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Gone are the days when a combined-cycle gas turbine could be expected to run for 8,000 hours or more a year. Increasingly, gas turbines are being deployed at peaking capacity or to fill the gap on a winter's day when there's no wind and little sun, for example. Simultaneously, widespread projections of soaring electricity demand in response to the electrification of transport and the meteoric rise of power-hungry data centers leave no questions about whether gas turbines will continue to play a major role in the power-generation portfolios of the future.

Switching gas turbines from baseload to peaking-type operations reduces their operating hours and impacts the economic model that has supported turbine deployment over the last decades. This is prompting owners and operators to take another look at how gas turbines are financed.

Shifting Power Market Prompts Tough CapEx Decisions

The changes in energy macro trends coincide with another major influence specific to the gas turbine market: A period of rapid growth in gas turbine capacity during which many F-class machines were installed, such as the GE 7F.03. In the early 2000s, the bubble saw orders for baseload gas turbines skyrocket and the emergence of a standard model coupled with a set of ancillaries, such as the heat recovery steam generator. However, many of those machines are now reaching the end of their service life, having operated for around 200,000 hours, and a new trend is forming. 

Their turbine rotors will have to be replaced and either the whole machine will be scrapped and a new plant developed or, as an alternative strategy, the turbine internals will be replaced. This upgrade to later and more advanced technology offers higher efficiencies with a wider operating envelope, better ramp rates, and better part-load capabilities than previous generations. In addition, more significant economic and engineering factors are at play when deciding to completely replace a power plant or upgrade and refurbish an existing facility.

A new facility requires more substantial capital investment than refurbishment. And, while in both cases a more efficient and flexible machine will emerge, a wide range of economic and engineering factors must be considered. Critical factors include:

the anticipated volume of electricity sales,

the scale of capital investment and potential payback periods,

These considerations become more important in light of a new operating regime in which a plant may produce power for far fewer hours than a baseload facility.

Given the challenging economics facing new builds and supply chain issues, which tend to favor refurbishment, many plant owners are looking to replace turbine internals to achieve desirable performance characteristics as cost-efficiently as possible. However, uprating a turbine rotor comes with challenges, notably the requirement to increase airflow through the machine as a consequence of the new combustion characteristics. Essentially, more power means more air. Refurbishing the turbine internals means increasing the performance of the air inlet and its filtration systems without increasing the pressure drop across the filter house or diminishing filtration performance that might negatively affect the turbine efficiency.

An upgraded rotor and higher airflow would conventionally mean a bigger filter house, but this requirement is constrained by the available footprint at a brownfield site. Indeed, a larger filter house will not fit in the same footprint as an existing unit because an uprated system often has to be wider and taller. Many sites are critically restricted in width, especially if there is more than one gas turbine onsite with a fixed distance between them. In addition, height restrictions can also come into play due to power cables, fixed downstream ducting, or some other systems installed near the turbine. With space constraints affecting the available options, improving airflow performance is only possible by installing filters that run with a higher flow rate or fit within the same space.

Fortunately, while turbine technology has advanced to deliver improved performance, so have air inlet filtration systems. By using more modern and higher flow-rate technology, it is possible to have a filter house of similar dimensions to meet site constraints. Recent developments in filter elements can deliver appropriate airflow characteristics with no appreciable drop in air quality. The key development is that the filter geometry has changed, enabling a higher air flow rate for the same performance and improved nesting to optimize the space required for each filter. The changes in filter geometries—for example developing a generally triangular cartridge rather than a round one—were executed to reduce pressure loss and increase airflow throughput through the same space and reflect changing market demands. 

This is only part of a series of air inlet assemblies, such as weather hoods and coalescers, evaporative coolers, pulse cleaning, and anti-icing systems, that will be required to squeeze into the same footprint. With the correct technology in place, this is achievable, and it may be possible to use the same support structure that had served the existing filter house for additional CapEx savings.

Owners are increasingly attracted to replacing end-of-life rotors in gas turbines. As a strategy, it represents an opportunity to upgrade to the latest power-generation technology with the lowest CapEx. The promise of increased power output, higher efficiencies, and better part-load flexibility are within reach and increasingly important in the current and rapidly evolving generation. Removing the need to replace the entire air inlet system could be a significant factor when considering CapEx, ultimately driving the decision to refurbish a power plant or start again from scratch.

