The captain has several choices of propulsion power, including batteries only, and
combinations of three diesel electric engine
generators that feed electrical power directly to the drive motors or the batteries.
and from the gear to the generator. The
two main engines and generators were
shipped to Sipco Mechanical Linkage
Solutions, Houston, Texas, U.S.A.
Sipco supplied the gears, installed the
flex couplings between the units,
packaged the engines, gears and generators into a single unit, and sent these
electrical power plants to the shipyard
for installation.
The smaller 55 k W engine was sent
directly to the shipyard where a constant speed 55 k W Marathon generator
was installed. All three electrical power
plants are connected to a series of
Siemens 422055 inverters. The inverters are interconnected with each other
and change electric power to DC and
back to AC as needed.
Two of the inverters are connected to
a pair of Siemens 100 kW electric
motors and drive a 965 mm diameter
by 863 mm pitch propeller through a
Sipco gear. The gear reduces the electric motor speed from 3000 to 600
r/min. Two more inverters are connected to another pair of 100 k W electric
motors and likewise drive a 965 mm
diameter by 863 mm pitch propeller
through a Sipco gear.
Sipco also packaged the electric
motors with the gears connected by
flex connections. The output of the
gear drives a shaft that was installed at
the shipyard via a flange connection at
the output of the gear.
The inverters also serve to supply AC
power to a switchboard that supplies
ships power to the boat. Numerous
panel boards are located throughout
the boat to distribute both 115 Va.c.
and 208 Va.c. power as needed.
Another inverter serves to distribute
power to a pair of 245 Ah absorbed glass
batteries made by East Penn Manufacturing Company Inc., of Lyon
Station, Pennsylvania, U.S.A.
This is the unique hybrid feature of the
boat. The batteries can be recharged by
the diesel engines or via a shore power
connection when the boat is at the dock.
The inverters also permit power to flow
out of the batteries and into the electric
motors for ship propulsion.
Another key to the ELFA propulsion
is the control system that takes commands from the helm. The Kobelt control levers located at the helm, in the
engineer’s control station and two on
wing stations are connected by 24 V
wiring to a propulsion control system
that has two propulsion controllers, one
used as a backup. The system uses an
SAE CAN (controller area network) bus
network using J1939 protocol and is
connected to the two main engines and
to the batteries via separate battery
management units (BMU). The network communicates to both diesel
engines, which have the same CANBus
address. The two BMUs have separate
CANBus addresses.
The BMUs have control over charging and the monitoring of the battery
bank including the battery bank over-current protection devices. The priority
established by the control system gives
priority to satisfying the ship’s electrical
load and then the propulsion system.
The operator has a series of power
sources for propulsion including the
two main engines each driving a 155
k W ELFA generator, an auxiliary diesel
engine rated at 55 k W driving one constant speed generator and two 360 volt
battery banks rated at 245 Ah.
The operator of the vessel will have
the ability to select combinations of
power sources to first provide ships
electrical service and then propulsion.
One of the combinations available is
to operate the vessel with batteries
only, providing a clean and silent
propulsion source. The propulsion
control system will manage the drives
within the limits of the power available.
In many cases the batteries can be
charged at night with clean, quiet shore
power to ensure the battery banks are
at optimum charge for operation.
The components of the ELFA system have a built-in communications
chip that relays detailed information
about the system to a laptop computer
in the pilothouse.
When the engines are operating they
burn biodiesel fuel, a mixture of diesel
and recycled cooking oil.
Pollutants from diesel exhaust are a
major problem in the Pittsburgh area.
Emissions modeling indicates that
marine emission from river traffic may
be as much as 30% of the total diesel
engine particulate matter in the area.
The ELFA propulsion system is set
up with the future in mind. New technologies such as solar, wind and fuel
cells have the ability to generate electricity and can be connected to the
inverters when such technology is
commercially available.
The combination of hybrid propulsion, biodiesel fuel and battery charging via shore power results in a vessel
with absolutely the lowest emissions
possible under today’s technology.
Water pollution is at a zero level. All
gray and black water is held in storage
tanks in the hull and pumped ashore
when the vessel is at dock.
Capacities include 7570 L of biodiesel fuel, 6891 L of potable water and
5299 L of black water.
Another main focus of the boat
design was the use of energy conserving and recyclable materials. The vessel
was designed using the LEED process
(Leadership in Energy and Environmental Design), a system usually reserved for land-based buildings. Over
110 systems on the vessel were analyzed. And the results promote some
new technologies never before used in
the maritime industry.
“The integrated hybrid diesel-electric
propulsion system gives us incredible
flexibility to run the boat on different
power sources, reduce our dependence
on petroleum-based fuels and even
upgrade the system when new technologies are commercially available,”
said Thomas. A
