Using Supercritical CO2 for THC Extraction in Cannabis Oils

Extraction

In today’s hot cannabis market, growers need to be smart about their THC extraction approach when making THC oil from their harvest. With so many product types and extraction methods, ROI can be impacted, even for the worse, if you focus on the wrong things.

Profitable products have really changed over the years. In the past, it was flower power. However, now the flower has gone the way of commodity in terms of pricing. It’s no secret that smoking anything, of any kind, is becoming less socially acceptable and carries significant health concerns:

“Smoked herbal cannabis is the most common method of consumption for cannabis product around the world, but can be unhealthy and dangerous due to the fact that toxins and carcinogens are released from the combustion of materials [15]” (Aieta & Rovetto 2017).

Instead, refined oil extracts and end products are where the market is at. With the rollback of prohibition, new methods of manufacturing cannabis and hemp-derived products are becoming more popular. Vaping has emerged as the most popular option for consumption available to consumers.

Vape cartridge oil quality varies depending on the extraction technique used to produce it. Not only that, but different THC extraction methods carry various risks from safety and product quality to consistency. Supercritical CO2 extraction offers oil that’s more fluid, and less viscous than alternative extraction techniques, which makes it perfect for vape cartridges.

Why CO2 is Safer for THC Extraction

According to the paper “Supercritical carbon dioxide extraction of cannabinoids from Cannabis sativa L” from The Journal of Supercritical Fluids:

“The extraction of cannabis to make other forms of concentrate is a function of the solubility of THC and other cannabinoids in different organic solvents (mainly hydrocarbons and alcohols). Solvents like methanol, ethanol, chloroform, butane, hexane, etc. are currently applied, however safety considerations related to their toxicity and flammability exist [4]” (Aieta & Rovetto 2017).

As our Senior Technical Advisor, Cole, pointed out in our December 2018 article “CO2 vs. Ethanol Safety Concerns,” people often ask him, “‘what happens once the city finds out I need gallons upon gallons of ethanol on site?’ I can confidently tell them that the city will be deeply invested in monitoring their business on a regular basis” (Holstrom 2018).


Many extraction facilities run into bottlenecks in production. extraktLAB’s Model 140 CO2 extraction machine were designed with throughput and future scalability (up to one ton per day!) in mind. A 24 sq. ft. footprint and low energy use means lower overhead costs for production.

In fact, our Model 140 supercritical CO2 extractors offer, “some of the fastest processing on the market,” according to the GreenRushDaily article, “10 Best Cannabis Extraction Machines on the Market.”

Why use Supercritical CO2 for THC Extraction?

thc extraction

Distilled THC oil from supercritical CO2 extraction

extraktLAB’s supercritical CO2 technology is 99% efficient and leaves behind less than 1% of your trim’s valuable cannabinoid content. Supercritical CO2 also creates a clean, green and consistent product as:

“The extraction method features essentially define the quality of the final product. Among the various extraction techniques, we can highlight the use of supercritical fluids as extraction solvents…Supercritical fluid extraction (SFE) is a technology used in large scale for extraction of essential oils and a large variety of bioactive components from vegetable matrices [16-19]” (Aieta & Rovetto 2017).

Supercritical CO2 extraction is the longtime method used within the food, drink, and perfume industries because it’s safe and healthy, when compared to alternative extraction techniques. extraktLAB’s certified products and GMP manufacturing process take these high standards to another level.

If you’re a grower with loads of underpriced flower on hand, then it’s time for you to benefit from highly valuable end products. extraktLAB’s Model 140 supercritical CO2 extractor turns 8kg of trim (17.6 lbs) into 600-1200 grams of crude oil every 60 minutes. In other words, you’ll see a fast return on your valuable harvest.

Call us today at 651-600-0036, or submit a contact form below, to see what we can do to help your business grow!


REFERENCES:

Rovetto, Laura & Aieta, Niccolo. (2017). Supercritical carbon dioxide extraction of cannabinoids from Cannabis sativa L. plant material. The Journal of Supercritical Fluids. 10.1016/j.supflu.2017.03.014.

Hanna, Ab. “10 Best Cannabis Extraction Machines On The Market.” GreenRushDaily: 02 August 2017. Website: https://greenrushdaily.com/products/best-cannabis-extraction-machines/

Holstrom, Cole & Shakal, Andrea. “CO2 vs. Ethanol Safety Concerns.” extraktLAB: 06 December 2018. Website: https://extraktlab.com/extraction-process-safety/

Frequently Asked Questions

Can ethanol become contaminated during ethanol extraction?

Yes, ethanol can become contaminated during ethanol extraction. It is important that you address the contamination with testing and reuse protocols. guidance for solvent reviews have been published by the FDA in 2010. Please refer to the many articles in this blog for more information on cross-contamination with extraction.

What is the labor difference between ethanol extraction vs. Co2 extraction?

