Sawdust Fuel


Don't waste that pile of beautiful sawdust under the table saw! A clean shop vacuum makes gathering the sawdust quick and easy and it has a couple of nice uses.

(Note:  If you wish to use it as fuel, make sure to avoid mixing sawdust from ordinary wood with dust from treated lumber, composites, or other materials. Burning treated lumber sawdust is an especially bad idea since the wood contains toxic chemicals.)

The first and a common use for sawdust is as a spill cleanup. The absorbency is wonderful for those disgusting clean-up jobs. Fill a large, empty popcorn tin and add a label. One can will last for many years.

Perhaps the best use for the sawdust is as a fuel, either dry or mixed with candle wax. Mixing with candle wax results in a fuel that is easy to light and that provides plenty of energy from a small volume. Paraffin may be purchased in blocks but large candles may be purchased for amazingly low prices in the days following Christmas. The large red candle in the photo was found on a clearance table along with many others for a quarter each!

Making the fuel is a simple process. First, weigh the candle and measure out the same weight of sawdust. (More wax may be used, perhaps up to 2:1 weight ratio, if more energy density is desired.) Then melt the candle in a large pot and remove from the heat. Don't overheat; the wax should not begin to smoke. It would be a good idea to do the whole job outside, away from brush and other flammable materials. Remove the wick, and add the sawdust. Stir the sawdust until the wax is evenly distributed. I used my bare hands but the bottom of the pot is a little warm! A pair of non-absorbent gloves might be a good idea. Mix quickly so that the wax doesn't have time to solidify. Once the mixing is complete, spread the sawdust on a large sheet of paper to cool. The spreading helps prevent clumping. Once the sawdust cools, store it in a large cookie or popcorn tin like the spill cleanup can above. It is important to store the product in a metal container; it is flammable, after all.

One great use for this fuel is as a super kindling! Just lay out a line of the fuel beneath the logs in the fireplace and light one end. The two photos below were taken about a minute apart and the flame lasted for over five minutes.

    

The fuel may be stuffed into paper Souffle cups or tiny "dentist" paper cups to form little fuel pods. Warm the fuel with a hot air gun to make it pack nicely. The fingers seem to be the tool of choice for the packing. To use the fuel pod, simply light the lip of the cup.

A simple camping or emergency stove that will heat a single can of soup or beans with a single fuel pods is easily constructed from a four inch galvanized pipe coupler (found with the galvanized vent pipe at the hardware store) and a piece of fencing screen:

Bend every other tab of the coupler up into the inside to support the disk of heavy fencing screen. The straight tabs become the legs. The body of the coupler holds the heat in and shields the warming can from the wind. Note that this stove must only be used outdoors.

The photos below show the little stove in action. A full can of tap water is heated from 25C (77F) to 80C (176F) just as the flame is burning out. That's just perfect for heating a can for eating but more heat would be needed for cooking the contents. Another pod  or a larger pod would be the simplest approach.