Shaft-Generator / PTO Credit

Electric power produced from the main-engine shaft (PTO mode) instead of a running aux engine. Recognised EEDI Category-B credit under MEPC.1/Circ.815 and a common FuelEU saving.

DesignPTO

PTO operation

PTO electric output at reference loadkWPTO hours per year (or voyage)h

Reference aux

Aux engine SFOCg/kWhAux engine fuel (displaced)Main engine SFOCg/kWhSFOC of the ME supplying the shaft, which now consumes a bit more fuel under PTO load.Main engine fuel

Aux fuel displaced: 672.00t

Extra ME fuel burned: 560.00t

Net CO₂ saving: 410.59t

Changing the inputs requires JavaScript. The calculator above shows its default inputs and result. The formula, symbols, and regulatory sources are shown in the Formula section below.

Formula, assumptions, and limits

F_\text{saved} = \frac{P_\text{PTO} \cdot h \cdot \text{SFOC}_\text{AE}}{10^6}

Symbol	Meaning	Unit
$P_\text{PTO}$	Electrical output produced by the shaft generator	kW
$h$	PTO running hours	h
$\text{SFOC}_\text{AE}$	SFOC of the aux engine that would otherwise run	g / kWh
$\text{SFOC}_\text{ME}$	SFOC of the main engine supplying the PTO	g / kWh
$F_\text{saved}$	Aux fuel displaced	t
$F_\text{extra}$	Extra ME fuel burned to cover the PTO load	t
$C_{f,\text{AE}}, C_{f,\text{ME}}$	CO₂ factors for the aux and ME fuels	t CO₂ / t fuel

Source: IMO MEPC.1/Circ.815 - innovative energy-efficient technologies; MAN Energy Solutions - *Shaft Generator Packages*

In short

Fuel and CO₂ impact of running a shaft-generator (PTO) instead of an auxiliary engine.

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