Analysis considers impact of cofiring pellets at Finland plants

By Erin Voegele | November 05, 2013

Finland-based Helsingin Energia recently announced a collaboration with the Finnish Environmental Institute and Tampere University of Technology to evaluate the environmental impacts of replacing a portion of the coal used to fire its Salmisaari power plant with wood pellets. The plant currently generates 160 MW of electricity and 480 MW of heat. According to information released by Helsingin Energia, the plant is scheduled to begin cofiring pellets in 2014, at an initial inclusion rate of up to 10 percent. The study modeled the current production and consumption volumes of the power plant, and compared with a scenario in which approximately 7 percent the fuel was comprised by pellets in 2015.

A press release issued by the company specifies that the collaborative study determined that while the cofiring of wood pellets would reduce the climate impact of the Salmisaari plant, the impact is not large when only a small proportion of pellets is used.

The study included a lifecycle assessment of the pellets that considered the manufacture, transportation and final utilization of the fuel. “When assuming that biomass carbon dioxide emissions are climate neutral, the climate impacts of mixed combustion of pellets are smaller than those resulting from the combustion of coal alone,” said the company in its release. “Mixed combustion of pellets even in smaller proportions increases transport to the power plant. However, transport of fuel, chemicals and waste only accounts for a few percent of the emissions, and the increased traffic resulting from the combustion of pellets barely registers in the total climate impacts.”

Information published by the company specifies the study used inputs consistent with Russian and Polish coal, which is imported by ship. The pellet fuel was assumed to be domestically produced from waste timber sawdust and trucked approximately 100 kilometers to the plant.

According to Helsingin Energia, the analysis also determined that cofiring at small proportions would not require significant technical modifications to the energy production process, and would not meaningfully impact the facility’s consumption of water, chemicals or power.

Additional evaluations will be carried out to consider the environmental impacts of cofiring 40 percent pellets at the plant. In its statement, the company said the Helsinki City Council is scheduled to make a decision in 2015 whether to build a new biofuel-fired power plant, or modify the Helsingin Energia’s Salmisaari and Hanasaari power plants to consume higher rates of biomass fuel. Both faciliites are scheduled to begin cofiring at rates of up to 10 percent next year.