More on switchgrass for biomass
A few weeks ago there was some discussion here about the use of switchgrass
and other grasses for biomass production. I'm working on the development of
a new Web site (http:// www.eap.mcgill.ca) for Ecological Agriculture
Projects (EAP). While preparing back issues of Sustainable Farming magazine
for inclusion on the site, I noticed this article and thought it might be
of interest in the context of that discussion of fiber crops. Sustainable
Farming is published by REAP - Canada. You can contact them at
<email@example.com> for subscription information.
The article, along with others from back issues of Sustainable Farming and
a selection of key sustainable ag. documents gleaned from the EAP
collection, will be available on the web site in early April. For more
information about EAP and its services, contact: <firstname.lastname@example.org>
The article follows:
Prairie grasses may be a Canadian fibre of the future
Properties are claimed to be close to hardwood
by Graeme Rodden
Making pulp from such fibre sources as bagasse, cane, straw, hemp, etc is
usually associated with tropical countries with a much lower population
density. Unfortunately, as has become quite clear recently, these "vast
reserves" no longer exist in most northern countries. At the 8th
International Symposium on Wood and Pulping Chemistry held in Helsinki in
1995, three Finnish researchers discussed work being done in Finland on
non-wood materials as pulp furnish. Canada has been slow to grasp this
concept, but now, as fibre shortage realities hit home, research is showing
that some nontraditional fibres could have a place in the Canadian pulp and
REAP (Resource Efficient Agricultural Production) believes it may have an
answer to the problem. REAP started life as an organization studying
sustainable agriculture, working directly with farmers. This developed into
on-farm research. Within the last year, the research has attracted interest
from the pulp and paper industry. "There is real concern for our long-term
fibre supply," stated REAP's executive director, Roger Samson. "No solution
has yet been found with traditional forestry."
REAP is experimenting with fast growing C4 species that include corn, cane,
and prairie grasses (switchgrass). C4 species accumulate solar radiation
more efficiently than C3 species (wheat, soybeans, trees) and need less
water. They thrive on "hot" conditions (hot, as defined by Samson, means
corn can be grown). In Canada, this includes the southern Prairies and
eastern Canada as far north as Trois-Rivières, Ac. Samson compared
switchgrass (Panicum virgatum) to petroleum, saying, "We have a low-cost
material. We need to find out what we can make with it."
Based in Ste-Anne-de-Bellevue, Qc, REAP has two 12-acre test plots on the
grounds of the Macdonald campus of McGill University in
Ste-Anne-de-Bellevue. In 1996, REAP partnered with Domtar, Noranda and
Natural Resources Canada to put another 35 acres of switchgrass plantations
in eastern Ontario and south-western Quebec. It is trying to identify the
fastest growing grasses for this region of the country and which are best
suited for pulping. So far, Samson stressed, "Switchgrass is by far the
Compared to straw, switchgrass provides a much better yield, 10 tonnes per
hectare (t/ha) versus 1 t-ha for straw. It also has better fibre
giving a slightly longer and thinner fibre. Its ash content is also lower.
Compared to trees, the lining fraction is easier to pulp.
Switchgrass is one of the three dominant tall grass species of the North
American prairie. It has a huge root mass that is about 3m deep. The roots
regenerate at a rate of about 25% annually. Soil sustainability is not a
problem as the decomposing root mass regenerates the soil. "Even if you
remove all the above ground matter," Samson added, "you still improve soil
Samson discussed some of the other benefits that could be realized.
- The problems associated with harvesting crop residues are removed.
- Production costs are low.
- The C4 species are adaptable to soils that cannot sustain grain
- They are a good rotation crop. Stands can last more than 30 years but
Samson said that expected improvement through breeding would cause farmers
to replant with higher yielding strains perhaps every 10 years.
- It is a one-year rotation with harvesting done mechanically and the grass
bales like hay.
- It can be grown on lands not considered "prime" and close to mills.
- Yields are consistent.
REAP did its first analysis studying fast growing willows as a potential
fibre and energy crop before moving to switchgrass. The U.S. Department of
Energy has been evaluating switchgrass as an ethanol feed-stock since the
mid-1980s. In 1992, Agriculture and natural Resources Canada provided a
grant so REAP could study grasses as a feedstock for energy markets. "As
prices stayed low and there was no sign of a carbon tax, we realized fibre
markets were the immediate future," Samson explained.
The first pulp and paper company REAP approached was Domtar. This was more
matter of geography as Domtar R & D centre is in the neighbouring town of
Senneville. The company saw the potential for non-wood fibres and decided
sponsor a fellowship at Paprican. The post-doctoral student has just
completed his first year at Paprican and he is working full-time on this
project. At Domtar, the focus is on printing and writing papers such as the
bond paper produced at its Cornwall, On., mill.
Domtar's manager, analytical science, Krishan Goel, said the use of
switchgrass is not longer a question of viability. The work has advanced to
the stage in which Domtar is starting research with REAP on the harvesting,
baling and transport of the fibre. If the costs are determined to be lower
than for hardwood, then the process will be one step closer to
commercialization. Goel added that Domtar is also studying hybrid poplar
which has an approximate 10-year rotation and that the switchgrass "must"
compared to this.
Pulping results in the laboratory have been encouraging, showing a 45%
yield. Goel also said quality is similar to hardwood pulp. He estimates
switchgrass pulp could replace 15 to 20% of hardwood pulp in a paper
Domtar is looking at chemical pulping processes such as kraft, Soda
anthraquinone (AQ), soda AQ with polysulphide, and draft AQ. All gave good
results with similar yields, but Goel noted that soda AQ had the best
There are some drawbacks. After pulping and bleaching, freeness is very low
so the pulp cannot be refined too much. Drainage is also limited, but Goel
noted that if the grass pulp is only 15 to 20% of the furnish, this can be
overcome. Also, with the new generation of paper machines, freeness is less
of an issue. Bleaching and pulping costs are similar.
The Centre specialisé en pâtes et papiers (CSPP) at the CEGEP de Trois
Rivières saw some of REAP's work and asked for switchgrass samples to test.
CSPP has been working with Cascades on similar projects but with corn
stalks. Samson said the switchgrass is easier to harvest and provides a
better quality fibre. Soil sustainability is also better.
Samson said that CSPP was pulping chemi-mechanically. How the grass is
pulped may depend on its end use. CSPP also said that the pulp was at least
as good as hardwood. "it could be a popular substitute," noted Samson. "It
could even be used as a composite to work with plastics."
Paper machine trials are schedules for the fall. Pulping and bleaching will
be done on a larger scale than before and the paper sent for printing.
Samson and Goel both said a full-scale pulping plant is still three to five
years away. Samson expects the technology to evolve quickly and
commercialization could come sooner than expected.
Samson said that switchgrass can provide a new fibre supply system for the
future. "We have a secure supply and price stability versus wood or
fibre. We can have sustained biomass production to match growing markets.
gives a good opportunity to farmers to diversify."
REAP wants to transfer all its agricultural knowledge to the industry. It
can supply the system - growth, harvest, transport - up to the mill gate.
From Sustainable Farming, Fall 1996. Originally appeared in Pulp & Paper
Canada magazine. Graeme Rodden is editor of Pulp & Paper Canada magazine.