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Turning forestry waste into soil additive, reducing logging emissions

A company has found a new use for forestry waste that would otherwise be burned, releasing emissions into the atmosphere. Source: Castanet Silvachar Environmental is working to turn forestry waste into biochar, a soil additive that has been used for thousands of years to help retain moisture and lock nutrients into the earth. “Biochar has a high surface area, which allows it to absorb liquid, solids and gasses disproportionate to its size, just due to its surface area and the porosity of it,” said Silvachar’s Kevin Smith. Biochar’s porosity can help in a home garden or even for large agricultural applications. “You think of how much fertilizer gets put on agricultural fields each year or multiple times a year, and realistically they’re losing up to 60% of those nutrients,” Mr Smith said. “Lost through leaching out of the rooting depth of the plant, or if it runs off the surface of the soil into creeks and rivers, causing blue-green algae blooms. “So, what biochar does is actually capture and retain those nutrients but allows the water to still flow through and filter.” Biochar is made from organic material, which is part of what differentiates it from regular charcoal. It also requires more heat to create. “Charcoal is made at a lower temperature; you can make charcoal around 250 to 300 degrees Celsius, whereas biochar starts being made around 400, 450, up to 750 degrees,” he said. “And what it’s basically doing is cooking the biomass at a high temperature in a low oxygen environment.” He said this process speeds up the decomposition of the organic material and cleans out anything else from the cells of the material, “leaving behind the scaffolding of carbon.” Since the company’s process does not involve fully burning the material, it is much lower in emissions than simply burning waste material. “I like to call it cooking,” Mr Smith said. “If you limit the amount of oxygen, then what you’re getting is basically cooking of the material until those gasses reach oxygen, then they combust. “So, it’s a very clean burn because the carbon isn’t burning just the gasses.” Silvachar uses the waste from forestry and logging operations to create the company’s biochar, what Mr Smith says helps reduce the carbon footprint of one of British Columbia’s biggest industries. “After logging, all the tops, limbs and branches and cut ends from the harvesting process gets piled, and currently they get burned,” he said. Silvachar is part of Silvatech Consulting, a forestry consulting business, and this relationship with the logging industry gets the company access to all of the biological waste material it needs. The material is taken from slash piles and ground up “wood chip style,” then put into a reactor to be cooked down into biochar. And since Silvachar’s reactor is movable, it can be taken right to where the waste is being created. “It fits in a 20-foot sea can and it can be loaded on a truck and moved within the day,” Mr Smith said. “We can move our reactor closer to the feedstock, at the valley bottom, rather than trucking the feedstock hundreds of kilometres.” Over time, Mr Smith said Silvachar plans to expand its biochar operations throughout the province to help process the waste generated by logging. “Right now, by burning it, that equates to 9% of the British Columbia’s global emissions each year,” he said. “So, there’s 5 million tons of it that gets burned and we’re looking to at least reduce that as much as we can as we expand.” Mr Smith said biochar is recognized as a carbon negative product for carbon credits, and purifies water, reduces water usage, reduces the need for fertilizers, and can increase crop yield. He said the best way to use biochar for a residential lawn is to mix it with a dry fertilizer and then spread it around like a normal fertilizer. For a home garden use, the product can be mixed into a nutrient-rich topsoil. “It is simply a soil additive which will amplify and retain the nutrients that you do add,” he said. “Once you apply it, it remains in the soil for centuries. “And you can add more fertilizer, compost or manure to your soil, and the biochar will soak that up… and have a nice, slow release during the growing season.”