

The Case for Burying Charcoal (2007) - mmphosis
http://www.technologyreview.com/Energy/18589/

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camccann
Aside from the carbon sequestration aspect, "burying" charred biomass is very
interesting from a standpoint of improving soil quality, as mentioned briefly
in the article--though it's not really burying so much as churning it into the
topsoil.

As an illustration, it's now known that the rich, fertile soils of the Amazon
river basin are actually _man-made_ , via a process of soil enrichment thought
to involve burying smoldering wood to create charcoal, then breaking the char
up and mixing it into the soil along with manure and other organic waste. The
natural soil of the Amazon is actually very poor and infertile otherwise!

See also: <http://news.ycombinator.com/item?id=934117> (I commented there as
well along similar lines)

Related articles on Wikipedia: <http://en.wikipedia.org/wiki/Terra_preta>
<http://en.wikipedia.org/wiki/Biochar>

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jurjenh
I read the same articles, and this does seem to have potential in multiple
fields - reducing carbon emissions, potentially increasing soil quality and
hence crop yields (although I do believe this is specific to certain types of
soil) - which may indirectly reduce the requirement for some types of
fertilizer.

And one of the amazing things of the "terra preta" of the amazon is that it
seems to regenerate itself - unlike modern fertilizing which is generally
required annually - this may indeed make it a disruptive technology from ~2500
years ago!

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paul
If only we could somehow bury coal...

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jurjenh
Having just re-read the article, I can only come to the conclusion that it has
editorial spin - I can't see how this can possibly reduce CO2 emissions,
unless the charring releases enough useful fuel to supplant the original heat
required, which is not stated anywhere.

To turn matter into biochar requires heat input - so generally this means
burning some sort of fuel - which releases CO2. Leaving the matter as it is,
or burying it does not require this fuel, hence the CO2 "savings" are even
greater. To do all this to sequester carbon seems to be missing the point, and
we'd all be better off by not burning anything in the first place.

What may prove to be useful is the extraction of other products, and the
potential soil benefits. If a compelling case can be made for these alone,
then it might indeed be useful. The carbon sequestration / global warming
aspects seem to only be adding political spin to the issue.

~~~
camccann
_To turn matter into biochar requires heat input - so generally this means
burning some sort of fuel - which releases CO2. Leaving the matter as it is,
or burying it does not require this fuel, hence the CO2 "savings" are even
greater. To do all this to sequester carbon seems to be missing the point, and
we'd all be better off by not burning anything in the first place._

Well, organic matter normally releases carbon when it decays, so just leaving
it as-is would be carbon neutral, liberating the carbon the plant originally
drew from the air to grow.

On the other hand, the pyrolysis process requires energy, yes, but releases
very little carbon from the material being processed. The resulting carbon-
rich biochar doesn't rot, so the carbon isn't released back into the
atmosphere but remains in the soil, while new plants grow in place of the old
ones, pulling more carbon from the air.

The claim in the article, presumably, is that the carbon output associated
with the energy to heat the biomass is less than the amount of inert carbon
added to the soil, making the entire process effectively remove carbon from
the atmosphere.

Highly doubtful that the amount of carbon thus extracted would be significant,
though. The soil improvement aspect is far more interesting to my mind, the
carbon stuff is probably just a way to get more attention.

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furyg3
_Unlike coal, biomass is carbon-neutral, releasing only the carbon dioxide
that the plants had absorbed in the first place._

Um... What?

Coal is also "releasing only the carbon dioxide that plants had absorbed in
the first place". It's a question of time. If you're burning biomass faster
than you're producing it, it's not carbon-neutral.

