Newer and Better Ways to Process Hemp
While growers of hemp are working their way through the right and wrong ways to raise a crop, researchers are continuing their march forward trying to find even more uses for this versatile plant.
At the University of California Riverside, Dr. Charles Cai led a group that decided to start at the beginning to deconstruct the hemp plant, separating its fiber, sugars, extractives, and lignin in an all-chemical process that utilizes 99 percent of the product.
“This process can simultaneously make multiple hemp products although the primary one is a pulp fiber, somewhat like you’ll find in the paper pulp industry,” he says.
Utilizing the Co-solvent Enhanced Lignocellulosic Fractionation (CELF) chemical process Co-solvent Enhanced Lignocellulosic Fractionation, the plant is deconstructed into a variety of usable materials. Originally developed for research in the production of biofuels, the process has shown significant promise for the hemp sector.
The hemp processing method separates the plant for various purposes, thus maximizing total use of the overall plant material. Because the process is chemical, it eliminates several steps necessary for the more traditional mechanical processing method.
Sustainable construction materials have been the initial result. Says Cai, “Nearly 1.3 million homes are built in the U.S. each year utilizing hundreds of millions of tons of materials, many not manufactured to eliminate adverse effects on the environment.
“We focused on developing sustainable practices utilizing natural plant-derived materials and low-emission processes to replace conventional products and came up with an industrial hemp fiber as a promising candidate for a durable hempcrete insulating material.
“Our environmentally safe and more efficient pulping method (CELF) is capable of processing raw hemp stalks and fibers at large enough scale to support the growing demands of the building industry. By simply changing the CELF reaction conditions, the physical and chemical disposition of the pumped fibers can be controlled.”
Current pulping processes rely on caustic solutions at elevated temperature and pressure to separate cellulose fibers from lignin and sugars. One ton of biomass transformed into cellulose fiber also expels seven tons of a process byproduct known as black liquor, costly to clean up, detrimental to the environment.
“Our alternative pulping method easily processes large volume of hemp fibers with safer chemicals and virtually zero emissions by relying on renewable tetrahydrofuran, a solvent derived from dehydrated sugars, using less than one percent sulfuric acid as a catalyst. You get exceptionally higher pulping efficiencies at lower operating temperatures and short contact times. Because no gasses are produced, the threat of releasing harmful pollutants is eliminated.”
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The researchers have picked up some partners and are working together to develop a renewable lignin-based resin to aid in production of high durability, lightweight, composites and repair materials.
“Once we produced modified hempcrete using the CELF-pulped method, we compared it to conventional hempcrete currently available. Our samples exhibited excellent bonding with lime and showed an improved physical constitution.”
In developing a techno-economic model for a CELF-based hemp pulping operation, the resultant numbers make eyes blurry, but prove the point that “a production plant, co-located on a 1,000-2,000 acre cultivation site, could operate year-round at 85 percent capacity and generate annual gross profits of $6.6 million from food supplements and construction materials alone and about $80 million if extractives containing CBD are also manufactured.”
Their numbers showed a payback period of between two and four years, causing Cai to report, “Compared to American hemp extractive-only operations producing full-spectrum CBD, this integrated operation would be at least 60 percent more profitable per ton of hemp processed.”
In their initial $12,000 EPA grant as part of competition that focused on people, prosperity, and the planet, Dr. Cai and his eight-member team intended to focus on developing a single, immediately commercializable, product. What they found was an ability to pull apart every part of the plant in its natural form so they could utilize almost 100 percent of the entire plant in the form of sugars, lignin, and fibers as well as CBD extract.
“I feel mechanical technologies tend to be not very scalable,” he says. “They’re labor intensive and have stringent requirements. If you use a chemical approach, you’re able to pull apart the molecules themselves to make industrially- and commercially-relevant products by isolating and extracting all the plant components. We don’t add anything to the process itself. Bottom line, this is probably the most environmental way to extract the most value from all of the hemp plant.
“By converting the age-old, labor intensive, mechanical process into a new, more advanced, chemical process that has already been refined in the biofields of space and energy, you can get economies of scale previously impossible. The aim here is not to use one process to make one product, but to utilize the entire plant all at once so you’re not sacrificing capital expenditure on just hedging your bet on a single product.”
Emphasizing their ultimate goal is analogous to every grower’s goal — maximizing yield — Dr. Cai says his team has already proved their thesis. “We went to Oak Ridge National Laboratory and using the world’s fastest supercomputer (Titan), we ran one of the largest simulations ever done at a molecular level and it showed this process is scientifically innovative and effective. Our chemical method of deconstructing plant matter makes it a Swiss Army knife for all plant processing.”