By Lee S. Langston

I sell here, sir, what all the world desires to have— POWER." These were the words of early British industrialist Matthew Boulter to James Boswell, quoted in Boswell's Life of Samuel Johnson, which was published in 1791. Boulter's enterprise, the Boulter and Watt Co., had the Scottish engineer and inventor, James Watt, as a cofounder. The company manufactured the Watt steam engine, which Robert Fulton used on his steamboat. Boulter and Watt went out of business long ago, but the world's desire for power has not let up. Instead, it has multiplied many times over since Boulter met Boswell.

Mankind's increasing need for power is being fulfilled by gas turbines in all corners of the planet. In 60 years of existence since 1939, gas turbines have come to dominate aviation engine sales and are becoming the new power producers of choice in the world electricity market.

The gas turbine market is young compared to that of, say, steam turbines, but it is large for its age. According to information provided to the International Gas Turbine Institute by Forecast International, the value of gas turbine production worldwide totaled about $28 billion in 1998, a 12 percent increase from 1997. Researchers at Forecast International, the Newtown, Conn., market research company that tracks the gas turbine marketplace, report the value of production because those numbers are more reliable than factory sales estimates. Because the sale of gas turbines is largely a contract business, there is generally a steady movement of inventory to customers, so changes in production imply trends in sales.

The largest portion of the 1998 market—64 percent, or some $18 billion—is associated with aviation gas turbines. About $15 billion went to the worldwide civil aviation field, while the remaining $3 billion was for manned military aircraft.

During 1998, sales and production of military aircraft gas turbines continued to decline as governments worldwide trimmed military budgets. Meanwhile, major airline carriers, although battered by heavy losses in the past, have been turning profits in the last few years. Their prosperity has led to increased orders for engines.

The aviation engine parts aftermarket, however, has been undergoing a major adjustment, which continued last year. In recent years, aircraft engine technology has advanced, and civilian and military customers have demanded that manufacturers supply longer lasting engine components. This development has reduced the need for repair and overhaul service providers, which have declined in numbers as work disappeared. Consolidation among the service companies continued in 1998, as engine manufacturers continued to take them over.

The decline of the aftermarket has been a characteristic of the aircraft engine business for decades. Fifty years ago, an aviation piston engine manufacturer could expect aftermarket sales of parts to amount to 20 or 30 times the business in new engines. With the advent of the jet engine, aftermarket parts volume dropped to three to five times the value of sales of new engines. The reduction was an important contributor to making air travel affordable and reliable, and airlines profitable.

The main application by far in the nonaviation segment of the gas turbine market is electrical power generation. The value of production of nonaviation gas turbines in 1998 was about $10 billion, and 85 percent of that, or $8.5 billion, was destined for electric power applications. Use as mechanical drives, such as gas pipeline compressors, and for marine propulsion accounted for the remaining 15 percent of the nonaviation market. According to the IGTI Marine Committee, 1998 saw the introduction of gas turbine propulsion into the large cruise ship market.

ABB Power Generation's sequential combustion GT26 gas turbine will be used in the new $215 million combined cycle power plant to be built in Shoreham on the south coast of England. The plant will open in late 2000.

The market for electrical power gas turbines has increased greatly in the last decade. Because of their record breaking high operating efficiencies (40 percent for simple cycle units and almost 60 percent for combined cycle installations), their ready availability, low capital and operating costs, and clean combustion with a low level of pollutants, gas turbines have become the dominant means of new electrical power generation worldwide.

The electric power market is huge. Sales of electricity in the United States total more than $200 billion per year. Currently only about 15 percent of the world's installed electric generation capacity is gas turbine powered. Also, events in the electric power market are being driven by immense future needs of much of the world's population, mostly in underdeveloped countries, and by the global deregulation of electric utilities, which will tend to drive out less efficient power producers.

Last year, the value of gas turbine production for power generation represented a gain of more than 21 percent, from $7 billion in 1997. At the same time, production for aviation increased 12.5 percent. At those rates, it is possible that in the not-too-distant future the value of gas turbine production for power generation could exceed production for aviation.

During 1998 the electric power gas turbine market presented a complex picture. For some years, Asia has been the growth market, but the financial crises in that part of the world in 1998 brought a swift end to near-term growth. South American prospects for gas turbines sales stayed strong, but it is a much smaller market than Asia. In the last half of 1998, orders for large gas turbines in North America have surged, as electric power producers came to grips with the realities of electric utility deregulation.

Real market drivers for gas turbines have always been improved performance, increased durability, and lower costs, brought about by the continued application of new and hard-won technology. The following synthesis of reports from IGTI Technical Committee chairs and other volunteer leaders highlights the important technical issues and progress in 1998.

Combustion and controls: There are new concerns associated with aviation gas turbines brought about by low emission requirements. The recent growth in regional commuter aircraft is extending low-emission technology to the design of small engine combustor components.

