For hundreds of millennia, humans have depended on wood as a reliable source of fuel. Today, driven by the twin policy imperatives of mitigating greenhouse gas (GHG) emissions and improving energy security, the global wood-based bioenergy market is growing. There are many benefits to used wood-based bioenergy. It is renewable, reduces our dependency on fossil fuels and offers new market opportunities for the forest industry growth. But they’re also contentious. The economic and environmental benefits of replacing fossil fuels with wood-based bioenergy are complex, and debates are ongoing on issues such as environmental sustainability of biomass procurement, profitability of supply chains and carbon neutrality.
With the most biomass per capita in the world, and 6.5% of the world’s theoretical bioenergy potential, Canada is well positioned to play an increasing role in the future of global bioenergy and the emerging bioeconomy. Canada’s forests cover 347 million ha, accounting for about 9% of the world’s forest and 30 % of the world boreal forest. Natural disturbances such as fire and insects constantly affect Canada’s forests. For example, since 2000, fires across Canada have consumed an average of 2 x 106 ha year–1. Mountain pine beetle and spruce budworm, the two most damaging native insects affecting trees in Canada, have damaged millions of ha annually during a major outbreak (in average 2.2 x 106 ha year–for the Spruce budworm and 4.9 x106 ha year–1 for the Mountain pine Beetle). Considered as wood waste, the yet untapped biomass from disturbed forest areas could provide a substantial amount of dead and low-grade trees to supply the bioenergy sector.
Nicolas Mansuy and co-workers from the Canadian Forest Service, Laval University, Queen University, University of British Columbia, and University of Wisconsin reviewed in a WIREs Energy and Environment article the opportunities and challenges of salvage logging of biomass after natural disturbances to supply wood-based bioenergy. Despite being variable in time and space, salvaged feedstock from fire and insects could theoretically provide about 100 x106 oven Dry ton (ODT) biomass per year, in average. From a land use perspective, it does not compete with the fiber supply of other conventional forest industries or with food production and allows leaving living trees untouched. From a sustainability perspective, existing policies for harvesting of woody biomass in Canadian jurisdictions could definitively support an increase in biomass removal. Multiple guidelines have been developed not only to minimize the effect of biomass removal on forest resilience, including soil nutrient, erosions, and biodiversity, but also to improve biomass harvesting operation. This type of biomass is also particularly suitable for the bioenergy sector since the moisture content drops rapidly after disturbance. However, uncertainties remain as to the development of competitive and profitable supply chains, because of the large distances between the locations of this feedstock and available processing sites. A further measure to mitigate risks is to develop flexible supply chains that can rely on multiple sources of feedstock, with conventional forest products and waste streams being integrated to optimize biomass flow and uses. Another uncertainty lies in the time needed for a benefit in climate change mitigation to occur. Salvage feedstock have the potential to generate atmospheric benefits relatively rapidly (decrease GHG emissions relative to a reference scenario) but attention should be paid to the factors that may shorten the time required to achieve such benefits. These conditions include enhancing forest regeneration after salvage harvesting and focusing on substituting GHG-intensive fuels such as coal.
The authors conclude that salvaged biomass is part of novel feedstock for bioenergy systems and that further research and development is required to address the sustainable conversion of salvaged feedstock in bioenergy systems and to create new value-added products for the forest sector. Momentum in the wood-based bioenergy sector will develop only if both the forest industry sector and the energy sector collaborate toward innovative and integrated forest management and procurement solutions, making it possible to extract maximum value from the resource while maintaining its sustainability. As climate change will likely increases natural disturbances occurrences and extents in Canadian forest, advanced forest monitoring and flexible wood supply chains are required to maximize the benefits, ecological and economic, of the forest sector.
Kindly contributed by Nicolas Mansuy, Julie Barrette, Jérôme Laganière, Warren Mabee, David Paré, Shuva Gautam, Evelyne Thiffault, Saeed Ghafghazi.