A cost analysis of bioenergy-generated ash disposal options in Canada

The burning of wood for bioenergy produces significant amounts of ash residue that requires disposal. We constructed a cost model to evaluate the unit costs of three ash disposal methods in the Canadian context: landfills owned and operated by the bioenergy facility, municipal landfills, and forest site application. The model accounts for costs related to the pretreatment, transportation, and disposal of ash at a landfill or forest site. Model parameter values were assigned appropriate distributions (based on published literature and industry surveys), and Monte Carlo simulations were employed to produce a range of model outputs for each disposal option. Results indicate that existing landfills (if available for ash disposal) are likely the most cost-effective option (median value of $77 per tonne), although applying ash to a forest site is only ∼15%–20% more costly (median value of $92 per tonne). Indeed, the unit cost estimates across disposal options have considerable overlap. This suggests that close examination of firm-specific circumstances is highly warranted when choosing a disposal approach, even in the absence of accounting for potential environmental benefits associated with forest site disposal of ash.