Today there are various techniques to extract different cannabinoids from biomass. Two commonly used extraction methods for both cannabidiol (CBD) and tetrahydrocannabinol (THC) are supercritical CO2 and ethanol – both of which are generally effective in practice.
However, as you consider extraction methods, you’ll find there is no one perfect solution.
In this article, we will explore each method and its pros and cons.
However, after considering both, we believe that you will agree with most experts and customers that supercritical CO2 extraction is the best option.
Supercritical CO2 extraction has the highest throughput and the lowest operating costs. At the same time, it provides high-quality, pure, and consistent oils.
Let us compare ethanol extraction techniques and CO2 extraction methods based on the following parameters:
Ethanol extraction requires organic food grade ethanol in order to create products that are considered organic. Supercritical CO2 extraction has no special requirements to create organic products.
With ethanol extraction, typical cannabinoid recovery including carbon scrubbing is about 50-80%. It may require high-cost consumable carbon to remove chlorophyll. Carbon absorbs CBD and THC lowering recovery.
Supercritical CO2 extraction has 85-95% cannabinoid recovery. The method does not require carbon.
Because ethanol is expensive, it requires significant recovery measures. 90-95% ethanol recovery leads to high operating costs. Low expense CO2 does not need as much effort for solvent recovery. CO2 can be recycled within a run or batch.
Disposal of extracted biomass
Biomass extracted with ethanol is hazardous waste and ethanol has to be removed. It can also be toxic or flammable due to the type of ethanol used and thus its transportation is regulated.
Biomass extracted with supercritical CO2 extraction is clean. It is a source of food-grade amino acids. Its transportation is not regulated.
With ethanol extraction, you can avoid winterization by using a process of extraction at < -20 ֯C. However, this leads to high energy expenses. On the other hand if ethanol extraction is warm, it needs winterization.
With the supercritical CO2 extraction method, we can avoid winterization with subcritical extraction. Without winterization, however, CO2 extraction is much slower.
Ethanol extraction has a substantial fire hazard risk for indoor deployment.
Supercritical CO2 extraction has no fire hazard risk. Proper installation reduces static and asphyxiation risks.
Infrastructure requirements and costs
Ethanol extraction has a high cost for hazardous building occupancy. It also requires special room classifications and limitations.
Supercritical CO2 extraction has minimal requirements. It can operate in industrial buildings with classification F2.
Cost of the equipment
Ethanol extraction equipment will cost you approximately $2-3M USD for 1 ton per day
Supercritical CO2 extraction equipment cost is $3-4M USD for 1 ton per day
Operating costs of ethanol extraction vary greatly due to ethanol cost, losses of ethanol, consumables, and reduced recovery. However, you’ll also need to consider the investment of high insurance premiums, hazardous waste disposal, and energy costs into your operating costs.
Ethanol extraction can be scaled to 10 tons per day in less than 450 m2 with hazardous (H2,3) occupancy, with about ~7000 amps, 230V, 3 phase cooling capacity, and C1D2 special rooms.
Supercritical CO2 extraction is scalable easily to 10 tons per day in less than 450 m2 in F occupancy with ~2400 amps 230V 3 phase.
Solvent sourced cross-contamination risk
Ethanol extraction has risks of herbicide, pesticide, solvent contamination, extraction byproduct, and build up.
CO2 has no risks of cross-contamination.
Cost of solvents
Food-grade ethanol has a high cost. Specially denatured solvents are cheaper but carry non-food grade contaminants.
CO2 has a lower price per kg.
Terpenes add full spectrum flavor and aroma. With ethanol extraction, terpenes can be lost or damaged during processing.
With supercritical CO2 extraction, we harvest terpenes prior to extraction during the decarboxylation process.
Ethanol extraction requires a high carbon footprint to produce ethanol. You will also need tons of cooling capacity to cool ethanol to < -20 ֯C. Another issue is disposing of hazardous biomass waste after processing.
CO2 is nontoxic, renewable, and recaptured. The American Chemical Society considers it a green solvent.
To sum it up, supercritical CO2 extraction has many advantages over ethanol extraction for all parameters except for up-front equipment cost. Moreover, CO2 extraction method has significantly lower operation costs. Let us look at this in more detail.
Operating Costs Matter
In this section, we will compare the difference in solvent cost for a 1 ton per day Ethanol and CO2 system.
Approximate equipment cost for Ethanol extraction is $2,000,000. For CO2 extraction, it is $4,000,000. However, let us look at other expenses with each of the extraction methods.
Ethanol extraction start-up solvent cost is $7,000. For CO2 it is just $500. Ethanol loss per day is $3,500, while CO2 loss per day is $115.
Based on this information let us compare 1-year and 10-year solvent loss cost for each of the methods. 1-year ethanol loss cost is $1,260,000. 1-year CO2 loss cost is $42,048. Consequently, 10-year solvent loss cost is $12,260,000 for ethanol and $340,000 for CO2.
Having all these numbers, we see why CO2 is a much more profitable business proposition than ethanol extraction.
CO2 extraction has the lowest operating costs and the highest cannabinoid recovery levels. Therefore, it is the best choice for your hemp extraction business.