Alstom Power
GT24 / GT26 Gas Turbines
Unparalleled performance, maximum return, advanced-class sequential combustion for 50 Hz and 60 Hz markets.
Alstom's GT24 (60 Hz) and GT26 (50 Hz) gas turbines combine unique sequential combustion technology, welded rotors, and annular combustors to deliver high efficiency, low emissions, and unmatched operational flexibility. With over 6 million fired hours across more than 140 units, the GT24/GT26 is one of the most proven advanced-class gas turbines on the market.
70+
Years of Innovation
6M+
Fired Hours
98,000
Starts
140+
Units in Fleet
200
Turnkey Plants Delivered
1,500
Engineering & R&D Professionals
GT24 and GT26, Right Turbine for Your Grid
Both models share Alstom's sequential combustion architecture and design heritage. Selection depends on grid frequency.
High part-load efficiency for 60 Hz markets
- ApplicationNorth American & Asian 60 Hz grids
- Turndown11% CCPP load
- Spinning Reserve500 MW in 10 min (KA24-2)
Industry-leading 50 Hz combined-cycle performance
- ApplicationEuropean & global 50 Hz markets
- Turndown20% CCPP load
- Spinning Reserve350 MW in 15 min (KA26-1)
Shared Technical Specifications
NOx Emissions
15 vppm at 15% O₂ dry
NOx Reduction vs. Prior
−40% over wide load range
Hot Start-up
30 minutes
Ambient Range
−30°C to +55°C
CCPP Efficiency
Near-constant 80%–100% load
Inspection Extension
+30% in maintenance mode
Fuel
Gas + dual fuel oil capability
Fleet Hours
6 million fired hours
Key Benefits
Alstom's GT24/GT26 delivers superior versatility worldwide, maximising return to customers through a powerful combination of performance, reliability, and operational flexibility.
Operational Versatility
Two online-switchable operating modes, performance optimisation for peak demand, and maintenance cost optimisation offering up to 30% more operating time between scheduled inspections. Switching between modes requires no hardware changes and can be done while the plant is online.
Low Emissions, 40% Less NOx
Sequential combustion technology produces 15 vppm NOx at 15% O₂ dry, 40% less NOx over a wide load range compared to previous-generation designs. Low emissions are maintained at part load without any hardware changes.
Fuel Flexibility
Alstom's robust sequential combustion chamber accommodates a wide range of fuel compositions without changing hardware. The GT24/GT26 can also burn fuel oil in place of fuel gas at high load, switchover can be accomplished while the plant remains online.
High Availability & Reliability
Over 140 units in operation have consistently achieved availability, reliability, and service factor performance that meets or exceeds class averages. EV and SEV combustors require no parts replacement prior to Hot Gas Path Inspection (HGPI) C inspection, maximising uptime.
Fast Start & Wide Temperature Range
30-minute hot start-up with spinning reserve capability delivering 500 MW in just 10 minutes (KA24-2) or 350 MW in 15 minutes (KA26-1). Operates from -30°C to +55°C ambient, suited for diverse environments worldwide.
Load Range Efficiency
Almost constant efficiency between 100% and 80% CCPP load. Industry-leading turndown capability maintains 11% (GT24) or 20% (GT26) combined-cycle load during periods of low power demand, unique in the industry.
Sequential Combustion Technology
Alstom's proprietary sequential combustion is exclusive to the GT24/GT26 and is the foundation of its superior efficiency, low NOx, and load range performance. Two combustor-turbines in series burn fuel in two dry low-NOx stages, enabling high performance without raising emissions.
Compressed Air → EV Burner
Compressed air from the 22-stage subsonic compressor is fed into the EV burner, creating a homogeneous, lean fuel/air mixture. The vortex flow induced by the burner shape breaks down at the EV exit into the combustion zone, forming a central recirculation zone.
1st-Stage EV Combustion
The mixture ignites to form a single, low-temperature flame ring. The inner recirculation zone stabilises the flame in the free space within the combustion zone, avoiding wall contact. The annular EV combustor distributes hot gas circumferentially at a highly uniform temperature.
Hot Exhaust → HP Turbine → SEV
Hot exhaust gas, low in oxygen content, exits the first combustor and drives the single-stage high-pressure turbine before entering the SEV (Sequential EV) burner via the diffuser.
