Making pellets out of sawdust... why don't more lumber mill companies do this?

[forestfan]

I hear that many lumber mill companies have tons of sawdust being produced - so much that they consider it to be waste and have to pay to have it disposed. Does that sound right?

I thought that at a minimum, it would usually be economically advantageous to gather it up, burn it in a boiler, and either lower your electricity bill or get the local utility to pay you for sending them electricity. And I expected that if you're in an area where wood pellets are valuable, then it would be even more advantageous to choose that rather than electricity generation.

Thoughts? Is gathering sawdust for pelletization or for electricity generation more challenging than I'm assuming? 

[rusticretreater]

The market for pellets is not all that big and any sizeable number of pellets hitting the market would oversupply it in short order.

There are markets for sawdust, but you also have to supply the right sawdust.  Not all sawdust is suitable for pelletizing, compressing, pulping or what have you.  I have an uncle who would get the sawdust from the local Merrilat Cabinet factory to use in his cow sheds.  Then it would end up back in the fields.

[forestfan]

What are you mainly thinking of when you say "right sawdust"?

Right size, consistency, moisture, type of wood? Other things?

And when you say there's a market for sawdust, are you saying that there are people who will both pay you for it, and also pick it up?

I assume markets of this nature only exist in specific places, right? And that in many places, there is truly no market, and sawmills have to pay to have it disposed of?   

[beenthere]

forestfan
Welcome to the Forestry Forum.
You have some good thoughts, which are not new as sawdust disposal has been a problem since sawing wood has been around.

Use the search button here and you will have a number of hits for such discussion in this forum since its beginning. Pelletizers have been around and exist, as well their problems trying to make wood pellets have been a major hurdle to overcome, or outlast, or the reason to just throw in the towel.

But don't give up if you continue thinking about solving the sawdust problem. 

[WV Sawmiller]

   I'd read the thread below. We talk some about the pellet making issues some here.

    From what I see the only people making money with pellet mills are the pellet mill salesmen. Seems to cost more to make them that what you get from selling so need government or other subsidizing.

https://forestryforum.com/board/index.php?topic=121096.0

[barbender]

If you're close I'll haul you all you want for free😁

[SawyerTed]

The process for making pellets seems simple.

Use waste small wood fibers/cheap sawdust and press, right?

The devil is in the details.  Sawdust alone doesn't bind together very well, enter the hammer mill.  

Then most sawdust and small wood fiber contain some moisture - sawmills saw mostly green logs, and keeping a roof over sawdust can be costly or blowing waste into a walking floor/dry van is another expense.  So sawdust often contains too much moisture, enter a drier - more$$$$.  Then add binder.  

Small pellet mills alone are pretty cheap $2-5k.  You get what you pay for, small mill, small production.  Then, where's the market?  (That should be the first question).  Here bags of pellets are cheap enough in bulk that a small operation couldn't pay the utility bills to make them. 

The costs tied up in waste disposal need to be as close to break even as possible.  It's cheaper and less handling to sell sawdust to the chicken houses and horse barns or just compost it. 

[Magicman]

I toured a big commercial pellet mill and learned that successful pellets are made from paper mill quality wood chips, hammer milled, and dried to the proper moisture content, not sawdust.  The only way that the pellet mill was successful was government subsidy.  I was not impressed.

[Ianab]

With the amount of farming in our area the mills have no problem selling all their sawdust, most going for animal bedding.  For a small mill sawdust can be a problem, but if you are producing truckloads a day, it's a saleable product, and it's a lot simpler to simply load a truck and deliver it, vs making pellets with a more limited market. One large commercial operation supplies sawdust to poultry farmers, then removes the "used" material, and processes that into fertiliser, as it's got plenty of chicken poop in it now. In that case, the sawdust is actually being used twice (and the company gets paid both times)

Larger mills just feed all their waste into a boiler to run kilns, or ever a co-gen plant to generate electricity. So to them it has value as fuel already.

