{"id":349,"date":"2010-04-16T23:11:44","date_gmt":"2010-04-17T09:11:44","guid":{"rendered":"http:\/\/washedashore.com\/eggsntea\/?p=349"},"modified":"2010-04-16T23:11:44","modified_gmt":"2010-04-17T09:11:44","slug":"biochar1","status":"publish","type":"post","link":"http:\/\/ahualoa.net\/farmblog\/2010\/04\/biochar1\/","title":{"rendered":"Biochar retort, experimental design, first trial run"},"content":{"rendered":"

My friends Josiah<\/a> and Jay<\/a> 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<\/a> 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<\/a> and the Twin Oaks<\/a>, particularly as built by Kelpie<\/a> 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.<\/p>\n

I did my first trial fire-up yesterday. The trial results are from this picture<\/a> onwards.<\/p>\n

<\/a><\/p>\n

Results were promising, but need tuning. I learned a lot from this trial run. Some indications:<\/p>\n

    \n
  1. The kiln fire needs to be strong and hot and heat up fast.\u00a0 My kiln burned moderately, for a long time, so it didn’t fully cook the retort.<\/li>\n
  2. More air inputs.\u00a0 I was hoping to limit openings to focus the heat inside.\u00a0 I put vents on the left and right and front, but the fire seemed to want more air.<\/li>\n
  3. A round barrel in a square box isn’t great geometry for a fire, which tends to burn separately in the four corner “zones”.\u00a0 I could try stacking the blocks in a more circular arrangement, like a hexagon\/octagon.\u00a0 If i stay with this arrangement, i’ll need air vents specifically pointing into each corner.<\/li>\n
  4. Chimney.\u00a0 I figured a simple rectangular hole at the back should suffice, since it worked for Kelpie<\/a>.\u00a0 But mine didn’t seem to draw well. Charcoal kilns for a thousand years have had proper chimneys.\u00a0 I’ll probably need one too.<\/li>\n
  5. Insulation.\u00a0 I used regular CMUs because they’re cheap and available.\u00a0 No doubt better insulation would result from using firebrick<\/a>, thereby focusing more heat inside.\u00a0 I could also fill\/bury the hollow tile walls, even if they’re dry-stacked.<\/li>\n<\/ol>\n

    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.\u00a0 However, the goal remains easy, cheap, reliable full pyrolysis<\/a>.\u00a0 If it doesn’t pan out with this design, i could always switch to a pit, or hybrid brick-lined pit, or other ideas.<\/p>\n","protected":false},"excerpt":{"rendered":"

    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 […]<\/p>\n","protected":false},"author":3,"featured_media":0,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[10],"tags":[],"class_list":["post-349","post","type-post","status-publish","format-standard","hentry","category-biochar"],"_links":{"self":[{"href":"http:\/\/ahualoa.net\/farmblog\/wp-json\/wp\/v2\/posts\/349","targetHints":{"allow":["GET"]}}],"collection":[{"href":"http:\/\/ahualoa.net\/farmblog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/ahualoa.net\/farmblog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/ahualoa.net\/farmblog\/wp-json\/wp\/v2\/users\/3"}],"replies":[{"embeddable":true,"href":"http:\/\/ahualoa.net\/farmblog\/wp-json\/wp\/v2\/comments?post=349"}],"version-history":[{"count":15,"href":"http:\/\/ahualoa.net\/farmblog\/wp-json\/wp\/v2\/posts\/349\/revisions"}],"predecessor-version":[{"id":364,"href":"http:\/\/ahualoa.net\/farmblog\/wp-json\/wp\/v2\/posts\/349\/revisions\/364"}],"wp:attachment":[{"href":"http:\/\/ahualoa.net\/farmblog\/wp-json\/wp\/v2\/media?parent=349"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/ahualoa.net\/farmblog\/wp-json\/wp\/v2\/categories?post=349"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/ahualoa.net\/farmblog\/wp-json\/wp\/v2\/tags?post=349"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}