POWER October 2021 - 8

Gas Turbine Technology Advances
That Could Boost Their Future
Relevance
Gas turbines have grown into a hallmark
of the modern power system
for their high efficiency, reliability, operational
flexibility, fuel flexibility, and
low-emission power options. But if gas
turbines are to remain relevant amid the
anticipated proliferation of renewables,
energy storage, and decarbonized gas-
including hydrogen, ammonia, synthetic
methane, and other green fuels-research
and development (R&D) to enable
emerging applications must be a
high priority, the global gas technology
industry concedes.
According to ETN Global, a Brusselsbased
nonprofit trade group representing
the entire gas turbine technology
value chain, future gas turbine applications
will include the hybridization of gas
turbine technology with renewables and
storage, and retrofitting them to ensure
they can combust high volumes of hydrogen
and other renewable fuels. But
modern gas turbines must also operate
with increased energy efficiency and
performance, and be even more operationally
flexible. Finally, along with a reduced
carbon output at existing assets,
future systems must work toward zero
emissions or integrate carbon capture,
utilization, and storage (CCUS) solutions.
ETN laid out its recommendations for
gas turbine technical areas that deserve
R&D priority in a July-released biennial
report. The recommendations were informed
by a diverse board that includes
academics from European institutions;
utilities, including Enel and Uniper; gas turbine
manufacturers, such as Siemens Energy,
Ansaldo Energia, and Baker Hughes;
energy companies, including Equinox and
TotalEnergies; and government researchers,
such as from Germany's national
aeronautics and space research center,
and the Norwegian Research Centre.
In the report, the board highlights recent
environmental developments in Europe
that are posing new urgency and
placing new demands on technology development.
These include looming coal
and nuclear phase-outs, ambitious net-zero
policy frameworks, new hydrogen and
methane reduction strategies, a review
of the Industrial Emissions Directive, and
the emergence of sustainable finance.
Following is a broad overview of the tech8
1.
HYFLEXPOWER, a four-year project to demonstrate a fully integrated power-to-hydrogen-topower
project at industrial scale and in a real-world power plant application, is converting a 12MWe
combined heat and power (CHP) plant at Engie Solutions' Smurfit Kappa pulp-and-paper
industrial site in Saillat-sur-Vienne, France. According to Siemens Energy, which is supplying
a 100% hydrogen-capable industrial gas turbine, the project will this year install the hydrogen
production, storage, and supply facility. Next year, it will embark on an initial demonstration to
combust a natural gas and hydrogen mix. Courtesy: Siemens Energy
nical areas highlighted in the report.
Operational Flexibility. While the
changing power landscape will require
reliance on open-cycle gas turbines (OCGTs)
or combined cycle gas turbines
(CCGTs) to provide flexible backup in
the near future, over the long term, gas
turbine research must support the enhanced
capability for fast load changes.
" As counterpart to [renewable energy
system]
partial
dispatchability, power
plants based on GT-derived technology
will be required to start-up and shut
down quickly (recently built combined
cycle plants feature 15-30 minutes hot
start-up, 60 minutes warm start-up), react
to load changes (some case studies
suggest up to 40-50 MW/minute) while
minimising the impact on components
life consumption and emissions, " the
report says. This will require scrutiny
at both a component level ( " design to
life " ) and a system-level (to include, for
example, integration with batteries, compressed
air or liquified air storage, and
power-to-X-to-power systems [Figure 1]).
Fast cycling, however,
will also require
combustion advances to address
emissions. Design changes addressing
material and component fatigue should
also be a priority, the report says, noting
a " probability of severe harm, such as
damage accumulation on hot gas path
components, degradation of thermal
barrier coatings, creep-fatigue of turbine
buckets, cracking and degradation of
combustor. " This aspect is compounded
by emerging requirements to reduce
capital and operational expenditures to
keep gas turbines competitive in a cutwww.powermag.com
throat
market. R&D will need to focus
on the entire plant, including the bottoming
cycle. Emerging contenders to
the classic water-steam bottoming cycle
so far are Organic Rankine Cycles and
carbon dioxide (CO2
)-based cycles (either
pure or with dopants, Rankine and
Brayton) with different cycle configurations.
Operational flexibility, however, is
currently benefiting from digital tools,
including advanced instrumentation and
new sensor technologies.
Boosting Power Generation Efficiency.
While original equipment manufacturers
(OEMs) report heavy-duty gas
turbines are now able to achieve efficiencies
of more than 42.5% (ISO standard)
in simple cycle configuration and above
62.5% in combined cycle mode, the average
efficiency of new installations in
Europe " is much lower (~50%) than the
aforecited values, " the report notes. Efficiencies
are also challenged by frequent
operation in partial-load conditions. Owing
to inherent thermodynamic and material
limitations, " some voices from the
industry are already calling for other cycles, "
such as the reheat Brayton cycle,
for future CCGTs.
Meanwhile, though gas path design of
compressors and turbines has achieved
unprecedented optimization, further efficiency
gains could be attained through
turbine clearance control. " Future systems
able to further minimise tip-leakage
flow at the compressor and, more
importantly, the turbine whilst avoiding
physical contact between rotating and
stationary parts are needed, " the report
says. Efficiency gains may also come
POWER | October 2021

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POWER October 2021

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