Ideas for biochar

Out company has alot of woody biomass I'd like to turn into biochar, ideas on way to make it and sell or distribute it thanks for the time

Hello Clay. Welcome to Permies!

What a wonderful resource! Is this from a sawmill? What kind of wood do you process?

From the photos, I can see what appears to be sawdust, some long-stranded or shredded material, and a pile of branches/tree ends in the background. Is that correct?

We buy tree length and make rnd fence post, the pile are shavings and the big pile are tree ends and blocks cut off

The shavings are tough to char, probably easiest to sell them as mulch.  The ends can be burned down to coals then quenched with water.   I have made quite a bit of it this way by pumping my quench water out of a creek.  A standard 2” pump works well.  The more the better.  A few pages to flip through, but the link below details my process.

What type of wood is it?

Hardwood logs make decent coals when open burned, but the pine seems to need to be processed down into 1-2” thicknesses to char well using this method.

Maybe you have a mechanical means to do this.

A retort kiln is an option, but much more capital and labor (loading) intensive.  Several videos of some large ones on youtube.  They tend to be for producing fuel charcoal, but could easily be used for biochar.

If I understand correctly, you would like to turn this wood waste into a revenue stream. Good idea.

Biochar is in a weird space as a bulk commodity. Only a handful of people know what it is, and what it can do. Before you produce it in quantity, have a few buyers lined up. But there's a fair amount of investment required so make sure the market and the numbers line up before you commit.

From a revenue perspective, I would look at selling the raw material instead. Sift it to separate into coarse material (used for mulch) and fine material (for making wood pellets). These are established business streams.

Edit: I know there are mobile kilns mounted on big rigs that turn forestry slash into good quality biochar. This may be more practical than building the facilities to do it yourself.

That is an enviable resource, Clay. I'm drooling...

Where are you located and what sort of budget do you have? Also, I see that this is a roundwood mill...what is the output over time? You could have a batch or continuous process that takes this and produces not only biochar, but also lots of thermal energy that could be used in all sorts of ways. At the moment, I'm drafting a business case for a large timber processor that generates tons of residue (mostly sawdust) four days a week, and we're in the middle of a full-blown electricity crisis thanks to about a generation (see what I did there) of insufficient investment on the part of our little power cartel. At least a dozen mills have shut down around the country in the past week, with many more on reduced hours.

We are located north central arkansas. We sell mulch and sell the cull post to a mill that chips them up and sells fuel but that doesn't put a dent in the pile

Are there large chicken or cattle operations nearby? If the biomass is dry, it's good bedding.

So this becomes a long list of questions.  Biochar in and of itself will not pay the bills.  So where does your money come from?  What else do you need to produce to biochar?  What can be done to improve quality at low cost or to add value to the process?  What is your end goal product?

First a quick understanding of what biochar is.  It is basically carbon black(aka charcoal) from which all volatiles have been removed by boiling them off in an oxygen free environment for use in some other process.  Original material size, how fast it is heated or cooled and other things control pore size in the carbon.  For it to have the "bio" component then it must be mixed with manure or other nutrient sources to charge it with both life and nutrients.  This process takes time as well as another material sources that you do not have showing in what you posted.  Part of this can be the ash from the wood you burned for fuel to run this process.  But likely you need a large scale animal feeding close at hand.  If you have this great.  But it may be you will need to drop the bio and just sell char which is about the lowest value product you can have to sell as it has almost no value.

So how do you pay for it?  One suggestion for smaller scale operation I am going to suggest might include a power generation station with wood gas powered generators.  Set up so you had some steady generation with fuel storage so you could spool up for peak demand power just a couple of times a week with say 1/3 of your horsepower going your steady state and the rest going to peak power which brings in way more money all be it for just a few hours a week.

What might an ideal system look like.  A large bunker storage system being preheated with your waste heat both to preheat and also to dry the moisture out that will interfere with the out gassing process.  From there say half your wood product into a rotatory kiln steady state and half into the fuel to do the charring.  Output is wood gas, char, ash and possibly CO2 for a greenhouse or ag booster and of course you will have an air pollution stream to destroy or neutralize too.  This gives you char but it isn't bio yet.

