POWER September 2016 - 14

3. Finding its sea legs. Ocean Power Technology (OPT) in July deployed its first commercially
designed PB3 PowerBuoy about 4 miles off the coast of New Jersey. Another PB3 array is
slated to be deployed off Kozy Island in Japan following a planned stage gate review. Courtesy:
OPT
technology since the firm was founded
in 1994. Development of the wave energy
conversion technology for naval
and civilian applications was catalyzed
by small-business innovative research
(SBIR) funding awards from the U.S.
Navy. By 1997, following trials of a handful
of PowerBuoy designs in the Navy's
wave tank facility and in the Atlantic
Ocean, OPT demonstrated that the buoy
could operate for more than 11 months
at sea and endure harsh ocean conditions.
Beginning in 2001, the company
began developing more wave power systems
at the Marine Corps base in Oahu,
Hawaii. In 2005, it installed its first 40kW
buoy 1 mile off the coast of Oahu.
That unit connected to the grid for the
first time in 2010, following 4,400 hours
of operation.
Deployment of the PB3 PowerBuoy (Fig4.
Buoyant. About 3.4 meters (m) of the 12.8-m-long PB3 PowerBuoy sits above the waterline.
Conversion of wave energy is carried out through a direct-drive generator that continuously
charges an onboard battery pack. Courtesy: OPT
ure 3) marks a major milestone for the
company. The PB3 incorporates " multiple
enhancements " over early prototypes,
including a redesigned power take-off,
a battery pack, a higher voltage power
management and distribution system, and
a new auto-ballasting system, which the
company says allows for faster and less
costly deployment.
Designed to be moored at a single
point, the PB3 PowerBuoy produces
300 W of continuous power (depending
on ocean conditions) and 7.2 kW at
peak (1 hour per day). As it floats over
ocean depths of between 20 meters (m)
and 1,000 m (Figure 4), it constantly
recharges itself by harvesting energy
from waves and then converting that
wave energy to power through a directdrive
generator. That power then charges
an energy storage system, which
delivers power to meet application and
end-user needs. Its modular battery has
a capacity of 44 kWh and is scalable to
150 kWh.
The PB3 technology was demonstrated
for a Navy project to provide
power to coastal security networks and
" survived
rigorous sea trials,
including
operation off the New Jersey coast
through Hurricane Irene in 2011, " the
company said.
The news follows OPT's six-month lease
agreement with Japanese firm Mitsui Engineering
and Shipbuilding this June, a
deal valued at $975,000 for PB3 PowerBuoys
that are planned to be deployed off
Kozy Island in Japan following a planned
stage gate review. OPT will also provide
engineering support, deployment planning
and logistics, and ocean performance
data collection and analysis. Mitsui and
14
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POWER September 2016

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