Phil Stevens

If the volume of water is big enough (at least several hundred litres) and it starts off relatively pure, there will be a background population of benign bacteria that keep it clean enough by metabolising organic matter and outcompeting pathogens. John Daley talks about this a lot. We have thousands of households here and in Australia who use plain unfiltered tank water and have no issues.

Concrete tanks are the best for enhancing this process because they also raise the pH of the water (and improve the taste).

Willow is a good idea. What about alder? I think that's pretty bendy and it grows in the PNW.

Edward Lye wrote:
It is especially dire in Australia since there is so much solar piped
into the grid. Investigate the duck curve to know more.

It's a good problem to have, because now a whole bunch of Aussies get three hours a day of free electricity. Flattening the duck curve by doing loads of laundry, charging EVs, and heating pools.

Edward Lye wrote:Banks of these can stabilize the grid and produce biochar and sequester
carbon.

That's super interesting, especially the use of molten salt as the carrier. The video was a little murky on what is happening to the syngas, but maybe they're burning it to spin the turbines.

I'd love to be able to make a batch of biochar in ten minutes. Yesterday I spent 5 hours on a burn and probably got a yield of 500 litres. My yields get better in summer when the wood dries out more, but I have to build up inventory because I'm selling the stuff and winter meant I went for over four months without making any.

You could re-pyrolyse commercial lump charcoal to drive off the volatiles, but you'll need to provide sufficient heat. Once that's factored into the process, it might be more rewarding to make your own from wood scraps. I would advise against using briquettes, because those may have binders added that you don't want in the finished product.

When I start a burn in a kontiki (a cone-shaped vessel for making biochar) I build a platform with long sticks about 2/3 of the way from the bottom and lay tinder and kindling on this. Lighting this way has been 100% reliable for me and this avoids the fire smothering itself with its own smoke and CO2 at the bottom of the container. By the time the sticks collapse and the whole thing falls to the floor, it's going strongly enough to create turbulence and keep itself oxygenated.

Doing this in a drum is a little more tricky, because the sides are vertical. But you could just load up with loose small-diameter branches and build your starting charge on top of that. This is also the method I use to get a pile burn going in the open: light the top.

This is one of my faves from Studio Ghibli. I lost count of the number of times I watched it with my kids.

Glenn Herbert wrote:Steel barrels over the riser do not wear out in less than decades of normal use. Thomas Rubino is in an extreme climate and building situation where the RMHs had to burn almost all day every day, and his barrels did not wear out; one was retired because the RMH design was changed, and the other is still going strong as far as I know.

I think the bit about running continuously is an important factor. I just replaced the piped mass on my 4" J-tube with a half barrel (cut lengthwise) covered in cob. It needed to happen, because the flue in the mass was getting clogged with ash that I couldn't reach from the cleanout points, and as I took it apart I discovered that the thin galvanised steel flue pipe itself was deteriorating badly and the rust flakes were contributing to the blockage. The postmortem suggests that the way I run this RMH is probably part of the issue: I only burn on cold nights in winter for the most part, and sometimes there will be a week or more between fires. Also, the fires tend to be short duration, 3-4 hours typically, so the mass never got fully warm and that led to lots of condensation in the pipe. That's a recipe for corrosion and I saw the results...but I did get eight or nine years of service before failure and teardown.

Now, I'm hoping that the stratification chamber as a replacement for piped mass will alleviate this problem, but the underlying factors won't change. I will still be burning sporadically through the cold season, so there will still be plenty of opportunity for moisture to condense on the inside of the bell and start rusting it out. I'll keep an eye on this, using a USB endoscope and the inspection/cleanout hatch I put in the side of the bench. Maybe i will get twenty years out of this setup before the drum collapses.

So the rule of thumb for RMH construction is still valid: Mild steel anywhere but the initial drum location over the heat riser is at risk, either from spalling and destruction by high temperatures, or downstream from condensation and rust.

Another data point: Sometimes, if I go back to an earlier page in a long and image-heavy thread like this one, not all the images load. If I do a hard refresh (Ctrl + F5) in the browser, they usually come back. I haven't run across the issue often enough to do a more detailed analysis, but I'm assuming that it is related to the browser's local cache.

Well, anecdotally speaking, I know a guy who has put bits of plastic in two different J-tubes. He always waits until they're up to operating temperature and rocketing along nicely, and then he'll drop in a few bits of plastic alongside the wood that's burning. He goes for a low ratio of plastic to wood, always keeps an eye on the exhaust for any visible smoke (none), and occasionally walks downwind to see if he can detect any "off" smells (again, none). He's done this with polyethylene, polystyrene, nylon, polyester, PET, milk jugs, sandwich bags, bale twine, and broken garden hose. The only thing that was ever left behind was fibreglass reinforcement that was embedded in a plastic coated tarp that was used as an outdoor billboard (great source of cheap tarps if you need to cover stuff).

This same guy also has a downdraft gasifier modification in his indoor wood fire, and has been known to throw the odd plastic bag or scrap in there when it's burning nice and hot. Either way, RMH or home fire, he's getting heat value out of a waste product.

As long as we stay away from chlorinated plastics and are certain that the combustion is clean and complete, this is a low-risk activity. However, there is a considerably chunk of the general population, and (probably more importantly) official departments of Sad Making, that would be aghast that anyone would contemplate doing this. So I tend to talk about it in hypothetical terms most of the time.

Compared to what passes for recycling in most places nowadays, which usually looks like either a short trip to landfill or bulk cargo carriers going to the global South where it gets burned in piles or washed into the ocean, this seems like one of the least bad options. It also means you don't have to rinse out the last bit of yogurt, bacon juice, or Sriracha sauce.