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81 comments on Avoiding Harmful Solutions (to Our Climate and Energy Problems)
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Although many energy / climate change solutions have problems and unintended consequences, there is a rather unknown technology that needs to get more exposure with those of us considering these issues. The process starts with the pyrolysis of biomass, uses the volatile gas and its condensates as a fuel source, then recycles the remaining biochar back into the soil.
Pyrolysis is the process of heating of organic matter in the absence of oxygen until the material is thermally degraded and gasses are driven off. The gaseous products, typically hydrogen and volatile hydrocarbons, can be burned directly as an energy source, or can be processed further into a liquid bio-oil. What remains after the gasses have been driven off is almost pure carbon biochar. The biochar could also be burned as a fuel, but the new thinking is that it is much better to recycle the biochar back into the soil.
Returning biochar to the soil has been shown to significantly improve soil fertility and structure. Although the black carbon is not itself a required nutrient for plants, presence of the biochar improves the availability of existing nutrients. The carbon also reduces leaching of nutrients from the soil. The result is that biochar generates higher yields and makes conventional fertilizers go further and last longer.
Biochar is highly persistent in the soil. Unlike other forms of soil organic matter such as compost, leaf mold, and manures which are completely degraded by soil microorganisms in a few years, biochar remains largely intact for hundreds, perhaps thousands of years. For a bio-fuels operation, this means that every time crops are harvested and processed, a good fraction (up to 40%) of the carbon that the plants took from CO2 in the atmosphere will end up buried in the soil for many hundreds of years.
So we have a process that builds soil, generates energy, and remove CO2 from the air. Just about any type of biomass can be used as a feed stock for pyrolysis, so an obvious place to start is with agricultural and forest waste products.
There is much research still to be done, but there is very good reason to look carefully at processes that return biochar to the soil. Much of the motivation for current research comes from the realization that ancient Amazonian civilizations built their sustainable agriculture by making their own soil with copious amendments of biochar.
For further study, check out the Terra Preta web site and information clearing house:
http://terrapreta.bioenergylists.org/
A recent article on the potential carbon negative bio-energy by Cornell professor Johannes Lehmann is found here:
http://www.css.cornell.edu/faculty/lehmann/publ/FrontiersEcolEnv%205,%20...
An article on the potential for carbon sequestration with this approach is here: http://www.css.cornell.edu/faculty/lehmann/publ/MitAdaptStratGlobChange%...
One of the more interesting approaches for making the biochar into an actual fertilizer is being done by Danny Day at http://www.eprida.com
If you look in some of the old books, it's called "Wood Gas Generators".
The problem is that the biogas is highly volatile and toxic. Several long-chain molecules, etc etc. Great stuff if you want to start a chemical company.
Also great once the population goes down to about half a billion people in the world, then the biosphere can absorb the unburned bits.
Heres a flight into pre-history....{tongue firmly in cheek}
Around 20,000 years ago,the atlantians found themselves in a bind,their energy source,which had allowed them to reach the same effective level of civilization as we enjoy today,produced carbon dioxide,just as we do.Their scientist,found the same way of pulling carbon from the atmosphere as we have,though biochar.This began the process of trapping the carbon in the soils,and acting as a enriching process of the poor jungle soils
Although the rest of their civilization collapsed,the use by pre-historic tribes in the amazonian forest of biochar,allowed a "new"way of life to develope...and new civilizations,and the great wheel turned again...
Thanks Sonny. Nice story. Would those be the Atlantic Atlantians, The Sunken Isle west of Wales Atlantians, The Aztalan Atlantians, The Minoan Atlantians, or the UFO Atlantians?
"If you want Change, keep it in your pocket. Your money is your only real vote."
My vote is the Minoans had it the best. All those others were so ersatz; they probably happened after the Minoans spread their version of Fox News around the globe.
I, for one, am skeptical of biochar. It seems like a troublesome way of achieving approximately the same affect as leaving crops or crop residue in place.
To me, this seems like a great example of the problem the story outlines. Although Tera Preta may be an ancient technology, it's sustainability has yet to be critically evaluated. The fact that the technique can be used to generate useful gases and charcoal may seem wonderful, but the other side of the balance sheet is missing. You still have to move the dry the biomass, move it around, burn it, capture the gas, and move the charcoal back to the fields. Frankly, I see some real issues for loss of nutrients. The bio-mass doesn't just contain carbon, but that's all that is being returned to the soil. For the same reason, pollution from the bi-products of burning bio-gas also concern me.
Biochar may be worth a look, but a critical review also seems necessary.
Do you really think that potassium, phosphorus and other nutrients are destroyed by carbonization? Just about everything save nitrogen remains in the solids, and we can always fix more nitrogen.
You don't have to dry the biomass much; it's just a question of how much you have to burn to drive the process. You don't have to move it much either; the process works very well at a small scale, maybe right at the field. You don't have to capture the gas (though condensing the liquids may be economically worthwhile). And it sequesters carbon on a scale of thousands of years, in a form that won't be oxidized away because someone came at it with a plow.
Biochar is definitely a silver BB.