Energy efficiency of ships: what are we talking about?
In July 2011, the International Maritime Organisation (IMO) adopted the ‘Energy Efficiency Design Index’ (EEDI), which sets minimum energy efficiency requirements for new ships built after 2013 (in terms of CO2 per ton capacity-mile). Such a measure is long overdue; design speeds, the beam (the width of a ship) and Froude number (the speed-length ratio) of ships built in recent decades have all generally increased often resulting in the only improvements to ship efficiency being due to economies of scale.
In addition to implementation loopholes and the potential for delays in the EEDI, there is a growing realisation that the EEDI alone may not drive the adoption of the most efficient available technologies.
Arguably the biggest drawback of the EEDI is that it only applies to new ships. Discussion took place at the IMO during the 63rd session of the Marine Environment Protection Committee (MEPC 63) on the merits of applying the EEDI requirements to existing ships as a way to set a benchmark measure of fleet efficiency. This proposal was ruled out although recognition that action is needed to reduce emissions from all ships led for calls at MEPC 64 for “immediate measures” starting with ways to measure fuel burn and possibly later the development of additional efficiency measures.
This paper investigates opportunities to establish such a benchmark measurement, studies different metrics and proposals already under consideration at the IMO or in the EU and identifies possible options in the current EU discussions on monitoring, reporting and verification.