Monitoring of fuel consumption and greenhouse gas emissions from international shipping is currently under discussion at the EU level as well as at the IMO. There are several approaches to monitoring, each with different characteristics. Based on a survey of the literature and information from equipment suppliers, this report analyses the four main methods for monitoring emissions:
- Bunker delivery notes (i.e. a note provided by the bunker fuel supplier specifying, inter alia, the amount of fuel bunkered).
- Tank sounding (i.e. systems for measuring the amount of fuel in the fuel tanks).
- Fuel flow meters (i.e. systems for measuring the amount of fuel supplied to the engines, generators or boilers). And
- Direct emissions monitoring (i.e. measuring the exhaust emissions in the stack).
The report finds that bunker delivery notes and tank soundings have the lowest investment cost. However, unless tank sounding is automated, these systems have higher operational costs than fuel flow meters or direct emissions monitoring because manual readings have to be entered in monitoring systems.
Fuel flow meters have the highest potential accuracy. Depending on the technology selected, their accuracy can be an order of magnitude better than the other systems, which typically have errors of a few percent.
By providing real-time feed-back on fuel use or emissions, fuel flow meters and direct emissions monitoring provide ship operators with the means to train their crew to adopt fuel-efficient sailing methods and to optimise their maintenance and hull cleaning schedules.
Except for bunker delivery notes, all systems allow for both time-based and route-based (or otherwise geographically delineated) systems.