We operate under the principal of conservation of mass. I know that is stating the obvious, but doesn’t it have some implications w.r.t. pricing C versus CO2? The process of extracting hydrocarbons for combustion, for instance, is to some extent a removal of carbon from the “inactive cycle” and introducing it into the active cycle. The fact that it “becomes” CO2 is just the physics and chemistry of combustion. The relative “amount” of CO2 is largely determined by the ratio of C:H in the particular fuel (I know I am oversimplifying… but it is still a good approximation.).

If you accept this, aren’t you are more likely to consider putting the price on carbon at the source, and perhaps more specifically carbon from the “inactive” cycle (i.e. the “naturally sequestered” stores in coal, oil, etc.). Cleaner hydrocarbons (lower C:H ratio) would attract less of a price (e.g. natural gas). “Credits” would only be earned if you could clearly demonstrate that you were somehow removing *carbon* from the “active cycle” and restoring it relatively permanently to the “inactive cycle”.

For instance, I was reading an interview that Tim Flannery gave regarding Terra Preta, which is basically the burning of organic waste in the absence of oxygen, to create charcoal and hydrogen-rich gases. The charcoal is then buried deep in soil and apparently stays locked out of the active carbon cycle for perhaps thousands of years. Let’s *suppose* this “technology” actually proves effective in sequestering carbon. How would you “credit” the charcoal? By estimating the CO2 that was pulled out of the atmosphere? Or just credit the carbon that gets buried? How would we “equate” the biochar with underground geosequestration of CO2?

I know that I didn’t touch on agricultural CO2, or deforestation, which are not “inactive” sources of carbon, but even there isn’t it really an issue of oxidizing C to create CO2?

This is not my area of expertise. Maybe it is really “six of one, half dozen of the other issue” (or 3.67 of 1, one of the other! ). But if you have a paragraph or two, or a link, on why you prefer CO2, I would enjoy reading it. Best regards, and thanks for all your excellent efforts and contributions.

I do think that switching back and forth between the two is confusing to most people, so I think that someone who talks or writes regularly on this issue should pick one. Relatedly, I think you are less likely to make a mistake if you 1) consciously stick with one and 2) be sure when you are interviewing people that you asking them which one they are using.

Finally, if the public needs to better understand one concept, it is probably that CO2 concentrations will keep rising even if we freeze emissions. So I think it best to focus on CO2.

That said, I will try to remember to do the conversion once in each post when it comes up.

tidal — Pyrolysis does not make Terra Preta, a uniquely Amazonian soil type. It makes biochar. If the goal is to permanently sequester carbon in the ground, making biocoal is far better. See my comments on previous threads.

In the UK things seem to be slowly switching over to CO2 but there’s still policy wonks and the like who only think in C.

That said, carbon dioxide should be the standard.

If I am going to demonstrate to somebody, say in an booth, the relative environmental cost of burning fuels I can have a 6.6 lb bag of coal and a gallon gasoline can with a jug of water that will represent the 19.4 lbs of CO2 that is in the atmosphere from that gallon. Keeping 19 lbs of dry ice at 19 lbs on Earth Day will be quite a trick locally where temps. average about 82 F. I can however show that it will take about 20 lbs of dry wood chips to get the 5.5 lbs of charcoal we have to bury to sequester the emissions from a single gallon of gas. I can then wave a printout of the virtuous carbon cycle from the Eprida website to show them that securing the carbon can be a benefit instead of a cost.

I’m not really sure how I could convince them to get rid of 16 lbs of fuming, hissing dry ice. It would be good to have some as a contrast though to show the difficulty of handling the stuff. It would have to stay in a “no-touching” lexan box. People get that carbon removed from the ground has to be returned to the ground as carbon.

Terra Preta or biochar vs. “biocoal”

David- I’m not sure where you get your information that there is somehow some advantage to burying “biocoal” as vs. biochar or Terra Preta. Terra Preta (378k results on Google) or biochar (21K hits on Google) seem to be the preferred usage for carbonized biomass used for fuel AND soil amendment whereas “biocoal” (6.5K hits Google) seems to be used in reference to the fuel usage only.

Adding the word “abstract” to the primary in a search reinforces this impression and justifies the impression that Terra Preta (terra preta+ abstract, 12.6K hits) is the common scientific usage with biochar (biochar + abstract, 1.6K hits) gaining ground and biocoal (biocoal + abstract) having limited use largely in reference to biomass to fuel operations. A review of the scientific literature available on Google scholar also supports my hypothesis yielding 11K articles or citations for Terra Preta and 78 (as in 78) for biocoal.

What has been repeatedly demonstrated is that adding powdered charcoal to active soil results in increased root and plant growth, thereby sequestering atmospheric carbon in addition to the carbon buried. It is therefore generally agreed that char in the active soil zone yields a carbon sequestration factor > 1. You seem to keep disputing this without references to evidence. So whether you are beating some kind of personal drum or muddying the waters could you please desist?

20 lbs of CO2 emitted for a gallon of gasoline (direct emissions).
Another 4 or 5 pounds upstream (refining, etc.)

Terra Preta is a uniquely Amazonian soil type with high carbon content.

Biochar is a product of pyrolysis of biomass. If woody biomass is used, the traditional name is charcoal.

Biocoal is the result of hydrothermal carbonization of biomass, a completely different (and exothermic) process from pyrolysis.

For permanent sequestration, biocoal is perferable. Being precisely high-grade coal, we know it will stay securely buried for millions of years. Biochar will not. Read a recent report on the subject:

http://terrapreta.bioenergylists.org/node/578