Steve Hiner is the Chief Engineer of Parker Filtration Group's Altair Business Unit, Filtration & Energy Solutions Division.

When deciding to refurbish or renew, gas turbine plant owners have to weigh engineering and economic factors, including the turbine’s footprint.

CapEx: New Gas Turbine Models and Filtration Footprints

GE Aerospace, Boeing, NASA, and the Oak Ridge National Laboratory will develop an Open Fan engine design model. Engineers will simulate flight conditions to study the aerodynamics of a wing-mounted Open Fan engine. Simulation enables the design to achieve more efficiency, increased performance benefits, and lower noise levels. x

The Department of Energy awarded this project 840,000 supercomputing hours via its INCITE program, which supports computationally intensive projects. The partners have access to Argonne National Laboratory’s Aurora supercomputer and Oak Ridge National Laboratory’s Frontier supercomputer, both capable of processing test data at over a quintillion calculations per second. 

Open Fan designs lack the traditional jet engine casing, permitting a larger fan size with reduced drag and improved fuel efficiency. Previously, GE Aerospace modeled the performance and noise levels of Open Fan engine parts with exascale computing. Increased computational power allows the replication of a full-size integrated engine and aircraft in the design phase.

“Advanced supercomputing capability is a key breakthrough enabling the Open Fan engine design,” said Arjan Hegeman, General Manager for Future of Flight Technology at GE Aerospace. “Airplane integration is critical. Today’s announcement with Boeing, NASA, and Oak Ridge National Laboratory to simulate the latest airplane and engine designs continues a longstanding legacy in the aviation industry.”

CFM International’s Revolutionary Innovation for Sustainable Engines (RISE) program, launched in 2021 and developing the Open Fan engine, demonstrates aviation technology and completed more than 250 tests. The RISE program develops advanced engine architectures and compact core and hybrid electric systems for compatibility with 100% or unblended sustainable aviation fuel. It also:

Targets more than 20% improved fuel efficiency

 emissions over modern commercial engines

“We aim to do something our company has never achieved before — introduce a new jet engine that is 20% more fuel efficient than our most advanced commercial engines today,” said Hegeman. “This represents a jump in technology development that usually takes multiple generations to achieve. Supercomputing helps make it possible.”

In early November, GE Aerospace signed a maintenance, repair, and offload (MRO) offload agreement with the Cyprus-based United Aerospace Maintenance Co. (UAMCO). The 

 for CFM LEAP engines and allow GE Aerospace to satisfy its MRO capacity and open ecosystem obligations for CFM. The ecosystem includes:

CFM internal capacity delivered by GE Aerospace and Safran Aircraft Engines

External capacity from Premier MRO workshops

External capacity from competing third-party MRO providers

Headquartered in Larnaca, Cyprus, UAMCO obtained EASA approval for quick-turn maintenance for LEAP-1A engines installed on Airbus A320neo fleets. The company also received MRO approval for LEAP-1B engines equipped on Boeing 737 MAX aircraft. UAMCO will fulfill the engine maintenance requirements of customers in Europe, the Middle East, and Africa. Currently, the company is partnered with GE Aerospace On-Wing Support to perform on-wing and near-wing retrofits for the updated reverse bleed system in LEAP-1A engines. UAMCO employs two teams that can perform installations globally.

DOE awarded GE Aerospace, Boeing, and NASA supercomputer access to study open-fan aerodynamics to reduce drag and improve fuel efficiency.

GE Aerospace Teams Up to Simulate, Model Open Fan Engine on Aircraft Wing

Decentralized Energy Systems: Toward Carbon-Neutral Energy Solutions for Gas Turbines

, compares decentralized systems to centralized heat and power units and highlights its advantages—including modularity, the possibility to exploit waste heat avoiding energy transmission losses, and reducing energy distribution costs. 

Giuseppe Tilocca, Scientific Officer at ETN Global, reviews these advantages in detail, as well as trends and emerging market opportunities. He also dives into gas turbines and how they fit into decentralized energy systems.

Q: Can you provide a background on ETN Global and its report on decentralized energy systems?

ETN Global is a non-profit association. We have OEMs, users, the R&D community, suppliers—the entire spectrum of stakeholders. We mainly work on technology, but we also delve into market and policy. We gather users’ challenges every year through high-level meetings and transform them into pathways for technical requirements.