From there you need to charge the char.  So how.  One portion of it can be the minerals etc in the ash.  But you need life and other nutrient sources to do the charging.  Now ideally if you are bringing the manure in you would like to use part of your waste heat to bring it up into the 140 to 150 degree range long enough to sterilize it of seeds and of biologically harmful bacterial like fecal coliform.  Now you might be sending the char out to be mixed with feed and bedding in an animal operation.  Likely another third of your wood would go that way to be part of the end component.

So what do you want to produce and what resources do you have to produce them?

Clay,
As someone who is kind of in your same shoes (I run a large furniture factory in nc), I can tell you that the sawdust isn't easy to turn into biochar. I did some a while back but the way I had to do it was by building a retort kiln using a drum on its side as the burn chamber. My initial attempts proved fruitless, as the sawdust is such a good insulator, that I wasn't able to get enough heat but to about 1/3 of the packed drum. My solution for this was to fill the drum about half way up, then lay it down, and as the burn continued, I kept rolling the drum inside the retort to let the sawdust inside kinda tumble as the burn progressed. It was a headache and cut the amount per burn down significantly. Another thing as well is that your pile appears to be outside and exposed to rain. To turn any of that into biochar, you are gonna have to use much more fuel energy to drive the water out first, making the whole process much more inefficient. What I would recommend is looking into a wood pelletizing mill or even better would be a sawdust log press similar to what the company RUF makes. They make machines that can handle the amount of waste you are creating, but keep in mind there is a desired moisture content level that is pretty low, i believe around 9-15%. Hope this helps some.

Welcome, Rusty.

Good post.

Just for a little perspective here...I put together business cases and proposals for large timber processing operations to do this sort of thing. Right now we have more prospects than usual because our electricity wholesale market is utterly chowdered and big industrial customers who opted for spot price contracts saw their prices go up to $1000/MWh in the past few weeks. There is no way to run a mill with costs like that.

First off, sawdust, chip and bark with a high moisture content is really hard to turn into biochar by artisan methods that most of us in the permies community use. You can't do it in a pit, trench, or kontiki even when it's dry, because it packs down. You could load it into containers and do it in a retort, but it needs to be under 20% moisture content (and as Rusty pointed out, it needs a long residence time in the kiln, which means you can't process much per shift). So that is a lot of handling and a significant chunk of the process heat being cannibalised to dry the sawdust before loading. If you can make the numbers work, it's feasible but I think all that handling would drive up the operating costs and you'd end up with little or no profit margin. And because the mill is a business, I am guessing that they aren't set up to do a big project like this just as a community service.

However, there are rigs that can produce biochar from damp sawdust and they run 24/7. You might be able to justify the expenditure on a continuous-feed machine based on the three main yields from the process: Heat (which could be used somewhere else in the mill, or to generate electricity), biochar for local markets (local because shipping eats margins), and carbon credits on voluntary markets. Depending on the revenue from these sources, we can show how they will pay for themelves in a few years' time and are self-sustaining on an operational basis.

There's a company that produces this style of biochar equipment that has headquarters in Missouri. There was one of their machines in northern Mississippi until recently, as the owner packed up and moved it to the rice-growing region of California. So yes, it's possible, but the business case needs to be solid.

As with firewood, mulch, and other materials like this, it might be good to start small. You can get your production process down before scaling. Also, prices in smaller quantities tend to be a bit higher rates per unit. So a small bag of biochar will sell for more per unit of weight than by the yard, just like a bundle of kindling will sell for more than 2 logs of firewood.

This is a great example of a problem turned into an opportunity.  Great answers, people.  Hopefully we can help the OP move into a more profitable and sustainable situation.

John S
PDX OR

I appreciate all advice and avenues thank yall

This post caused some thinking and it is written up on the link below.  I encourage poking holes in the thinking.

char out of fine materials