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Market returns for hemp stalk, fibre, hurds or seed depend on a number of factors, including:
The Canadian hemp industry is at a stage in its development where the actual
income per tonne is difficult to determine, because full scale production
has not been attempted. Economies of scale are expected to reduce costs
significantly, but actual processing and capital investment figures can
only be estimated, and are largely based on the experiences of other countries.
The market prices expected for hemp are derived from current market prices
for the next best alternative.
Although hemp has innumerable potential uses[21] this study will focus on the more common, large scale commodity products for which hemp has promise as a potential alternative input. The most often quoted uses of the fibre which define the necessary processing technology are as follows:
1)Energy source (whole plant):
Because of its high yield potential, hemp has been acclaimed as an ideal
biomass fuel. It can be burned as is, or processed into charcoal, methane,
methanol, ethanol, or gasoline. Typical methodology for the processing
of hemp for fuel is destructive distillation or "pyrolysis".
Destructive distillation involves the subjection of hemp hurd to heat and
distillation in the absence of air. Hemp charcoal as a biomass fuel can
be burned in today's coal-powered generators. Alternatively, Methane can
be produced by the anaerobic decay of hemp. Also, ethanol is typically
made from cellulosic biomass, and hemp is an excellent source of high quality
cellulosic biomass.
Although no processing would be required for this application, high transport
costs would necessitate regional processing or power generating plants.
The economic potential of this application in the short term is questionable,
however, since hemp would have to compete with other agricultural waste
products. North American agriculture currently generates over 350 million
tons of cellulose waste a year (straw, corn husks, etc.) much of which
is burnt in the field but has energy generating capacities generally at
least equal to hemp (see table below).[22]
Plant Energy Output (kJ/kg) Corn 16510 Grains, Cereals 17610 Rape 20170 Wood 18660 Hemp 16450
Source: H. von Buttlar, "Hemp: Perspectives for use as a Boiler Fuel,"
GHK Kassel/Universitat
Since these agricultural "waste" products currently generate
no additional revenue for the farmers, any amount would be incremental
income. To grow hemp specifically for this purpose, then, would neither
take advantage of hemp's unique fibre qualities, nor would it command any
premium price over the likely nominal costs for such agricultural waste.
2) Building material (bast, core or whole plant):
The possible building material applications for hemp range from an input
for fibre board to insulation to hemp houses. Although the bast fibres,
because of their high tensile strength, have significant potential as replacements
for glass fibres for fiberglass or as a replacement for asbestos in fibre
cement, such applications would require the bast fibre to be separated
from the hurds. Joe Hickey of the Kentucky Hemp Growers Co-op has reported
that a major fiberglass manufacturer calculated the market value of bast
fibre to be $2000/ton.
Composites, which include paneling, medium-density fiberboard, trusses,
and support beams, comprise the fastest-growing segment of the wood-products
industry. In 1994, building materials accounted for 20 000 tons of assorted
crops, in 1996, it is expected to account for 500 000 tons.[24] Washington
State Univ.'s preeminent Wood Composite Laboratory has tested hemp for
use in medium-density fiberboard, and lab results show that hemp is up
to twice as strong as wood. Certain other low-cost agricultural waste products
are already being used in this process (straw, for instance), but hemp
has a significant advantage because of its high tensile strength. Current
prices for wood chips used in fiberboard production are approximately US$100/t,
while straw is sold for as little as US$10/t for animal bedding.[25]
Hemp hurds, traditionally considered a waste product are now being used
fairly extensively in France for insulation materials and when combined
with lime naturally petrify to create a pourable building material. This
material is five times lighter, yet stronger than concrete, and has superior
insulation and fire retardant properties. The most renown of these processes
has been patented by a French company Isochanvre.
3) Paper (bast, core or whole plant):
Although in 1994, non-wood fibre sources accounted for only 7-10% of
total paper and board production worldwide,[26] they have become the target
of widespread interest as traditional wood sources are being depleted,
and consumers demand tree-free alternatives. Hemp has additional environmental
advantages, since compared to wood fewer chemicals are required to convert
the low-lignin fibres to pulp (thus reducing waste water contamination),
and hemp requires less, if any, bleaching. Hemp paper also has a much greater
resistance to decomposition, is not subject to age related yellowing, and
can be recycled much more often than wood.
In Australia there is ongoing research into the viability of pulping the
whole stalk, although a study at the Agrotechnical research Institute in
the Netherlands concluded that it is better to pulp bast and hurds separately.[27]
When processing the whole stalk, a mix of long and short fibres is obtained
which has similar properties to (and so would compete price-wise with)
good de-inked wastepaper stock, but it drains slowly, and its throughput
on standard papermaking machines is two to three times slower than wood.
Australian Newspaper Mills technical manager Len Johnson reports that hemp
for newsprint "just looks prohibitively expensive." Nevertheless,
Johnson said that in laboratory experiments "we have confirmed that
mechanical pulping gives rise to a useful pulp using the whole stem of
hemp." At the commercial production and marketing level, however,
Johnson said that hemp pulp "competes head on" with TMP softwoods.
