What is the best method for botanical extraction? Even though the cheapest and most popular method for botanical oil extraction continues to be hydrocarbon (volatile) in nature, the technological advances in supercritical CO2 (non-volatile) extraction are giving volatile extractors a run for their money.
What Is Botanical Extraction?
To understand botanical extraction, it’s important that we first define botanicals. A simple definition of botanicals is that they are plants that are believed to have health benefits, a pleasing smell or taste, or both.
Botanicals have traditionally been used in herbal remedies. By pinpointing and separating (extracting) specific botanical components from the rest of the plant, you can create concentrated herbal products which produce a targeted effect.
More recently, the practice of botanical extraction has been applied to hemp. Thanks to botanical extraction, we can pull out desirable active compounds such as CBG, CBD, and terpenes (terpenoids) from the rest of the plant.
How Does Botanical Extraction Work?
At its most basic, the practice of extraction involves the plant matter itself and a solvent. Many different types of solvents can be used, each with its own pros and cons. Some of the more common types of solvents used for botanical extraction include:
- Supercritical CO2
Biomass is combined with a solvent to create a solution containing the cannabinoids and terpenes. Depending on the solvent, the resulting extract will need to be further refined to remove any undesirable compounds such as chlorophyll and plant fats and waxes.
To learn more, read our post about the different options available for refining your extract once the oil has been separated from the hemp plant material.
Why Choose Supercritical CO2 Extraction?
Other hydrocarbon-based solvents such as ethanol may seem like they require less overhead cost, but the operating expenses of ethanol extraction systems increase dramatically once you’re ready to scale up. Ethanolic extracts also require more processing to arrive at the desired output. By contrast, CO2 botanical extraction is:
- Safer than volatile extraction methods.
- Healthier than volatile extracts as it contains less residual solvents.
- Able to offer higher yields with shorter runtimes.
Cut Through the Red Tape
Plus, supercritical CO2 extraction is the standard for use in the food and drink industry. So, it makes sense to avoid any future regulations and red tape by sticking with an extraction method that is tried-and-tested, especially if you’re planning on creating botanical extracts for human consumption.
Whether you’re looking at starting up a new extraction business or need to scale up an existing extraction operation — we’ve got you covered! extraktLAB’s Series 110, 140 and 180 CO2 extraction machine are the way to go. Watch the video below to get a sense of the level of clean, high-quality oils and terpenes our extractors can produce:
Frequently Asked Questions
Does hemp biomass need to cure before extraction?
No, the material does not need to cure. Our methods complete the final drying step in a vacuum oven to bring the water content down from 10% to the 1% – 1.5% range for efficient CO2 extraction.
Can the drying process be accelerated using higher temps/lower humidity?
There are several drying methods used by growers to accelerate drying, but this is outside our scope of solutions. We recommend researching the agricultural methods to find what works best for you.
What are the typical conditions to dry hemp for extraction?
Harvest drying methods are outside the scope of our solutions; however, you want to dry the biomass to roughly 10% water content for quality storage to prevent mold or mildew.
When producing CBD from hemp, which part of the plant is typically used?
Typically flowers and leaves – no stems or stalks. Some producers will sort out the flowers and process them separately, but most processing includes the leaves and flowers.
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 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|
|$ 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|
|$ 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:
- What is the direct labor to process?
- What is the energy to process?
- What are the solvent losses?
- What are the direct material startup costs including solvent startup costs?
- What are the cannabinoid recovery rates?
- How much solvent do I use, reuse, and when do I need to replace the solvent with fresh solvent? and at what interval?
- What is the insurance cost for each option?
- What is the cost of hazardous waste disposal?
- What is the cost of solvent removal?
- What is the cost of reuse of the solvent?
- What is the cost of HAP emissions?
- 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.
- Standard labor
- Standard materials
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?
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.
Is CO2 cheaper than ethanol?
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.