In all fairness, as long as trees keep growing you don't need to account for CO2 emissions from burning wood. Current carbon is not the same as fossil carbon. Let's not feel guilty for being part of the active biological cycle and that way we can focus our ingenuity and energy on doing cool stuff.
The prevailing wisdom regarding moving fruit trees is to do it when they're dormant. If you're in the Northern Hemisphere, that ship has probably sailed and unless you're willing to wait until winter, then keeping the soil around the roots as intact as possible will give you decent results.
Your plan is good...you probably don't even need to go out that far from the trunk if the trees have only been in the ground for a year, and don't forget that soil is heavy. If you can, lift each root ball out and set it on a big piece of burlap, then gather that up and tie it around the base of the trunk to keep the soil in place. When it's time to plant, you can untie the "bag" after you've set each tree in place and leave the material to rot in the earth.
All of the above. Some of it gets bucketed onto the compost heaps, but most gets drained onto the paddock. We have acidic soils here so the high pH is a bonus for watering, but I dilute it about 25% so that roots don't get a shock.
I think we're all staying very relevant here, Leigh, and I'm glad you raised the issue of supplemental feed. The OP asked about efficiencies per acre, and my question amounts to this: Whose acre? If you are reliant on bought grain to make up for insufficient pasture, then the effective acreage required to support your livestock goes up. So do other inputs required to grow that grain, in most cases.
We could also consider what it might look like if you were to grow your own grain for feed...what sort of net gain (or loss) would you get with your climate, soil type, and methods if you grew grains instead of, or in rotation with, a permanent pasture? Not saying that it shouldn't ever be done, but I'm all for honest accounting as well as respecting the natural dietary requirements and health of the animal.
I'll note that every cattle beast I've raised has tried to get its snout into the chickens' grain, so I know how much they like it even though it's really not good for them. I still have a weakness for Doritos.
Not all of us are able to make a rocket mass heater, or have the time or desire to make one, but that doesn't mean we don't want one! I would LOVE to make this thread into a master list of rocket mass heater builders. If you have made a rocket mass heater and might consider building one for someone else, post here with a link to your build! The link can be a thread, a facebook gallery, a website, etc.
I can't guarantee that the below people will be open to making a stove for you--they are the people who I have seen mentioned here on permies and at inventor events.
Chris Sturgeon, Whitehorse, Yukon, Canada. Has built a functioning 6" underfloor RMH in his greenhouse, and would be happy to give assistance to others.
Steve Fairbairn, Regina, Treaty 4 lands, Saskatchewan, Canada. Has built 6-inch, 8-inch RMH and a 8-inch batch box. Beenhired to put on a 2 day workshop which we built 8-inch RMH in a greenhouse. Can be seen in the innovators RMH DVD where he worked under Tim, building the oven, water heater and the griddle. Always glad to help people with there RMH.
Satamax Antone, French side of the Italian border, 3 hours from Marseille, 1 hour from Grenoble. 1 hour from Torino. Grumpy old fart, who only does what he wants, when he wants. Hard to deal with. But if your project tickles his fancy. The outcome might be real nice!
Leigh, feeding grain to dairy cattle is a minority phenomenon here in the world's highest exporter of milk. The farmers who have over-intensified beyond what their land will support in terms of pasture production have to supplement, but they tend to feed silage as their first choice. Mind you, a lot of that silage is maize and has ears in it, but it's not ripened grain. Then there are the ones who feed palm kernel expellate, which is the byproduct of the palm oil industry in the tropics. This is unpopular with a lot of the public (and the more enviromentally minded farmers) and on top of that it smells bad and probably isn't all that great for the animals. Grain definitely isn't...rumen acidosis is a thing.
That's also probably assuming that the beef is slaughtered at 21-24 months. Earlier might give you a higher figure, as you're not converting as much feed into motion and manure. And if you grow a beast for 3-4 years or more, those percentages might drop below 1.
