Fueling Change

Category: Alternative energy | Date: Apr 05 2008 | By: admin

Time to get our hands dirty. In my last post, I spoke of why cooking briquettes made of agricultural residue and other dry biomass can be a great alternative to illegal charcoal production in the Virunga National Park — or most anywhere for that matter. Now let’s see what it takes to actually make these briquettes.

Get your residues
To begin with, you have to gather your residues. Sounds a bit comical doesn’t it? “Well, I’m going out looking for residue today…” OK, so I’m a residue nerd. What we need is any biomass residue — by that I mean anything that once grew out of the ground or is made from something that did — that will readily burn. That leaves us (pardon the pun…) a lot of options, but most likely, we’re talking about collecting leaves, grasses, rice husks, jatropha or moringa olifeira husks, coconut husks, coffee husks, corn husks, straw, and the like. We’ll need about 125 -150 kg of dry material per day to keep one press busy. If we can come upon sawdust and paper scraps we may be able to reduce this amount by as much as 40%.

Dry and pulverize your residues
One of the keys to a good briquette is that it compresses well and doesn’t fall apart. In order to achieve this, the fibers making up the briquette must interlock and stick together. This means that all your materials being used must be ground or pulverized before being pressed. In the most primitive (and slow) briquette making operations, a mortar and pestle is used. As the Legacy Foundation points out, though, this approach can mean that briquette makers are spending 70% of their time hand grinding. This could be a major disincentive to people trying to make the switch from illegal forest charcoal to residue briquettes. In more advanced operations, however, a hand-cranked grinder can be used — or even a modified chipper or lawn mower.

Make your residue slurry
Once the mix of residues has been ground, it’s time to turn it into a damp slurry. The goal here is to create a mixed mush of all your ingredients. As you might imagine, this is where all of the various residues starting sticking together and interlocking, which is the key to making a briquette that doesn’t fall apart. But, because our mix still has a lot of it’s organic structure left, it’s still going to want to resist being pressed into a tight and compact briquette. We need to get our slurry ingredients to relax and get comfortable with the idea of being pressed tightly together with a bunch of residues that they don’t know. This process is similar to the breaking down of wood lignin in the paper making, except here, we aren’t using toxic chemicals.

Residues that compost together, stick together
To get our various residues to relax, we’ll need to spread them out on a big sheet of black plastic, and then cover them with more of that same black plastic. For the next several days or weeks, depending on conditions, the residues will be having a “bacterial social”. All sorts of composting bacteria will be working to soften the attitudes of our residues, convincing them that true love comes only with closeness. The trick here, though, is not to overdo the composting - or the love. We only want to soften our residues, not turn them into soil. If we’ve put on a good decomposition party, we’ll have a group of disparate residues that are dying to be pressed into briquettes.

Hey, where’s the press?!
Detail, details… looks like we have all this great briquette mix, but no press. Better get on that before our residues have a change of heart. Be right back…

Next Post: Building a briquette press…

DONATIONS
A big “thank you” goes out to Alisa Y. who donated $100.00, Jennifer E. who donated $35.00, Chris and Kristi K., and Scott and Cindy N. who donated $25.00. Thanks for being a part of the solution!

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