Plant benefits
The advantages of aeroderivatives extend well beyond the turbines themselves. Read on to see how they can benefit your plant economics, flexibility, and maintenance--and even help you capitalize on alternative revenue streams.
The major component of LCOE for a peaking plant is attributable to total plant capital expenditure. This is why pure LCOE baselines are not a good evaluation criteria for peaking plants with low capacity factors. Instead, Net Present Value and Internal Rate of Return baselines are stronger evaluation points for such plants requiring short payback periods.
Project risks such as schedule delays, contractor cost overruns and unplanned costs such as regulatory compliance and codes and standards requirements have heavy implications on project total costs. These risks highly affect peaking project economics since it is capital expenditure sensitive.
The LM2500XPRESS and TM2500 solutions allow for cost overrun risk mitigation as the gas turbine package and auxiliary support systems are modularised, pre-fabricated and pre-commissioned as much as possible prior to delivery. This approach reduces the interface engineering risks between an OEM and a constructor, and also allows for a quicker installation and commissioning cycle .
The LM2500XPRESS and TM2500 both allow for a 3–4 month completion from Notice to Proceed, allowing for revenue streams to be capitalized faster upon financial commitment of a project.
The total on-site work scope is also vastly reduced because of the modular, pre-commissioned configuration, resulting in lower turnkey installed costs. This can make a difference where labour is scarce and labour costs are high.
As discussed, with a diverse energy mix of intermittent renewable energy sources, Australian power plant developers and operators face difficulties in forward forecasting of plant capacity factors beyond the 5–10 year timeframe, even though gas-fuelled power plants are often engineered for 25-30 year periods. Hence plant flexibility to transit from a peaking application to a mid-merit or base loaded application are highly valued criteria. For capacity factors exceeding 25–30%, a high efficiency solution capable of total plant efficiency above 53% LHV would have strong merit. The LM2500XPRESS and TM2500 gas turbine packages have the option of a High Efficiency Solution (HES). The HES involves the installation of a standardised and modular bottoming cycle, including a heat recovery steam generator, steam turbine, and associated auxiliary equipment, which can accommodate a phased installation approach.
HES (High Efficiency Solution) modularised bolt-on bottoming cycle configuration
The HES solution is completely modularized and skid mounted, reducing the installation and commissioning time on site (down to 12 months from NTP to completion). The HES solution is specifically engineered for the LM2500XPRESS and TM2500 solutions for a 1x1 or 2x1 combined cycle configuration and does not involve any onsite full seam welding activities between HRSG modules (the entire system allows onsite bolt-on installation practices).
With the HES solution, a plant is able to achieve 70% of total combined cycle power within 5 minutes, followed by 100% total plant power 25 minutes later. This creates the premise of a highly flexible plant capable of 5 minute fast starts and high combined cycle efficiency with load following capability. This makes the LM2500XPRESS/TM2500 HES solution one of the most flexible grid firming solutions available today.
The LM2500XPRESS and TM2500's maintenance intervals are typically 25,000 gas fired hours for hot section maintenance intervals, and 50,000 gas fired hours for overhauls. With a contractual services agreement in place, these machines can achieve up to 35,000 gas fired hour intervals by incorporating the appropriate preventative maintenance and monitoring regimes that are recommended by GE along with GE field services support. A peaking plant with 10% capacity factor would have approximately 30 years or more of uninterrupted operation prior to the first hot section interval, which translates to very low maintenance requirements and very high availability. It also results in lower fixed maintenance costs in terms of personnel and operator requirements.
The GE aeroderivative gas turbines are engineered to operate without consumption of lubrication oils. The only loss of lubrication oils is based on natural air vaporization of oils which is negligible.
Did you know? Maintenance events are about 50 times more frequent each year with high-speed reciprocating engines than with aeroderivative turbines.
The GE aeroderivative gas turbines also allow for various ancillary services revenue streams to be capitalized more effectively. The LM2500XPRESS and TM2500 have the ability to provide primary and secondary frequency response services with a ramp rate of up to 240 MW/min, voltage support via reactive current injection and absorption, spinning reserve, and non-spinning reserve with 5 minutes fast start capability from cold iron to full load. The LM2500 gas turbine can also participate in inertia contribution services without the need for additional hardware. It has an optional clutchless synchronous condensing feature based on its multiple shaft configuration, allowing the power turbine to spin freely without the need for a disengagement clutch. This is a key feature allowing peaking capacity to still be provided within 5 minutes while inertia contribution services are provided. The LM2500 gas turbine provides up to 1.2 MWs/MW of inertia, which is higher compared to alternative technologies in similar MW class such as reciprocal gas engines. The LM2500 gas turbine inertia contribution levels can be increased by increasing the size of the generator. The LM 2500 gas turbine also has blackstart capability allowing it to play a crucial role in system restart services.
The ancillary services segment is poised for growth not only in countries such as Australia, but other regions in which are experiencing high levels of renewable energy penetration. For example, the ancillary services segment for the Californian grid is worth approximately $70-80MM USD per annum. The creation of an ancillary services segment allowed for the average clearing price for energy in California to be reduced.
The LM2500XPRESS gas turbine package is delivered in 10 modules which are pre-wired, pre-fabricated and pre-commissioned. A 165-ton train can be utilized for heavy lifting or the various modules, followed by a 40-ton crane for smaller components that need to be lifted onto the major modules.
The various other modules such as the air filter, auxiliary skid, turbine vent fan, and generator silencer modules weigh below 10,000 kg. The TM2500 is engineered with trailers taking into account turning radius requirements per road safety standards which allows for simple road transportation exercises from the port of import to an actual site location.
The LM2500XPRESS modules are also engineered to fit standard road worthy trailers in terms of module dimensions to allow easy transportation by professional transportation companies. This allows for quick delivery of equipment to sites especially when there are road access and weight limitations which are commonplace in areas in need of quick power, compared to alternative technologies such as reciprocating engines which involve intensive transportation activities due to heavier load bearing activities and the need for larger clearances due to reciprocating engine block sizes. The engineering philosophy of a modularized, easy to transport gas turbine package, allows for faster installation and commissioning schedules on site. GE can provide guidance on installation footprints to arrive at the best site layout.
Figure 12 –Installation of a GE LM 2500 Xpress gas turbine package