LAUSR

Coal-fired electricity generation is a major emitter of greenhouse gases (GHGs) in Canada and the Federal Government has taken steps toward mandated reduction in GHG emissions. One pathway to reduced emissions is via co-firing of coal with short-rotation coppice (SRC) willow grown on marginal land in Saskatchewan. This study uses a life-cycle inventory model to investigate the GHG emissions from nine scenarios for electricity generation with willow pellets at a retrofitted generating station in Saskatchewan. Torrefied and non-torrefied willow pellets from SRC plantations in the Prairie and Boreal Plains ecozones are considered. Direct co-firing of pellets and indirect co-firing via a circulating fluidized bed gasifier are modeled. The model output shows cumulative, levelized, and disaggregated GHG emissions. The scenarios account for the plantation establishment period required to reach a co-firing ratio of 40% by energy input. Torrefied and non-torrefied willow pellets grown in the Prairie ecozone indirectly co-fired with lignite coal result in 43% and 47% net cumulative GHG emissions reduction compared to the existing coal fired pathway. Direct co-firing of the same feedstocks results in a 34% and 31% reduction in GHG emissions, respectively. The biomass-based portion of all scenarios was found to produce negative net cumulative GHG emissions on a life-cycle basis with willow grown in the Prairies ecozone (i.e., GHG emissions from the willow plantation to the combustion of the pellet with coal). Co-firing is therefore a viable option for reducing GHG emissions from electricity generation. © 2017 Society of Chemical Industry and John Wiley & Sons, Ltd