[Stoves] [biochar] Methane from char-makers [1 Attachment]

[Crispin Pemberton-Pigott]

Greetings Friends

Regarding the incentive not to burn agriwaste badly: farmers in Hebei province (which surrounds Beijing) burn a huge amount of biomass each year to get rid of it and to put the minerals back. The only interest they have in selling it is if the price is high enough to justify the cost of collection, and in some cases, delivery.

When there is zero economic incentive (like having a saleable product) no one will bother with such an arduous task. To be frank, the government is not really concerned with the burning, it is all about the air pollution. If you want to burn it without smoke (which is not difficult) no one cares. Leaving on the ground means it rots to methane, either on top or as mulch.

As I have mentioned before, the Hebei Province has several factories that produce char from agriwaste and make liquid fertilizer on a large scale. It is not used locally, but exported to other nearby provinces because the product is subsidised at those destinations so the producers get a better price.

Some of the raw material is put into methane digesters and piped in to the local gas network. The opportunity to do that at a much larger scale is ever-present, but the cost of collecting it exceeds the gas value benefit.

Regards
Crispin


Han-Pieter,

No apologies required. This is a sensitive subject and the discussion has proved very informative. Thank you, in particular, for clarifying a number of points here that were previously missing in the discussion. First, the 20 time horizon. Yes, the GWP of methane declines rapidly over time, starting much higher than 25 and falling to 25 as the "at 100 years standard." I think that it is very important to make the short-term time scale of these calculations clear because I have never encountered them before. Everyone I know and all of the articles with which I am familiar use the 100 year standard. Second, there is your contention that TLUDs and Kon-Tikis operate in the same universe. I think that they do not. In our TLUDs, the rising gases, including of course, CH4, meet the air arriving at the gap above the barrel and instantly ignite. As they flame up the stack and above, they reach very high temperatures. Thermal gun measurements have reached almost 1,000 C. I do not believe that at this temperature we are throwing off much CH4. Our one closed room rest did not register any. Our troughs and trenches, like all Kon-Tikis and flame-caps, are another matter. Not having any data on temperature, James Joyce's comment, I do not know what the temperature is or whether it rises above 690 C.

Finally, with crop waste fires producing 5.82 kg of CH4/tonne of biomass burned and using the GWP multiplier of 25, CH4 from crop waster burning is a big issue, especially when combined with the other primary emission, NOx at 3.11 kg/tonne and a GWP multiplier of 298. When there are hundreds of billions of tonnes of crop waste that cannot be collected for high tech pyrolysis, this means that for every one of those hundreds of billions of tonnes, 1.073 tonnes of eCO2 is being emitted. Because this stuff can be charred only using loc-tech, the loss in the methan component of eCO2 calculations is very hard on anyone trying to find a way to engage the rural poor of the developing world in charring not burning. Profit margins are razor thin already and the potential of carbon sales at present offers the only hope that sustainable business models can be found.

You may be correct, but if so, there are a huge number of small farmers who will have no incentive not to burn.

M
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