In the context of controlling greenhouse gas emissions, the directive on a Europe-wide trading scheme may be perceived as one of the most important milestones in recent years. Prior to its start, however, a number of very specific design features have to be agreed upon. Regarding the allocation of allowances, a distribution (almost) free of charge seems to be the most likely choice. An aspect that has interestingly attracted little attention in the past is the question of how to allocate emission rights over time. The following paper analyses different allocation options in multi-period emissions trading that are currently discussed in the European context. The options are applied for the electricity sector which is simulated over two periods. The paper distinguishes between a market effect of emissions trading and compliance costs for meeting the emission reduction obligation. The market effect results from a price increase which is due to the fact that opportunity costs for using allowances must be considered. It turns out that the electricity sector as a whole gains from the introduction of the instrument due to the increase of the electricity price. With regard to the different allocation options, it is found that utilities have different preferences depending on the fuel used. (c) 2004 Elsevier Ltd. All rights reserved.