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
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.
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.
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.
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.
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
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.
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.
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
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 (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
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).