Amongst the approaches that have developed to improve environmental protection within the energy sector, strategic environmental assessment (SEA) has received relatively little attention. This is despite its potential to overcome some of the shortcomings associated with project-level assessment by intervening at higher levels of energy system planning. In this article, a review is presented of the extent to which SEA has been adopted and otherwise promoted in strategic energy planning processes in a wide range of countries throughout the world (with an emphasis on European Union nations). In this regard, the growing importance of regulatory compliance is underlined, especially within the EU, with a particular focus upon the application of SEA to grid systems. The case of the Belgian transmission system is described, illustrating a proactive approach to SEA. But the difficulties inherent in introducing SEA to an increasingly fragmented and liberalised sector are also drawn out, leading to suggestions by which these difficulties may be addressed. (C) 2010 Elsevier Ltd. All rights reserved.