post-processing is required.
The high setup costs may also be offputting for new players in the cannabis extraction industry. However, these may be partially offset by the lower electricity usage costs compared to CO2 extraction.
Commonalities between Hydrocarbon, CO2, and Ethanol Extraction
Hydrocarbon extraction, CO2 extraction, and ethanol extraction all use solvents to dissolve the active compounds in cannabis. All three types of extraction carry some safety risks and require knowledgeable management and skilled labor at least in a director or manager capacity.
The yields from all three solvent extraction techniques are good. However, selectivity varies according to the solvent, temperature, and pressure used. Experimentation and experience are needed to get the best results from each of these extraction methods.
Our Verdict
Hydrocarbon, CO2, and ethanol extraction have different use cases, advantages, and disadvantages. Hydrocarbon extraction can be used with any kind of cannabis starting material. CO2 extraction is only used with dry starting material. Ethanol extraction is primarily used with low-quality trim.
All things considered, hydrocarbon extraction is the most flexible and cost-effective method of the three, especially when biomass reduction technology is employed prior to extraction. Contact us to learn more about our cost-saving biomass reduction solution and to request a quote for your very own XLS Pro.
