[Ciolkosz] Biomass pelleting on the farm is an opportunity to produce
a densified value-added material. Now there are a variety of different
feedstocks that could be used to produce pellets-- Which one is right for you?
Let's take a look at three important considerations.
First, availability. What do you have on the farm
already that could be used as a feedstock for producing pellets?
Do you have an excess of crop residue? Do you have a field of switchgrass or some other
warm-season grass that's not being put to use? Maybe you have a woodlot on the farm?
Second, equipment. Now, farming equipment is typically very
expensive if you have to buy it new. So, if you can take and utilize what
you already have on hand in your pelleting operation, you're going to be much better off.
Three, the end use of the pellets. Biomass pellets can be used for a variety
of different purposes, and your feedstock can impact how well they perform for that end use.
Wood-based pellets tend to have a lower ash content
and work better in pellet stoves for heating homes.
Grass-based pellets, however, have a higher ash content and they're not as attractive for that
purpose, they have other uses instead. Now, if you can find a situation
where those three considerations line up-- where you have a readily available feedstock,
where you have equipment and facilities on hand, and you have an end use for those
pellets-- then you have a really nice scenario for producing biomass pellets on the farm.
Now, let's take a look at some examples of possible feedstocks
you could use to produce pellets on the farm, including forest thinnings,
perennial grasses, short rotation woody crops, and crop residues.
Forest thinnings. Now, a lot of farms have a woodlot and many of those woodlots are overgrown
and they really would benefit from a thinning or a timber stand improvement operation to allow
the higher quality and more desirable trees to grow better for the forest and to be healthier.
And when you do that, you end up taking a lot of woody material out of the forest.
That wood is usually not of a size and quality that makes it suitable for timber use,
however, it can be used to make pellets. Now, if you remove the bark from the wood before
you make pellets, those pellets are going to have a pretty low ash content, less than one percent,
and the energy content is going to be up around 20 megajoules per kilogram, and that's exactly
what you see in commercial-grade pellets that are sold at the store.
Perennial grasses. Now, perennial warm season grasses, like for example switchgrass
they've long been touted as being able to grow well on poor land or marginal soils,
needing very few inputs, providing a lot of ecosystem services and benefits,
and then also producing a high yield of material. However, those grasses typically aren't very
suitable for animal feed, for example. So, what are you going to use them for?
Well, you can use them to make pellets. Pellets made from switchgrass and other
warm season grasses tend to have a higher ash content than wood pellets though, so they're not
always as attractive for putting in pellet stoves for home heating and those kinds of applications.
However switchgrass especially is very well known for its water absorbing capacity and so absorption
spill cleanup and other sorbent applications are often real good markets for grass-based pellets.
Short rotation woody crops. Shrub willow and poplar are two examples of short rotation
woody crops-- fast growing trees that can be planted in tightly spaced rows
you then harvest them once every two to three years and utilize the wood that you harvest.
The plants then regrow after they've been harvested so you get multiple cycles of growing
and harvesting from one planting operation. Now, one thing to keep in mind with short rotation
woody crops is they typically require specialized equipment, and you're going to need to check to
see if that harvesting equipment is available in your region. Sometimes it is, sometimes it's not.
Crop residue. Crop residue is what's left over after you've harvested your oats, your corn,
your soy, that kind of thing. Basically, it's the straw:
the wheat straw, the oat straw, the corn stover. That material doesn't always have a market,
but it can be used to produce pellets, and those pellets that you make from crop residues
often have very similar properties to pellets made from grasses like switchgrass,
so they'll tend to have a little bit of a higher ash content, but they also have good absorbent
capacity and so they can be used for a variety of purposes similar to the switchgrass based pellets.
So, what have we learned? Well, we've found that there are three main considerations to keep in
mind when looking at a possible feedstock for pelleting on the farm: (1) availability,
(2) equipment, and (3) end-use of those pellets. We've also taken a look at four different examples
of possible feedstocks that can be used to produce pellets on the farm.
Now that you have that information in hand, I think you'll be well on your way
towards determining what's the right feedstock for you to use to produce pellets on your farm.