Is the beneficial use of wood ash environmentally beneficial? A screening‐level life cycle assessment and uncertainty analysis

Abstract

In this paper, a screening‐level life cycle assessment (LCA) approach is used to compare the potential environmental benefits and tradeoffs of different management options for wood ash, namely, agricultural land application, forest soil amendment, use in forest roads, use in concrete and mortar, and landfilling. Uncertainty analyses are used to evaluate the generalizability of the results obtained. Although decisions regarding the selection of a beneficial use option are site‐specific and depend on available local markets and wood ash characteristics, this study shows that it is possible to draw a few general conclusions from the application of LCA. All beneficial use (BU) options showed lower environmental indicator scores than those associated with landfilling, in addition to net potential environmental benefits. From an environmental perspective, results suggest that, only in a few situations, beneficially using wood ash might not produce potential net environmental benefits but would still be preferred over landfilling, and in a very few cases, landfilling would be preferred over a BU option. For instance, net environmental benefits may be compromised if wood ash needs to be transported over long distances before it can be beneficially used. Out of the four BU options evaluated, the use of wood ash in concrete to replace Portland cement showed the greatest potential environmental benefits. However, the application of wood ash on agricultural or forest land showed greater environmental benefits than the use in concrete in cases where both its liming and fertilizing potentials are assumed to be achieved at the same time.

Limited effect of wood ash application on soil quality as indicated by a multisite assessment of soil organic matter attributes

“…Applying wood ash to forest soils in Canada does, however, present an opportunity to gain value from potentially increased forest productivity while enhancing the environmental sustainability of harvesting operations (Hannam et al, 2017). Furthermore, diverting wood ash from landfill for application to forest soils can reduce disposal costs and extend lifespans of landfills (Gaudreault et al, 2020; Hope et al, 2017).…”

The sociometabolic transition of a small Greek island: Assessing stock dynamics, resource flows, and material circularity from 1929 to 2019

“…A more sustainable use of biomass does not only imply a reduction of material input levels but holds numerous potentials, if focusing on synergistic effects between the island's economic sectors. If wood combustion for domestic heating would be reduced by 20% it still produces 1.2 kt/yr of wood ash which could be used to replace cement, fertilizers, or could be used in road construction (Gaudreault et al., 2020; Oburger et al., 2016). Even if reduced by 50%, Samothraki's sheep would still produce 75 tons of wool annually, a valuable resource with a broad spectrum of applications, currently not utilized (e.g., as fertilizer pellets in horticulture or as isolation material).…”

“…A more sustainable use of biomass does not only imply a reduction of material input levels but holds numerous potentials, if focusing on synergistic effects between the island's economic sectors. If wood combustion for domestic heating would be reduced by 20% it still produces 1.2 kt/yr of wood ash which could be used to replace cement, fertilizers, or could be used in road construction (Gaudreault et al, 2020;Oburger et al, 2016).…”

Wood ash versus expanded clay aggregate as internal curing water reservoirs in high performance concrete

“…The production of different biomass ashes is increasing as the generation of energy by burning of plant-derived organic matter (mainly forestry and agricultural wastes) is increasing because of its renewable and CO 2 neutral nature [22,23]. The most promising beneficial use of biomass ash is its addition to agricultural soils to reduce their pH (liming effect) and to provide nutrients [24]. However, despite this feasible option, most biomass ash is still disposed of in landfills [25].…”