Pushing the 60% Efficiency Gas Turbine Barrier

Gas turbine makers GE, Siemens, and Mitsubishi Heavy Industries (MHI) in the last week of May separately profiled unprecedented results from development or testing of three innovative combined-cycle gas turbine (CCGT) technologies.

GE Launches Flexible, Efficient CCGT

GE launched its FlexEfficiency 50 Combined Cycle Power Plant—what it called “a first-of-its-kind” power plant engineered to deliver an “unprecedented combination of flexibility and efficiency.” The 510-MW power plant is said to be capable of offering a fuel efficiency of greater than 61% while featuring a one-button start in under 30 minutes.

GE said at the launch of the turbine in Paris that the plant was designed to cost-effectively integrate renewables into power grids on a large scale. According to the Financial Times, the plant’s 50-Hz gas turbine will initially be manufactured in France and be targeted at the European Union, which has set a goal that renewable power should provide 20% of all energy by 2020. GE has announced no plans for a 60-Hz U.S. model at present.

The new CCGT, which cost more than $500 million in research and development, draws from the company’s jet engine expertise “to engineer a plant that will ramp up at a rate of more than 50 megawatts per minute, twice the rate of today’s industry benchmarks,” GE said.

Development of the turbine began in 2004 after studies about how to best integrate intermittent renewable technologies into the grid showed that power systems of the future would characteristically see “more variability and uncertainty in the net load.” These systems could be managed with favorable “policies, power market structures, operating strategies, and investment incentives”—and advanced gas turbine technologies with flexible attributes would play a key role, GE said.

The company said GE engineers were able to avoid the “typical tradeoffs between flexibility and efficiency by approaching the plant design from a total equipment and control systems perspective.” Essentially, the FlexEfficiency 50 integrates a next-generation 9FB gas turbine that operates at 50 Hz (the power frequency that is most used in countries around the world); a 109D-14 steam turbine, which runs on steam produced from the waste heat from by the gas turbine; GE’s advanced W28 generator; a Mark VI integrated control system that links all of the technologies; and a heat-recovery steam generator (Figure 1).

1. Model of efficiency. GE launched its FlexEfficiency 50 Combined Cycle Power Plant in May—a 510-MW power plant capable of offering a fuel efficiency of 61% and more. Courtesy: GE

The gas turbine will now be tested in GE’s full-loading $170 million testing facility in Greenville, S.C., at full capacity in a variety of real-world power plant conditions, beginning in 2014. Commercial operation and first achievement of 61% is expected in 2015.

GE already has a couple of buyers. In June, China’s Harbin Electric Co. signed a memorandum of understanding for the purchase of four 9FB gas turbines before 2013, including two that incorporate FlexEfficiency technology. And in June, the plant was selected by MetCap Energy Investments, a Turkish project developer, for what GE says is the world’s first integrated renewables combined-cycle power plant. That plant, to be located in Karaman, Turkey, will be rated at 530 MW and is scheduled to enter commercial service in 2015. (For more on integrating renewables and fossil fuels, see this issue’s cover story.)

Siemens: H-Class Turbine Exceeds Expectations

Just days before GE’s launch of its new technology, Siemens announced that it had achieved what it called a “new world record in power plant efficiency” with the SGT5-8000H gas turbine at E.ON’s Irsching 4 plant in Bavaria, Germany. The decade-long innovation program for its new generation H-class gas turbine had surpassed 578 MW and reached a net efficiency of 60.75%. The Siemens turbine had been designed for 400 MW in simple-cycle duty and for 600 MW in combined-cycle duty (Figure 2).

2. More than expected. A Siemens Energy–built combined-cycle power plant—Irsching 4, near Ingolstadt, Bavaria, featuring Siemen’s H-class turbine—has achieved an efficiency of 60.75% and an output of 578 MW. This image shows the SGT5-8000H gas turbine in the foreground, the SGen5-3000W generator, and the SST5-5000 steam turbine—all of which are arranged on a single shaft. Courtesy: Siemens Energy

Siemens Energy CEO Michael Suess said in a statement that with this achievement, Siemens had “left all current records with regard to output and efficiency far behind,” and “raised the bar for operating flexibility.” Siemens tested a number of corresponding load gradients and found that more than 500 MW could be put online in 30 minutes and stable load gradients of 35 MW/minute could be run—“absolutely exceptional figures,” he said.

Development of Siemens’ H-class turbine involved 250 engineers, scores of workers, and the construction and operation of a prototype plant in Irsching that required an investment of €500 million ($734 million). The turbine was included in mid-2009 as part of a combined-cycle facility by adding a bottoming steam cycle featuring a heat-recovery steam generator and turbine operating at 600C. The trial operation period is expected to be completed this summer, when E.ON will take over commercial operation of Irsching 4.

Siemens has sold six new 60-Hz versions of the plant to Florida Power and Light, which is expected to receive them in 2012. South Korean utility GS Electric Power and Services Co. has also ordered a single-shaft combined-cycle plant featuring the 60-Hz version, which is scheduled to go online in 2013.

Testing of MHI J-Series Also Makes Headway

Meanwhile, MHI in May announced it had achieved a gross thermal efficiency that exceeds 60%, and “the world’s highest turbine inlet temperature” of 1,600C during test operation of its J-Series gas turbine, which began in February this year at a verification testing combined-cycle power plant at the company’s Takasago Machinery Works in Hyogo Prefecture. MHI said the accomplishment marks final confirmation in the testing of the new 60-Hz M501J, which MHI developed in the spring of 2009.

Theoretically, the higher a gas turbine’s inlet temperature, the greater is its thermal efficiency. The company claims that the turbine outperforms the 1,500C-class G-Series turbine, which held the record for the highest inlet temperature so far. The M501J has also achieved a rated power output of about 320 MW and 460 MW in gas turbine combined-cycle power generation applications, in which heat-recovery steam generators and steam turbines are also used (Figure 3).

3. Massive possibilities. Test operation of Mitsubishi Heavy Industries’ (MHI’s) J-Series gas turbines, the 60-Hz M501J, has shown that it can achieve a gross thermal efficiency of more than 60% because it is able to reach the “world’s highest turbine inlet temperature of 1,600C,” the company said in May. Courtesy: MHI

MHI is now developing a 50-Hz version, the M701J gas turbine, targeting first shipments in 2014. It adds that it will apply J-series verification results to the development of technologies to enable even higher temperature gas turbines. For now, MHI is expected to deliver six J-Series units to Kansai Electric Power Co.’s Himeji 2 power plant.

—Sonal Patel is POWER’s senior writer.