Vortex Mixing in SEV
Four delta-shaped vortex generators in each SEV burner form four pairs of vortices. Fuel is injected through an air-cooled lance and distributed through four jets into the vortex pairs. Surrounding the fuel jet with cool carrier air delays spontaneous ignition until the mixture reaches the combustion zone.
2nd-Stage SEV Combustion → LP Turbine
Ignition occurs spontaneously when the fuel/air mixture reaches self-ignition temperature in the SEV combustor free space. A single stable flame ring operates across the entire load range. Hot gas then expands through four low-pressure turbine stages. Neither the EV nor SEV require parts replacement before HGPI C inspection.
Design Advantage
Neither the EV nor SEV combustors require any parts replacement prior to Hot Gas Path Inspection (HGPI) C inspection. This mechanical simplicity, combined with welded rotors, high-efficiency 3D compressor blade profiles, and multiple variable guide vanes, assures the high reliability and availability of the GT24/GT26 across its entire service life.
Combined-Cycle Power Train
Alstom has extensive experience with both single- and multi-shaft powertrain arrangements, in all operating regimes from baseload to daily start and stop. Every component is system-integrated for high thermal efficiency and wide operational flexibility.
Steam Turbine
- HP turbine shrink-ring design for sustained efficiency
- Welded rotor for fast start-up and low maintenance
- Single-bearing design for compact arrangement
- Single axial and lateral-exhaust designs available
Turbogenerator
- Air-cooled TOPAIR and hydrogen-cooled TOPGAS generators
- High efficiency, reliability and availability
- Low maintenance requirements
Gas Turbine
- GT24 (60 Hz) and GT26 (50 Hz)
- Sequential combustion, the powerful core
- Annular EV and SEV combustors
- 22-stage subsonic compressor with 3D blade profiles
HRSG
- Single-row harp, 3× less stress than multi-row designs
- Optimised for high-cycling, daily start/stop
- Drum type and once-through technology
- High thermal flexibility for quick start-up
Applications
The GT24/GT26 is proven across combined-cycle, repowering, co-generation, and desalination co-generation worldwide.
Combined-Cycle Power Plants
The sequential combustion process provides optimum exhaust temperatures and high efficiency over the full CCPP operational load range, near-constant efficiency between 100% and 80% load. Four rows of variable guide vanes control inlet air flow for optimal part-load performance.
Contact us →Repowering
Alstom's hybrid plant concept integrates the GT24/GT26 into conventional steam plants, improving efficiency by 50% or more. Combines operating flexibility, continuous fuel optimisation, low O&M costs, and moderate capital investment, adding 25+ years of efficient life to existing plants.
Contact us →Co-generation & Desalination
The KA26 combined-cycle unit offers high flexibility for both heat and power production. Proven in the world's largest IWPP at Fujairah 2 (UAE), 2,000 MW with 130 MIGD desalination capacity, and in district heating CHP plants such as Niehl-3 (Germany, >60% overall efficiency).
Contact us →Global Reference Plants
GT24/GT26 gas turbines power plants on every continent, from 360 MW single-shaft reference plants to 2,160 MW national flagship stations.
Taranaki Combined-Cycle
GT26 single-shaftNew Zealand · 360 MW
First GT26 single-shaft reference plant, continuous baseload since July 1998.
Lake Road Generating Facility
3 × GT24Connecticut, USA · 792 MW
Dual fuel (natural gas primary, distillate oil backup). Commercial operation May 2002.
Pembroke Power Station
5 unitsUK · 2,160 MW
Largest gas-fired power station in the UK. Annually reduces CO₂ by 6–10 million tons vs. coal.
Fujairah 2
GT26United Arab Emirates · 2,000 MW + 130 MIGD
Largest newly constructed IWPP in UAE at time of contract (2007). Hybrid desalination plant.
Keppel II
KA26Singapore · 800 MW
18-year maintenance contract. Commercial operation since 2013.
Hai Fu Power Plant
KA24Vietnam · 980 MW
Over 12,000 starts between 2001 and 2013. Outstanding starting reliability.
