Energy requirements and environmental impacts associated with the production of short rotation willow (Salix sp.) chip in Ireland

Abstract

Willow Salix sp. is currently cultivated as a short rotation forestry crop in Ireland as a source of biomass to contribute to renewable energy goals. The aim of this study is to evaluate the energy requirements and environmental impacts associated with willow (Salix sp.) cultivation, harvest, and transport using life cycle assessment (LCA). In this study, only emissions from the production of the willow chip are included, end-use emissions from combustion are not considered. In this LCA study, three impact categories are considered; acidification potential, eutrophication potential and global warming potential. In addition, the cumulative energy demand and energy ratio of the system are evaluated. The results identify three key processes in the production chain which contribute most to all impact categories considered; maintenance, harvest and transportation of the crop. Sensitivity analysis on the type of fertilizers used, harvesting technologies and transport distances highlights the effects of these management techniques on overall system performance. Replacement of synthetic fertilizer with biosolids results in a reduction in overall energy demand, but raises acidification potential, eutrophication potential and global warming potential. Rod harvesting compares unfavourably in comparison with direct chip harvesting in each of the impact categories considered due to the additional chipping step required. The results show that dedicated truck transport is preferable to tractor-trailer transport in terms of energy demand and environmental impacts. Finally, willow chip production compares favourably with coal provision in terms of energy ratio and global warming potential, while achieving a higher energy ratio than peat provision but also a higher global warming potential.

Simulation of environmental impact scores within the life cycle of mixed wood chips from alternative short rotation coppice systems in Flanders (Belgium)

“…the effects of harvesting cycles [42] or carbon dynamics [58,59]), considering specific SRC species (willow clones, poplar clones, etc. ; [44,52]). Researchers have also attempted to refine input and output data inventories at both farm and industry gate (e.g.…”

“…Moreover, LCA has been particularly suitable when the goal was to expand the environmental impact analysis to other relevant ecological burdens, such as resource depletion, acidification, eutrophication, ozone depletion, ecotoxicity, land use, etc. (e.g., [50][51][52][53][54]). …”

Greenhouse gas and energy based life cycle analysis of products from the Irish wood processing industry

“…The energy ratio for chip production from sawmilling with an integrated CHP plant is lowered by the additional energy requirement for biomass energy in the CHP. The energy ratios of wood chip production are in the range of SRCW chip production which ranges from 9.29 to 19.38 (depending on fertilisers applied, harvesting methods, and transportation distances) (Murphy et al, 2014a The energy ratios for wood pellets in scenarios 3 and 5 production are lower than those reported for miscanthus pellet production (3.6 -6.2) (Murphy et al, 2013). The energy ratio for pellet production in scenario 5 is less than one, the energy output is lower than the energy input, therefore it is not a viable process for the production of sustainable energy.…”

“…Conversely, wood chip production in each scenario has a lower GHG impact than the production of SRCW chip which causes emissions of 5.84-11.65 kg CO 2 -eq per GJ depending on fertilisers applied, harvesting methods, and transportation distances (Murphy et al, 2014a). …”

Benchmarking Environmental Impacts of Peat Use for Electricity Generation in Ireland—A Life Cycle Assessment

“…Future research on the peat-for-energy system could make use of dynamic LCA methodology to determine the effects of the temporal variation of emissions in the peat for energy scenario and the peat conservation (reference) scenario. In addition, further research on peat for energy in Ireland should focus on the environmental impacts of the implementation of co-firing targets at the three peat-fired power plants, using indigenous biomass sources such as energy crops [46,47], forest residues [48], and co-products from the wood processing industry [49].…”