Char "Meltdown"

My char retort in action. Made from a simple stainless steel vessel. Before use, I removed any plastic or rubber parts, replacing them with steel and copper. 

They say that a picture is worth a thousand words, but it is hard to capture exactly how awesome this burn was. I had trouble finding time to create this batch, because financial pressures and the rapidly closing tree planting window has required me to spend all of my time elsewhere. I had to burn some wood and decided that the char could wait no longer. Here is a bit of context to help understand what you are looking at. I reduced five gallons of very dry sawdust to char in about two hours. My last burn, with fresh sawdust which took over five hours to "cook". That burn created massive amounts of steam during the first of those five hours. This was another animal altogether!

One consequence of the speed at which the dry material liberated hydrogen and oxygen is that the pressure inside the vessel went way up. As you can see by the flame, we had some fear that material inside the vessel might fly up and clog an outlet creating a massive and rapid increase in pressure that would be catastrophic. Luckily, the removable lid had enough blow by to allow the hot gasses to escape. You can see the flammable gasses escaping around the lid (where the wing-nuts are) This burn was so fast, and so hot, that when the process was finished, the lid had partially melted. The next upgrade to the device will be to make a new lid of steel rather than aluminum.

The other thing that the image cannot convey is the sound. It was like we had a rocket engine in our yard. The clean burning flame was about two feet long for the duration of the burn and the fiery jet was almost unimaginably persistent. It became reduced slightly a couple of times, but by simply jostling the container a few times to "stir" the contents, the flame continued as the material inside was charred. Because I live in a state where wood products are a major industry, I have been experimenting with charring the sawdust. It helps to reduce waste and can easily be scaled up to industrial levels without the time (and energy) consuming process of crushing. Even though I have a great method of crushing the char from wood, it is still a bit messy and as long as clean sawdust is readily available, I will continue to use it. After seeing the efficiency of this burn, I may have to commit to using dry material for making char instead of the fresh stuff.

Wood may seem dry when you buy it, but this sawdust had aged for about a month in the open air of my garage. I suspect that it lost over half of the moisture that had been contained in it. I may have to weigh two samples, before drying and after drying to get a better idea of how much water is in the fresh sawdust. My retort and I are available for demonstrations and during my half-day presentation I will demonstrate and discuss a variety of options and methods for producing or procurement of char, grinding methods and optimal size of char for agricultural and garden use, inoculation, water holding capacity and the biology of organisms that inhabit char. All speakers fees and honoraria will help to enhance our programs and offset costs of our school of sustainability.