I got this from the biochar forum that I left alone for a few months. In a way many have still not got it. This farmer is trying to force a bit of sense into the debate.
For biochar to be used in agriculture, the first thing that must happen is that the amount of movement in minimized as much as possible. It all costs energy and time needed elsewhere. Gathering biowaste from a farm and shipping it to a distant plant in order to then haul back biochar is not a practical option. Also the mythical biofuel that would supposedly pay for all this is bunkum.
Pyrolysis oil is mostly an organic acid with poor thermal output. Its highest and best use is to be burned during the biochar manufacturing process. This may be strong language, but a number of folks are pushing pyrolysis with dollars in their eyes that never get around to appreciating the thermal equation. It is just not worth it even in a perfect environment.
As I have posted from day one, this is all about designing to operate at the farm level.
My own posts have pretty well described and unearthed methods available to subsistence farmers without anything other than themselves. The Amazonian Indians build a civilization on it and our own subsistence farmers can rebuild tropical agriculture.
Returning to our modern farmer, the reason we want to load biochar into the soils is to provide a mechanism to capture and retain nutrients until the plants need them. It very much integrates and enhances with all best practice and just as clearly compensates for bad practice.
The reason for this is that elemental carbon while immobile itself is able to attract free ions and hold them at least weakly until a stronger attractor shows up and pulls it away. This means that the enhanced soil is able to prevent leaching of nutrients. This was the savior of tropical soils in the Amazon for two thousand years and the resultant soils are in use o this day with little fertilization.
North America, the obvious and sufficiently copious feedstock is corn stover with anything else that may come to hand. The advantage to the farmer is that several applications will hugely alter the soil itself and hugely reduce any need for supplementation with any form of costly additives. This is also a permanent solution that lasts for centuries.
That is the fundamental case for the application of biochar everywhere. Corn stover is certainly the best prospect wherever possible.
The actual production of biochar on the farm has been discussed actively and I do not know if we have advanced far yet.
It makes sense to build a bunker in which to pack dry corn stover with tractor hauled material. It makes sense to first lay down a layer of poles to allow an even air flow around the bottom of the mass. Water needs to be available for quenching the charge. Capping can be done with a layer of dirt and metal sheets. This is experimental but once done a few times, reasonable control should be easy.
The bunker format should allow for char removal with a front end loader. If it can all be done with bricks, mud and sheet metal then it can be very cheap. Fire bricks as a liner would be nice, but a simple layer of dirt could solve the problem also. This could be even done with corn roots. If one is using concrete blocks for walls one does not want them to get too hot and calcine. Sand bags full of earth would also work.
Once we knew to look for primitive earthen kilns we found plenty of information and technical assistance.
Bio-Oil and Biochar May be Future of Corn Stover
Sat, November 28, 2009 9:26:12 PM
The problem is that the farms that need bio-char are the same farms that do not practice sustainable agriculture.
I'm a farmer, this also means that I am a business owner. You have to prove to me that I need biochar more than I need my way of farming.
There is a whole new wave of farming that is sustainable and does a pretty darn good job harnessing the sun. Some of us are dredging up old soil science theories developed prior to the NPK revolution and are working on methods that work quite well. Biochar is simply another "fuel" source for my soil. Call it "another amendment" or just another "method" to make u for an unsustainable practice.
I do question the value, as a society, in spending time and energy to harvest biomass waste from a previous harvest, spending energy to transport it, spending energy and resources to convert it, then spending energy to transport it again, then spend energy and time storing it and then using it in the field. I have yet to see a model (and I will admit that in what little time I have...I am a farmer after all...I have not read everything on biochar) that works well on the scale needed for my farm, much less the needs for those farms number in the tens of thousands of acres.
My interest in char is to have an onsite facility that I can afford to operate, that is easy to operate, that costs less than a tractor to purchase and has the same return, and that I can use to convert true waste biomass, not the energy biomass that I return back to my soil. I want to use this in concert with animal waste from my own farm, composted and stirred together for at least 600 days, and then used as amendment on my land.
The original concept that I call into question is saying: After draining your soil of energy with your main crop, we want you to strip the remaining biomass that you normally till under and sell it to us. In return you will buy at a higher cost biochar to replace both the energy taken from the soil by the crop as well as the remaining biomass you did not plow under and sold. I am simply questioning the cost vs benefit. That's a lot of energy and soil fertility that is lost and I am TRULY doubtful that a farmer can economically purchase biochar to replace what was lost, especially when there are some REALLY good rotation/cover crop/alternative crop methods being worked on right now.
It seems odd that I am selling biomass and then will buy it back in a somehow better state. How can it cost less than what I sold it for and required to harvest (time, money, and energy) and reapply (time, money, energy).
Does this make sense? To me it does not.
If (in the model discussed originally in this topic) you want to use the farm as a carbon sump then your biomass source NEEDS to be off the farm for it to work. What you want is a cheap source, someone that is literally wasting biomass and looks at it as a nuisance, someone that would not mind receiving payment for that biomass, and someone that does it on a large enough scale to matter. THEN you can sell it to large scale unsustainable farms that harvest more energy then they put back and need to purchase energy to amend to their soil so they can continue growing. That is the way you make biochar profitable, useable, and sustainable, assuming farms can continuously apply tons of biochar and build up a healthy soil over decades (I have yet to see studies to say that is possible).
I am not saying that biochar does not work and that you need to prove to me that it does. I think it would fit into a sustainable system if used as simply one part of a much large puzzle. I just think there needs to be a reality check in some of these ideas that involve us farmers.
Just some quick thoughts on the matter and a reply to your question before I retire.
Carriage House Farm
Century Farm Est. 1855 Ohio