POWER April 2023 - 22

GAS POWER
Gas Power Outlook:
Gas Turbines Will Play a
Vital Role in Decarbonization
Natural gas-fired power generation has seen its ups and downs over the past couple
of decades. In some cases, highly efficient combined cycle units were taken offline
because they just weren't needed. But the future looks bright. As coal-fired plants
are retired, gas-fired plants will often be needed to take their place.
S. Can Gülen
O
Power Plant in
n a cold and dreary October day
in 2013, I paid a visit to the Ulrich
Hartmann Combined Cycle
Ingolstadt, Germany.
At that time, the plant was owned by
E.ON and in commercial operation
since 2011. Based on Siemens Energy's
SGT5-8000H gas turbine, the plant was
the first one to break the 60% net LHV
(lower heating value) efficiency barrier.
On the day of my visit, at 10C ambient
temperature, the monitors in the operator
room indicated 540 MW net output at
60.3% efficiency.
Several years later, when I was writing
my book on gas turbine combined cycles
(CRC Press, 2019), the plant, now owned
by Uniper and renamed Irsching Unit 4,
was in " cold standby, " that is, one step
removed from being completely " mothballed. "
(Even at the time when I visited
the power plant in the fall of 2013, the
plant was averaging only one-fifth of its
planned capacity.) Apparently, the generation
from coal and renewables (mostly
wind from what I could see) was such
that there was really not much need for
power from a plant (even a world-recordholding
one at that!) burning very expensive
natural gas imported from Russia.
Today, Irsching Unit 4 is fully operational
and running in support of the wind
generation and at baseload as needed
(except for a 32-hour period in January
due to a leak). According to information
received by Industrial Info Resources
Inc. (IIR), in spite of the ongoing conflict
in Ukraine, the plant has enough gas to
operate at least until the end of the year.
When I was driving from Aachen to
Frankfurt in late November last year, I
passed by a coal-fired power station going
(apparently) full blast with the plumes
from the two natural draft cooling towers
covering the sky. On the other side
22
of the Autobahn, a few lonely wind turbines
with their slowly turning blades
highlighted the contrast in Germany's
generation portfolio (see Figure 1 depicting
the situation last November). With
an aggregated carbon footprint of 554
grams of CO2
equivalents per kWh in
November 2022, Germany was one of
the worst polluters in Europe. (One day
in January, while writing this article, the
number went over 800!) So much for the
vaunted Energiewende.
Gas Turbine Advances
In terms of emerging technologies in the
gas power realm (read: gas turbines),
I do not have anything new to add to
those ably covered in an earlier POWER
article (see " Gas Turbine Technology Advances
That Could Boost Their Future
Relevance " in the October 2021 issue).
I would also like to draw readers' attention
to a National Academies report,
Advanced Technologies for Gas Turbines
(2020), which is publicly available. (I was
one of the contributors.)
At the end of the day, for a technology
that started in earnest in the 1930s
with the pioneering work of Dr. Hans
von Ohain and Sir Frank Whittle, to expect
proverbial " eye-popping " advances
is naive. In the last three decades, the
admirable increase in gas turbine combined
cycle (GTCC) efficiency from the
low 50s (percent LHV) to above 60% can
be attributed almost exclusively to the
increase in turbine inlet temperatures
(TITs) from 1,300C to 1,700C, which, of
course, was primarily driven by advances
made in metallurgy, manufacturing (such
as single-crystal super-alloy hot-gas-path
components, including stator vanes and
rotor blades), and cooling techniques.
In early 2023, the goal post is set at
65% net GTCC efficiency, which, at least
based on the published ISO baseload
www.powermag.com
1. Germany's carbon intensity and electricity
production in November 2022. Source: electricitymaps.com
rating
claims of major original equipment
manufacturers (OEMs), is not too
far ahead. The next target-70%-will
require new tricks, including a change
in the underlying Brayton cycle. In the
past, attempts to do just that, including
through external (steam) cooling of
the hot gas path and reheat combustion,
failed to make a big dent in performance.
Although proven in the field,
both attempts fizzled commercially due
to complex designs with unfavorable operability
and installed (and maintenance)
cost implications. On paper, both technologies
can make a significant contribution
to cover the five percentage points
from 65% to 70%. However, it is quite
unlikely that the OEMs will dust off either
technology. (Note that " sequential
combustion " gas turbines are still being
offered by two OEMs and steam cooling
of stationary parts is still a feature in one
OEM's product line.)
POWER | April 2023
https://www.electricitymaps.com http://www.powermag.com
POWER April 2023

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