1 Application of Hybrid Life Cycle Approaches to Emerging Energy 2 Technologies  The Case of Wind Power in the UK 3 Thomas O. Wiedmann,* ,†,|| Sangwon Suh, ‡ Kuishuang Feng, § Manfred Lenzen, || Adolf Acquaye, ^ Kate Scott, # 4 and John R. Barrett r 5 † CSIRO Ecosystem Sciences, GPO Box 1700, Canberra, ACT 2601, Australia 6 ‡ Bren School of Environmental Science and Management, University of California, Santa Barbara, California, United States 7 § Department of Geography, University of Maryland, College Park, Maryland, United States 8 ) ISA - Integrated Sustainability Analysis, School of Physics, The University of Sydney, NSW 2006, Australia 9 ^ Stockholm Environment Institute, Grimston House, University of York, York, U.K. 10 # Sustainable Consumption Institute, School of Earth, Atmospheric and Environmental Sciences, University of Manchester, Manchester, 11 U.K. 12 r School of Earth and Environment, University of Leeds, Leeds, U.K. 13 b S Supporting Information 30 1. INTRODUCTION 31 To avoid some of the most extreme consequences of climate 32 change there is growing scientific consensus that global tempera- 33 ture rise should not exceed two degrees Celsius. 1 Over 100 countries 34 have adopted this target as a guiding principle for mitigation. 2 For 35 the United Kingdom (UK), this would mean a drastic reduction 36 of territorial emissions of 14% annually, allowing the UK to emit a 37 total of only 2.5 Gigatonnes of carbon dioxide equivalents 38 (Gt CO 2 e) of greenhouse gas (GHG) emissions between 2023 39 and 2050. At present, the UK is set to use this amount up by 2014 40 assuming that emissions align with the carbon budgets outlined 41 in the UK’s Low Carbon Transition Plan. 3 42 Scenarios that demonstrate an 80% reduction in UK GHG 43 emissions by 2050 highlight the growing role of the electricity 44 sector in achieving this target. 4 It is estimated that carbon dioxide 45 emissions from power stations accounted for 32% of the UK’s 46 total CO 2 emissions in 2007. 5 Increasing demand for electricity 47 in the UK (e.g., for transport) means that a virtually complete 48 decarbonization of the electricity sector by 2050 will be required. 49 However, in all the scenarios attempting to define a low carbon 50 pathway for the UK, the indirect GHG emissions across the 51 whole life cycle of power stations are not taken into account. 52 Energy models have ignored the fact that upstream emissions are 53 associated with any energy technology. The requirement to 54 almost replace the entire energy infrastructure over the next 55 20 years means it is essential to gain an understanding of the scale 56 of indirect emissions. It is important to know how much of the 57 remaining 2.5 Gt CO 2 e of GHG emissions that the UK has left to 58 emit past 2022 will be used up by providing the new low-carbon 59 electricity infrastructure. 60 Electricity generation by wind power is currently one of the 61 fastest growing renewable energy technologies worldwide, with a 62 trend toward large-scale production, and has been chosen as the Received: March 3, 2011 Accepted: May 26, 2011 Revised: May 24, 2011 14 ABSTRACT: Future energy technologies will be key for a 15 successful reduction of man-made greenhouse gas emissions. 16 With demand for electricity projected to increase significantly in 17 the future, climate policy goals of limiting the effects of global 18 atmospheric warming can only be achieved if power generation 19 processes are profoundly decarbonized. Energy models, how- 20 ever, have ignored the fact that upstream emissions are asso- 21 ciated with any energy technology. In this work we explore 22 methodological options for hybrid life cycle assessment (hybrid 23 LCA) to account for the indirect greenhouse gas (GHG) 24 emissions of energy technologies using wind power generation in the UK as a case study. We develop and compare two different 25 approaches using a multiregion input-output modeling framework  Input-Output-based Hybrid LCA and Integrated Hybrid LCA. 26 The latter utilizes the full-sized Ecoinvent process database. We discuss significance and reliability of the results and suggest ways to 27 improve the accuracy of the calculations. The comparison of hybrid LCA methodologies provides valuable insight into the 28 availability and robustness of approaches for informing energy and environmental policy. Environmental Science & Technology | 3b2 | ver.9 | 4/6/011 | 13:49 | Msc: es-2011-007287 | TEID: sls00 | BATID: 00000 | Pages: 7.3 ARTICLE pubs.acs.org/est rXXXX American Chemical Society A dx.doi.org/10.1021/es2007287 | Environ. Sci. Technol. XXXX, XXX, 000–000