The acorns here fall off when they are ripe, and if I don't collect them the chickens and ducks eat them up. The only pruning I do on the oaks is removing the low branches that are liable to poke me or anyone taller in the eye, and to repair storm damage. The big tree lost about a third of its canopy a few years ago when we had a dying cyclone come through in April when the leaves were still on. That required some chainsaw work.
Hi Justin and welcome to permies! Where are you? Climate, soil, and species will all play parts in determining how quickly a seed-grown tree bears acorns. I have a 20-year-old royal oak (Quercus robur) that is nearly 15 m tall and produces lots of acorns every year. One of those sprouted seven years ago, I potted it up, then planted it by the front gate. It bore acorns last year (age 6) and there are now seedlings under it. So there is a data point. Our climate is maritime temperate (never hot, light frost), annual rainfall 1200 mm, soil is silt loam with decent fertility, and trees in general grow fast here.
I get what you're saying, John, but I would do the exact opposite. Bigger chunks for clay in order to get more aggregate structure, and a fine grind for sand. I like having a blend of particle sizes because of the different functions they perform and the fact that our soil, although it's classed as silt loam, has tendencies similar to clay in terms of waterlogging when wet and turning to brick when it's dry.
Our climate is pretty similar to PNW, mild with wet winters and dry summers, and we have a volcanic ash component that gives us a clay fraction, but nothing like Cascades Cement. What I'm seeing in the beds with significant amounts of biochar is that the topsoil is far more friable than it used to be and doesn't go rock hard when it dries out.
It might be worth trying a couple of test plots side by side to see if fine vs coarse makes any difference in your situation.
Chiming in to echo Phil G...most jurisdictions allow landowners with livestock to destroy dogs that roam onto their property. If it makes you squeamish you might be able to hire someone to do the deed.
It just happens that I know the guys that run the major grow business on the East Coast. I'll ask what they're doing. This whole line of inquiry came up because I met a couple people who design heat and CO2 enhancement systems for commercial growers and they're interested in biochar. So next I started thinking about RMH applications as well.
Yeah, definitely go with untreated water. Or go straight to your inoculating solution. This has some real potential for small scale and as long as you don't have rocks in your original product the unit ought to last quite a while if you're giving it plenty of rest between cycles. Heat building up in the windings is what tends to kill these things.
Lots of greenhouse operators pump extra carbon dioxide into their buildings to boost plant respiration and growth. A clean-burning RMH puts out mostly CO2 and water as exhaust. Now, in my glasshouse at least, the last thing I really want in the "indoor" atmosphere is more water since it's already humid. But wouldn't it be cool to goose it up to 1000 ppm CO2?
I can think of several ways this could go badly wrong. But hear me out...if there was a condenser at the flue outlet to dry the gases, you'd basically be fertilising the plants every time you ran the heater. Maybe have a barometric damper on the stack that redirects once the system is up to clean operating temperature, and obviously some good ventilation options for the structure as a whole, including a purge feature.
Even powdered biochar will still have about the same water retention as granular or lump material. You would need a really fine grind to start breaking it down to the point where you lose the porosity. I don't think a garbage disposal will get it that small....we're talking about nanometer scales here. Try it and see...weighing up samples is easy.
The bigger discussion is the actual water holding capacity of pure biochar compared to mixing it with soil. My average sample holds three times its weight at saturation, but in consulting my Big Book I see a caveat in chapter 19: Much of this is in the spaces between the particles, and when you get soil into the picture things change. The other thing that happens is that clay and soil microbes will clog pore entrances over time, which reduces the ability of water to get in and out quickly.
Of course, fitting an electrostatic precipitator as C. Letellier describes above wouldn't be all that hard, either, and you could collect and weigh the captured fly ash after each burn for the sake of science. I'm pretty content after a few years of observation that mine isn't putting out anything objectionable.
Anything solid that does get out the stack of my 4" RMH is going to have to be really tiny and lightweight, because the stack gas velocity is so low by the time it reaches the flue cap. All I ever see coming out is steam. When It's time to tear down and rebuild the core (hopefully April) I will inspect the last cleanout and see what has settled out where the flue exits the mass.