[Southside]

Compost it and you have a value added product.  I sell a little, basically to those customers who see the composted pile and ask nicely if they can buy some.  I want it for the organic component it adds to our soil.  Moisture retention, soil tilth, and weed suppression in the produce when top dressed.  As long as it's composted it does not tie up nitrogen and makes for a great soil amendment.  

[Brad_bb]

This was one of my first questions when I got a mill in 2014.  What to do with the sawdust.  We talked about pellet mills.  Seems such a waste not to use all the saw dust.  But....the problems were:
1.Pellet mills, even the small ones, are a large capitol cost.  
2.Making pellets requires careful control of moisture content.
3.How much time do you want to dedicate to making pellets.  When you have a sawmill, you want to spend your time milling lumber, not making pellets.  By the time you mill, clean up, do all the stuff you need to, to stack and air dry lumber, all your maintenance.... you don't want to add another time draw to the list.  Anything that takes much time away from milling, is not making you money or being productive.

In the end, If you have a place to put your sawdust to compost, great.  I don't cut as much as some other guys, but I saw enough to be able to keep up burning my sawdust in two Vortex burn barrels(Look that up on youtube).  Learning how to burn sawdust is a learning curve. You can burn green sawdust.  You need some hot coals from burning some wood first preferably. If not some fuel oil.  Once you get the sawdust started, it sill slow burn because it has to dry the dust adjacent to the burning dust via the radiant heat and when enough moisture has left, it will start to burn.  I've found that dumping dust in one side of the barrel so it creates a 45 degree angle from one side of the barrel to the other, it allow the dust to start at the base and slowly burn up the slope.  If you have more burn-ables on top to create more radiant heat and create more of the air draw form the vents in the barrels, it will burn faster.  Only fill the burn barrel 25% full at one time and after that burns, add another 25%.  You also have to learn how to pour onto the hot coals so flames don't climb up the saw dust stream and burn you.  With the coals in the bottom, I quickly dump and to some extent is smothers them except at the base of the slope.  Green dust won't want to flame up, but you will invariably have some dry dust in the top of the can, or some that has dried on the ground, so you have to be careful.  Dry dust can burn quick like gasoline being dumped on a fire.  You should never use gasoline when you burn.  If you have to, use diesel because it takes a hotter temp to burn.

[Ron Wenrich]

There is a  market for wood pellets by sending them to Europe so they can keep their carbon emissions in check.  Pellets are considered a renewable resource, so it offsets the fossil fuels.  But, to be a player, you need to make a large quantity or find a broker who does.

Composting is probably a good option.  If you have any chicken houses in the area, add manure to speed up the process.  After it composts, put it in bags and sell as lawn soil.  You can probably get a good local business.  But, sales are very seasonal. 

Most small mills in my area sell dust as animal bedding.  We have a pretty sizable farming base as well as hobby farmers.

[doc henderson]

one of my waste barrels in the shop is for stuff to burn in the fire barrel and includes when I sweep up the floor.  I keep the hair on my arms and eyebrows in check if I dump the barrel into an already blazing fire.  the dust flares 6 feet in the air.

[PoginyHill]

The biggest hurdle to making pellets or briquettes is moisture. Unless you already have dry waste of the appropriate size, you'd need a dryer. Much bigger expense and operating costs than a pelletizer or hammer mill. Some of our veneer and plywood operations use briquette makers as a way to deal with dry waste, but green waste (wood chips, sawdust) is either burned, sold, or used to make mulch. Briquettes are handy because they can be used wherever traditional firewood can be. And the machinery is cheaper than a pelletizer, I think.
Co-gen is an option (wood-fired boiler and a turbine generator) but, as has been alluded to, that doesn't have a great return without government subsidies.

[DanielW]

What IanB says is correct: Any mill large enough to have a sizable quantity of sawdust has a market for it. Us small-scale operators may leave slabs, dust, and chips in the bush, but in a full-scale commercial sawmill every byproduct has a value and is used or sold. IN the US for instance: Look at 'Scott's' fertilizer and lawn-care plants, and you'll find many of them are built across the road from commercial mills, because they use the chips and dust for their mulch. And lots of commercial mills have regen/cogen steam plants that allow them to burn their dust and chips in one form or another.

