7.3 EPA-developed estimates

Emissions are calculated for each time interval between consecutive AIS messages for each vessel and allocated to the location of the message following the interval. Emissions are calculated according to Eqn. (7.1).

\[\begin{equation} Emissions_{interval} = Time(hr)_{interval} \times Power(kW) \times EF(g/kWh) \times LLAF \tag{7.1} \end{equation}\]

Where:
\(Emissions_{interval}\) = mass of emissions estimated for each time interval between AIS messages for each vessel, typically calculated in grams and then converted to tons when emissions are aggregated
\(Time(hr)\) = length of time between AIS messages, measured in hours
\(Power(kW)\) = calculated in kWh for each AIS message, for each vessel, for each of the three engine groups on a vessel: propulsive (main), auxiliary, and auxiliary boiler engines
\(EF\) = assigned emission factors for each ship type and engine group on the vessel in g/kWh
\(LAFF\) = low load adjustment factor, a unitless factor that reflects increasing propulsive emissions during low load operations and varies according to the calculated propulsive power