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# Not Enough Land To Store The Biochar!?

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Hi all,

a good friend became depressed recently when he tried to work out how much biochar we'd make if we tried to scrub our annual Co2 emissions, AND WHERE ON EARTH WOULD WE FIT IT ALL??? Be kind, as he loves biochar but neither he nor I are scientists. So what's been overlooked in these figures?

http://one-salient-oversight.blogspot.com.au/2012/06/limits-of-biochar.html

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What, didn't the article have enough data to check the assumptions?

EG:

I recently did some basic equations about Biochar. If Biochar were the sole way that carbon is removed from the atmosphere, how much land would be needed to store the stuff? The calculations ended up being very pessimistic indeed. Armed with these calculations I sent off an email to the boffins at Real Climate. NASA scientist Gavin Schmidt responded and pointed out that I had wildly overestimated the amount of anthropogenic carbon in the atmosphere but, when taken with carbon that had been sequestered into the ocean, the final figure ends up being 400 billion metric tonnes - an amount that doesn't take into account future emissions.

How much Biochar can be used as a soil amendment? According to this, the amount is around 23.2 metric tonnes per hectare. It was just a matter of then dividing the amount of anthropogenic carbon by 23.2 and see how much land is required to sequester Biochar. The result is very depressing:

In short, 23.2 metric tonnes per hectare is not enough. Even if every single hectare of above ocean land mass is sequestered with 23.2 metric tonnes of biochar, the result is not enough to remove anthropogenic carbon. In reality, sequestering of biochar could not be achieved over the entire earth's surface, so I've given figures there for 10% of the earth's surface as well as 5%, which would require a Biochar sequestering of up to 23 times what is recommended.

So, the questions are:

1. What amount of sequestered Biochar is too much? At what point will it turn from being a soil amendment and become toxic to plant growth?

2. What would be the effects of deep Biochar sequestering, whereby Biochar is sequestered up to 10 metres underground rather than just existing within the 1-2 metres?

3. Is it viable to use carbon as a resource to replace current commodities such as iron, aluminium, glass and so on?

The good news, I suppose, is that a cylindrical storage container 50 metres high and 18.25 kilometres wide could effectively store all 400 billion metric tonnes of carbon (at 2.267 grams per cm³ = 90,680,00 km³, volume of cylinder = πr²h) if necessary.

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What, didn't the article have enough data to check the assumptions?

EG:

To be honest I missed the link, :doh:

I suppose juggling between two forums, searching for and uploading files, while recording and mixing, drinking, watching tv and last but not least baking all at the same time is probably not the best way to handle things....or it could just be that i've misplaced my glasses....I dunno.

3. Is it viable to use carbon as a resource to replace current commodities such as iron, aluminium, glass and so on?
What are you're standards to qualify as viable? there are many uses for carbon and new uses seem to come along frequently. A couple examples carbon fibre, aerogel, and carbon nanotubes all of which find new applications fairly frequently and are stronger for less weight than metal, glass or stone in many applications but are VERY expensive at the moment.....but like anything else I expect that as technology to produce them improves will become more affordable.

2. What would be the effects of deep Biochar sequestering, whereby Biochar is sequestered up to 10 metres underground rather than just existing within the 1-2 metres?

I would expect that as mentioned above it would be quite expensive....But if retired mines and oil wells were to be filled the expense of digging deep holes to bury it would be saved...would be a good way to back fill active wells while still removing oil methix. Though I wonder how one would go about removing Co2 from the atmosphere to utilize it in any manor. If it is practical to do so even. At source harvesting such as collecting it directly from exhausts and brewing vats etc. seems very doable.

Even if every single hectare of above ocean land mass is sequestered with 23.2 metric tonnes of biochar
Why do you not include the surface under water? or for that matter the ocean itself where as a solid it would sink and be buried in short order by sediment.?
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I think the reason my friend was feeling disappointed was that Biochar is sold as a means of sequestering Co2 into soil that is advantageous not *just* for the climate but also for the soil. Our soils are carbon deprived, and at the optimal level of 23 tons / hectare (which I have since found the International Biochar Initiative says can be as high as 50 tones per hectare) improves crop yields, preserves nitrogen in the soil, reduces water loss and erosion, and most importantly of all, improves microbial fungi growth. This microbial fungi ends up sequestering 5 times the carbon of the original biochar!

But my friend was depressed because he saw that over time, all the world's farmlands would eventually be saturated and the economic demand for biochar would drop off.

But it's got me wondering. Is that 23 tons / hectare / year? Or every few years? How often does the biochar need to be added? It might not be a once off event.

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I think the reason my friend was feeling disappointed was that Biochar is sold as a means of sequestering Co2 into soil that is advantageous not *just* for the climate but also for the soil. Our soils are carbon deprived, and at the optimal level of 23 tons / hectare (which I have since found the International Biochar Initiative says can be as high as 50 tones per hectare) improves crop yields, preserves nitrogen in the soil, reduces water loss and erosion, and most importantly of all, improves microbial fungi growth. This microbial fungi ends up sequestering 5 times the carbon of the original biochar!

But my friend was depressed because he saw that over time, all the world's farmlands would eventually be saturated and the economic demand for biochar would drop off.

But it's got me wondering. Is that 23 tons / hectare / year? Or every few years? How often does the biochar need to be added? It might not be a once off event.

I'd be willing to bet if it was cheap enough farms the world over would be using all that could be made for many decades to come. As a way to eliminate carbon from the atmosphere, it should only be a part of a much larger multi-approach strategy. I believe every little bit of positive action is worthwhile including what each of us as individuals can do to reduce our personal carbon footprint.

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