Hydrocarbon extraction (and particularly BHO hydrocarbon extraction) is the most common way to isolate cannabinoids and terpenes to create highly potent extracts like wax, shatter, budder, and crumble. For the uninitiated, though, hydrocarbon extraction can be a confusing concept. How does it work? What are the pros and cons? And is it really better than the alternatives?
What Is Hydrocarbon Extraction?
Hydrocarbon cannabis extraction is one of several common methods used to separate cannabinoids (like THC and CBD) and terpenes (the aromatic essential oils) from cannabis and hemp.
A hydrocarbon solvent strips the desired compounds from the plant material through a process of dissolution. From there, the compounds are further processed and refined. The residual solvent is purged from the resulting extract during post-processing, although it’s common for some traces of the solvent to be left behind.
Many extraction techs prefer the hydrocarbon process because it’s efficient, relatively low-cost, and capable of excellent yields. But like all extraction methods, hydrocarbon comes with a list of pros and cons that must be considered.
What Types of Hydrocarbons Are Used for Cannabis Extraction?
Hydrocarbon extracts are most commonly produced using butane or propane—or a combination of the two. Both are flammable, non-polar, liquefied gases, but there are some important distinctions.
First, propane has a very low boiling point compared to butane (-43.6°F vs. 31.1°F). This allows for better terpene preservation, as some of your terpenes will burn off at higher temperatures. Propane, though, is much more expensive than butane, which is part of the reason why butane remains the preferred solvent in most labs. Butane is also more efficient in some cases as propane requires greater pressure.
In some cases, extraction techs will use a blend of propane and butane to achieve the greatest efficiency and maximum terpene preservation at a lower cost than using propane alone.
How Does Hydrocarbon Extraction Work?
In a hydrocarbon extraction, the cannabis plant material is placed inside of a tank where the cannabinoids, terpenes, and flavonoids are stripped from the plant material. The resulting solution is then purged of residual solvent and removed from the system.
Hydrocarbon extraction can occur in a closed-loop or open-blast system.
Closed-loop systems are the safer and more common option. In most states, they’re even required by law with solvent-based extraction. A closed-loop system, as the name suggests, is entirely enclosed. The solvent has no contact with the outside environment. In a typical closed-loop system:
- The solvent is placed in the tank and chilled to a temperature below the boiling point of the solvent.
- The solvent then passes through a narrow material column to absorb the plant matter. The active compounds are dissolved and collected by the solvent, resulting in a crude oil mixture.
- The mixture passes into a collection tank, which is heated to evaporate the solvent. The remaining vapors are pulled out of the collection tank by a gas compressor and cooled back into liquid form.
- The liquid solvent returns to the solvent tank, and the process is repeated until the remaining solvent evaporates.
- The extract is removed from the closed-loop extraction system and further refined according to the needs of the extractor (often via dewaxing and/or winterization).
Open-loop extraction systems, or open blast systems, work very similarly to the closed systems, but the major difference is that the tube is open-ended. This method dates back to the 1990s, before enclosed extraction was perfected. The combination of heat, pressure, and hydrocarbon solvents in an open system creates a high risk of explosion and is therefore not recommended under any circumstances.
When setting up any type of extraction lab, it’s best to work with knowledgeable cannabis extraction consultants, as you’ll also need to set up a lot of ancillary equipment and navigate the complex regulatory requirements.
What Are the Pros and Cons of the Hydrocarbon Extraction Method?
Hydrocarbon extraction has a number of benefits and drawbacks:
Pros of Hydrocarbon Extraction
- The hydrocarbon extraction process can pull cannabinoids and terpenes from cannabis of any quality. In other words, you don’t need a high-quality starting product. Even if you’re just working with trim, you can get a complete extract.
- Hydrocarbon is effective for full-spectrum extractions, as the solvents target all different types of trichomes and active compounds.
- Hydrocarbon extraction is known for having a better throughput than other solvent-based methods. With a high-quality closed-loop system, you can benefit from a rapid extraction process and a good long-term return on investment.
- Hydrocarbon extraction equipment can be almost fully automated. Modern systems are equipped with touch screens that can be pre-programmed and operated remotely.
