Questions about Biochar

[bazman]

Hi All

I would like to offer myself as a resource with regards to questions about Biochar, production systems, biomass sources, emissions, effects on climate change and anything else you may come up with. I work with many of the worlds leading engineers and soil scientists working with in the field of Biochar, so anything outside of my knowledge range can be sourced.

[cottager]

Awesome! Thanks bazman

I've made a little, just for myself, but wouldn't mind knowing how to make small-scale production, large surface area char.

I'm nearly there (it's a bit like bread making ... all about the holes lol).

[bazman]

I would suggest the best way to make your own Biochar is via a batch gasifier like my Fatboy system. Duel skin up draft top lit interrupted combustion gasifier.

http://www.biochar.net/fatboy-gasifier/
and my updated Fatboy2
http://www.biochar.net/fatboy-v2-gasifier/

Applying water (quenching) will help increase the porous structure of the biochar as the steam jets thought the carbonised biomass.

V3 is on the drawing board. Charmaster Dolph from northern NSW has challenged me to develop a unit based on a larger recycled gas tank. I intend to again share/open source the plans once I start this project.

[eco4560]

'Charmaster Dolph' sounds like a character in Dungeons and Dragons....

[bazman]

Dolph is a good guy, but not to far from a D&D character.

[NGcomm]

Hi bazman. I was checking out the gasifier made by Peter Davies of Real Power Systems last Thursday and I have a question that I hope you can help with. A lot of people talk about pyrolysis kilns which only hit around 600-650c for biochar. My issue with this is that at this temperature a lot of lignite-tar creosote is produced which is a strong anti-septic. This, when mixed into the soil, kills off a lot of the bacteria and mycelium, the exact reason biochar is being produced so as to provide a habitat for these sentient beings. My question is, although the pore structure is changed at higher temperatures, is it changed so much that it isn't worthwhile running at a higher temperature, like 1,000c+ so you get rid of the creosote?

The Real Power System is being run primarily as a bio-generator. It runs a gas generator and produces around 10-15% in biochar/charcoal as a residue of the process so it is not primarily made to produce the biochar. It has worked, in real world testing of multi thousand tonne throughput with sewage, wood waste and even old tires. I am simply trying to work out the balance between energy production (gas-gen) and biochar production. If the output is not defined as biochar (as I believe the IBI are trying to state it isn't) and to lower the temperature so it fits into their definition then it appears that we create a product that kills more biota than it helps plus produces less energy output than it could. Thoughts?

[bazman]

The optimal temperature for Biochar production is around 550 deg C, Temperature ranges around the 350-400 mark are left with excess volatile matter. You can smell excess volatiles in Biochar produced in systems like my Fatboy so I always compost the Biochar which removes those types of issues. Processing at 1000deg C will greatly reduce the carbon content and is a lot harder to achieve. I will be talking to a gasification engineer today so I will ask the question and get his point of view.

The IBI have 3 levels of what it classes as Biochar which is mainly based on the Biochar's organic carbon content, I feel this is not really the right way to head as it should be classed on Biochar's fixed recalcitrant carbon content. A recalcitrant carbon content above 60% is what you should be aiming for when producing a quality Biochar.

[NGcomm]

Thanks bazman. Great information and I look forward to the engineers comments. FYI the bio-gen system I checked out produced 1200c before dropping to 600c, it could also be moderated quite easily to stew away at around 450c at 10% of normal throughput if energy generation wasn't needed. A brew had been sitting in the system for 12 hours at that level and took around 12 minutes to fire up to full heat and energy production.

Tell me if I am wrong but you appear to agree with me on the creosote/volatile matter issue. I wonder how many people know that biochar needs to be treated before it is used in soils otherwise the house (biochar) will kill its inhabitants (biota). Sounds like IBI should be stating that biochar is dangerous to your living soils unless appropriate inoculate has been included?

[bazman]

A lot of variables come into play, technology, feed stock, heat range and processing time. I have no real data on the system you are referring to, it sounds like it is developed around producing energy more so than producing high quality Biochar. The smell test is quite a good indicator of the level of volatiles in the Biochar, the Biochars I work with which are produced at 550 deg C have no volatile smell with no detectable Polycyclic aromatic hydrocarbons (PAHs). They are safe to apply directly to soils. What you produce at home is a different matter, that is why for my 'backyard' designs I always suggest mixing the produced Biochar into composts.

You have to also think about the long term effects as Biochar will stabilise into a more soil like structure over a few years and any volatiles will get broken down as long as you have not used crazy amounts of Biochar without post processing.

Using wood coals from home combustion stoves is even worse. I get asked a lot about using them, they are potentially full of volatiles and I always stress this fact and that if they want to use them they should compost them which will help buffer some of those negative effects.

All the Biochar I sell comes with a small bag of humus compost inoculant with suggestions to add other components like liquid sea kelp and/or fish emulsion to help improve the blend. While my poultry litter biochar contains manure nutrients my new wood based Biochar won't contain that same value of nutrient making post blending even more important. I often say Biochar is like an empty sponge, you need to let it soak up nutrient and positive biota before application to your soils.

[S.O.P]

Did you ever add Biochar to your worm farm as it was processing? Would worm bacteria find a home in the char?