POWER September 2023 - 19

TOP PLANT
had to comply with the hydraulic specifications, "
he said.
The biggest challenge, however, en1.
Voith Hydro deployed a heavy transport
operation to get the 54-ton housing for its innovative
six-nozzle horizontal Pelton turbine
from its manufacturing facility in St. Pölten,
Austria, to Verbund's Gerlos 1 plant site in the
Ziller Valley in Tyrol. Courtesy: Voith Hydro
in the elaborate power engineering involved
and who trusted the company to
" deliver what it promised. " After extensive
tests and pilot programs, Austrian
utility Verbund agreed to pilot the technology
at Gerlos 1, a pumped storage
facility in Austria's scenic Ziller Valley.
Built in several stages between 1939
and 2007, the 317-GWh project's four
vertical Pelton turbines-a combined capacity
of 65 MW-were approaching the
end of their technical lifetime. While the
project specification originally envisioned
replacing the four existing vertical turbines
with two conventional horizontal
Pelton turbine units (each outfitted with
two nozzles), Voith's overhaul proposed
a single 80-MW horizontal turbine with
six nozzles. Making use of the existing
space more effectively was a significant
driver, Mack noted. " The powerhouse
ceiling was too low, and the powerhouse
area was too small for a vertical one, " he
said. Running at 500 revolutions per minute
(with a maximum head of 617 meters
[m] and a maximum discharge of 16 cubic
meters per second), the newly developed
turbine achieves an efficiency level that
compares to vertical machines featuring
the same number of nozzles and the
same runner installed, Voith underscored.
A Logistical Swerve
Still, installing the single turbine presented
notable challenges that required innovative
and diligent problem-solving. After
the four older units were dismantled, the
scope of work involved modifying the
new unit's penstocks and installing the
new turbine and generator components.
Fitting the innovative turbine in the existing
structure required close coordination
with Verbund, Thomas Eismayer, Voith
Hydro's project manager for delivery of
the turbine, told POWER. " On the one
hand, attention had to be paid to minimum
interference on the existing civil
structure while, at the same time, we
September 2023 | POWER
tailed heavy transport of complex parts
to the plant site, particularly given the
site's remote location, said Eismayer.
Gerlos 1 is located at the southern end
of the holiday resort village of Rohrberg
in the Zillertal on the steep slope of the
Rohrerberg. For example, the turbine's
first-of-a-kind housing was manufactured
at just under 9 m long, more than 6 m
wide, and more than 4 m high. It weighed
a stunning 54 tons. Though Voith Hydro
began manufacturing the turbine housing
in Italy, Austrian authorities abruptly
announced an unexpected highway construction
project, forcing Voith Hydro to
reconsider its carefully strategized logistical
plan, Eismayer said. Acting urgently
to meet the delivery date, Voith Hydro
decided to transport the housing earlier.
Leveraging its in-house flexibility, the
company shifted to finalizing the housing's
manufacturing at its facility in St.
Pölten, Austria, and prepared to deliver it
using a different route (Figure 1).
As part of the " logistical masterstroke, "
the heavy transport operation
was completed within three nights, Voith
Hydro noted. Diligent logistics were also
required for the turbine, which was manufactured
in the Czech Republic, as well
as for the installation's other complex
parts. " Here, again, it pays off that we're
talking about one unit replacing four, " the
company underscored.
Spurring a Pipeline of Projects
The pioneering six-nozzle horizontal Pelton
turbine was ultimately put into operation
in October 2022, and it has since
operated as designed. Voith Hydro noted
the successful operation at Gerlos has
spurred interest worldwide. A second
project featuring two HP3+ turbines is
now under development to replace five
vertical turbines at Illwerke's 157-MW Vermuntwerk
pumped storage in Vorarlberg,
Austria. " We have several inquiries, one
from Italy and one from India, regarding
the same concept, " said Robert Schager,
a Voith Hydro project manager.
Mack added that a substantial market
opportunity for the turbine exists at hydropower
plants equipped with Pelton
turbines in South America, Norway, the
Alps, and the Himalayan region, where
many existing turbines were built after
the war. " The big advantages would be
in retrofits and modernization simply because
you can replace existing turbines
by increasing the power without too
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POWER POINTS
Winning Attributes
✔ Envisioning, developing, and piloting
a breakthrough that revolutionizes
140-year-old Pelton technology.
✔ Modernizing a 75-year-old
hydropower plant to boost its power
density and efficiency.
✔ Implementing an urgent logistical
solution to avert a delay.
✔ Collaborating with a customer
to pioneer a solution that could
reshape hydropower.
much work in the civil structure-and
that, of course, helps you in the complete
cost, " he said. " However, for new
powerhouses, this makes sense when
the maintenance of horizontal machines
is compared, " he added. Compared to
conventional horizontal solutions, " this
machine makes a much smaller building-the
powerhouse itself is around
30% smaller compared to a traditional
horizontal machine, " he said.
Innovation Requires Confidence
Voith Hydro credits its team's experience
and flexibility in completing the first-of-akind
project on time and within budget.
Crucially, however, the company also
highlighted its long-standing relationship
with customer Verbund. " Our business is
actually an extremely conservative business, "
noted Schager. Pairing with an innovative
customer like Verbund that had
confidence in the solution was vital to
get the revolutionary concept to a successful
pilot, he said. Eismayer, meanwhile,
underscored the importance of
good communication for successful firstof-a-kind
project execution. " The benefit
of working with Verbund is that we have
a really good relationship, and they are
technically also experienced, which was
important for effective communication
during the design phase, " he said.
Mack, who steered the turbine
through its conception, prototype, and
ultimately, realizing it as a commercial
product, in addition pointed to company
vision. " Developing a solution like this
requires members of management at
Voith who have the necessary vision to
see that such an idea will be successful, "
he said. ■
-Sonal Patel is a POWER senior
associate editor.
19
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POWER September 2023

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