POWER July 2023 - 15

PLANT OF THE YEAR
2. Estrella del Mar III's construction was carried
out at ST Engineering's Benoi shipyard in
Singapore. To maximize space utilization, each
component is optimized with regard to function
and footprint. For example, the SGT-800 is
used as a pre-assembled single-lift complete
package with small footprint. Courtesy: Siemens
Energy
is that they address land constraints and
related costs in dense urban environments,
and second, the company holds
lengthy experience owning and operating
power barges.
In 1990, when Transcontinental became
the first independent power producer
in the Dominican Republic, it
initiated operations with the 40-MW Estrella
del Norte, a barge equipped with
Wärtsilä engines. In 2000, it installed a
second 72-MW Wärtsilä-engine barge,
Estrella del Mar (it sold both barges in
2009). And in 2012, it began operating a
third barge, the 104-meter (m)-long Estrella
del Mar II. Comprising six Wärtsilä
18V50DF dual-fuel engines in combined
cycle mode, the 108-MW facility continues
operations. Seaboard has publicly
said, however, that it is exploring sale or
relocation of the barge.
However, in 2017, the company complied
with a state request to replace the
barge's power with a new natural gas-
fired power plant ostensibly to reap efficiency
gains with a smaller emissions
profile. A critical key challenge Seaboard
faced is to keep costs competitive. " For
Seaboard's Power segment, the Dominican
government sets a cap on the
electricity spot market prices and establishes
the dispatch order of who sells
into the power grid based on a merit list.
To sell to the power grid, Seaboard competes
with producers utilizing various
types of fuel and generation technologies,
including hydro, solar, wind, natural
gas, heavy fuel oil, diesel, or coal, "
Seaboard explained in recent financial
documents. " Typically, dispatch is done
based on a merit list with lower-cost
power plants dispatched before those
with higher costs. "
After exploring the feasibility of a natuJuly
2023 | POWER
ral gas-fired barge-mounted power plant
with a capacity of up to 150 MW with
Siemens Energy, Seaboard in December
2018 contracted a consortium comprising
Siemens Energy and ST Engineering's
marine arm for an SCC-800 2x1C
SeaFloat power plant. Under the contract,
the consortium set out to provide a
" turnkey plug-and-play " concept. Heading
up the power portion, Siemens Energy
assumed the task of supplying two
50-MW Siemens SGT-800 gas turbines
and a 47-MW SST-600 steam turbine.
In addition, Siemens Energy banded
with AES's Fluence Energy to provide a
5-MW/10-MWh battery energy storage
system for frequency regulation control.
The project also includes a once-through
steam generator (OTSG) that was supplied
by a Canadian company. The hybrid
solution was designed to help " the plant
to operate at full capacity with highest
fuel efficiency, " and " at a lower cost in
comparison to a similar land-based power
plant, " Siemens Energy noted.
ST Engineering's Marine segment,
which is an established turnkey shipbuilder,
meanwhile, took charge of the
engineering, procurement, and construction
of the self-supporting barge, the balance
of plant, transport of the floating
power plant to the Dominican Republic,
and installation of the floating power
plant. ST Engineering also assumed the
task of building the plant on the barge at
its Benoi shipyard in Singapore.
Engineering a Marvel
From the start, the team set out a rigorous
work plan to meet a tight timeframe
of 28.5 months. The first task involved
designing the first-of-its-kind power plant
from a blank slate. " We started with a
plate of steel, " recalled Tyroller.
The team's crucial challenge was to fit
all the project's components on a barge,
including its liquefied natural gas fuel
supply. Other considerations
POWER POINTS
Winning Attributes
✔ A first-of-a-kind project that
responded with agility to a pressing
energy security concern.
✔ Siemens Energy's innovative fullsize
combined cycle gas turbine
plant design was nearly fully built
at a Singapore shipyard, then
transported 10,600 miles by sea
and installed at owner Seaboard
Corp.'s location on the Ozama River
in Santo Domingo, Dominican
Republic, without disrupting the
existing supply.
✔ Delivering the unique vesselmounted
power plant project
required a careful workforce
alignment that synergized multiple
capabilities in several countries,
including to seamlessly meld
shipbuilding and power plant
engineering. It overcame notable
challenges, including pandemic
disruptions and other delays.
✔ Along with the plant's marineoptimized
dual SGT-800 gas
turbines and an SST-600 steam
turbine, the 148-MW Estrella del
Mar III integrates a battery energy
storage system to compensate for
power shortages and frequency
drops.
included
ensuring the barge wouldn't block the river
and that its height clearances wouldn't
exceed bridges on the Ozama River.
In Singapore, an ST Engineering
team pooled multiple software programs
to digitalize the entire design
process, including 3D modeling, stress
analysis, and optimization solutions.
Simulations,
notably, included noise
emissions from structural-borne and
airborne noise contributors. " Given the
complexity of the process and highvoltage
systems, we are taking every
precaution to ensure that all operations
are meticulously planned and carried
www.powermag.com
✔ The plant, Siemens Energy's first
demonstration of its SeaFloat
mobile asset concept, is a model for
ecological, economical, efficient,
and resilient power generation
that resolves weight and space
constraints-and proved less costly
to build compared to a similar landbased
plant.
out. Mitigations include engaging consultants,
endless hours of review, and
detailed studies of the systems that
would become part of the floating system, "
Terry Heng, ST Engineering Marine's
project engineer, noted in 2019
as the project was well underway.
Among the project's many other notable
design elements is that it incorporated
energy re-generation and wastewater pollution
control " in a bid to achieve positive
environmental impact, " ST Engineering
reported.
" Energy
re-generation was
15
http://www.powermag.com
POWER July 2023

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