Jim Hilton pens a column on forestry each week for the Williams Lake Tribune.

Jim Hilton pens a column on forestry each week for the Williams Lake Tribune.

FOREST INK: Air current burners are environment-friendly wood waste disposal systems

Biochar can aid in forest health and eliminate large amounts of wood waste at the same time

I have been experimenting with various methods to make biochar from dead branches and mill wood scraps. Biochar, as a porous carbon substance that retains water, makes nutrients more available thereby strengthening plants in agriculture, gardening and woodlands.

It is produced naturally by forest fires (especially large burn piles) and agricultural field burning but relatively little biochar is produced and a lot of smoke pollution also results.

By using top burning of small wood piles or wood burned in old steel drums with help from a leaf blower has enabled me to keep smoke to a minimum and produce a respectable amount of biochar per kilo of raw material.

One of my concerns has been the waste of heat during the process of making the char. It turns out that Air Burners Inc. Located in the southern U.S.A. have had similar concerns resulting in over a dozen systems to try and make their burners as flexible and efficient as possible.

The T-24 Burn Boss weighs five tons can be moved easily with a pickup in a typical logging show or fire guard operation and costs $65,000. Whole logs and root balls can be processed without treatment like grinding resulting in high through puts of 13 tons per hour. Some customers have been making close to $2,000 a day from the biochar as well as being able to operate in any weather because the burners smoke free operations meet all U.S.A. EPA standards.

The larger models are also portable but are designed for longer set ups and have high through puts of 25 tons per hour. They can be powered by on board diesel engines or electric motors if near a hydro grid but for those more remote areas, the PGF systems can generate their own electric power as well as producing significant thermal energy for drying materials.

One set up shows the heat being used in a lumber drying kiln. The power generating systems come in 100 – 500 kilowatt sizes or the largest one megawatt version. With the potential savings on diesel and the ability to use the large amount of thermal energy created these air current burners could have a place in a number lumber or wood pellet processing industries.

What comes to mind for me is how this kind of system could be used in the remote operations like West Chilcotin Forest Products near Anahim lake where the use of expensive diesel powered generators along with having to air dry their lumber were some of the factors that made their operation non viable. These larger systems cost around $200,000 including some options for recovering the biochar and over $800,000 for electrical generating systems.

It should be noted that in most cases these burners do not generate much biochar per weight of biomass burned. As noted in the advertisement they rely on recovery of the biochar at the end of the day from coals produced through pyrolysis by being covered by the ash.

Recently, the U.S. Forest Service, keen on using biochar in forests around the country, has recognized the simplicity of this and has teamed up with Air Burners to develop a way to optimize biochar production in a firebox, to aid in forest health and also eliminate large amounts of wood waste or forest slash at the same time.

This is underway through a CRADA, a research and development agreement between the U.S. Forest Service and Air Burners. A decisive factor for the government was that the standard firebox is already officially recognized as an environmentally sound way to burn or dispose of wood waste. For more information google www.airburners.com.


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