LM2500 STILL REIGNS SUPREME WITH U.S. NAVY
NEWTOWN, Conn. - From the replacement of steam in the 1970s through the early part of the 21st century, the GE LM2500 has monopolized the supply of marine propulsion gas turbines to the U.S. surface combatant fleet.
General Electric has been able to translate this monopoly into a strong international position that has seen it win around 40 percent of the market for marine gas turbines. Until very recently, this translated into the LM2500 being the "go to" gas turbine for warship production programs. Indeed, for most of the last 30 years, the main rival to General Electric's LM2500 marine gas turbine was not other gas turbines but the increasingly capable supercharged and turbocharged diesel engines. It is notable that a powertrain consisting of four diesels is now becoming commonplace for ships in the 28,000- to 32,000-shp range that would previously have had gas turbine propulsion.
The LM2500's monopoly of U.S. Navy surface combatant power came to an end when the Navy selected the Rolls-Royce MT30 to power its new DDG-1000 Zumwalt class destroyers. The primary reason for this choice, other than the perceived need to diversify procurement, was the development of fully integrated electric propulsion, which made more effective use of the power generated by the ship's engines. IFEP also increased the flexibility with which that power could be exploited, making it possible to switch energy use between propulsion, sensors, weapons, and hotel services at will.
With the impending introduction of energy-intensive weapons such as lasers and railguns, this flexibility of energy use was a significant factor. The great attraction of using four gas turbines was the ability to conserve fuel by running only as many engines as needed for a given speed. IFEP removed that consideration and made the weight and volume savings achieved by switching from the four existing units to two more-powerful engines attractive. Although the DDG-1000 program was drastically cut back, the MT30 was also adopted for the LCS-1 Freedom class, putting the MT30 and LM2500 into direct competition. However, over the last year, it appears that the LM2500 has re-asserted its position.
Another competitor arose during the early years of the 21st century - Zorya-Mashproekt of Ukraine. This was the only supplier of gas turbines to the Soviet Navy, and the collapse of the Soviet Union had driven the company to seek replacement customers on the international market. The Zorya gas turbines lack the cutting-edge technology of their GE and Rolls-Royce competitors but are inexpensive, robust, and relatively simple to run. As such, they are attractive to newly emerging maritime powers.
The major challenge that faces the LM2500 over the next few years lies within the DDG-51 Arleigh Burke program. This was restarted after increasing expense and doubts over the basic design of the DDG-1000 caused the truncation of that program. Future variants of the DDG-51 will use the IFEP concept, but it is unclear whether the redesigned powertrain will retain the four existing LM2500s, replace them with two more-powerful LM2500 variants, or shift to a pair of more powerful engines. If that route is selected, it is by no means clear that the MT30 would be adopted; both the LM2500+ G4 and LM6000 would be equally viable candidates. Our forecast assumes that in the short term, at least, the existing four-gas-turbine layout will be retained.
The civilian market for marine propulsion LM2500s remains a severely limited niche. The fuel consumption of gas turbines has proven to be a major disincentive to their adoption. Although there was a move toward using gas turbines to power hydrofoil and surface-effect ship ferries in the 1990s, this ran afoul of fuel costs, and those ships have been either scrapped or re-engined with diesels. At this time, the only significant civilian use for marine gas turbines is in cruise ships, where their low emissions and instant power response are valuable assets that offset their fuel consumption.
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