Considering this specific report, we all know that the energy sector is transforming very quickly, and it’s mainly driven by the increasingly high share of renewable energy sources. In this scenario, which is dominated by variable sources, the demand for daily, weekly, and seasonal flexibility is set to grow dramatically. To meet the system requirements while accomplishing the ambitious decarbonization goals, we need to support traditional centralized generation with a mix of centralized components, such as demand response and stability generation. 

It is about going into the critical role of decentralized energy systems to achieve carbon-neutral energy solutions, particularly focusing on the integration and application of gas turbine technology.

Q: How do you define a decentralized energy system, and what is its advantage over centralized heat and power units?

Historically, we established centralized energy systems, meaning large plants located far from consumers. The reason behind it is merely economy of scale and efficiency, so it is cheaper to have one big plant than many small ones; however, with the increasing integration of variable renewable energy sources, which are inherently decentralized, we now need to adapt our infrastructure and incorporate technologies that are traditionally used for centralized energy. By definition, a decentralized energy system is located close to the consumption nodes—so on the end user side of the network—and therefore it’s connected to the distribution grid rather than the transmission grid.

The advantages of a decentralized energy system are mainly modularity, the possibility of exploiting waste heat, and a positive contribution to stability. One of the main benefits of being close to consumption nodes is avoiding transmission and distribution losses and costs compared to centralized generation. Decentralized energy systems are pivotal in meeting the pillars of the energy trilemma, which stress the principles of affordability, security, and climate neutrality and hence align with the requirements for the transition toward 2030 but also 2040 and 2050.

Q: What are the biggest hurdles that decentralized energy systems face?

There are three main hurdles. Technologically, it is scale. Smaller equipment is proportionally more expensive than larger equipment, as are installation costs. As a result, capital expenditure per kW installed is less competitive than for larger equipment. Similarly, operating expenses may proportionally increase as size decreases; this includes maintenance, onsite operations, and fuel costs. (Smaller units usually have lower fuel-conversion efficiency.) These two hurdles may somewhat balance the benefits of reducing transmission and distribution losses.

On the user side, one of the many hurdles is commitment. This applies to residential, commercial, and industrial sectors. Investing in energy isn’t necessarily seen as a priority—in many cases, it’s far easier to plug into the grid and forget about it. This is not the case when energy is a primary cost, or you need heat or mechanical power.

One of the most challenging aspects of decentralized energy systems is the integration of different energy sources, energy technology, and energy products—they all need to coexist. You could have variable renewables providing power; you could have storage during a surplus or need storage as a battery or fuel; or you may have flexible technology to ensure available power. Having many sources, technologies, and products presents a huge quantity of data to manage and, in such complex systems, integration and controls are among the biggest challenges.

Q: What are some trends and emerging opportunities identified by ETN Global in this space?

With the increasing penetration of renewables and decentralization, we often hear the word “flexibility”, which we define as power balance. To maintain electricity and meet demand in Europe, we’ll need more than double the current flexibility by 2030 and five times more by 2050. There are not many available, affordable, and scalable alternatives for gas turbines’ long-term flexibility, so this is a focus of ours.

Energy balance is only part of the problem, as many auxiliary services are of critical importance to maintain a reliable power supply. We see the market moving toward integrating smaller units or virtual power plants in auxiliary market services. These two factors are even more relevant if we consider congestion and bottlenecks in the power grid that will limit interconnection capacity and flexibility—this will require substantial investment.

A matter we often forget is energy includes not only electricity but also mechanical power and heat, which are inherently decentralized. Electrifying high-temperature heat presents several challenges, which is why gas turbines in decentralized energy systems will have a role in providing flexibility, auxiliary services, mechanical power, and heat.

Q: How do gas turbines fit into decentralized and carbon-neutral energy systems?

In terms of decentralization, gas turbines are recognized for their low maintenance, fuel flexibility, and compactness. Their successful applications include primary generation, continuous power, and standby power. In these applications, they leverage low maintenance, especially for remote locations offshore. They’re fuel flexibility means they are often used with waste fuels that other technologies may struggle to run, such as flare gas from oil and gas, biofuels, etc. Gas turbines also have the potential to provide waste heat for residential, commercial, and industrial cogeneration applications.

Small turbines can help in remote locations with no access to the grid or access to an unstable grid. They’re expected to play a significant role in emerging economies like Africa, where natural gas will drive industrial growth. Standalone generation will provide cost-effective electricity access for nearly one-third of Africa by 2030. Here, smart grids and microgrids present significant opportunities. An EU-funded project studied the impact of integrating decentralized energy systems, including solar, wind, gas turbines, hydrogen, and biogas, onto an island near Norway. 

