Energy balance and greenhouse gas emissions of short or very short rotation Eucalyptus and Poplar coppices

Dedicated woody crops of the short rotation coppice type are being investigated for the purposes of satisfying future biomass demand. The aim of this article is to analyse the environmental benefit of these crops on the basis of their energy balance and their greenhouse gas (GHG) emissions. Several cropping scenarios under short or very short rotation cycles for eucalyptus and poplar are examined. Energy consumption and GHG emissions are accounted for through the environmental footprint as assessed from a complete count of all the flows throughout the life cycle from the production of seedlings up to burning the wood chips in a boiler house. For both these indicators, the crucial stages are harvesting, transportation, and fertilisation. Depending on the scenario, the energy ratio obtained ranges from 12 to 27 and GHG emissions are from 10 to 18 TCDE/ha, to the advantage of the longer cycles which require less fertilisation and offer higher yield. (authors)