CO 2 emissions attributed to annual average electricity consumption in OECD (the Organisation for Economic Co-operation and Development) countries Sampo Soimakallio a, * , Laura Saikku b a VTT Technical Research Centre of Finland, P.O. Box 1000, FIN 02044 VTT, Finland b University of Helsinki, Department of Environmental Sciences, P.O. Box 65, FIN 00014 University of Helsinki, Finland article info Article history: Received 20 July 2011 Received in revised form 27 December 2011 Accepted 29 December 2011 Available online 26 January 2012 Keywords: Electricity Trade CO 2 emission Life cycle assessment Uncertainty Climate policy abstract When regulating GHG emissions at the country or product level, it is critical to determine the GHG emissions from electricity consumption. In this study, we calculated production-based and consumption- based CO 2 emission intensities of electricity for the OECD (the Organisation for Economic Co-operation and Development) countries during 1990e2008. We examined the impact of annual development, allocation procedure in combined heat and power production, and electricity trade on CO 2 emissions. The studied factors significantly, yet highly variably, influenced the results for many countries. The consumption-based CO 2 emission intensity of electricity differed significantly from the production-based intensity for some European OECD countries such as Switzerland, Norway, Slovakia, and Austria. As the use of the production-based method in assessing, verifying, and monitoring the GHG performance of specific products can be highly misleading, the use of consumption-based methods are preferable. The absolute value of CO 2 emissions embodied in electricity net imports accounted for more than 5% of the overall national CO 2 emissions in at least some of the years studied for 13 European countries. The electricity trade and the related GHG emission leakage may increase in the future if effective emission reduction and regulation measures are not more widely implemented. Ó 2012 Elsevier Ltd. All rights reserved. 1. Introduction Ambitious climate change mitigation requires significant changes in many economic sectors, in particular in the production and consumption of energy [1]. As an energy carrier, electricity plays a fundamental role in modern society and is a mainstay of the worldwide manufacturing industry. While the consumption of primary energy has doubled since the early 1970s, electricity consumption has increased almost fourfold [2,3]. In 2005, CO 2 emissions from fuel combustion in power generation constituted approximately one quarter of all anthropogenic GHG (greenhouse gas) emissions globally [4]. According to many scenarios (e.g.[5]), the electrification of society is set to continue. Power has been increasingly traded between nations [6,7]. The transfer of electricity between utilities in neighbouring regions has been common practice for many years due to its economic effi- ciency, which derives from reduced overall requirement for reserve margins and balanced load fluctuations within the market area [6]. In 2008, OECD countries consumed 9244 TWh electricity, imported 372 TWh and exported 360 TWh [6]. Electricity trading between distant locations is limited due to transmission losses. For many countries, however, imported electricity accounts for a significant proportion of total electricity consumption. OECD countries for which imports accounted for more than 30% of total electricity consumption in 2008 were Luxembourg, Switzerland, Denmark, Hungary, Slovenia, Slovakia, and Austria [6]. Furthermore, new transmission system operator investments are underway, with those of European significance corresponding to more than 12% of the existing network until 2020 [8]. In addition, a unified electricity grid for Europe and North Africa by 2050 has been envisioned [9]. Electricity trading is, consequently, likely to increase. Analysis of the development of GHG emissions of nations and product systems can be carried out by using both prospective (scenario) and retrospective perspectives. In order to understand the feasibility of certain GHG emission development paths, the potential impacts of various technologies and structural changes in the energy system need to be assessed. In this kind of prospective assessment procedure, methods such as consequential life cycle assessment [10,11] and system-level modelling of energy systems [11e 13], land use [14], and economies [15], can be used. The assessment of historic GHG emissions by means of retrospective analysis is also important, both to obtain information on trends and for regulation at the country and product level. * Corresponding author. Tel.: þ358 20 7226767; fax: þ358 20 7227604. E-mail address: sampo.soimakallio@vtt.fi (S. Soimakallio). Contents lists available at SciVerse ScienceDirect Energy journal homepage: www.elsevier.com/locate/energy 0360-5442/$ e see front matter Ó 2012 Elsevier Ltd. All rights reserved. doi:10.1016/j.energy.2011.12.048 Energy 38 (2012) 13e20