The curious RMH enthusiasts among us might want to gather some data. Here's what I would try:
1. Get a quantity of fuel of a single type (e.g. all pine or all oak) and dry it well, then split it into several batches of equal weight.
2. Clean the RMH thoroughly so that there is no ash buildup in the system.
3. Burn one of the batches under normal operating conditions. When done, remove all the ash from the system and weigh it.
4. Repeat step 3 for all the batches.
5. Compare the fraction of ash recovered from the system versus fuel mass with a published analysis for the type of wood you are burning. If you're really curious you can conduct your own Loss on ignition sample tests.
If the ash fraction is the same or close to the standard, then this tells us that solid particulates are not going up the stack in any appreciable amounts. If it's lower, you're emitting particulates and a trap of some sort might be indicated. If it's higher, something is probably wrong with your RMH because that is a sign of incomplete combustion.
Hey Sam, it's a custom rig. Two 300 mm steel drums, powered by a 5HP 3-phase motor. It was built to crush bottles at a recycling facility. Then it did a gig pulverising volcanic scoria. Now it munches my biochar, and I'm just about to load the trailer with another half cube and go feed it. A really lucky find, since I'm gearing up to sell biochar and getting the crushing issue sorted was holding me up for a while.
I got lucky and found a machine that crushes my biochar into a nice crumbly mixture. Particles range from fines up to about 5mm with the occasional bigger bark flake or chunk that got through when a piece of unburnt material deflected the movable roller.
Friends of mine recently had a Passivhaus built. Under the concrete slab there is a 300 mm thick layer of polystyrene to insulate from the ground. So if you plan any new builds or additions that is a way to lock the stuff up and get a truly beneficial service out of it.
I reckon that in places where biochar might not be the bee's knees for the soil (and admittedly there are some) we can still use it for so many other things that it makes huge amounts of sense. Chuck into the compost heap. Use it as the basis of potting mix. Humanure and waterless toilets. Aggregate for plaster and mortar. Water filtration. Animal bedding. And as Doug points out, those fantastic prairie soils are all ending up in river deltas, so they need to be replenished and rebuilt.
Do it. I've covered some big patches of the property and just the reduced mowing is a huge relief. It's also easier to stay on top of some of the weeds that I want fewer of, like creeping buttercup, because even though they grow back up through the mulch, they're far easier to pull because the soil is so loose.
Exactly...that was pyrogenic carbon produced by thousands of years of prairie fires. Humans showed up and just went with the flow. My point was that adding biochar to those black soils would probably have diminishing returns.
Feel free to PM me if you have questions. I give workshops on pools here and have helped people start them up in the US as well. The one my family belongs to is sort of our virtual intentional community and has made a lot of things possible that would have otherwise been just plain hard (or expensive).
As long as the moisture content is reasonably low, they will burn. The problem you may face is feed rate and airflow through the fuel, since the J-tube is designed for sticks or kindling with gaps around and between the pieces. Corn, like pellets, small wood chips, or sawdust, will pile up on the bottom of the feed tube and create a non-burning zone where the air fails to penetrate. The next thing that happens is you lose combustion heat and could run into smokeback and draft issues.
Ask me how I know this....
There are designs that do incremental feeding of particle fuels, so it's definitely possible. You just don't want to dump a bunch in at once. Check the recently active thread on the Liberator heater and their pellet feeder for ideas.
Pits are great, Carl. Yours looks very fit for purpose and you'll find that cob coating bakes into a nice terra cotta shell. Yes, it will crack, and yes, you can just mud over the cracks and it works great. If you're able to quench with water, that has the added benefits of expanding the pore structure of your biochar and making it hydrophilic. Can you get your hand on an IBC tote? One of those should be plenty to put that baby out.
I do what Ellendra does plus one other labour-saving trick: I let the chickens eat as much biochar as they want, since they free range in the area where I produce it. Now most of the chicken poop around the place is black, including what they leave in the coop.
Running it through livestock (or worms) is perhaps the ultimate inoculation and application method.
