Comparative life cycle assessment of ethanol production from fast-growing wood crops (black locust, eucalyptus and poplar) Sara Gonza ´lez-Garcı´a a,b, *, M. Teresa Moreira b , Gumersindo Feijoo b , Richard J. Murphy a a Department of Life Sciences, Sir Alexander Fleming Building, Imperial College London, and Porter Alliance, London SW7 2AZ, UK b Department of Chemical Engineering, School of Engineering, University of Santiago de Compostela, 15782 Santiago de Compostela, Spain article info Article history: Received 20 January 2011 Received in revised form 13 January 2012 Accepted 15 January 2012 Available online 15 February 2012 Keywords: Robinia pseudoacacia Environmental assessment Eucalyptus globulus Populus spp Lignocellulosic feedstocks Second generation biofuels abstract A life cycle assessment (LCA) study was carried out to evaluate the environmental impli- cations of the production and use of ethanol from three fast-growing wood crops: euca- lyptus, black locust and poplar in flexi-fuel vehicles. The production of a blend rich in ethanol: E85 (85% ethanol and 15% gasoline by volume) was assessed and the results compared with those of conventional gasoline (CG) in an equivalent car. The following environmental categories were evaluated: fossil fuels use (FF), global warming potential over 100 years (GWP 100 ), photochemical oxidant creation potential (POCP), acidification potential (AP) and eutrophication potential (EP). The use of ethanol derived from black locust was found to be the option with the lowest impact in most categories with reductions of 97%, 42%, 41% and 76% for GWP 100 , AP, EP and FF respectively in comparison with CG. Concerning the production stage of ethanol (excluding the stages of blending and use), black locust has the lowest environmental impacts due to the low levels of agricultural inputs during its cultivation. The poplar scenario has higher impacts in AP and EP due to the emission of diffuse substances from fertilizer application and the eucalyptus scenario in GWP 100 , POCP and FF due to the use and requirements of heavy machinery during harvesting. The use of the LCA methodology has helped to identify the key areas in the life cycle of ethanol. Special attention should be paid to ethanol production related activities and forest activities oriented to the feedstock production. ª 2012 Elsevier Ltd. All rights reserved. 1. Introduction The world is progressively depleting its fossil energy resources. The current dependence on oil for the production of energy and chemicals results in substantial emissions of greenhouse gases (GHG) as well as the progressive depletion of non-renewable resources [1,2]. This has motivated more support for the development of renewable energies to develop long-term reliable sources of energy supply [3]. The transport sector is almost entirely dependent on fossil fuels and nearly 94% of the energy used was obtained from oil in 2007 [4]. This sector is also responsible for around 21% of GHG emissions, especially due to road transport [5]. In this context, new strategies promote the use of the biomass in the future supply of energy, chemicals and materials [6,7]. Intensive research on biofuels is focused on the identifi- cation of potential feedstocks as well as the development of advanced conversion processes. Nowadays, ethanol used in * Corresponding author. Department of Life Sciences, Sir Alexander Fleming Building, Imperial College London, and Porter Alliance, London SW7 2AZ, UK. Tel.: þ44 2075945389; fax: þ44 2075842056. E-mail addresses: s.gonzalez-garcia@imperial.ac.uk, sara.gonzalez@usc.es, sara.gez.garcia@gmail.com (S. Gonza ´lez-Garcı´a). Available online at www.sciencedirect.com http://www.elsevier.com/locate/biombioe biomass and bioenergy 39 (2012) 378 e388 0961-9534/$ e see front matter ª 2012 Elsevier Ltd. All rights reserved. doi:10.1016/j.biombioe.2012.01.028