A wood waste burner, known as a teepee burner or wigwam burner in the United States and a beehive burner in Canada, is a free-standing conical steel structure usually ranging from 30 to 60 feet in height. They are named for their resemblance to beehives, teepees or wigwams. A sawdust burner is cylindrical. They have an opening at the top that is covered with a steel grill or mesh to keep sparks and glowing embers from escaping. Sawdust and wood scraps are delivered to an opening near the top of the cone by means of a conveyor belt or Archimedes' screw, where they fall onto the fire near the center of the structure.