10. Good biochar has no smell. Even after it's been inoculated with something stinky, it will revert to no odour.
11. It will crush down easily into small fragments and fines. Incompletely charred pieces will remain intact.
12. If it's re-pyrolysed in a retort at 600C (average wood fire) the mass does not change.
13. If you burn it, the ash left behind is grey, not green or any other weird colour which would indicate metal contaminants like copper or lead.
14. The ash fraction left behind after burning is small, ideally less than 20% if you're using a woody feedstock. Biochar made from crop residues like corn stalks, straw or chaff will have higher ash content, and if you're using manure or sludge the carbon percentage can be well under 50.
Also, as a supplement to #7, good biochar can absorb 3x or more its own weight in water. Try it and see.
I put manure into a big steel trough, cover it with water and let it turn into a smelly brew. Then I bucket that over crushed biochar and let it soak for a week or more. Sometimes I use seaweed if I've got it handy (beach is 45 minutes away, so not always). I've also started putting it directly into compost bins as I add material.
OK, first of all 650-700F is a very different animal from 350F. You will get OK results at that temp range but it won't be the greatest quality. 350F simply will not cut it, no matter how long you let it cook.
As far as grains of salt go, there's a pretty good body of research now which goes into a lot of depth on the "little rocks." Some of those little rocks act as keystones in dynamic systems like soils that we're trying to improve, so I'm not quick to dismiss all of them. I've got the massive second edition of Biochar for Environmental Management (Lehmann and Joseph 2015) and in the chapters on physical, structural and macromolecular properties there are dozens of articles cited, plus charts and text describing the correlation between highest treatment temperature (HTT) and attributes like porosity, surface area, and formation of aromatic bonds and graphene structures.
Some of the basic science is good to know, because it has a major effect on how long the biochar will persist before breaking down, and how much good it will do in the meantime in the areas of water retention, aeration, nutrient absorption, and providing microbial habitat. Materials pyrolysed at lower temperatures have lower porosity, less internal surface area, and a general lack of aromatic bonds. They can also have high levels of condensed tars and oils (that's what is clogging up the micropores) which will weather and break down in the soil. In general, for woody feedstocks, a minimum HTT of 300C is regarded as necessary to get biochar that has the desirable qualities for soil application and the proportion of aromatic structures only starts to really kick in at 450C.
Here is a chart from the IBI current biochar standards. The H:C ratio is a measure of how much the hydrocarbons in the original cellulose and lignin have been broken down versus the carbon remaining:
So, what this says to me is that you need 300C (572F) at least if you don't just want a bunch of torrefied wood at the end, and aiming for 450C gets you a far better product if it's attainable in your situation. The reason terra preta works is that wood fires very easily achieve temps of 600-700C and so prehistoric cooking and rubbish fires would have been totally up to the task of making long-lasting and highly effective biochar.
Here is a good online summary of the process, including a description under "Stages of pyrolysis" explaining what happens at different temperatures:
Jim, biomass pyrolysis is exothermic and in the case of woody matter there is more than sufficient energy in the feedstock to drive the entire process (as long as the wood is dry). So if you're capturing the syngas output of a batch in your solar retort, it will be more than enough to "cook" another batch of equal mass. This is why pit and kontiki methods are so effective: we use that process heat right at the source and dispense with lots of technology to capture, scrub, store, and transport the syngas. Flame cap burns easily achieve 600-700C in the active zone.
So, as John suggests, you could use the solar concentrator to kiln-dry the feedstock on its way into your retort, where the output gas would provide all the heat required beyond startup.
 I just noticed you were aiming for process temps of 600-700F. This won't produce biochar, as it's nowhere near hot enough to drive off the volatile HC compounds and form the aromatic C bonds. What you will get out of that will be torrefied wood. We usually consider 450C to be a minimum for high-quality biochar that does all the good stuff in soil.
Hugo, any old hydrated lime will work. Pickling lime is the best (food grade) but since I get bags of agricultural lime for making plaster, limewash, and mortar, I just use that, at a rate of about 50g/l water. The ratio doesn't seem to be too critical, just enough that some lime settles out of solution.