Gas turbines’ carbon neutrality is not a matter of technology but fuel. Gas turbines can already use fuels like hydrogen, but the infrastructure for these fuels is missing.

Q: What are the advantages and struggles of gas turbines in these systems? What solutions and applications are addressing these issues?

Gas turbines enable flexibility. In decentralized energy systems, clean and dispatchable solutions such as gas turbines enable the energy transition—in fact, there is no energy transition without dispatchable solutions. We’re now seeing the role of gas turbines change rapidly in decentralized energy systems—moving from 8,000 operating hours per year to about 1,000 and from two to three cycles per year to two to three per day. This operational change will impact energy systems both economically and technically.

On the technical side, new market requirements will affect maintenance and operations. The R&D community is working on fuel flexibility to minimize emissions like NOx, which will position dispatchable, affordable gas turbines as sustainable and clean technologies for the energy trilemma.

Listen to the full podcast with Giuseppe Tilocca at 

ETN Global takes a deep dive into decentralized energy systems—advantages such as modularity, roadblocks for integration, and the future of power demand—and the role of gas turbines in a decarbonized future.

Q&A: Gas Turbines and Decentralized Energy Systems

Video interview with Albert Gomez of FS-Elliott

Driving Innovation and Excellence: FS-Elliott’s Approach to Customer Support and ESG

At TPS 2024, Albert Gomez, Vice President of Global Services at FS-Elliott, speaks about the company’s scope of operations, including engineering/manufacturing, post-sales support, extended warrantee programs, maintenance programs, and ESG initiatives. Watch the video to learn more about:

The benefits of using genuine new OEM parts from the manufacturer;

The importance of having service personnel trained and certified by the manufacturer to provide service;

The importance of adhering to industry standards and regulations.

At Turbomachinery & Pump Symposia (TPS) 2024, Albert Gomez of FS-Elliott talks about the company’s scope of operations and Environmental, Social, and Corporate Governance (ESG) initiatives.

Conference Coverage

The power industry is exploring several avenues to decarbonize power plants, including implementing carbon capture and storage (CCS) technology; however, retrofitting power plants means high operational and capital costs, i.e., total costs. GE Vernova has been exploring ways to reduce these costs and the overall footprint of a carbon-capture system through its exhaust gas recirculation (EGR) system, which increases the concentration of CO

“CCUS can be added to existing power generation plants; however, any CCUS project must look at the plant holistically to be more successful during integration. It is crucial to focus on integration with all systems, including gas turbines, heat recovery steam generators (HRSG), steam turbines, and plant controls,” said Jeremee Wetherby, Carbon Solutions Director at GE Vernova.

In October 2024, GE Vernova’s front-end engineering design (FEED) study, 

Retrofittable Advanced Combined-Cycle Integration for Flexible Decarbonized Generation

, found the effects of adding a system capable of capturing up to 95% of CO

 emissions at a combined-cycle power plant in Alabama could be reduced through a series of integration measures, including an EGR system. The study findings, released by the U.S. Department of Energy’s Office of Fossil Energy and Carbon Management, found integrating GE Vernova’s EGR system:

could reduce more than 6% of the total cost of the carbon-capture facility compared to installing carbon capture without the EGR system

could reduce total carbon-capture operational costs per year (total costs include reductions to capital and operating costs)

According to GE Vernova, the benefits of an EGR system compared to a non-EGR system include:

a large reduction of carbon-capture facility footprint and cost of absorber

lower operating costs due to reduced amine degradation

less energy-intensive separation due to higher concentration of CO

more steam turbine power output due to lower steam consumption

“Think of a slider bar where CapEx reductions are at one end and operational benefits (including costs and capture rate) are at the other end,” Wetherby said. “If owners slide that bar toward CapEx, EGR can enable them to reduce the size of the capture equipment, which can reduce its land footprint and cut costs while maintaining up to 95% capture. Operators who harness EGR-enhanced carbon-capture systems can make capital-expense savings of up to 10% including a performance boost."

“At the other end of the slider bar, an operator could calibrate its equipment to achieve more decarbonization, boosting the total carbon capture of its project from 95% up to 98%,” he continued. “That’s because the EGR system would increase the carbon concentration of the air at inlet entry from approximately 4% to 7%. It just depends on how the capture plant is engineered.”