[Ron Wenrich]

I helped to site a cogen plant back in the 80s.  We needed to locate a steady supply of fiber and it burnt 80,000 tons/yr.  That's about 10 trailerloads per day.  We had a steam user, so the plant actually didn't need subsidies to turn a profit.  I believe its still in use, but was converted to natural gas a couple of decades ago. 

Larger mills use their wood waste to fuel their kilns.  It probably could be done on a smaller scale.

[Brad_bb]

I've found that my hardwood waste slabs area great for mulch.  When I have the tree guys out in spring and fall or summer, I have them chip the slabs I have.  NO WALNUT goes into the chipper though.  I don't want it killing anything or taking the chance.  Ash and cherry have been great making a ton of mulch for my beds.  Just make sure not to make your slabs too thick.

[Ianab]

I helped to site a cogen plant back in the 80s.  We needed to locate a steady supply of fiber and it burnt 80,000 tons/yr.

The co-gen plants locally are integrated into the mill, AND the National power grid. More like a home grid tied solar power system, but with a 50mw breaker panel. They don't have to buy fuel, because the mill produces tons per hour, and they convert it into steam to operate kilns and generate most of the power the mill needs. Any excess can be sold to the national grid, or extra power pulled from the grid if needed. So the problem of sourcing fuel is solved, they have a huge stack of it out back. If they sold those byproducts as pellets etc, they would then have to buy electricity or Nat Gas, which would cancel out any potential profit from wood pellets. 

The power generated only accounts for about 2% of the countries generation, and the mills use most of that themselves, so it's not really about the power they are selling, it's the energy they don't have to buy.

[KEC]

Regarding the "right" or wrong sawdust, some sawdust is bad news for animal bedding and maybe for people working around it. If I remember correctly, Eastern Hemlock and Black Cherry sawdust can be a problem.

[Ianab]

Local mills exclusively cut pine, which is "mostly harmless". Walnut isn't good in animal bedding as horses have a bad reaction to it. So there are certainly species that can cause problems. ANY sawdust can be a health hazard if you breath enough of it, just some species are more toxic than others. 

[SwampDonkey]

There is a local softwood mill here making pellets at their operation, have for a few years. There is a hardwood mill north of here that have made pellets for a few years now. 10 years ago, there weren't enough pellets to feed the domestic market. It mostly went to Europe. No trouble now getting pellets, but it's still exported. I see a lot of companies in Maine that sell pellets from the local mill. There are heating fuel outfits in Maine, like Daigle Oil, that sell them in bulk trucks for pellet furnaces. I can remember sawdust furnaces around here for years. If the sawdust is off the planer mill, it's nice and dry. Off the saw it's pretty wet sawdust. Mills traditionally sold clean sawdust to pulp mills, but after 2008 a lot of them went away so the pellet industry developed. Any sawdust with bark and such usually goes as hog fuel. We have a number of heating plants and mills themselves that use hog fuel. 34 years ago was the end of big cone shaped sawdust burners at sawmills. There's a market for all of it. One thing I will say is that pellets are getting pricey. Split firewood delivered or your own is still the cheapest heat source. I'd rather lug a 10-15 lb stick of wood than to handle 50 lb bags. :D

[Ianab]

Wood pellets are a "thing", and there is a market for them. They simply aren't a thing locally. Sawdust / wood shavings / firewood (from slab wood etc)  you can sell. along with a few stray MW of electricity. 

So the "waste" isn't wasted, it's used in some way.  

[SwampDonkey]

Around here pellet stoves are common. I know of 4 such stoves within a mile of here.

[moodnacreek]

There are endless products that come from wood but in business you need a market. 

[WV Sawmiller]

SD,

   What is hog fuel? Oink - Oink?