Can I make biochar out of coffee grounds?

I have just learned about biochar, just so you know.

I collect about 25 gallons of used coffee grounds daily (from coffee houses, etc). I use them as an ingredient in a composting mix I make. I also collect a lot of cardboard boxes which I use for layering and soil building.

So... I was thinking that I could certainly use some of the boxes for fuel and some / all of the coffee grounds for biochar creation.

Anyone have any experience?

Thanks!

Maybe go a different route, and use saprophytic mushroom to mycelliate it, then use the spent; hardened block, once it has fully dehydrated.
There's just so many specs (of coffee) it'd be hard to even know if it worked.

Cool, thanks. I actually collect a lot of grocery compost as well, and get mushrooms of every variety in fairly good shape on a regular basis.

So, I think you are saying to contain the coffee grounds in something (like one of the boxes). Then to introduce the mushrooms (I get lots of portobella). Then to wait till the mushrooms completely break "compost" the grounds.

Does that sound right?

Its a good idea, and I already sortof do the mushroom thing with the cardboard boxes.

In any case I might try a batch or two of biochar and see how it works. I'll post my results if they are any good.

Your enthusiasm is great, although I was merely saying what I know to be possible with coffee grounds and bio-char.
Mushroom cultivation has stages and procedures, for best results.
With the, "waste streams" you're capitalizing, I encourage you to look into Mycology more as it is quite a valuable skill-set for building soil.

Of course you can!

Anything made of carbon can be returned to carbon.

There is a story of a young boy who won a prestigious science award for inventing a way of turning styrofoam into biochar pellets--very encouraging.

Also, somewhere in this marvellous community, I watched a guy make trailerloads of biochar on open ground, out of branches, killing the fire with a garden hose. Took, literally, minutes. At the end he quips, "So I hope you're all out of excuses." Made me giggle.

The business with the retort is daunting, and you get so little out of those little coffee can setups and stuff you see on youtube. Let me try to find that open ground clip again...

There it is.

Steve Somethingorother from SkillCult.

I really enjoy his point of view, very no bullshit.
You can get hooked watching his videos.

https://youtu.be/ixtxNfU9Rb8

This is the open ground version--later in his thinking, pertains to brushy stuff.

For all the very qualified people using retorts out there, this guy must really piss them off--but for the amount of product produced for the time and effort invested, it's pretty hard to shake a stick at him.

Thanks a million for all the input!

@Dyllian I am very interested in the mushroom thing. I certainly have all the "tools". From what I understand, trees and woody shrubs like a more fungal soil. I am working on a largish bank of black currants with the thought of selling jam at the farmer's market. It would be a novelty here and I think I could make decent money at it. So, right now I am planting my currant starts in little row / mounds covered with cardboard boxes that are inoculated with mushrooms. I didn't really try to be picky... I just throw all my mushrooms between the flattened boxes. Not sure if its a good idea or bad.

@Michael Thanks for the links. I had seen this guy before, but not these particular videos. I have some experience with low-oxygen burns. I actually like the simplicity of the "kontiki" setup... and there was some guy that made a similar setup (if less efficient) with a 55 gallon drum laid on its side and a "scallop" cut out of it.  That is what I am going to try with some of my coffee grounds. We'll see how it goes:

https://www.youtube.com/watch?v=lOSDwp20EKM

The coffee grounds are such a great compost booster, as it is, (as they have nitrogen in a very usable form once it's composted a bit), I would think that finding another source for your carbon / char, might be better.  That said, you seem to have a lot of coffee grounds at your disposal.... so, fly at 'er, if that's what you wanna do.  If you have other potential sources for carbon, though, I would consider making great compost with the coffee grounds, and then using that to inoculate your char with nutrients.  

Thanks! Yes, I have an enormous amount of grounds... and I live in the desert, so carbon sources are few and desperately needed.

I use clay (we have a lot of clay), coffee grounds, sand and compost mix to make soil. Then I add it to my "field" which just has grass at the moment. In a year or two I will till it to get rid of the grass, and hope to add bio-char at that time. After the (single) till, I intend to plant a lot of different things to see how they do in the high altitude.

I agree with Roberto, coffee grounds are such a high value resource that making biochar out of it should really be your last option and only if there isn't anything else available to char, which I doubt.
Besides that coffee grounds being such a fine grained substance it isn't the easiest thing to carbonize in volume anyway.

If you really have a lot of the stuff I'd use it at the end of a biochar pit burn to partially snuff the char before quenching the pit with water, the coffee will help buffer the alkalinity.

Oyster mushrooms have been proven to grow in coffee grounds if you can get them inoculated before green mold sets in. If you have one batch with oyster mycelium running in it, switch some of the mycelium to the grounds as soon as you get it. Mix it through thoroughly.

Regular grocery store mushrooms (portabella, crimini, button-same species) are quite difficult to grow reliably in a home DIY set up.  They are easy to grow in a huge industrialized system, which is why the mafia dominates production of them nationwide, but that's a different story.  

Keep your oysters moist and in the shade, even though that's hard to do in the desert.

John S
PDX OR

I read the OP and immediately thought, "Really -- biochar coffee grounds?  Why would you want to do that when you could add them directly to the soil?"

But as I think about it, it makes a tremendous amount of sense.

Coffee grounds added to the soil will degrade and disappear within a year.  Yes, a significant percentage of the nitrogen will probably remain in the system or will find it's way into the plants that grow, but the biomass itself will be gone, with perhaps 2% humus remaining.  The conversion rate of biomass to humus is tremendously low.  If it were not that way, the rainforest would be a mile high.  

But to char those coffee grounds would alter them so that they will last 1000 years or longer in the soil, becoming a reef that microbial activity will inhabit year after decade after century.  If you are getting that quantity of coffee grounds, you'd be able to amend garden soil to 10% biochar with little difficulty, and you'd never have to amend it again.

So how would you go about it?

I like the trench method shown in one of the video links above.  Start a fire in the trench, get a bed of coals burning at the bottom, dump a bag of DRY coffee grounds onto that bed of coals.  I would imagine that most of the grounds would fall down between the coals and settle into the bottom.  Then another layer of wood --- perhaps 6 or 8 inches.  When that burns down, dump enough grounds into the pit to fill in the gaps and cover most of the coals.  The heat should be enough to char the coffee without putting out the fire.  Another layer of wood -- let it burn down -- another layer of coffee grounds.  

The key, from my perspective, is that there are enough coals in the bottom of the trench so that the coffee can filter down through the coals and settle on the bottom.  Because there isn't much mass to the individual grounds, it won't take anything at all to burn them up.  Almost like sawdust.

OR . . .you could use this method, putting the coffee grounds into a sealed tin and putting inside a wood-stove to char.

Good idea. I’ve been using this method in a wood stove of making biochar for a month, discovered in that Edible Acres video. Works wonderfully and beats our home while simultaneously making the biochar without significant emissions.
The only problem with coffee grounds, I believe, is that the fine texture means little space between them and apparently the procedure won’t go well. There will be a big chunk unburned in the middle. But I was just about to try it (hence my search that led me here).
I’ll report back on my results, good or bad.

I’m not at all impressed with the ‘open burn’ biochar processes.
Yes, they are efficient and easy for the person gaining the char. But the environmental impact is awful; a LOT of emissions released. It doesn't fit with my personal take on permaculture, as it seems to do global damage for personal benefit. But that’s just me personal opinion.
A great alternative is to make any sort of biochar in a wood stove. It works like a closed retort and our model has a feature that reburns any escaped unburned gases. So we get our biochar and the gases burned heat our home and do other tasks- with lower emissions.
Who else is doing this?
Earthdave