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Aeros Capable of Hitting Multiple Targets

Peter Kelly-Detwiler

Aeroderivative gas turbines are highly flexible units, capable of being deployed in many applications. The manner in which they are deployed varies globally.

Derived from aircraft jet engine technology (hence the name), aeroderivative gas turbines are prized for their reliability, small footprint, low weight, high efficiencies, and relatively short maintenance cycles.

In Europe, their main use is in district heating and industrial applications, where they provide both heat and electricity. In most other locations, they are more frequently deployed in power systems. Owing to their flexibility and ability to follow customer load, aeroderivatives are frequently deployed as peaking units, but they're also used in some regions as baseload generators.

Different Horses for Different Courses

The modes of utilization for these turbines often depend on the specific industrial applications or characteristics of local power systems, and they tend to be grouped by geography.

In Europe, the majority of the units serve industrial customers or district heating loads, with thermal output applied across various applications.

Industrial users value these machines particularly for their short outage durations. Compared with heavy-duty frame turbines, where shutdowns may last two or more weeks, aeroderivatives can be quickly put back into service. In many cases, aeroderivative outages last no more than a few days, according to GE Power, with spare engines frequently carried on site or leased with minimal delays.

In contrast with Europe, according to Turbomachinery Magazine, the majority of aeroderivative gas turbines in North America are employed in the electricity sector. These are used chiefly as peaking plants—closely following load during periods of high demand. On this continent, the machines are rarely used for baseload power, in part because more efficient and larger combined-cycle plants had already established themselves and gained a dominant position.

The Renewable Normal: Peaking Applications

The remarkably rapid growth of renewables is providing new and growing opportunities for aeros to prove their worth as peakers. In California, where penetration of solar power is extremely high, grid balancing and firming services are increasingly valuable. In the state, a large fleet of aeroderivatives receives compensation for starting up at least twice daily and generally running for less than four hours at a time. The run times per start for Aeroderivative LMS100 machines vary between two and four hours in California and 54 hours in Australia, according to Turbomachinery Magazine.

The addition of energy storage can further enhance the performance of these aeroderivative assets. According to Power Engineering, in a first-of-its-kind deployment, a plant was recently installed in California that combines a 50-MW LM6000 aeroderivative turbine and 10-MW battery. The battery—combined with a controls system—increases the inherent flexibility of the aeroderivative turbine, giving it sufficient lead times to commence operations and achieve the desired level of output. Use of the battery also eliminates water and fuel use when the turbine is operating in standby mode.

As power systems evolve, the generating technologies that stand to gain the most will be those that are either the most efficient or the most flexible. Profitability will likely lie at each end of the dispatch curve: in the form of efficient plants running in baseload mode or a highly flexible asset that can quickly ramp up and down.

That implies that the most efficient H-Class turbines in combined-cycle applications will lead. However, they have difficulty in precisely following load. In areas with many renewable assets, where frequent dispatches are required and various balancing services are highly valued, the nimbler and smaller aeroderivatives will be needed and valued.

Flexing Some Muscle in Developing Nations

In much of the developing world, the power grid is less centralized and is still being expanded to meet a growing need for electricity. Here, there is a more frequent split in utilization of aeroderivative turbines for peakers vs. baseload units. In many cases, the smaller, simple-cycle aeros are deployed specifically to serve as baseload assets. They have specific advantages in this regard that make them attractive.

According to Power Engineering, aeroderivatives can get up and running faster than frame machines, although that gap has narrowed somewhat with newer combined-cycle turbines. Aeros have start times under less than 10 minutes, something frame combined-cycle turbines simply cannot match. Perhaps more importantly, their smaller size and modularity make them a good fit for these growing grids. Aeroderivative gas turbines are also easier to service than heavy-duty combined-cycle plants that typically run on rigid maintenance schedules; the short outage durations are a boon to asset managers and grid operators.

Aeroderivative gas turbines are so flexible, small, and lightweight that they can also be packaged and delivered in the form of mobile fleets, commissioned within timeframes under two weeks. According to International Turbomachinery, for example, six trailer-mounted aeroderivative turbine packages were delivered to Angola in 2016 to meet the country's power needs. Whether stationary or mobile, aeroderivatives are often the right fit for evolving grids with fewer overall generating assets and a need for limited downtime and higher operating flexibility.

Given their attractive features and high degree of flexibility, aeroderivative gas turbines will continue to be deployed across the globe in a variety of applications, meeting the constantly changing needs of industrial customers and power grids alike.

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