Print
Email
Save
By Douglas J. Smith IEng, Senior Editor
Over the last few years, there have been drastic changes among gas turbine suppliers. Siemens has taken over Westinghouse while ABB has sold its power generation group, including the gas turbines, to Alstom. GE, in addition to taking over some of its former license holders and packagers, purchased S&S.
 |
According to Energy Ventures Analysis Inc., Arlington Va., a record 51,805 MW of new gas turbine based capacity is expected to be added by the end of 2001, Figure 1. This is a 117 percent increase over the capacity added in 2000. However, this will be overshadowed in 2002 and 2003 when more than 80,000 MW is expected to be added each year.
For the period 1998-2007, 305,304 MW of gas turbine based power plants will be in operation, under construction or actively in development. All of the additional capacity in development and under construction is expected to be on-line by 2007.
 |
By 2007, power plant developers are expected to add 20 to 40 percent to their current gas turbine based capacity. The three leading states: Mississippi, Arizona and Illinois, will add 133 percent, 77 percent and 66 percent respectively of new gas turbine plant capacity, Figure 2. In 2001, Texas (9,220 MW), California (3,110 MW) and New England (3,059 MW) are expected to be the most active states for new gas turbine capacity.
A major factor in the booming market for new gas turbine based capacity has been the stable and relatively low natural gas prices. However, even with the increase in natural gas prices in 2000 the market for new gas turbine plants continues to grow. Some of the reasons given for the continued interest in gas fired turbines include:
- Easier siting and permitting
- Availability of financing
- Shorter construction time for simple-cycle applications
- Lower emissions and increased efficiency.
Since the early 1990s, gas turbine manufacturers, aided by government funded research and development, have made substantial improvements in gas turbine technology. These improvements have resulted in lower costs of manufacturing, improved fuel efficiencies and increased reliability.
Buyers and Sellers
 |
By far the number one developer of gas turbine power plants is Calpine, with Duke Energy, Panda and Southern Energy all fighting for second place, Figure 3. The top 10 developers will account for 45 percent (136,580 MW) of the total gas turbine capacity expected to be in operation by 2007.
Calpine Corporation, the fastest growing independent power company in the U.S., plans to be the largest electric generator in North America by 2005. According to Peter Cartwright, Chairman, President and CEO of Calpine, the goal is to have 60,000 MW of base load capacity and 10,000 MW of peaking capacity by 2005. In 1995, Calpine's total capacity was a relatively small 268 MW.
Founded in 1984, Calpine currently has 5,900 MW in operation and 14,000 MW under construction. Recently the company announced a further 16,200 MW of new projects. Currently the company has a $15 billion construction program.
In April 2001, GE Power Systems received a firm order from Calpine for 35 model 7FB and 11 model 7FA gas-fired turbines. The schedule calls for the delivery of five gas turbines in 2002 with the remaining 30 units being delivered in 2005. With this latest order, Calpine now has firm orders for 203 gas turbines, all scheduled for delivery between now and 2005.
According to Ron Walter, Calpine Vice President for Planning and Development, the orders for the 203 gas turbines is split evenly between GE Power Systems and Siemens Westinghouse. The decision to go with these vendors was price, performance and lifetime reliability of the equipment, says Walters.
Can the Vendors Meet Delivery Schedules?
The predominant gas turbines being ordered are the "F" and "G" classes manufactured by GE Power System, Siemens-Westinghouse, Alstom and Mitsubishi.
Initially, the gas turbine buyers were skeptical about the suppliers being able to meet the delivery schedules. However, their fears have not been warranted. According to Gary Townsend, Director of Proposals, Black & Veatch, the gas turbine manufacturers have met all delivery schedules. In some instances the deliveries has been ahead of schedule, says Townsend.
At this time, all of the available manufacturing capacity for 60 Hz gas turbines is committed through 2005. Because of this, it is very difficult to order a gas turbine for delivery before late 2005 or early 2006. However, many people involved in developing gas turbine power plants say that the probability of all of the projects being constructed is highly unlikely. Even if they are constructed, commercial operation of some plants will be after 2006.
In order to meet the large increase in orders for gas turbines the vendors have streamlined the production and manufacture of gas turbines. Companies like GE Power Systems launched rigorous campaigns to audit major suppliers to ensure that they are able to meet the increased volume. In addition to existing vendors, GE has also begun qualifying new vendors who are able to meet the accelerated delivery schedules.
