[Bioconversion] Grass Pellets

[Roger Samson]

Tom and all

We have been working on grass pellets and other agrifibres for energy since
1991. We have had to wait for the combination of high energy prices and
advances in combustion technology to get the industry commercial.

Agri-fibre pellets/cubes from the crop milling residue industry are now
commercially being used in Ontario and Manitoba for applications including
greenhouse and farm building heating applications and crop drying. In Canada
we can pellet/cube and burn oat hulls, pin oats, wheat bran, soy hulls, corn
fibre, flax shives, corn cobs, sunflower hulls and combinations of these
fuels. Whole plant corn has also been harvested mid winter (after leaching)
and direct burned without processing by one Canadian geeenhouse producer.
Corn cobs can also be used without densification. I have been burning late
fall and overwintered switchgrass in my house for the last two winters in a
gasifier pellet stove. Canadian farmers will be planting small acreages (the
most I have heard is 150 acres) of switchgrass and prairie sandreed this
year as we anticipate that the cheap crop milling residues are soon going to
be used up. With energy grasses in Eastern Canada, delayed harvesting
reduces the potassium content to about .35% at the time of late fall
harvesting and 0.06% if spring harvested. Summer harvested switchgrass is
like wheat straw about 1.2% potassium. I don't know anyone that can burn
summer harvested switchgrass or wheat straw over an extended period. 

Wheat bran or middlings is a cheap binder for difficult to pellet fuels
using standard pellet equipment. Switchgrass needs a little more energy to
pelletize than alfalfa but less than wood fibre. The energy aspects of
growing grasses and their grinding and densification was recently reviewed
in our recent paper: "The potential of C4 grasses for developing a global
Bioheat industry".
Critical Reviews in Plant Sciences   Publisher:  Taylor & Francis   Issue:
Volume 24, Number 5-6 / September-December 2005   Pages:  461 - 495
http://journalsonline.tandf.co.uk/(4nmnk455r4ngnnnkx1r22u45)/app/home/contri
bution.asp?referrer=parent&backto=issue,7,7;journal,2,72;linkingpublicationr
esults,1:103858,1


Necessity is the mother of invention. There are now about a half dozen
Canadian combustion technology companies selling a range of small to medium
sized equipment (10 kw to 2 MW) with the ability to efficiently burn
agri-fibre feedstocks with moderate levels of potassium and chlorine. Some
equipment has more fuel flexibility than others, you need to shop around.   

The grass pellet fuel cycle can produce 7 times more net energy gain from an
acre of land than a corn ethanol fuel cycle (If George Bush is listening
this is 7 times faster a way to find energy independence). Even direct
combustion of grains is getting more popular in Canada this winter. If oil
can stay around $65/barrel and natural gas at $10 mmbtu, we are going to see
an enormous industry evolve which will drive up grain prices to about
$200/tonne. Great for crop producers but it will put an end to the grain
burning and ethanol industries. The green energy revolution from grasses is
poised to replace king corn as the energy champion of farmers.  

Roger Samson
Executive Director
Resource Efficient Agricultural Production (R.E.A.P.) - Canada Box 125
Centennial Centre CCB13 Ste. Anne de Bellevue, QC, Canada H9X 3V9
E: rsamson at reap-canada.com
W: www.reap-canada.com
"Working to create ecological energy, fibre and food production systems"

-----Original Message-----
From: stoves-bounces at listserv.repp.org
[mailto:stoves-bounces at listserv.repp.org] On Behalf Of Tom Miles
Sent: Friday, February 03, 2006 9:41 PM
To: 'Clinton M'; stoves at listserv.repp.org
Cc: bioconversion at listserv.repp.org
Subject: RE: [Stoves] Grass Pellets

 
At Andrew's suggestion let's migrate this to bioconversion. It's really more
germane to developed economies but may be of interest to this list as well. 

Production of grass pellets.

Specific power consumption for fuel pellets is about 50 kWh/ton plus straw
preparation and processing which absorbs another 50 kWh/ton. Power, labor
and extrusion die wear are usually the main costs. A 250 Hp pellet mill will
produce about 4 tph in straw pellets, 5 tph in wood pellets and up to 7 tph
in recycled paper pellets.  

REAP Canada has done quite a bit of work on switchgrass pellets. So Roger
Samson can give us a clue about production. Their papers can be found on the
REAP website. The REAP reports show both production and burning equipment. 
http://www.reap-canada.com/bio_and_climate_3_2.htm
http://www.reap-canada.com/library.htm 

Joe King and Richard Nelson at Kansas State University have also studied
switchgrass pellets. 
http://www.engext.ksu.edu/biomass/_Background.htm

Iowa State University has reported on switchgrass pellets. There is a small
pellet mill in Southern Iowa that makes them. 
http://www.agmrc.org/agmrc/commodity/biomass/switchgrass/switchgrassprofile.
htm

That mill and the Chriton Valley Biomass Project ( http://biomass.ecria.com/
)got a lot of attention this week after President Bush mentioned switchgrass
in his State of the Union message. If you saw ABC World News Tonight on
Wednesday you saw about 10 seconds of our fields and equipment.  

Here in Oregon we pelletize seed cleaning from our grass seed production.
Since they are already sized they are pretty easy to pelletize. But the
outer plant parts have high concentrations of nutrients which cause slagging
in the hot firebox. So they have only been used in local pellet stoves in
combination (50:50) with wood pellets. I don't know of anyone who is using
them on a regular basis as fuel these days. Not many feed pellet mills are
set up for whole straw in our area. One that was closed his doors when he
retired some years ago. His pellets sold at prices competitive with grass
hay which has about the same (low) nutritional value.


Tom