Coast Guard Warns Against Wood Pellet Fire Hazard

The United States Coast Guard issued a Safety Alert November 27 warning of the danger of cargoes of wood pellets spontaneously combusting. It said that in a two-week period, two unmanned barges loaded with wood pellets had caught fire while waiting at a Mississippi River fleeting facility. No one was injured, but damage to the barges was extensive.

While spontaneous combustion is not common, it can happen due to the binders and chemicals in the pellets, the alert said. The International Maritime Solid Bulk Cargoes Code notes that “wood pellets containing additives or binders may ferment over time if moisture content is over 15 percent, leading to generation of asphyxiating and flammable gases which may cause spontaneous combustion.” Wood pellets in enclosed spaces can produce off-gases, including carbon monoxide, carbon dioxide and volatile organic compounds (VOCs).

Warning signs can include visible moisture, cargo decay and discoloration, elevated cargo hold temperatures (above 168 degrees F), and carbon monoxide and hydrogen sulfide gas generated by cargo decomposition.

The first identified hazard in the case of the two barges was visible smoke from already smoldering pellets. Heat from the smoldering cargo melted the hopper covers, introducing oxygen that supported “rapid and uncontrollable fire growth.”

The Coast Guard strongly recommends that shippers of wood pellet cargoes and owners and operators of hopper barges carrying wood pellet cargo:

• take steps to isolate cargo from external moisture sources, including ceasing cargo operations during inclement weather and maintaining hopper covers to prevent rain ingress during transport;

• plan deliveries to minimize long-term storage, particularly onboard barges;

• conduct routine temperature readings to detect early-stage cargo decomposition; and

• ensure that personnel conduct frequent rounds to identify signs of smoldering.

Spontaneous combustion of wood pellets is a recognized hazard at ports and terminals. In May 2021, an explosion and fire occurred at a wood pellet storage warehouse at the Port of Brunswick, Ga. In February 2017, a conveyor belt loading a silo at the Port of Port Arthur, Texas, with 10,000 tons of wood pellets caught fire, setting the wood ablaze and sending a cloud of black smoke into the air.