Life cycle assessment: an application to poplar for energy cultivated in Italy

Abstract

The development of the bioenergy sector has led to an increasing interest in energy crops. Short rotation coppices (SRC) are forestry management systems in which fast-growing tree species are produced under intensive cultivation practices to obtain high wood chips yields. In Italy, most SRC plantations consist of poplar biomass-clones. SRC plantations can be carried out with different management systems with diverse cutting times; consequently, the cultivation system can be crucial for attaining high yields depending on: i) short and ii) medium cutting frequency. Nowadays, the larger part of Italian SRC is based on 2-year cutting short rotation forestry (SRF) but the best quality of wood chips is linked to 5-year plantation medium rotation forestry (MRF). This work compares an SRF and an MRF poplar plantation located in the Po Valley in northern Italy. In particular, a life cycle assessment (LCA) was carried out to evaluate their energy demand and greenhouse gas emissions. The LCA software SimaPro 7.10 was used to create the LCA model and to assure an accurate impact assessment calculation. The analysis shows several differences between MRF and SRF in terms of fertiliser requirements and intensive agricultural activities. Results highlight that MRF produces a more sustainable wood chip production than SRF according to energy and environmental concerns. Furthermore, hot spots were identified in both SRF and MRF due to the high energy consumption and the related emissions. These hot spots were: i) mineral fertilisation; ii) mechanical weed-control; iii) harvesting and biomass transport.

Keywords

• energy crops, life cycle assessment, poplar, medium rotation forestry, short rotation forestry.