Millar Western ramps up $42M cleantech biogas project

The first use of anaerobic digestion technology at a chemi-thermo-mechanical pulp (BCTMP) mill in the Western Hemisphere, the major cleantech project will test the process in the coldest climate yet.

“The project was a long term fit for our pulp mill,” Ron Reis, senior vice-president of Millar Western’s pulp division, said. “We recognized that environmental issues today are a growing concern for the public and we wanted to put the mill in a position where we could do a better job in the future both from a greenhouse gas emissions and organics discharged into the river point of view.”

The plant is currently in start-up mode, and is expected to reach full production by the summer.

While the project took four years to complete, Millar Western is demonstrating to Canadian pulp producers how to generate green power, while creating the potential to increase pulp production, reduce treated waste discharge, and lower greenhouse gas emissions—all goals of the government agencies supporting the project.

Earl Jenson, team leader for the bio-processing group at Alberta Innovates Technology Futures (AITF)—a research agency funded by the province—said government support or regulation will be needed to encourage other pulp mills to adopt anaerobic digestion technology, as the current economics don’t justify the significant investment.

“It’s a great idea, but the unfortunate thing is that the economics are challenging,” Jenson said. “It needs programs to help shave off some of the capital cost-intensiveness.”

Jenson added that while cheaper fuels are available, the environmental and production dividends could be powerful motivators for companies to take a serious look at the technology.

The Millar Western pulp mill produces about 320,000 air dried metric tonnes (ADMT) of pulp annually. As with all pulp mills, one of the major challenges Millar Western faces is how to minimize the environmental impact of disposing of liquid and solid waste streams. The company’s current disposal method is to discharge treated water into the Athabasca River. A large amount of the solid waste they collect in the form of sludge is then applied to land as organic fertilizer.

Following the $42 million investment, Millar Western now has a two-stage effluent treatment system featuring anaerobic digesters and then aerobic treatment in staged lagoons prior to discharge. Biogas is produced when the waste stream is agitated in three anaerobic digester tanks and microbes go to work breaking down some of the wood fibre in a high temperature and oxygen-free environment.

The biogas rises, and is then collected, conditioned and burned in biogas-fuelled reciprocating engines equipped with power turbines. Ultimately, the biogas will generate 5.2 megawatts of green power for the plant.

This system will reduce Millar Western’s fossil-fuel consumption by 11 percent, its water consumption by 10 percent and its discharge of organics into the Athabasca River by 65 percent. The process will also eliminate the equivalent of 40,000 tonnes of carbon dioxide annually, as well as reduce the amount of sludge the company hauls for land disposal by 40 percent.

Meanwhile, the new two-stage treatment system will allow Millar Western to increase pulp production by between 5,000 and 10,000 ADMT annually, while realizing annual net savings of about $8 million.

Despite the savings, Reis stressed government support for the project was critical.

“Without government grants, we would not have gone ahead,” he said. “The risks were too high and the returns were not high enough.”

Millar Western received $17.5 million in provincial funding through Alberta’s share of federal ecoTrust for Clean Air and Climate Change funds, as well as a $6.75 million Investments in Forest Industry Transformation (IFIT) grant through Natural Resources Canada.

Because Millar Western was the first pulp producer to apply this technology on an industrial scale, Reis said he has no doubt other pulp mills could use the company’s experience to build similarly-sized plants more cheaply on shorter timelines.

Tony Kryzanowski is a freelance writer based in St. Albert, Alta.