Cons of Hydrocarbon Extraction
- The biggest disadvantage is that you’re dealing with highly flammable solvents. Even in a closed-loop system, the risk of fire or explosion exists. For example, leaking butane lines aren’t always immediately apparent, but they can be deadly, especially when combined with insufficient ventilation.
- While the equipment itself is more cost-effective than CO2 systems and certain ethanol systems, the cost of actually building and maintaining a hydrocarbon lab can be extraordinarily high. Almost all hydrocarbon systems require a C1D1 room, which can cost six figures. Aside from the closed-loop system, you’ll also need ancillary equipment like chillers, heaters, and vacuum ovens.
- Hydrocarbon extraction can be destructive to the plant tissue. Solvents like butane and propane can destroy cannabinoids and chlorophyll during the dissolution process. As a result, hydrocarbon isn’t a great solution for isolating individual cannabinoids like CBD or THC.
- Hydrocarbon extraction often requires a lot of additional post-processing before you’re left with a usable extract.
- Even with extensive purging, a small amount of residual solvent commonly remains in the final product. This residual solvent will usually show up on a certificate of analysis, and it can compromise both your product and your brand.
How Does Hydrocarbon Compare to Other Extraction Methods?
Aside from hydrocarbon, your other most common extraction methods are ethanol, CO2, and solventless.
Ethanol extraction is another solvent-based method that can be completed in a closed-loop system. It’s much slower than hydrocarbon, in part because ethanol has a much higher boiling point than butane and propane (173°F).
Ethanol also recovers fewer cannabinoids. Whereas hydrocarbon usually results in 90% cannabinoid recovery, ethanol usually results in 50-80% recovery. On the plus side, ethanol extraction has less of a need for post-processing.
Carbon dioxide extraction requires a very different type of system that can process supercritical CO2 (carbon dioxide in a fluid state) using high temperature and pressure.
These extraction systems tend to be more expensive than closed-loop solvent extraction systems, but they’re also more eco-friendly. CO2 extraction is a popular method for producing edibles and vape cartridges, and it leaves behind no solvents or chemical residues.
Solventless extraction uses only heat and pressure to separate the compounds from the plant. A starting material (flower, dry sift, or bubble hash) is placed between two heated plates, which are then pressed together with several tons of force.
Solventless extraction is the safest, most eco-friendly, and most cost-effective extraction method available. With a pure hash rosin extraction, it’s possible to preserve up to 90% of cannabinoids without sacrificing safety or cost.
Hydrocarbon Extraction vs Distillation
Distillation is another process that often coincides with extraction. But whereas hydrocarbon extraction uses solvents to separate cannabinoids and terpenes from the plant material, distillation takes the resulting crude oil and further refines it into something purer.
Once the initial extraction process is complete, you can use a rotary evaporator to remove additional contaminants and volatile compounds. The resulting pure extract is referred to as distillate. Extractors often use the distillation process to isolate specific cannabinoids. You can create THC distillate or CBD distillate, among other types.
The process works by heating the substance into vapor form and then cooling it back into liquid form. Because different cannabinoids have different boiling points, you can remove unwanted compounds and isolate the desired compounds simply by applying the optimal series of temperatures.
Is Hydrocarbon the Best Type of Extraction?
Hydrocarbon extraction offers a number of benefits: It recovers more cannabinoids than ethanol, it’s more cost-effective than CO2, and it’s much safer than it used to be. Nevertheless, the drawbacks still outweigh the benefits—especially when you consider newer and more efficient alternatives like solventless extraction.
If you’re still in the planning stages or looking to expand an existing lab, you might find that solventless is a better way to go. It’s possible to get up and running for $50,000 to $100,000 (depending on the needs of your lab), the regulations are far less stringent, and you can still create the same types of waxy, glassy, and viscous cannabis extracts that consumers love—enjoy the same potency with none of the impurities.
If you do decide that hydrocarbon is the extraction process for you, be sure to prioritize safety and purity with each extraction. It may take a bit longer and cost a bit more, but it will make all the difference for your lab, your customers, and your brand.