Net gains from biochar not equal to gross. Adding biochar to soil lowers ability of rest of soil to hold carbon. Still net gain, but not as big of one.

In non-tropical climates there is a limit to the percent of the soil that can be charcoal. Past a certain percent the ability of the soil to  grow crops is lowered - even if nitrogen is added. Only in tropical climates can charcoal be indefinitely added to the soil.  

If biochar is produced by traditional charcoal making technology that you add a lot of black carbon and NOx to the atomosphere. The net result may produce more emissions than are fixed, especially since black carbon has much greater warming effects than CO2.  There are advanced charcoal making techniques, but these are capital intensive, which is a barrier in developing nations where much farming is subsidence farming.

Bottom line. Biochar as real sequestration potential once we drastically lower our emissions. Biochar, along with other forms of agriculture and forestry carbon fixing might someday fix as much as 2% to 5% of our current annual emissions per year. If someday we can lower world emissions to near zero, various forms of forced bio-fixing of carbon may tip us over the edge into small net negative emissions. I doubt they can do more than that.  They certainly will never make drastic emissions reductions unneccesary.  

Both Gar and Pan need to provide references for some extraordinary claims. Especially for this one: "are we relying on the very flawed study of char in boreal forest soils to paint a larger picture?" How flawed please? Which study?

And Pan, criticism is not dismissal.

- The truth always sounds like what you already believe.

There have been studies and problems occur at way less than 10%, under 1%. As to drastic emissions cuts being "off the table" what you mean is we are not doing it now. But we are not doing massive biochar now either. And, if you follow the link you will see right in the article an admission that there are problems, and the need for further research to solve them. Of those advocates who know what they are doing, not even the most optimistic thinks we are ready for full deployment everywhere today. But you know there is a lot tropical soil out there, so knowing how to do it right in the tropics is a damn good start.

Also, being realistic about the potential is not "dissing" biochar or agricultural sequestration in general. Right now ag/forestry/land use change is responsible for at least 20% of ghg emissions. If we can change those sectors from a 20% emitter to a 1% or 2% sequestrator, that is close to a quarter of the problem tackled! That sure as hell is not an argument against biochar. It is an argument not to overestimate what it can contribute, and the importance of doing it right. Doing it right means using advanced methods of charcoal production that produce little air pollution and especially few NOx or black carbon emissions. It means doing it only in tropical climates. Also, it means not clear cutting forests to turn them to biochar, but using biochar to dispose of waste on existing agricultural land. For example all over world rice straw is burned after rice harvest, because rice fields won't absorb all waste straw generated. In place entire rice paddies and fields are burned in place to not only dispose of waste but get rid of pests. Supply these tropical rice farmers with advanced clean charcoal burners and pay them for using them, and you generate biochar in a setting where the downsides already exist. You still have to careful of social side effects. (I can think of lots ways this could hurt subsidence farmers, and end up as a major environmental justice issue. ) And since we DON'T know net as opposed to gross sequestration, no tradable offset generated. Give the farmers a straight subsidy. Don't generate permits to burn coal for doing this.

You have to be as careful with social issues as technical ones. For example I can imagine this being deployed in a way that only rich farmers and corporations can take advantage of it, increasing their advantage over subsidence farmers. Or I can imagine  requirements put on it without adequate support that disrupt the lives of subsidence farmers who take advantage of it. The key is that if you have technology that works you need to still make sure the proposals for how to deploy it come from the communities, not from rich Notherners who don't understand the social networks they are introducing tech to. Also make sure that the downsides are clear to adapters so they can   decide what compensation is needed for it. For example, burning fields in place saves labor and kills pests. (It is also already a form of biochar, i.e. a highly polluting one.) Again, this is not a "don't do biochar". It is "do biochar right; doing it right is possible, but not simple". Also remember there is a lot we still don't know.

"Slower but steadily accumulating changes had been under way for thousands of years [AGW from agriculture], and the total effect of these earlier changes nearly  matched the explosive industrial era increases of the last century or two."

Under a Green Sky by Peter Ward Ph.D., a Seattle area paleontologist writing about mass extinctions from CO2 causing Hydrogen sulfide from stagnant oceans killing sea and land based life, and destroying ozone thereby causing the extinction of most plants, plankton, and animal species.

Beware of magic bullets, they can misfire.

Producing Biochar can have a nice offtake in the form of syngas. The syngas could be used for power generation and if sourced from agricultural waste such as crop residues could offer substantial GHG reduction.

The likely cost effective scenario would be a central gasifier processing agricultural residues within a 50 km radius.

Alternatively instead of gasification one could go the pyrolysis route and capture the volatile which would happily run in a diesel.

"...this boils down to--implementability. Is that a real word?"

Is it a cascade effect, like bees swarming? The hive decides it's time for radical change and moves.  

Is change like this triggered by key intuitions  bouncing around the collective subsconscious?

The value system flips to a new state in a very short time span, like it happened at the start of WW II.  Or suddenly 80% of US believing the Iraq invasion was necessary.

When do 80% decide quality of life tops quantity of consumption and possesions?  Then the solutions implement themselves, so to speak.

http://amazngdrx.blogharbor.com/blog John Schneider, Northern Wisconsin

biochar is also known as terra preta and has an astounding history in the Amazon.  google either and you will hit thousands of postings on the appropriate forums.

Wood is likely an inappropriate feedstock but crop waste is not.

so called negatives in the boreal forests, i have not seen and I am monitoring this.  likely a grasped straw by a nitpicker.

the real discovery is that adding biochar allows a full rich soil to be manufactured in all apparent environments.  this bold claim is still not completely verified but progress is underway everywhere and we are still looking for exceptions (they surely will be found even if ridiculous)

regards

arclein

That is the problem with charcoal kiln technology used to make biochar.  It is basically partial combustion of the wood, most of the energy wasted and carbon sent into the atmosphere.  

Pyrolisis, the separation of the bio-oil from the wood with heat, in the abscence of oxygen, does not burn the biomass.  The oil can be stored and used as fuel for grid backup.  That enables wind and solar.

The pyrolisis heat energy can be cogenerated by a solid oxide fuel cell running on the pyrolisis oil or biogas, so that whenever grid backup is needed, waste wood is converted to biochar, and pyrolisis oil is extracted for future use.

Joint biogas and pyrolisis oil plants feeding a farm based grid backup generator of this type could bolster a local renewable smart grid, and that could nearly eliminate reliance on fossil fuel and nuclear power, when enough local systems were connected in a regional grid.

Biochar soil amendment soaked in organic fertilizer would be a valuable, carbon sequestering, carbon preventing product.  A great way to restore the soil to its natural carbon sink activity.

Eliminating chemical fertilizer provides a huge GHG savings too.

http://amazngdrx.blogharbor.com/blog John Schneider, Northern Wisconsin