Aquila started its biomass project in 1997 at the W. N. Clark Station in Cañon City, Colo., with the granting of a permit to burn up to 5 percent wood. The W. N. Clark units are an 18 MW coal fired unit built in 1955, and a 24 MW coal fired unit built in 1959.

Aquila wanted not only to burn biomass to displace coal, but also to produce a significant positive environmental impact. This meant working with the Bureau of Land Management (BLM) and the United States Forestry Service to explore options and overcome challenges.

The BLM was in the process of establishing contracts in the forest under their care, primarily to clear some of the undergrowth and forest slash. This would help eliminate or reduce the devastating effect of forest fires. The waste would have to be either land filled or disposed of as huge piles in the forest – both terrible options for the environment.

The timing was perfect to initiate a biomass program. What was waste product to the BLM turned out to be an excellent fuel alternative for the W.N. Clark Station.

The first wood was burned in 1999. As a supply of wood started to trickle into the W. N. Clark Station, problems began to mount. The size and type of the wood pieces became an issue, at one point nearly taking one of the units off line due to plugging of the fuel distributors. It was also discovered that cotton wood trees have a tendency to grind into long stringy pieces. The filaments would wrap around the rotating parts of our coal handling equipment, shutting down the crushers that break up large chunks of coal and the flippers that flip the coal into the boilers.

The wood that was purchased had to be reground into smaller pieces, which was expensive and, based on BTU value, made it a fuel more costly than coal. In addition, suppliers of the woody biomass were few, and in 2002 Colorado had one of their worst forest fire seasons, further reducing the quantity of woody biomass.

Aquila persevered, and the BLM and their contractors worked on improving the process. BLM efforts to promote healthier forest intensified. The right sized wood chip was reached and W.N. Clark Station was now burning wood with few problems. However, plant operators still could not obtain the 5 percent permitted amount, and the cost of woody biomass continued to be an issue.

In June 2005 Aquila ran out of supplies of wood, and there were no contracts in place to get deliveries of wood into the plants. Aquila was happy to burn wood, but could no longer support the program unless the cost of the product became more reasonable.

Shortly thereafter, coal prices increased nationwide and the cost of woody biomass came down. It became a win-win situation to continue the project.

We have since increased the amount of wood we burn, but have yet to reach the 5 percent level allowed in our permit. We continue to work toward this limit. We have found an additional supplier of wood from a local pallet manufacturing company. The product is chipped to the proper size and has a good BTU value. This is also a product that would be land filled if we were not able burn it in our boilers. Capital improvements in the form of a more efficient blending facility also would be called for to reach the 5 percent level.

Aquila is now able to keep an abundance of wood on site for continued generation of Renewable Energy Credits (RECs). Before Colorado’s Amendment 37, i.e., the renewable portfolio standard, we would sell these RECs into the wholesale market to supply green energy. In 2005, we sold 720 RECs from the W. N. Clark Station to the United States Forestry Service. Since the passage of Amendment 37, we no longer sell those RECs into the wholesale market, as they have become part of our total renewable energy compliance program.

The 720 MW of RECs sold in 2005 represented 18 months of effort. The goal for 2007 is to generate 1,000 MW of RECs from our Colorado generating plants through a combination of our biomass and biodiesel programs.