Specific Fuel Consumption [g/kWh] for Marine Engines

This blog provides an overview of SFC curves for marine diesel engines

Specific Fuel Consumption (SFC) of marine engines ranges between 155 and 225 g/kWh on optimal load settings, which are typically around 85% Maximum Continuous Load (MCR). Two key factors for marine diesel engines are engine speed (low, medium, high) and engine type (two-stroke or four-stroke). Specific fuel consumption increases greatly at low power (30% Pmax) and dramatically at idle (7% Pmax). When an engine is idling, its specific fuel consumption can increase by a factor of two. At the same time, idling engines are prone to stalling, clogging and require a significant amount of maintenance, potentially requiring service once every three weeks. For these cases, Sustainable Ships recommends load levelling by means of electrical energy storage.

This blog is used as a reference for estimation fuel consumptions and emission savings for the Decarbonizer. it is subject to continuous change.

 
 

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Low engine loads

There is little to no publicly available data for engines running at very high loads or idling, i.e. between 1-10% load. This is almost never measured when engine test certificates are prepared. From experience ‘in the field’ it is known that SFC can go as high as 1.500 [g/kWh] at 1% engine load for large-sized medium speed marine engines. For smaller sized auxiliary engines, this could be even higher but Sustainable Ships has so far not met anyone who knows more on that topic. It is known that smaller sized engines easily consume 1 [kWh/liter] at 10% load.


Rules & Regulations

Engines are heavily subjected to increasingly stringent rules and regulations, subject by IMO and thus class. Especially NOx tiers are relevant. Click on the below rules and regulations to learn more.


References

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IMarEST - Design of propulsion and electric power generation systems Douwe Stapersma Hans Klein Woud

HOK Marineconsultant ApS - Energy demand and exhaust gas emissions of marine engines

Douwe Stapersma - TU Delft Main propulsion arrangement and power generation concepts

MIT - Diesel engine continued

Wikipedia - Brake specific fuel consumption

Wärtsilä 46F - Marine Engine Product Guide

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