The direct labor between the two techniques is essentially the same. However different configurations of equipment and different workflows can improve labor content and headcount. The concept of value-added Labor in this instance is very important. Value added labor is the labor content that is spent by the laborer on Direct conversion of the product into something the customer values. In reality most operations have a very low value-added labor in a very high overhead component to direct labor. We suggest the use of lean techniques and Value Stream mapping to improve workflow, reduce inventory, and by extension reduce the headcount required to produce a unit.

What is the electrical cost of ethanol extraction vs. Co2 extraction?

Processing a ton of hemp per day into extracts  can be an energy-intensive process depending on how the hemp is extracted. The following table compares the energy expense for ethanol extraction versus the energy expense for CO2 extraction:

Energy cost for Ethanol Extraction for 1 ton per day at 1 gallon ethanol per 1 lb of hemp
18711 litres to cool from 25 to -20
16840 litres to heat and evaporate after ethanol loss
454 kwhr to Cool from 25 to -20
481 kwhr to heat to boiling point
3105 kwhr to evaporate
4040 kwhr total @ 100% Efficiency
75% Efficiency
5387 kwhr Total
$           0.09 per kwhr
$          506.36 per day

 

Energy cost for CO2 Extraction at 1 ton per day including winterization
636 litres to cool from 25 to -20
636 litres to heat and evaporate after ethanol loss
15 kwhr to Cool from 25 to -20
18 kwhr to heat to boiling point
117 kwhr to evaporate
151 kwhr total @ 100% Efficiency
75% Efficiency
201 kwhr Total
$           0.09 per kwhr
$        18.92 per day for winterization
43.20 Kwhr per day for Co2 extractors
$         3.88 Per day for Co2 extractors
Would you recommend ethanol extracted oils for Vape products?

Due to the risk of chemical contaminants that are found in 25 to 30% of  ethanol extracted oils, we recommend that CO2 oils be used for Vapor Products.

Is it possible to make a solventless extract with CO2?

It is absolutely possible to make a solventless extract with CO2. Solventless extracts are typically made with subcritical CO2 extraction methods.

Does ethanol extraction have a greater throughput than CO2 extraction?

Hemp processing equipment can be scaled for 1 to 5 tons of extracted hemp per day. It’s generally not a fair comparison to compare the throughput on an instrument from two different companies. What is fair is to specify the throughput At the tonnage process per day and then look at the operating cost for that process. You can also look at the equipment and Facilities cost to accommodate that level of Production. after you have all of your costs accounted for including the hidden costs, then you can calculate the net present value for each investment.

What are the most common denaturants in ethanol?

Denatured ethanol is a mixture of denaturants and pure ethanol. Chemical companies add the denaturant to Pure ethanol so that they will not be consumed as a food.
Denatured recipes are published by the ttb that is administered by the National Bureau of Alcohol Tobacco and Firearms. There are many different recipes. one of the most common denaturants used in ethanol extraction is heptane. However there are other substances that may be used including acetone, isopropyl alcohol, methanol and other longer chain alcohols.
Is very limited data on the safety of heptane over the long term exposure. In fact the limit that the FDA has placed on the amount of heptane in a tincture for example was established in the 1990s on the basis of a single study published in 1981. That study the effect of heptane on Sprague dawley rats. That is why there are many disclaimers and the general guidance from the FDA is to limit the amount of solvent in any drug that is consumed.

Doesn’t ethanol extraction equipment remove all the ethanol from the biomass after extraction?

No. Approximately 5 to 10% of the ethanol is left in the biomass and is counted as a solvent loss. These solvent losses add up to operating costs. This is especially true if organic ethanol is used or food grade ethanol is utilized as the extraction solvent.

If you had an ethanol extraction facility, would you ever use CO2 just for stripping terpenes?

Ethanol extraction typically destroys the terpenes when the ethanol is removed from the extract or is distilled from the winterized oil. Many ethanol extractors are seeking a way to preserve the terpene profile of the plant in the output oil. To this end people have tried techniques such as Steam distillation, CO2 stripping, and vacuum distillation.
Certainly, CO2 can be used to strip terpenes from Hemp biomass Prior to ethanol extraction. However, vacuum distillation is by far the most gentle and effective way to harvest the terpene profile prior to ethanol extraction.

How do I model and compare the financial return of ethanol extraction vs Co2 extraction?

There are many inputs that need to be defined when creating a financial model comparing two different extraction methods. The first decision to be made is to decide what the financial metric will be used to make a decision on the superiority of one method over the other. 

In this case, we recommend the use of the Net Present Value as the way to model the return of each extraction technique because it accounts for the cash flow associated with the operation. Many ethanol extraction companies try to make the argument that ethanol extraction is lower cost because the equipment cost is less. However, the equipment cost will have very little impact on the overall profitability of the operation at the same throughput.

The best way to compare the two techniques is to fix the throughput so that an apples-to-apples comparison can be made. Comparisons such are payback time and return on investment can mislead someone into making a bad investment decision. 

So if we fix the throughput at one ton per day the cost of the hemp is equal between the techniques and operating cost variance is the only contributing factor.     

