I grew up being taught El Nino isn’t a big deal and it’s just the seasons going through their normal cycle. But with Super El Nino, I finally bothered to read about climate change, and now it’s a rabbit hole I can’t get out of. I calculated my own personal carbon footprint, and I feel disgusted with myself :(
I looked up all the ways to decrease my own footprint- but now I learned that’s not enough, we also need to capture and lockup all the extra carbon that’s in the air now too.
I read about all the ways to do that, and I learned about biochar and it’s relatively the quickest way we have right now that locks carbon up for at least a century if done right.
So I thought about ways to make biochar that’s actually impactful, and of course it has to be a collective action not just the individual.
Now I’m thinking, why don’t cities adopt a biochar bin for their residents just like Stockholm? Is this something I can advocate for my own community?
Hey, I can answer this one. I did my M.Sc on amending soils with biochar.
I’m not sure what Stockholm is doing, though.
To get good recovery of biochar, you need a pretty controlled environment. It’s also energy intensive to make; you need a heat source that’s not going to produce CO2, ideally, and cut into the benefit that you’d get by sequestering carbon in the first place. Like if it takes 1 ton of waste wood fuel to make 1 ton of biochar, it’s pretty much a wash. You could use green energy I suppose, like it you had a hydro grid set up to fire whatever furnace you’re cooking the stuff in, but that’s not always available or scalable (in the sense you can do it everywhere).
You CAN make biochar crudely, and we’ve been doing so for centuries, but the rub is that your recovery quickly drops and decreases in recovery are increases in CO2 produced. I was toying with this idea to manage non-merchantable timber on mines, and using the char as a soil amendment.
Suppose everything DOES work the way we want, though. Good recovery, cheap energy, people onboard. We now have a mountain of char and no place to put it. You could go underground mines). Stockpiling it aboveground would a nightmare and massive fire hazard… Etc. Etc.
I like using char to store carbon and it’ll stay for a long time, but you can’t just capture it at the source like you can with other forms of carbon capture and storage. Those other methods don’t work well either… At least with char you have a solid to manage rather than stuffing gas underground and hoping the earth doesn’t fart.
Like a lot of things, char use like you envision is ‘we would if we could but we can’t so we wont’.
Wait, isn’t charcoalisation an exothermic process? Am I remembering that wrong?
You get gas by products you can use to keep things going but it’s a lot of energy to dry the feedstock if needed and get it up to temperature. Again, you can make char crudely, but it’s environmental benefit drops quickly.
Ah, right, the drying. Green wood is, like, mostly water. You can season wood outdoors, but it takes many months, so then you have the cost of the space as well. Usually they just use a drying kiln for lumber, in modern practice.
I think about this stuff fairly often, so I was pretty sure about the chemistry. I wasn’t trying to argue, or undermine you, there. Sorry if it came across that way.
No, all good. It’s been a while since I thought about char, and honestly a lot do my stuff was based on ‘what does it do?’
Please explain why tilling that mountain into the soil is not an option :D
Because soils in and of themselves are generally productive. Aerating soils (tilling) boosts the microbial community, making it consume organic matter in the soil. Biochar is highly stable, so it wouldn’t be consumed, but instead the existing organic matter, which acts as the massive pool nutrients would then be consumed. So what you’d see, is a priming effect at least a few years, followed by a drop in soil productivity.
Biochar is useful as a soil amendment in the right conditions, but its effect is really situational and highly dependent on cooking temperatures and feedstock. I used stuff cooked around 380C in an attempt to allow for some of the feedstock’s more available carbon forms to be accessible to microbes. It didn’t really work like that, but I ended up with an N boost in my soils, which we suspected was due to proving more microbial habitat (due to char surface area).
It’s also really good at catching and holding onto leaching metals, and nitrogen too, in the right conditions
My dad makes it from twigs in a paint can, that he puts in his woodstove. He mixes it with leaf mulch and household compost to amend his garden. He’s been doing this for years, and his garden seems nice and productive. Any tips or things to watch out for? I have considered that there could be a point where he should stop adding biochar.
Just watch the pH. Hotter chars are more basic. The benefit you’re seeing is probably due to increased water holding capacity and the microbe habitat I mention earlier.