The Yellow Farmhouse Garden

January 16, 2010

Black Gold? Biochar

Filed under: Energy,Fertilizers — bob @ 11:09 am

Many years ago, when I was just a kid, I learned from my Dad that all things being equal, the darker color a soil appears, the more fertile it is.  I thought about that for awhile. In my young brain I thought, ‘well then why not color the soil using coal or something like that, after all isn’t coal just really old, compressed trees and plants’ ?  That idea was dismissed later by someone I knew as being  just an over-simplified childish idea.

As it turns out, 100′s of years ago in the Amazon River area, the people living there were actually using a similar technique to improve the soil.  They were burning wood in such a way to make charcoal. This charcoal was then added to the soil as a “fertilizer”.

The charcoal added some minerals, such as potash and the like. Its main function was to improved the soil texture and retain  plant nutrients to make them available for growing crops.

Archaeologists have discovered that the remains of these ancient gardens treated with charcoal are much more fertile that the surrounding areas, even after all of those centuries have passed. Plus, the carbon that was created from that process is still pretty much in tact.

Fast forward to the present day. Scientists have told us that carbon dioxide from burning fossil fuels released into the atmosphere has built up to a point where it is affecting our weather and we need to do something about it.

A major problem with carbon dioxide is that it is a gas and as such is hard to keep from being released into the air. So scientists have developed a few schemes to deal with this gas, such as pumping it into underground caverns, or trying to chemically combine it with calcium to make calcium carbonate.

Another problem with carbon dioxide is that as CO2 it contains 2 oxygen molecules for every 1 carbon molecule, so it is not “pure carbon”.

Charcoal, on the other hand, is nearly 100% carbon, no oxygen. It is also a solid, so it will not escape into the air…ever. In the soil it will very,very slowly release carbon. It is not poisonous and as was pointed out earlier, it actually is a beneficial substance.

A tree is also a solid and holds carbon. The difference with a tree is that even though it absorbs carbon dioxide from the air and holds it in the form of wood, the tree will eventually die, decompose and re-release all of that carbon back into the atmosphere. It may take a couple of hundred years but it will happen.

Charcoal is made from burning wood or other plant material in the absence of oxygen. The ancient  South American  Indians produced their charcoal in specially designed pits.  Now days, we can use a more controlled process to produce our charcoal. By manipulating combustion temperatures, the charcoal produced can be converted into a more refined product called “biochar”.

Our modern biochar process produces other gases that can be siphoned off and used to fuel the charcoal making process itself plus still have enough surplus gases left over to produce  bio-fuel for powering electrical generators.

Where do we get the raw materials for biochar?  Some proponents of biochar propose that we harvest trees to use as the raw material. I saw an estimate somewhere that in order to remove the amount of CO2 we produce in a year, we would need to cut down around 4% of our trees annually. That is a huge amount of trees, we would need to form an entire new industry just to cut trees and re-plant them. That would certainly help with our unemployment situation.

Others in the biochar industry feel that farmers could be paid for their unused plant materials such as corn stalks or wheat stubble and use that as the material for biochar. The farmers would then need to purchase the processed biochar as a soil amendment to replenish the carbon in their soil lost during crop production.

Biochar seems to be as close to a “magic silver bullet” as anything out there for reducing carbon dioxide. If you add soil replenishment and new jobs, you get a three for one deal.

Maybe this is that “Green Industry” that Governor Grandholm has been looking for.


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