Here are the twelve key questions that need to be defined in order to do a comparison:

  1. What is the direct labor to process?
  2. What is the energy to process?
  3. What are the solvent losses? 
  4. What are the direct material startup costs including solvent startup costs?
  5. What are the cannabinoid recovery rates?
  6. How much solvent do I use, reuse, and when do I need to replace the solvent with fresh solvent?  and at what interval?
  7. What is the insurance cost for each option?
  8. What is the cost of hazardous waste disposal?
  9. What is the cost of solvent removal?
  10.  What is the cost of reuse of the solvent?
  11.  WHat is the cost of HAP emissions?
  12. What is the depreciation for each option including building costs for H2 vs F2 occupancy?

Once these questions are answered you will be able to build a pro forma income statement. 

Revenue

  • Standard labor
  • Standard materials
  • Overhead

Gross margin

  • SGA
  • R&D

Net Margin

You can then hold SG&A and R&D constant for both techniques and account for the difference in depreciation to get to a net margin number.  

A cash flow statement can then be generated from net margin. One thing to note is that depreciation must be added back to net margin as it is a non-cash expense on the income statement.  

Cash flows are then added up for 5 consecutive periods (years) including the initial outlay of cash for startup working capital.  Those cash flows are then discounted at a discount rate (Weighted average cost of capital estimate at 13-17%).  

If you do this analysis, you will find that CO2 extraction will absolutely crush ethanol extraction in terms of net present value.  

Does it cost less to process hemp with Co2 compared with Ethanol?

Yes.
In fact the operating cost for CO2 extraction is dramatically less than the operating costs associated with ethanol.

Extraction with Ethanol is a process that is typically run at low temperatures. First the ethanol is cooled to below -20oC before it is introduced to the hemp. Cooling the ethanol reduces the amount of extracted chlorophyll and waxes. If you account for the energy required to chill the ethanol down to those low temperatures and then also evaporate after use, the energy bill for extracting ethanol is approximately 3-6x the cost of extracting with CO2. However, the energy cost is really not the key driver in the overall operating costs.
Ethanol extraction requires a significant amount of ethanol to be used per pound of hemp. In fact, about 1 to 1.5 gallons of ethanol must be used per pound of dry hemp in order to extract. Hemp is a very absorbent biomass material and the ethanol must fully saturate the hemp plant before any extraction can take place. For this reason a large volume of ethanol is needed to extract cbd from hemp.
The key cost driver or ethanol extraction is recovery of that solvent from the biomass. Even though many ethanol extraction equipment companies provide centrifuges and or presses to eliminate the amount of ethanol left over in the biomass, The best equipment will provide only a 90 to 95% recovery of the ethanol. This 5 to 10% loss in ethanol is a huge cost driver for extracting ethanol.
For example, suppose you wanted to process 1000 lb of hemp. You would need 1000 gallons of ethanol to start out at a cost of $16-33 per gallon for food grade ethanol for a total cost of $16,000 to $33,000. If you recovered 90% of the ethanol the ethanol loss would be $1,600 – $3,300 per 1000 lbs. Furthermore if you process 1000 pounds per day, this would be your daily loss.
In contrast, you will lose the equivalent of about $70 per day for CO2 extractions for the exact same process.
Besides energy and solvent usage, there are many other hidden costs related to extraction with ethanol including solvent reuse costs, insurance cost, increased facilities cost, and testing costs.

Can CO2 be used to extract other botanicals?

CO2 is used to extract many different kinds of biomass. The most famous and successful industrial process for CO2 extraction is the coffee decaffeination process. However there are many other essential oil extracts that are used in the supplements industry that utilize CO2 extraction. Hops is a good example. cops are used to brew beer and add flavor to beer. CO2 traction is used to extract the essential bitter flavor from the house so that the flavors can be Blended and Preserved.

Is CO2 cheaper than ethanol?

Yes.
A pound of food grade ethanol when purchased in bulk is $4.71/lb at current price.
A pound of food grade CO2 when purchased in bulk is about $0.04/lb at current price.

What’s the purity of the CO2 used in CO2 extraction?

There are many grades of CO2 including industrial and food grade and medical grade. We typically use food grade but medical grade is also highly desirable. the specifications for each of these grades are published by the Compressed Gas Association or by your gas supplier.

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Meet Our CEO and Founder Dr. Jon Thompson, Ph.D

Dr. Jon Thompson

Dr. Thompson is a separations scientist, entrepreneur, and inventor. As a scientist, he has a strong technical background and industry experience in analytical instrumentation, in-vitro diagnostics, biotech, mining, and homeland security markets.

During his cannabis industry career, Dr. Thompson has earned a strong track record of winning and implementing medical cannabis licenses in well-regulated, medically-modeled states.

Dr. Thompson has assisted numerous companies to attain their goals in cannabis and hemp manufacturing, as well as market development, strategic marketing, and worldwide business-to-business alliance formation (including international markets).

Dr. Thompson has a track record of writing winning cannabis licenses and has implemented hundreds of start-up operations in Canada, Europe and throughout the US for various clients. Dr. Thompson received a Bachelor of Science degree in Biochemistry, Chemistry and a Doctor of Chemistry degree from the University of Minnesota.

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