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FOGHORN
sources. Once we start doing that, we start thinking more 
about inverters. And once we start doing that, a DC bus 
just starts to make sense.
Inverters and DC busses are not new to vessel operators. 
Every variable frequency drive on board—every variable 
frequency drive (VFD) running a thruster, pump, or 
fan—is an inverter, and a DC bus. Same hardware, same 
physics. VFDs are commonplace because the benefits 
are real: efficiency, precision control, reduced inrush, 
lower harmonics.
Once you have batteries connected through inverters, and 
loads running through VFDs, and an interest in letting the 
diesel run at its sweet spot, the question of how to wire it 
all together starts to change. The traditional approach—a 
single AC bus with everything synchronized to it—now 
starts to add inefficiency and complexity at every interface. 
FOGHORN FOCUS
The single most useful 
shift in thinking,  
for an operator evaluating 
battery power, is to  
stop treating the  
battery as a generator  
and start treating it as  
a tool—one tool in a  
power-system toolbox.
ILLUSTRATION: SPOC ENERGY

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