A life cycle approach was adopted for energy, green house gas (GHG) emissions and renewability assessment for production of 1 ton of Jatropha biodiesel. Allocation and displacement approaches were applied for life cycle inventory, process energy and process GHG emission attribution to co-products. The results of process energy and GHG emission analyses revealed that the amount of process energy consumption and GHG emission in the individual stages of the life cycle assessment (LCA) were a strong function of co-product handling and irrigation. The GHG emission reduction with respect to petroleum diesel for generating 1 GJ energy varied from 40% to 107% and NER values from 1.4 to 8.0 depending upon the methodology used for energy and emission distribution between product and co-products as well as irrigation applied. However, GHG emission reduction values of 54 and 40 and NER (net energy ratio) values of 1.7 and 1.4 for irrigated and rain-fed scenarios, respectively indicate the eco-friendly nature and renewability of biodiesel even in the worst scenario where total life cycle inventory (LCI), process energy and GHG emission were allocated to biodiesel only. (C) 2012 Elsevier Ltd. All rights reserved.