Many of the gas turbine vendors have also re-engineered manufacturing to reduce the cost and time to build the units. Using their "Six Sigma Quality Initiative" program, GE has been able to increase productivity at their Greenville, SC gas turbine plant.
Re-engineering of the manufacturing process at Greenville has reduced cycle time by 29 percent. Because of this GE Power Systems were able to ship 392 gas turbine units in 2000, a 112 percent increase over 1999. With re-engineering, GE has increased the Greenville's manufacturing capacity by more than 200 percent.
 |
According to Siemens Westinghouse, the company has orders for more than 400 gas turbines. Through 2003, approximately 95 percent of the backlog is secured through contract cancellation clauses, Figure 4. By December 2003, the combined manufacturing capacity of Siemens Westinghouse's German and Canadian facilities will have increased 250 percent MW in terms of MW output.
Although Siemens has some free capacity it is predominantly for 60 Mz machines.
Technology Updates
Siemens Westinghouse Power Corporation's W501F gas turbine, first introduced in 1990, was originally rated at 180 MW. However, recent improvements to the last row turbine blade has increased the maximum power capability to 215 MW, a 16 percent increase over the 1990 model. In the middle of 2000, the first upgraded units were shipped.
Evolutionary enhancements over the last 10 years have improved the efficiency of the W501F gas turbine by 6 percent and reduced NOx emissions by 67 percent. These improvement have come from increasing the compressor's first and second stage outer diameters, developing a new dry low NOx combustor, and upgrading the turbine's seals, vane cooling and the last row turbine blades. Designed for simple-cycle or combined-cycle operation the gas turbine can operate on all conventional gas turbine fuels.
GE Power Systems, Mitsubishi and Siemens Westinghouse have all developed steam cooling systems for the hot gas section of their gas turbines. Steam cooling will be used by GE Power Systems on the advanced "H" gas turbines while Mitsubishi plans to use it on their M501G/M701G turbines. Siemens Westinghouse's W501G gas turbine will use steam cooling.
 Manufacturing gas turbines in Greenville, SC. Photograph courtesy of G.E. Power Systems. |
Steam cooling will not only allow firing temperatures up to 2,600 F, it will mean a combined-cycle efficiency of over 60 percent. Although the steam cooled gas turbines operate at high firing temperatures the manufacturers say they are able to use conventional materials. According to Siemens Westinghouse, steam cooling allows their gas turbines to operate at higher rotor inlet temperatures while maintaining the same burner outlet temperature as conventional machines.
In May of this year, Siemens Westinghouse Power Corporation announced the commercial operation of the 360 MW combined-cycle Millennium plant in Charlton, Massachusetts and the 249 MW McIntosh simple-cycle power plant in Florida. The McIntosh plant will eventually be converted to combined-cycle operation. Both plants use the W501G gas turbine, which according to the manufacturers is the largest 60 Hz gas turbine in the world.
With the increased capacity and efficiency of gas turbines, the market for single shaft combined-cycle plants is expected to increase. Installation of the gas and steam turbines on a common shaft enables the plant to operate with a single generator. In addition, the turbines share lubricating and governing systems and have a smaller footprint.
Although Asia has been the leader in the installation of single-shaft combined-cycle power plants, there has been some action in North America, says Alexander Leyzerovich, a consultant to the electric power industry.
In Massachusetts, two single-shaft combined-cycle plants have been constructed. These are the 270 MW Agawam plant and the 4x260 MW Midlothian plant. In upstate New York, two 400 MW single shaft combined-cycle units, using GE Power Systems' 7H gas turbines, are also under construction. According to GE Power Systems, the first unit is expected to enter commercial operation in 2003-2004.
With shortened construction schedules, lower life-cycle costs, lower emissions, increased efficiency and flexibility, and the need to add capacity, the market for gas turbines looks promising. Although for the foreseeable future the need for new capacity in California and the Northeast will continue, Black & Veatch's Townsend believes that the average reserve margins for the rest of the country will increase to 30 percent by 2003. Even with a slowdown of the market after 2003, there will still be a need to add 20-25 GW/yr of capacity, says Townsend.
