Energy and greenhouse gas balance of the use of forest residues for bioenergy production in the UK

Abstract

Life cycle analysis is used to assess the energy requirements and greenhouse gas (GHG) emissions associated with extracting UK forest harvesting residues for use as a biomass resource. Three forest harvesting residues were examined (whole tree thinnings, roundwood and brash bales), and each have their own energy and emission profile. The whole forest rotation was examined, including original site establishment, forest road construction, biomass harvesting during thinning and final clear-fell events, chipping and transportation. Generally, higher yielding sites give lower GHG emissions per 'oven dried tonne' (ODT) forest residues, but GHG emissions 'per hectare' are higher as more biomass is extracted. Greater quantities of biomass, however, ultimately mean greater displacement of conventional fuels and therefore greater potential for GHG emission mitigation. Although forest road construction and site establishment are " one off" events they are highly energy-intensive operations associated with high diesel fuel consumption, when placed in context with the full forest rotation, however, their relative contributions to the overall energy requirements and GHG emissions are small. The lower bulk density of wood chips means that transportation energy requirements and GHG emissions are higher compared with roundwood logs and brash bales, suggesting that chipping should occur near the end-user of application. © 2011 Elsevier Ltd

Environmental impacts of various biomass supply chains for the provision of raw wood in Bavaria, Germany, with focus on climate change

“…The results for poor site conditions are similar to the findings by Whittaker et al (2011) and are mainly explained by a reduced biomass productivity and GHG emissions from general forest processes (fencing, planting, road maintenance, clearing) being attributed to lower timber volumes, thereby increasing GHG emissions related to one m 3 of raw wood. Furthermore, tree dimensions are lower, and higher energy and material inputs for the harvesting and forwarding processes are needed.…”

“…Murphy et al, 2014) or lower shares (e.g. Whittaker et al, 2011) in some cases which is, of course, plausible as transport assumptions can differ a lot between studies in terms of distances, payloads, and fuel consumption or utilization rates. Nevertheless, all these studies concerned with forest biomass transportation highlight the importance of transport processes for the total impact on climate change of raw wood.…”

How certain are greenhouse gas reductions from bioenergy? Life cycle assessment and uncertainty analysis of wood pellet-to-electricity supply chains from forest residues

“…The calorific value of the produced wood pellets at a moisture content of 10% (wet basis) was b i o m a s s a n d b i o e n e r g y 7 9 ( 2 0 1 5 ) 5 0 e6 3 [38]. b [69]. c [70].…”

Climate change mitigation potential of local use of harvest residues for bioenergy in Canada

“…forest management unit) use of bioenergy in Canada from harvest residues. Earlier bioenergy studies have used a variety of methodologies to examine the biophysical potential, generally related to specific activities at smaller scales (Valente et al, 2011;Domke et al, 2012;Repo et al, 2012;R€ oder et al, 2015), but few studies have attempted to determine national mitigation potential (Werner et al, 2010;Whittaker et al, 2011;Lundmark et al, 2014). Determination of the mitigation potential of forestderived products is complex because the forest sector interacts with energy and industrial products sectors, and a systems approach to analysis is required (Nabuurs et al, 2007;Obersteiner et al, 2010;White, 2010;Lempri ere et al, 2013).…”