It’s been a long time since we’ve blogged about tea. The field has been growing exceedingly well, particular in the wet wet weather which stayed wet until mid-April this year. Tea loves rain! Our February 22 harvest, a full-bodied oolong, was announced on facebook and did well. The May 1 harvest experienced difficult conditions, surprisingly hot and dry, which sun-cooked the leaves even before processing. More recently, we did a harvest on May 21 which was made into two kinds of green tea: classic Chinese green, and my attempt at a Japanese green. The Chinese turned out very good. For the Japanese, we don’t have one of those heated tables that traditional rolling is done on, so i improvised. The result is promising – it does taste like sencha – but probably not yet good enough to sell. You can try some if you come by the farm.
As a followup to my last biochar post, i was sent the following document from Karl Frogner of UBI. Karl asked me to make it available, so i’ve put it here: Biochar Ovens, until UBI has a place for it on their own site.
It describes experiments conducted in Mongolia on making biochar in a steel drum where the combustion occurs in a metal center tube. Innovative and fascinating! I want to try it here on my farm, but i’ll have to somehow locate some heavy large-diameter metal pipe, and be able to make holes in it.
My friends Josiah and Jay down in Puna are producing biochar using a classic pit method, which seems to work well. I may end up making char that way as well, but there is some criticism on the biochar list of open burns, saying that emissions aren’t fully combusted and carbon yield is low, recommending a kiln or even better, a retort (closed “cooking vessel”). So, i looked at plans online and found two approaches, the two-drum and the Twin Oaks, particularly as built by Kelpie in Oregon. The first approach is too small a batch and requires multiple drum sizes, the second requires expensive metalwork including pipes and welding. I came up with a hybrid of the two approaches which should be cheap, simple and high yield.
I did my first trial fire-up yesterday. The trial results are from this picture onwards.
Results were promising, but need tuning. I learned a lot from this trial run. Some indications:
- The kiln fire needs to be strong and hot and heat up fast. My kiln burned moderately, for a long time, so it didn’t fully cook the retort.
- More air inputs. I was hoping to limit openings to focus the heat inside. I put vents on the left and right and front, but the fire seemed to want more air.
- A round barrel in a square box isn’t great geometry for a fire, which tends to burn separately in the four corner “zones”. I could try stacking the blocks in a more circular arrangement, like a hexagon/octagon. If i stay with this arrangement, i’ll need air vents specifically pointing into each corner.
- Chimney. I figured a simple rectangular hole at the back should suffice, since it worked for Kelpie. But mine didn’t seem to draw well. Charcoal kilns for a thousand years have had proper chimneys. I’ll probably need one too.
- Insulation. I used regular CMUs because they’re cheap and available. No doubt better insulation would result from using firebrick, thereby focusing more heat inside. I could also fill/bury the hollow tile walls, even if they’re dry-stacked.
The half-charred results of this trial aren’t useless; they could still be used for a less-smoky cook fire, or dropped through my shredder to make mulch with a more stable carbon content. However, the goal remains easy, cheap, reliable full pyrolysis. If it doesn’t pan out with this design, i could always switch to a pit, or hybrid brick-lined pit, or other ideas.
I read the Transition Handbook last year. It’s a growing movement, and it’s full of great ideas for making sustainable local communities. There are lots of issues to figure out, about how to interact with local government, and finding the people who have the time and talent for organizing. I’ve spent some months thinking about how my community could use the Transition model, and there’s one other major issue: Geography. Transition works with face-to-face meeting; that’s a fundamental pillar. Not just monthly face-to-face either, but frequent. That means a community that lives close to each other, within a small area.
The area i live in, Ahualoa, is around 3×2 miles, 6 square miles. That might be OK size-wise, but there are drawbacks:
1. A 1000-foot rise from one end to the other makes getting around more energy-intensive.
2. Few roads (no grid or spokes) and no paths, so to avoid trespassing you have to walk/drive a long way, to go a short way as an ‘io flies.
3. Many sparsely-inhabited 20-acre lots means low population density.
4. No central point or public space. 60 years ago, we had several small schools and, i believe, a store. These are long gone. There’s nowhere to meet or barter.
You can see the pattern of big lots with few roads:
Unless we can improve these issues, Ahualoa remains in danger of being a 100% car-dependent ‘bedroom community’ to other places – which is a very bad place to be when only the rich will drive cars.