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The stalk of the hemp plant contains two types of fiber — the outer bast fiber which can be processed into long strands, and the inner woody core, or hurds, which are typically processed into material resembling wood chips. Following the harvest and field retting, a process whereby initial softening of the bast fiber occurs, the bulky stalks are baled and transported to a local fiber processing plant. A decorticator then breaks the stalks and removes most of the hurds. Further processing steps clean, card and refine the bast fiber. Alternately, the whole stalk may be burned as biomass for fuel.

The Hemp Stalk: Bast Fiber
Hemp’s bast fiber is among the longest and strongest of plant fibers, long prized for its versatility in making everything from clothing to canvas and cordage.

Textiles
The market for hemp apparel, footwear, luggage and other accessories is based on hemp’s reputation as a durable fiber for longer, more comfortable wear and colorfastness. Since the mid-1990’s, numerous apparel manufacturers have begun using hemp fibers in their designs. Adidas created a hemp fabric shoe. Armani designed a tuxedo made from hemp. Calvin Klein has used hemp for years and has listed it as “vegetable fiber.” Two Star Dog, a grass roots hemp company, produces apparel that is featured in Nordstrom. Hemp is as versatile as any other fiber and blends well with cotton, silk, rayon, linen and wool. Currently, raw materials must be imported from Eastern Europe and China, keeping prices up for domestic producers. Local supplies of hemp fiber will encourage more business development and acceptance of hemp as a mainstream fiber for a variety of apparel and accessories. This will be accelerated by the establishment of advanced fiber processing technologies which can convert hemp into a form resembling cotton which may then be further processed on cotton equipment.

Industrial textiles are a large market as well. Interface, Inc. of Atlanta, GA, a major carpet manufacturer, has chosen industrial grade hemp fiber to produce its carpet backing. After considering a variety of alternatives for its ecologically oriented approach to manufacturing, the company chose hemp for its strength and durability. Its corporate goal is to completely integrate natural fibers and recycling technology into its business model as an engine for future growth.

Biocomposites
Composites are materials made from a binder, usually a resin, and a reinforcement fiber. Composites in which the resin and/or fiber are made from renewable resources are often called “biocomposites.” Bast fibers, such as hemp and flax, have increasingly been used as the reinforcement fiber in composites where they can achieve higher strength and a reduction in weight. Most commonly, hemp, other natural fibers and polypropylene are blended into a non-woven mat, heated and compression molded into the final part. The result is a hard and durable shape that replaces traditional plastic or fiberglass processes. Alternately, when pressed as a flat board, it can substitute for many paneling applications that currently use wood.

Automobile manufacturers are the most visible users of biocomposites containing natural fibers. Ford, GM, DaimlerChrysler, Saturn, and BMW are currently using or experimenting with such materials for their door panels, trunks, head liners and other parts. In Germany, hemp fiber has significantly increased its presence in such automotive parts since 1997. Components using hemp fiber are also in development for the recreational vehicle industry. The same technology applies to furniture makers who can replace costly and labor intensive plastic and wood manufacturing processes with one-step biocomposite molding. Hemp, with its superior tensile strength, is an outstanding raw material for this potentially huge market. Replacing fiberglass with biocomposite materials may also be safer for workers.

The hydrocarbon absorbent market is a useful home for material generated from the waste stream of a biocomposites plant. Second quality, pre-compressed material offers a solution to a common problem of absorbing oil and hydraulic fluids. The matting offers safety for workers and prevents fluids from being washed into the environment. Completing the recycling circle, the energy content (its BTU value) may be recovered from the used mats by being turned into fuel pellets and blown into a combustion chamber. There are no emission issues and significantly less ash. Energy is recovered from the fiber itself as well as what the mat yields in hydrocarbon value. This may be applied in any thermogeneration plant that uses coal for generating electricity or heat. The Department of the Navy reviewed this proposal several years ago stating domestic supply constraints as the deterrent to development.

Insulation Materials
Another emerging market for hemp and flax fibers in Europe is their use in building insulation. These mats achieve the same heat retention as fiberglass mats, yet provide better sound insulation and are safer to handle. Due to the currently small production volume, they are more expensive, thus purchased primarily by eco-conscious consumers. However, the emergence of more efficient technologies for fiber processing and mat production promises to make these products more cost competitive in the future.

Paper
The expanding role of non-woods in the papermaking process provides a timely and lucrative opportunity for hemp in the printing and writing paper sector. Several U.S. companies, such as Crane & Company, Inc., the producer of U.S. currency paper, and Living Tree Paper have begun to blend hemp fibers into their papermaking processes for additional strength, appealing to environmentally conscious buyers.

