[Terrapreta] Lehmann Press Release from http://www.sciencedaily.com/releases/2007/05/070511211255.htm

[Michael Bailes]

Simpler Way To Counter Global Warming Explained: Lock Up Carbon In Soil And
Use Bioenergy Exhaust Gases For Energy

*Science Daily <http://www.sciencedaily.com/> —* Writing in the journal
Nature, a Cornell biogeochemist describes an economical and efficient way to
help offset global warming: Pull carbon dioxide out of the atmosphere by
charring, or partially burning, trees, grasses or crop residues without the
use of oxygen.

*When bioenergy is produced by pyrolysis (low-temperature burning without
oxygen), it produces biochar, which has twice as much carbon in its residue
than that from other sources. This makes bioenergy carbon-negative and
improves soil health. (Credit: Image courtesy of Cornell University)*
------------------------------

When bioenergy is produced by pyrolysis (low-temperature burning without
oxygen), it produces biochar, which has twice as much carbon in its residue
than that from other sources. This makes bioenergy carbon-negative and
improves soil health.

This process, he writes, would double the carbon concentration in the
residue, which could be returned to the soil as a carbon sink. The exhaust
gases from this process and other biofuel production could then be converted
into energy.

This so-called biochar sequestration could offset about 10 percent of the
annual U.S. fossil-fuel emissions in any of several scenarios, says Johannes
Lehmann, associate professor of soil biogeochemistry in the Department of
Crop and Soil Sciences at Cornell.

"Biochar sequestration, combined with bioenergy production, does not require
a fundamental scientific advance, and the underlying production technology
is robust, clean and simple, making it appropriate for many regions of the
world," said Lehmann. "It not only reduces emissions but also sequesters
carbon, making it an attractive target for energy subsidies and for
inclusion in the global carbon market."

Most plants pull carbon dioxide out of the atmosphere and lock it up in
their biomass or in soil organic matter. But taking this a step further,
Lehmann recommends heating the plant biomass without oxygen in a process
known as low-temperature pyrolysis. When returned to the soil, biochar
creates a stable, long-term carbon sink.

"Biochar also has been shown to improve the structure and fertility of
soils, to enhance the retention and efficiency of fertilizers as well as to
improve the productivity of soil," said Lehmann.

Capturing the exhaust gases from the pyrolysis process produces energy in
such forms as heat, electricity, bio-oil or hydrogen. By adding the biochar
to soil rather than burning it as an energy source (which most companies
do), bioenergy can be turned into a carbon-negative industry. Biochar
returned to soil not only secures soil health on bioenergy plantations but
also reduces greenhouse gas emissions by an additional 12 to 84 percent.

Compared with ethanol production, pyrolysis that produces biochar and
bioenergy from its exhaust gases is much less expensive, Lehmann said, when
the feedstock is animal waste, clean municipal waste or forest residues
collected for fire prevention.

Lehmann said that as the value of carbon dioxide increases on carbon
markets, "we calculate that biochar sequestration in conjunction with
bioenergy from pyrolysis becomes economically attractive when the value of
avoided carbon dioxide emissions reaches $37 per ton." Currently, the
Chicago Climate Exchange is trading carbon dioxide at $4 a ton; it is
projected that that the price will rise to $25-$85 a ton in the coming
years.

*Note: This story has been adapted from a news release issued by Cornell
University.*
>From the SCIENCE DAILY
http://www.sciencedaily.com/releases/2007/05/070511211255.htm
-- 
Michael Bailes.
"Human beings,
who are almost unique in having the ability to learn from the experience of
others,
are also remarkable for their apparent disinclination to do so."
Douglas Adams, "Last Chance to See"
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