I had an email from Austin at All Power Labs this evening; I had made several mistakes in my post about biochar, and of course he would like to make sure the information is correct, and so would I! I don’t ever want to mislead my readers. So, I am going to copy his email in full here. He also sent me a lot of photos of before/after biochar, which I will share with you if you like (just contact me and I’ll send them on) - they are impressive (although I haven’t seen any results in my own garden yet and will report them when I do. I have to say my artichoke plants are just as big as the ones in the pictures, so … jury is still out for me on this. The proof will be in the pudding! The important part is that Gill Tract saw a huge difference in their garden).
Here is the email, and I want to say that I really appreciate a company that is 1) local, 2) taking something out of the waste stream and making it work for good, 3) invested in solving the climate problem, and 4) totally committed to their company and feel it’s important to make sure that the info is correct and not distorted. SO thank you very much to Austin for pointing out my mistakes and setting the record straight!
“(Austin wrote:) In this paragraph, the highlighted portion ought to be corrected:
(Elizabeth wrote:) So, here’s the scoop. All Power Labs was originally created to make renewable energy using biomass. That is, make power by burning the waste products of agriculture or even our urban yards - tree trimmings, wood chips, etc. In the process of making this renewable energy, a by-product was produced - bits of what looked like charcoal, very light and made of pure carbon. Originally they just threw this product out. Then they realized it was biochar, and high quality biochar at that, and that it was a coveted resource for farmers and gardeners, as it does a lot of cool things in the soil (which I will detail in a bit). The original purpose of the company, making renewable energy for use, was having trouble finding a niche in the very large solar and wind energy economy we have in California. So, they pivoted a little into the biochar side of things.
(Austin) The biochar is not pure carbon. It is about 70% organic carbon. (Organic carbon—in a from derived from an organism— as opposed to mineral carbon, such as in chalk. Chalk is calcium carbonate. Carbonate minerals contain CO2 in their crystal structures.) The remaining 30% is a mixture of ash, and residual oxygen and hydrogen. Our walnut shell biochar is about 15-16% ash.
Charcoal is the “fixed carbon” fraction of woody biomass. About 80% of the mass of a chunk of wood consists of volatiles, which come off as wood smoke. The volatiles contain about half of the carbon of the wood, along with most of the hydrogen and oxygen in wood. (Remember, wood is largely cellulose, which is a carbohydrate. That’s where the hydrogen and oxygen come from.) The remaining 20% of the mass is fixed carbon—the carbon that is left once all of the volatiles come off of the material. That’s where the other half of the carbon content resides. The fixed carbon remains, and if it goes through high temperatures, resists decomposition because the enzymes used by bacteria and fungi to break down most organic carbon compounds can’t decompose most of the structures that are produced by fire. The higher the temperature, the more resistant to decomposition pyrogenic carbon tends to be. This quality of resisting decomposition is called “recalcitrance”. It is not an absolute quality; lower temperature processed biochars have a larger fraction that eventually decomposes; the high temp processed stuff (like ours) has a very small fraction that eventually decomposes.
(Elizabeth) Now more about the process. Above is a photo of the “Powermass Gasifier” which is the machine that turns biomass into both energy and biochar.
(Austin) The name of the machine is the “Power Pallet.” It is a Biomass Gasifier genset.
I attached a process explanation for you to get a sense of how it works. (If anyone is interested in this - let me know and I’ll send it on to you - E)
(Elizabeth) Biochar doesn’t decompose. It’s already been processed into its permanent form - pure carbon. This happens in the process of Pyrolysis. The volatile carbon in the biomass is burned off (and used for energy), and what is left is like the embers of a campfire. Totally indestructible, permanent bits of carbon.
(Austin) This description, of being “indestructible, permanent bits of carbon” is more apt for diamonds or pure graphite. Biochar is not totally indestructible. Depending on how it is made, a certain fraction can very slowly decompose, but the bulk of it does not participate in the carbon cycle. The proportions depend on the temperature of processing. The proper way to state this is that the carbon content of charcoal does not revert to carbon dioxide without combustion. When charcoal is interred in the ground as biochar, it is essentially “reverse coal mining”—the production of concentrated black carbon and putting it in the ground.
Also, for pyrolysis, we have an explanatory page on our website that would explain it in the context of how we make biochar. If you would link this page, we would appreciate it:
http://www.allpowerlabs.com/gasification-explained
(Elizabeth) They have a very high CEC (cation-exchange capacity) which means that they add nutrient density to the soil.
(Austin) CEC doesn’t add nutrient density, but it does add the ability to store nutrients. It is more like nutrient storage capacity. The key thing is that water soluble cation nutrients don’t just dissolve into water and leach out; the CEC sites act like velcro and cling on to water soluble cation nutrients, but hold them loosely enough that plants can get them off as they need them. High CEC soils can store a massive amount of nutrients without burning plant roots because the nutrients are not all dissolved in the water at once.
(Elizabeth) I also really appreciate that the biomass used to make this biochar is nut hulls from California orchards. This is taking something out of the waste stream, something that takes hundreds of years to decompose, and putting it to good use.
(Austin) The nut shells don’t take hundreds of years to decompose. Depending on how they’re disposed of, within a few years, all the carbon content in them is back in the atmosphere. This is sort of like how wood chips and nut shell mulch disappears like compost. ”
Let me just say again: I totally appreciate these corrections. I want to learn, too!