Johnson also said he was still "keeping an open mind" about pulping
hemp for newsprint, hoping that the process can be achieved at a lower
cost. Separated longer fibers cut to suitable length, he said, can be used
to make stronger papers, even as a "reinforcement" for newsprint,
where it could replace the 4% to 25% chemical pulp.[28]
While the hurds can make excellent tissue paper and packaging materials,
chemical pulping of the shorter core fiber is thwarted by the fact that
"it just won't drain on a paper machine." Once separated, however,
bast fibres are ideal for the higher priced but limited field of specialty
papers such as filter, currency or cigarette paper. Bast fibre also has
great potential as a reinforcing fibre for recycled paper and packaging.
Andy Graves, president of the Kentucky Hemp Growers' Co-op has, for example,
already received an offer from a boxboard recycler who wanted to order
20,000 acres of hemp to add strength to reused cardboard.[29]
As with its application for building materials, hemp faces stiff competition
from other non-wood fibres. Long-bast-fiber pulp, for example, may obtain
a premium price of up to 20% above top-quality long-fiber pine pulps,[30]
but will face strong competition from such fibers as cotton, sisal, flax
and abaca. Other non-wood fibres currently being researched for use in
pulp and paper are: kenaf, wheat and rice straw, and cereal grasses. In
particular, cereal grasses contribute a readily available surplus material
from grain cultivation, are cheaper than trees and require less energy
to pulp that wood. Another example is seedflax, a fibre very comparable
to hemp, and available in Canada in huge quantities virtually for free,
since it is a by-product of linseed oil production.[31]
Al Wong, president of the Vancouver-based Arbokem Inc., has compared straw's
low price and low pulp yield with wood's higher price and higher pulp yield,
and has determined that straw comes in at $58 per ton, while wood costs
$105 per ton. North America annually produces approximately 200 million
tons of fibrous crop waste, from which 100 to 120 million tons of papermaking
pulp could be produced. North American wood pulp production for 1993 was
estimated by the Canadian Pulp & Paper Association to be only 88 million
tons.[32]
4) Textiles (bast):
Hemp for textiles is perhaps the greatest value added use for hemp,
but it is also the most involved. Seeding and harvesting is critical to
ensure only the highest quality fibre, while processing is a multi-step,
capital and usually labour intensive process. After harvesting, the primary
bast fibres are separated from the hurds, after which they are "hackled"
to remove any remaining woody particles and to align the fibres into a
continuous "sliver" for either wet or dry spinning into yarn.
Secondary bast fibres (or "tow"), the by-products of fibre separation
and hackling can be carded and then spun into a lower quality yarn or twine.
Alternate fiber separation processes such as steam explosion, ultrasound
or pulping can be used to obtain various short fibre qualities (see below).
Although flax machinery can be adapted to produce hemp textiles at a similar
cost, more robust machinery would be better suited, especially for fibre
extraction. The proportion of bast fibre in hemp plants is typically in
the 22-30% range, but during processing, a loss of fibre in inevitable.
In U.K. trials, one tonne of hemp was calculated to yield 15% or 150kg
of line or high quality fibre. Further losses of 35% in hackling and carding,
5% in yarn production and a further 20% in boiling and bleaching the yarn
to accept dye, results in an net yield of 73kg, producing 182 square meters
of 400gsm (jeans weight) fabric. In addition 100 kg (10%) of shorter or
tow fibres would be generated, and 500kg of hemp hurds. The long term price
for hemp textiles has been estimated at US$7-10/kg - above cotton, but
below linen (flax), since flax has the advantage of having a higher spinning
limit, enabling a finer end product. The potential market is difficult
to estimate, except to say that, depending on price, it would be between
cotton's 50% of total fibre consumption and flax's 3%.[33]
5) Oil (seed):
When growing hemp for seed a much lower seeding rate (usually only 10-15kg/ha)
is used. A number of high yield, monoecious strains have been developed
specifically for seed production. These varieties typically yield 0.7-1.2
t/ha, of which 30-35% is oil.[34] This is somewhat lower than the average
oil extraction rate for canola of 42-43%, from average yields in Canada
of 1.27 tonnes per hectare,[35] but hemp oil has the advantage of having
unique nutraceutical properties, and a potentially valuable protein meal
and (lower quality) fibre crop by-products. A closer competitor would be
flax (linseed) oil, which has very similar uses and an oil content basically
identical to hemp.[36] Since plant densities between 80-400 plants per
square meter have been shown to have little effect on dry stem matter,[37]
seeding at a rate of 15 kg/ha (approximately 80 plants per square meter)
should result in both maximum fibre and seed yields.
Given the prohibitive price of importing certified seed into Canada from
Europe, another important element to seed production will be the production
of viable seed for Canadian farmers. As seed varieties are bred specifically
for local conditions and uses, yields of fibre and seed are bound to increase,
the cost of seed will decrease dramatically, and thus hemp cultivation
will be much more competitive. Finally, a somewhat unusual but serious
impediment to growing hemp for seed is that hemp seeds are a favorite meal
of birds.