Much of the energy and chemical intensive method for pulp processing is related to the removal of lignin, which bind the cellulose together. While lignin content of wood runs as high as 23-34% and rice and kenaf straw provide lignin at 9-15%, industrial hemp can be as low as 3%, enhancing the environmentally friendly aspects of non-wood paper production. Lower lignin content also generally corresponds to higher proportions of cellulose. Wood fibers are less than 50% cellulose while hemp (core) contains up to 77% cellulose, making it valuable pulping material.

In order for hemp to make significant inroads into this market, the establishment of a larger-scale and/or more efficient pulping operation will be required to make it more competitive with other pulp sources. The size of such a mill is limited by the fact that hemp as a light and bulky material is generally too expensive to transport outside a 50-mile radius. Thus, the model of small mills in local regions producing pulp from locally harvested hemp is appealing. It would create local markets, revitalize local areas with jobs and technology and help the environment all at once.

The Hemp Stalk: Inner Core
Hemp’s woody inner core is characterized by its low density and high absorbency. There is a large potential market if the core is processed correctly.

Animal Bedding
Currently, the vast majority of hemp hurds produced in the European Union is sold as bedding for horses and other animals. The Queen of England uses hemp bedding for her horses. Compared to the low-price competitor cereal straw, hemp hurd bedding exposes sensitive animals to less dust and fungal spores and achieves considerably higher absorbency, thus requiring less maintenance and minimizing odors. The market is becoming larger as breeders and trainers become aware of hemp core’s inherent benefits. Processing modifications have allowed hemp core to extend to kitty and other animal litters.

Hydrocarbon Absorbent
Oil spills are usually cleaned up with clay and polypropylene based products. The disposal of the spent oil produces its own environmental problems along with perpetuating the use of petroleum products and the hazards associated with this commodity. Using hemp core as an absorbent for oil spills is not only efficient and environmentally safer, but also the BTUs may be recovered in the manner described above.

Nitrogen Absorbent/Fertilizer/Soil Amendment
Unsanitary conditions on bird farms are compounded by the use of wood chips in the manure trays. Inefficient absorbents with little nitrogen uptake, wood chips result in toxic sludge, agricultural runoff and health problems. Technology exists to use hemp core for the absorption of manure and convert the absorbed product into pathogen-free organic fertilizer. The health and environmental ramifications of such a change speaks for itself and the material recovered produces a closed circle for the farmer with little change to his current methods.

Hemp hurds have also been demonstrated to be an effective ingredient in potting soils and other soil amendments with a potentially large market. Since hurds compete with wood waste materials, this market is currently less profitable than that for animal bedding.

The Hemp Stalk: Whole Hemp Stalk
Certain applications enable the stalk to be processed whole, the most compelling use being that of an alternative source of energy.

Biomass Fuel
Biomass (all biologically produced matter) conversion to fuel has proven technically feasible in laboratory tests and by continuous operation of pilot plants in field tests since 1973. In recent years, the production of ethanol – a proven vehicle fuel – from cellulosic biomass, such as cereal straw or wood, has moved into the commercial demonstration phase. As the “energy crop” is growing, it takes in carbon dioxide from the air and converts it into organic carbon, which accounts for most of the fuel value of biomass. When burned, the organic carbon is converted back to carbon dioxide, creating a closed loop for the atmospheric carbon. Petroleum, by contrast, consists of fossil organic carbon. Its combustion thus results in a net increase in carbon dioxide in the atmosphere. The release of carbon dioxide from the combustion of oil, gas and coal is the main cause of the greenhouse effect, i.e. the global warming and changes in weather patterns experienced over the last decades. The use of biomass for energy is thus a recognized, long-term element in the fight against global warming.

Various technologies exist to convert biomass into the gaseous or liquid fuels on which our economy relies. For example, starch from corn grown in the midwest has traditionally been the source of some of the ethanol used as a fuel additive in the U.S. Another option for the conversion of cellulosic biomass, such as hemp stalks, to ethanol is their hydrolysis to sugar, followed by fermentation and removal of the produced ethanol by distillation. The technical and economic viability of this technology is currently being investigated in several commercial products in the U.S. Because of the unrealistically low price of petroleum, both routes are currently only competitive with governmental support. However, technological innovation and increasing scarcity of fossil fuels will eventually make fuels from biomass competitive.

Depending on variety and growing conditions, hemp is a very effective producer of biomass. If hemp is grown for seeds, the biomass represents a valuable by-product. This offers new opportunities for farmers and contributes to America’s energy reserves. Baling equipment condenses the bulk of hemp stalks, reducing transportation costs from field to the conversion plant. As is the case with paper, processing locations must be located within a 50-mile radius, causing local development and creating jobs.


The above is excerpted from the The Vote Hemp Treatise: "A Renewal of Common Sense: The Case for Hemp in 21st Century America." Download a copy here (PDF file 63k).

 

 
 
 
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