Perhaps the greatest combustion challenges in 1998 have been presented by low NOx gas turbines. While low NOx combustion systems are not new in themselves, the push toward dual fuel, dry low NOx combustion systems in industrial gas turbines has been particularly strong over the last 12 months.

At this time it would be realistic to say that the design of these combustion systems is by no means settled, and control of them is still a significant challenge. Major engine companies are still some years away from being able to produce routine designs that work the first time.

As a result of these efforts, it is possible that NOx emissions could be reduced to single-digit parts per million within 10 years, down from the neighborhood of 25 ppm now, but those gains could be offset by the drive for greater efficiency. Increased turbine inlet temperatures will tend to increase NOx levels for fixed combustion technology. These developments are likely to result in all aspects of low NOx combustion technology (including control systems) steadfastly remaining a major research area in the gas turbine community over the next few years.

Turbomachinery: Parts count and cost are driving the turbomachinery part of the market. The trend is toward fewer, more highly loaded stages in multistage compressors and turbines. The technical challenge is to maintain reasonable efficiency and mass flow levels in these machines.

Advanced aerodynamic design methods accounting for stage interactions are being developed to model the flow in these more highly loaded machines. Steady state models as well as full unsteady analyses are under development.

Atlantic Projects Co. of Dublin is performing a combined cycle power plant installation in the United Kingdom.

Companies are aggressively looking for ways to reduce design cycle time in order to reduce development costs. In a supporting activity, NASA has a new initiative focused on dramatically reducing engine cost through the development of next-generation design tools that are expected to provide a 50 percent reduction in engine design cycle time in 10 years and a 75 percent reduction in 25 years.

U.S. government funding for turbomachinery technology programs has been dramatically reduced. The available funding generally requires a heavy cost share, thereby driving the funded programs toward those with very near-term payoffs.

To gain more leverage from their research dollars, companies are moving toward the funding of university centers with demonstrated competence in particular areas. This has the effect of concentrating funding at a few select universities.

An area that has seen focused development effort over the last 12 months is active stall control for compressors to prevent aerodynamic surges. This activity has been going on for some time, but continues to represent a challenge.

A final area that continues to attract steady and increasing interest is the active control of gap size between rotating blades and the engine case, for optimum efficiency. While also not a new concern, interest in this active clearance control has increased significantly during the last year.

High Cycle Fatigue: High cycle fatigue has been identified by the U.S. Department of Defense as a major problem area that impacts the development of new military aircraft engines and the maintenance and readiness of operational engines. Therefore, the Air Force, Navy, and NASA initiated a national program in 1998 to improve the understanding of high cycle fatigue phenomena and to reduce the occurrence of failures.

Ceramics: Progress continued apace in 1998 on the manufacture and the research of ceramics for gas turbine applications. Topping the list are applications of protective coatings, such as thermal barrier coatings for combustor liners, turbine airfoils, and endwalls, and environmental barrier coatings, to coat ceramic engine parts to protect them from chemical reactions with combustion gases. The acceptance of thermal coatings in the aircraft industry is strong, and is gaining in industrial and electric power generation applications.

Diagnostics: As more independent power producers come on line, the power generation industry is seeing a shift toward the sale of gas turbines under full maintenance contracts, and even "power by the hour" where the operators pay only as they use the gas turbines. These shifts in the market are placing an increased demand on diagnostic systems. During 1998 diagnostic systems with artificial intelligence continued to develop and will do so for the foreseeable future.

Microturbines: The prospects of a large microturbine market advanced significantly in 1998. These are very small gas turbines that produce power in the 25 to 100-kW range, small enough to provide electrical power to a McDonald's restaurant and furnish hot exhaust gases to heat domestic water and the building. Advances in power electronics now allow direct coupling of high-speed generators to microturbines without complex gearboxes. Although there are no significant sales yet, some estimate the potential market for these units at $8 billion to $10 billion per year and liken their future status in the electric power industry to that of the PC in a computer industry once dominated by mainframe systems.

Qualification and Performance Standards: At IGTI technical sessions on risk management and in other forums during the year, land-based gas turbine users as well as financial and insurance institutions expressed a desire for the establishment of a third party certifier of new electric power gas turbines.

Before a new aircraft gas turbine is introduced into the civilian market, it must be put through a certification process, involving extensive engine and component testing. In the United States, the certification process is controlled by the Federal Aviation Administration. There is currently no such certification process for electric power gas turbines.

In the past few years, as new, more advanced gas turbines entered electric generation service, a number of unanticipated and much publicized problems resulted in unplanned outages and significant repair costs. Proponents believe a third party certifier (similar to the FAA) could establish and oversee a process that would yield demonstrated levels of performance and endurance for electric power gas turbines. In the coming year more discussion and debate will be needed to determine the merits and necessity of a third party certifier.


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