AGW in general > Walking the walk

Terra Preta / Biochar - Theory and Practice

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Jim Hunt:
Laurent and I got into a discussion about Terra Preta on a thread about "Renewable Energy". I reckon the topic is worth a thread of its own, so here it is!

To set the ball rolling, here's the BBC Horizon programme that first introduced me to Terra Preta:

http://youtu.be/qqp_H95wjPE?t=29m

N.B. That YouTube link didn't work quite as anticipated. You may wish to skip to 29:00 or thereabouts to go straight to the Terra Preta part.

If you prefer browsing websites to watching TV programmes, here's Biochar Haiti:

http://biocharhaiti.wordpress.com/

and here's Biochar India:

http://www.biocharindia.com/



Neven:
I'm very interested in this as well. A research paper came out last week that said that very little of the CO2 gets locked through biochar. I'll see if I can find it.

Jim Hunt:
Here's some rather older research, funded by the UK's Department for Environment, Food and Rural Affairs:

http://randd.defra.gov.uk/Default.aspx?Menu=Menu&Module=More&Location=None&Completed=0&ProjectID=16168

They reckon that:


--- Quote ---Pyrolysis-biochar systems might abate approximately 7–30 t CO2eq ha-1 yr-1 using dedicated feedstocks compared with typical biofuel abatement of between 1–7 t CO2eq ha-1 yr-1. By each of these measures PBS appears to offer a more efficient way to abate carbon than alternative uses of biomass feedstock, or land to grow such feedstocks.
--- End quote ---

Neven:
Found it, Jim: Soils Cannot Lock Away Black Carbon


--- Quote ---Charcoal and other forms of black carbon do not, as previously thought, stay where they are buried

By Tim Radford and The Daily Climate

Environmentalists have argued that the use of biochar could slow and ultimately reduce global warming by taking carbon out of circulation.

LONDON – Climate scientists may have to rethink some of their old assumptions about carbon. US and European researchers have just established that black carbon, soot and biochar – the burnt remains from countless forest fires – doesn't stay in the soil indefinitely.

Around 27 million tons of the stuff gets dissolved in water and washed down the rivers into the oceans each year.

Black carbon or biochar has been hailed as one possible way of limiting greenhouse gas emissions, by taking carbon out of circulation. But this study, according to a report in the journal Science, "closes a major gap in the global charcoal budget and provides critical information in the context of geo-engineering."
--- End quote ---

That sucks, if true. I was hoping on experimenting with this stuff in 2-3 years.

Jim Hunt:

--- Quote from: Neven on May 03, 2013, 12:10:13 AM ---Charcoal and other forms of black carbon do not, as previously thought, stay where they are buried.

That sucks, if true. I was hoping on experimenting with this stuff in 2-3 years.

--- End quote ---

Yet the Horizon documentary speaks of "very dark soil that covers tens of thousands of hectares" associated with "exquisite pottery, much of it that dates from the time of Christ". It doesn't seem as though everything's been washed away "in the heart of the rainforest", even over a millenium or two?

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