GE Vernova completed FEED studies in collaboration with Ash Sharqiyah Operations & Maintenance Co.

 at three cogeneration plants in Saudi Arabia.

The 7E and 7F gas turbines, with modifications to their standard combustors, can already operate with hydrogen blends up to 100%. These FEED studies explored solutions to enable the use of blends including natural gas and hydrogen, with hydrogen accounting for up to 32% by volume. In addition, the studies established the required combustor system modifications to achieve this level of hydrogen blending.

This FEED study showed that integrating its EGR system could reduce more than 7% of the carbon-capture facility’s total cost compared to a facility without EGR. It also showed a 6% reduction in carbon-capture operational costs annually.

Looking forward, GE Vernova is planning to extend its advanced controls used to operate gas and steam turbines to operate the CCUS in such a way as to maintain the operating flexibility that customers may depend upon.

Jeremee Wetherby, the Carbon Solutions Director at GE Vernova, offers deeper insights into the benefits of retrofitting carbon-capture systems with an exhaust gas recirculation system.

Exhaust Gas Recirculation Boosts Carbon-Capture Efficiency and Reduces Costs, says GE Vernova

GE Aerospace signed a maintenance, repair, and offload (MRO) offload agreement with the Cyprus-based United Aerospace Maintenance Co. (UAMCO). The contract will quicken the work scopes for CFM LEAP engines and allow GE Aerospace to satisfy its MRO capacity and open ecosystem obligations for CFM. The ecosystem includes:

“UAMCO offers a set of MRO capabilities and capacity,” said Tom Levin, Vice President of CFM Commercial Programs at GE Aerospace. “We depend on strategically located providers like UAMCO to help us meet unprecedented demand for LEAP engines, decrease turnaround time, and maintain the highest standards of safety and quality.”

Headquartered in Larnaca, Cyprus, UAMCO obtained EASA approval for quick-turn maintenance for LEAP-1A engines installed on Airbus A320neo fleets. The company also received MRO approval for LEAP-1B engines equipped on Boeing 737 MAX aircraft. UAMCO will fulfill the engine maintenance requirements of customers in Europe, the Middle East, and Africa.

Currently, the company is partnered with GE Aerospace On-Wing Support to perform on-wing and near-wing retrofits for the updated reverse bleed system in LEAP-1A engines. UAMCO employs two teams that can perform installations globally.

GE Aerospace’s CFM LEAP engine portfolio delivers 15% improved fuel efficiency and lower carbon emissions over CFM56 engines—operators record up to 20% savings compared to earlier aircraft. The LEAP engine surpassed 60 million flight hours in eight years and, with over 3,500 LEAP-equipped aircraft in service, CFM customers avoided more than 35 million tons of CO

“This agreement validates our commitment to safety, quality, technology, and to a spirit of cooperation between the Republic of Cyprus and the United States,” said John Savvides, Chief Executive Officer at UAMCO. “CFM LEAP engines power the world’s most popular passenger aircraft, and we look forward to working with GE Aerospace on the maintenance of these engines.”

Last week, GE Aerospace and Waygate Technologies, a subsidiary of Baker Hughes, developed an 

 for commercial engines. The companies focused on using AI to enhance machine vision-based assisted defect recognition (ADR). They targeted high-pressure compressor inspections because they are among the most important and time-consuming MRO tasks.

The AI-assisted features will improve the inspection workflow and deliver greater reliability by reducing the learning curve for new inspectors and helping current inspectors identify previously difficult-to-detect defects. Users are expected to see an increased detection probability and a reduction in inspection-related mental fatigue. In addition to improvements over the Gas Power-assist ADR model, the automated data anonymization tool enables the protection of sensitive partner data and allows it to be added to the training dataset.

In late October, GE Aerospace announced that it will invest over 

 in its MRO and component repair facilities in Europe. The planned investment, part of the company’s $1 billion MRO spending surge approved in early 2024. The company aims to meet the increasing demand for services between GE Aerospace and CFM1 installed base. These funds will support engine test cells, new equipment, and new technology such as AI-powered enhanced inspection techniques. The AI enhancements will reduce turnaround times and expand component repair capability.

United Aerospace Maintenance Co. will fulfill the customers’ CFM LEAP maintenance needs in Europe, the Middle East, and Africa by conducting on-wing-support and near-wing retrofits.

Markus Kupper

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