an Union (EU) Emissions Trading Scheme, the European Commission put forward its suggestions for a review of the scheme on 23 January 2008. The main changes proposed by the European Commission include the introduction of a single EU cap for the trading scheme, and the harmonisation of allocation rules across the EU. The Commission proposes auctioning as the basic principle of allocation, with some types of installations receiving free allocation until 2020 on the basis of transitional rules. Likewise, exemptions may be granted to sectors ex