Nenana pioneers Alaska's first biochar boiler for municipal heating

Nenana has installed Alaska's first biochar-producing biomass boiler, a system that burns green wood and certain waste materials at 2,000 degrees while generating municipal heat, a city official said Wednesday at the Alaska Sustainable Energy Conference in Anchorage.

The BET boiler system converts 10 yards of wood chips into 1 yard of biochar as a byproduct, offering rural communities a potential alternative to diesel heating while addressing waste management challenges. The system can burn shredded plastic, paper, and cardboard mixed with wood chips, meeting EPA Phase II emission requirements.

Here is what gets lost in the enthusiasm for new technology: this is not a turnkey solution. A Nenana municipal official speaking on the panel warned that the system requires daily monitoring and hopper refills every other day during extreme cold.

"It is not a simple, quick solution," the official said. "It is something that takes a lot of commitment and dedication, and I would actually discourage people from starting a biomass project unless you know you have the follow-through, the buy-in, the commitment, and you're really in it for the long haul."

Nenana hired the project manager who led Tok's biomass project to avoid starting from scratch. The trade-off for the lower cost is the labor and responsibility; this is not like an oil boiler that can be installed and left unattended for months, the official said.

The boiler burns at 2,000 degrees through pyrolysis, a low-oxygen process that creates a clean burn. It takes about 1,600 degrees to fully consume waste materials that contain glue and other additives.

College Utilities in Fairbanks has purchased a larger BET system to experiment with PFAS elimination by mixing contaminated sludge with wood chips and running it through the boiler, the official said.

Nenana worked with Alaska Energy Authority, Denali Commission, U.S. Forest Service, USDA, and Rasmuson Foundation to secure assistance and avoid costly trial-and-error learning, the official said. The city set up a monthly call with that group to move the project along and connect with the right people.