Thursday, February 3, 2011

Making Charcoal from Agricultural "Wastes"

On a very cold and foggy morning last week we went out to the UC Davis Student Farm (an operational farm since 1977, which emphasizes hands-on, real-world application and courses in sustainable agriculture)...and apparently space for us to learn how to make charcoal.

The goal for the day was to learn how to produce charcoal from agricultural "wastes". Why? Because charcoal and wood are still used throughout the world for cooking indoors, thus adversely impacting indoor air quality and health as well as resulting in significant CO2 emissions world wide.

The UC Davis D-Lab class has over 25 students in it and we all set to work on various tasks. The process sounds simple, but actually is rather complicated and really more of an art form.

We were super lucky to have Ephrem Rukundo (he's the guy in the red hat --photo left-- with the shovel) in the class as he has worked throughout the world perfecting this process. THANKS Ephrem for showing us how to get the job done!

The process consists of burning the "waste"-- in this case we used corn cobs (you could also use coconut husks)-- pounding the carbonized corn cobs into powder, mixing the powder with a binder (we used tapioca, but in developing countries the more likely binder would be casava), and then pounding the mixture solid in a press. 

It's actually rather time consuming with multiple steps and really an art form. Key points along the way included determining when the fire was stocked properly; when to seal the drum; recognizing when the cobs were properly carbonized and thus time to open the drum; how much binder to use--the first batch we tried was a disaster because we mixed it in hot water rather then cold and couldn't get it to dissolve; and learning precision welding to build a functional press. The benefit/cost question remains, particularly if wood is abundant. However, if there is NO wood for miles and charcoal is not within purchasing distance AND you do have ag wastes...well, then perhaps the added time factor is worth the issue to further explore.

Well, we produced a short video to show you the process. We will attempt to barbeque (veggies, of course) with it and let you know how that goes.



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