Niehl-3 CHP
KA26 ecoHEAT™Cologne, Germany · 450 MW
Over 60% overall efficiency. 265 MW thermal heat supply for 50,000 homes. Saves ~500,000 t CO₂/year.
Haruvit
2 × KA26 single-shaftIsrael · 835 MW
Largest IPP project ever executed in Israel. Most efficient and flexible units in national fleet.
North Bangkok Block 2
GT26 (upgraded)Thailand · 850 MW
First power plant worldwide featuring Alstom's upgraded GT26 with improved efficiency and lower emissions.
Lifecycle Services
Alstom's service portfolio covers every stage of the plant lifecycle, from parts and repairs to long-term agreements and 24/7 plant support. Services are also available for other OEM gas turbines.
Long-Term Agreements (LTA)
Framework contracts that define fixed preferential prices and conditions in advance. Flexible and extendable scope covering parts, services, and almost any aspect of plant operations. Reduces administrative effort and simplifies planning.
Operation & Maintenance Contracts
Fee-based O&M agreements that mitigate risks, leverage Alstom's extensive experience in plant asset management, and can be fully adapted to your business strategy. Covers GT/CC plants through all lifecycle stages.
Plant Support Center™ (PSC)
24/7 operation support and remote monitoring with direct access to a global network of technical experts for troubleshooting, assessment, re-commissioning, and equipment trend analysis. Backed by proprietary knowledge management tools and fleet-wide engineering experience.
Parts, Repair & Field Service
Complete OEM-specification parts supply, reconditioning & repairs, technical expertise, operational support, field service, and performance improvement packages for GT24/GT26 and other OEM gas turbines.
Frequently Asked Questions
Technical and commercial questions about the Alstom GT24/GT26 gas turbine platform.
What is the difference between the GT24 and GT26?
The GT24 is designed for 60 Hz power grids (primarily North America and parts of Asia), while the GT26 is optimised for 50 Hz markets (Europe, Middle East, and most of the rest of the world). Both share the same sequential combustion architecture but are engineered for their respective grid frequencies. The GT26 offers a best-in-class CCPP turndown to 20% load; the GT24 turns down to 11%.
What is sequential combustion and why is it unique?
Sequential combustion burns fuel in two dry low-NOx combustor stages in series. The 1st-stage EV combustor burns fuel in an annular arrangement; exhaust gas then drives the high-pressure turbine before entering the 2nd-stage SEV combustor, where fuel is injected again and ignites spontaneously. This allows high turbine inlet temperatures and efficiency without proportionally increasing NOx, achieving 15 vppm NOx at 15% O₂ dry, and 40% less NOx versus previous-generation designs.
How many GT24/GT26 units are in operation?
The GT24/GT26 fleet comprises more than 140 units, which together have accumulated over 6 million fired hours and 98,000 starts.
What are the two operating modes of the GT24/GT26?
The GT24/GT26 offers two online-switchable operating modes: Performance Optimisation Mode, which delivers maximum output and efficiency, ideal for peak demand; and Maintenance Cost Optimisation Mode, which extends intervals between scheduled inspections by up to 30%, reducing maintenance costs. Switching between modes requires no hardware changes and can be done while the plant is online.
What ambient temperature range can the GT24/GT26 operate in?
The GT24/GT26 can operate in ambient temperatures from -30°C to +55°C, making them suitable for a wide variety of geographic environments from Arctic-adjacent sites to hot desert climates.
Can the GT24/GT26 burn liquid fuel?
Yes. The GT24/GT26 can switch from gas to fuel oil at high load when gas supplies are short or grid conditions change. This high-load fuel switchover can be accomplished while the plant remains online without interrupting power production.
What applications are best suited to the GT24/GT26?
The GT24/GT26 is optimised for combined-cycle power plants (CCPP), repowering of existing steam plants, co-generation (CHP), and desalination co-generation. Its near-constant efficiency between 80% and 100% CCPP load and best-in-class turndown capability make it especially valuable for flexible dispatch in competitive electricity markets.
Source Alstom GT24/GT26 Parts & Services
kodeksallc supplies OEM-specification parts, replacement components, and procurement support for the full Alstom GT24/GT26 fleet, including legacy ABB and Alstom lineage turbines now maintained by Ansaldo Energia.