#HTE

How Large-Scale Producers Turn Sawdust Into Something Useful

In the last entry we looked at the potentially negative effects of industrial-scale sawdust disposal. If Dr. Sheldon Duff is correct and it’s bad for the environment, what’s a large-scale producer of sawdust to do? In small batches it can be safely mixed with compost, but what can you do when you’re producing amounts like in this photo here?

One intelligent solution to disposing of sawdust may be, believe it or not, to burn it. Now I know what you’re thinking: Doesn’t burning wood release CO2? Yes, but so does most organic matter when burned. So if we’re looking at a situation where something is going to get burned anyway, the benefit of burning sawdust versus burning something else is that we’ve already got sawdust, and don’t need to go dig that something else out of the ground.

If there’s one industry that is going to be burning something no matter what, it’s the lumber industry. That’s because most commercial timber needs to be kiln-dried (in order to get the wood down to a manageable moisture content of 6-8%, as air drying can only get it down to 18% or so), and kilns require heat. It hardly makes sense for a lumberyard to purchase and burn coal or more wood when their own waste product is a source of essentially free energy, and that’s why a lot of lumber producers use sawdust to fire their kilns.

Lumber company J. Gibson Mcilvain, one of America’s oldest lumber suppliers and currently the country’s largest importer of teak, does exactly that. “At any given moment we’ve got seven million board-feet of wood on site, and six 40-foot container trucks leaving each week with 15,000 to 20,000 board-feet inside each,” says Shannon Rogers, JGM’s Director of Marketing. 

To process all of that wood produces a massive amount of sawdust. “All of our dust collectors funnel into 40-foot trailers, and we probably fill one or two of those each week,” Rogers explains. Thus, “All of our kilns are powered by boilers burning atomized sawdust. The sawdust gets dumped into its own room where an auger turns and feeds it into the combustion chamber. We’ve got a guy whose job it is to monitor the temperatures, but other than that it’s pretty set-it-and-forget-it.”

Even with the kilns going, JGM can’t discard of all the sawdust they produce. “We probably end up going through about half of it,” Rogers says. “The other half we sell to a company that turns it into pellets.”

Turning sawdust into pellets brings several advantages. The first is that compressing dust into pellets reduces its overall volume to just 1/10th the size, making it vastly easier to store and transport. The second is that pellets are a lot easier to feed into a boiler, for those that don’t have a fancy auger-feeding system. Here’s an example of how Ontario-based Gildale Farms turns sawdust into pellets, and doesn’t use any glue or binders to do it:

Pellet Pros is a company that produces machines that allow you to transform your own sawdust into your own pellets. They’re not quiet, but they’re neat:

Following—or perhaps spurring—the growth in popularity of pellets, a company called Pellet Pro (not to be confused with Pellet Pros) produces a line of barbecue grills and smokers that run on pellets.

Next we’ll look at another potentially delicious way that sawdust can be used in food production.