Despite the fact that the structure and technology of most modem wind turbines differs little over a wide range of power ratings, results from existing life-cycle assessments of their energy and CO2 intensity show considerable variations. While the range of energy intensities reflects economics of scale, their scatter is due to discrepancies in the energy contents of materials and the analyses' methodology and scope. Furthermore, energy intensities depend crucially on the country of manufacture, turbine recycling or overhaul after the service life, and the choice of tower material. In addition, CO2 intensities vary with national fuel mixes. Measures of life-cycle energy or CO2 emissions can be employed in policy and planning, especially for comparative risk and sustainability assessments, and source switching and capacity growth scenarios. If these measures are to assist decision-making, uncertainties in life-cycle assessments should be minimised by compliance to a standardised methodology, and by use of input-output-based hybrid techniques. (C) 2002 Elsevier Science Ltd. All rights reserved.