The Woody Biomass Utilization Database is a project of the Western Governors' Association designed to increase awareness of the use of biomass resources for economic development and environmental sustainability. Program objectives highlighted include biomass energy and heating activities, education programs, and projects and technologies involving biomass residue resulting from forest health treatments to reduce wildfire hazard risk.
Title: Canon City, CO - Biomass Co-Firing Demonstration Project and Study
Type:
  • Biomass Co-firing
State: Colorado
Program Description: Colorado Co-Fire Power Plant

Co-Firing Project

A pilot project in the co-firing of waste wood with coal to generate electricity was conducted at the Aquila, Inc. power generating station in Canon City in 2005. The project was co-sponsored by the Department of Energy (DOE) through the Western Governors' Association, Colorado Governor's Energy Office of Energy Management and Conservation (OEMC), and Aquila, Inc. The project used wood chips derived from necessary forest thinning projects required to reduce wildfire hazard risk. By co-firing the wood with coal, air quality was protected from the emissions potentially produced by forest fires or prescribed burning operations. In addition, co-firing wood with coal reduces emissions from the coal itself.

Offsetting the Increased Cost

The cost of wood chips to burn in a boiler is higher than the market price of coal. The trees must be felled, limbed, chipped, and transported to the power plant. In this case, Renewable Energy Certificates (RECs) were sold on the voluntary market to offset the higher cost. The co-firing project made Aquila, Inc. the first utility in the United States to sell RECs based on biomass utilization. Additionally, Environmental Resources Trust (ERT) issued EcoPower Certification for the biomass cofiring process. This allowed Aquila, Inc to issue up to 1,395 MWh of RECs based on the initial certification.

W.N. Clark Plant

The W.N. Clark Plant in Canon City was the site of the project. The plant has 38.5 MW capacity with 2 units built in the 1950's, with coal-fired B&W stokers. The wood chip feedstock for the power plant was derived from a thinning project at the U.S. Air Force Academy. Aquila purchased 840 tons of wood chips derived from treating 136 acres of forest. The green wood chips also included bark and needles. The wood chips were mixed with coal prior to entering the chutes. Aquila found that it is preferable to burn dry chips for better energy output. And they found a need to sort and re-chip larger chips, as strands over 3.5 inches tended to clog the chutes. Aquila's permit allowed them to burn up to 5% wood to 95% coal. The project showed reduced emissions of sulfur dioxide, carbon dioxide, nitrogen oxide and mercury by co-firing. Methane and nitrous oxide were slightly increased by burning coal with wood. The carbon dioxide emissions were measured at 1.298 lbs/KWh burning coal only, and 1.201 lbs/KWh burning coal with wood chips.

The project was completed in September, 2005. Its accomplishments include documenting the costs and benefits of co-firing woody biomass with coal, and establishing ERT certification for the RECs created through woody biomass cofiring process. The RECs were sold to the US Forest Service.
Barriers identified for continuing the project included the higher cost of wood chips to the cost of coal, and a lack of understanding among brokers, utilities and consumers of the benefits of using biomass to generate power. The REC provides a mechanism to offset the cost of harvesting, chipping and transporting the wood.

Contact Information

For more information on this project, contact Scott Haase
by phone at: 303-275-3057 or by email at: scott.haase@nrel.gov
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