Peaking Plant Applications
Get a closer look at how our aeroderivative gas turbines are a great choice for Australia's grid.
PEAKING PLANT APPLICATIONS
A quick look at solutions for Australia
Global challenges, local scale
GLOBAL CHALLENGES, LOCAL SCALE
With renewable energy penetration in electricity segments gaining momentum not just in Australia but globally, the operating profile and dispatch criteria of traditional base load power plants have had to respond accordingly.
Fast start, high ramp rates, part load operation and cyclical load following dispatch profiles are typical requirements of a grid with high renewable energy penetration. This is a result of renewable energy generation technologies that are intermittent, and may not be dispatchable at all times, which means grid control measures can no longer purely depend on forecasted supply and demand characteristics of users and generators.
This white paper abstract takes a look at the transition of the South Australian electricity grid, from a traditional base load-controlled grid to one of intermittent, non-dispatchable renewable energy supply, and the impact of this energy mix. Then, power generation technologies that best fit the peaking and grid firming segment criteria will be discussed, including fast start peaking and grid firming technologies.
Finally, if you're interested in reading the entire whitepaper, you'll be invited to download it at the end.
Look closer: South Australia's renewable energy transition
LOOK CLOSER: SOUTH AUSTRALIA'S RENEWABLE ENERGY TRANSITION
South Australia power generation type 2009/2010 (data sourced from https://www.aemo.com.au/media/Files/Other/planning/0400-0013%20pdf.pdf)
In 2009 the South Australian grid consisted predominantly of fossil fuel generation technologies, with coal and natural gas generation being the main base loaded power generation supply in the state.
Based on South Australia's ambition to reduce carbon intensity, renewable power generation developments were given financial incentives such as tax rebates, and electricity retailers were required to source a proportion of energy from renewable resources, which encouraged a surge in green field wind and solar projects.
The levelized cost of electricity (LCOE) of renewable energy sources are approximated at $3-6 US cents/ kWhr per (as cited by Lazard Levelized Cost of Electricity Analysis version 13) for large scale wind and solar generation projects. This has forced base loaded generators dependent on fossil fuels such as coal and gas power generation to switch from a base loaded power profile, to a midmerit, cyclic profile as a result of not being able to compete on an LCOE basis, especially when there is a surplus of a renewable power generation.
This phenomenon was experienced in South Australia, which gained a surplus of power generation, especially during daylight hours, forcing older coal fired power stations that were not able to be subjected to cyclic loading profiles due to maintenance impacts to be duly decommissioned. Existing large base loaded gas fired generation technologies were also not able to compete on an LCOE basis due to high costs of fuel gas ($8-9 USD/GJ yielding LCOE of $8-$12 US cents/kWhr for existing plants), forcing them to transition to a peaking generation profile with multiple starts per day. This resulted in the transition of the power generation portfolio in SA.
The shortfall of spinning frequency response reserves within the South Australian state made it vulnerable to frequency and voltage disturbances when running in an islanded mode.
South Australia Generation Type 2016/2017 (data source: AEMO)
The South Australian power grid became highly dependent on renewable energy resources, predominantly wind energy. This incentivized power producers to invest in new solar and wind generation projects, while minimal investment was made on transmissions networks, or grid firming and peaking technologies to accommodate a grid with high renewable energy penetration.
This inadvertently made the South Australian state more dependent on the Victorian interconnector for power shortfalls during grid events. In a scenario where the Victorian interconnector is disconnected, the South Australian region would be islanded, which would require the region to be self-sufficient for base loaded power generation.
It's not an uncommon problem. See how utilities and operators must constantly fill the gap between supply and demand, and how GE can help.
In September 2016, torrential weather resulted in South Australian transmissions lines and pylons being damaged, causing a contingency event on the grid due to voltage depressions below allowable limits based on protection settings of various wind farms. This caused certain wind farms to be disconnected from the grid, resulting in a shortfall of power generation.
Historically, in such events, spinning synchronous generation technologies such as gas and coal generation allow enough time for load shedding to automatically take place in the South Australian region to avoid a complete system blackout. However, with the region heavily reliant on renewable energy generation during the contingency event which could not supply the equivalent amount of inertia, the rate of change of frequency exceeded the response capability of load shedding systems to avoid a system blackout. As a result, South Australia went into a complete state blackout for more than four hours.
Since the South Australian event in September 2016, many measures have been taken to increase grid stability and to allow better management of grid events whilst still maintaining high levels of renewable energy generation.This includes battery storage systems, fast start peaking and also grid firming dispatchable power plants, which have made the South Australian network more resilient against statewide blackouts.
The learnings from the South Australian region are being discussed and applied to other regions in Australia to ensure grid resilience during the transition to a high renewable energy grid. The lessons learned, and measures taken, are applicable to other regions around the world that are also forecasted to be heavily reliant on renewable power generation. The result of this is the emergence of the peaking, grid firming, and energy storage segment. GE's aeroderivative gas turbines are a great fit for these segments. In the next two sections, you'll find out why.
Aeroderivative gas turbines
Benefits for Australia
AERODERIVATIVE GAS TURBINES: BENEFITS FOR AUSTRALIA
Within GE's portfolio, our aeroderivative gas turbines provide the highest degree of flexibility, and also the most competitive installed cost for peaking market applications. The LM2500XPRESS and TM2500 gas turbine solutions have been specifically engineered for peaking applications.
Meet the modular aeroderivative duo
The criteria for peaking plant applications results in the modularized LM2500 Dry Low Emissions (DLE) gas turbine as the primary and most competitive solution on a $/kW installed basis. The LM2500 has two standardized solutions, a trailer mounted configuration (TM2500), and a land-based configuration, both of which are highly modularised, allowing short installation and commissioning schedules within approximately 3-4 months from Notice to Proceed to completion.
For applications in which mobility is not a priority, the LM2500XPRESS solution is a great fit. The LM2500XPRESS maintains the modularized configuration philosophy that is applied on the TM2500 without the trailer base frame, meaning it's engineered for more permanent installations.
The LM2500XPRESS has industry leading availability and reliability on a per unit basis (fleet average reliability 99.8% and average availability 98.5%), very important criteria for a peaking plant.
Take a tour of the LM2500XPRESS
The LM2500XPRESS package is also rated at plant net 32.5MW at ISO at an efficiency of 37.7% LHV and also is delivered equipped with the gas turbine engine, auxiliary support systems, generator, generator circuit breaker, and control house on prefabricated, pre-wired skids. These skids can be deployed, installed, and commissioned within 4 weeks of equipment delivery (assuming that the site is prepared and ready for installation).
The TM2500, rated at plant net 32.5 MW at ISO at an efficiency of 37.7% LHV, provides the best value for applications in which temporary power is required, but also provides the added advantage of being mobile, so it's easy to relocate to other site locations with minimal demobilization requirements.
The TM2500 is delivered with the gas turbine enclosure, air filter, auxiliary support systems, generator, generator circuit breaker, control house containing the motor control centre and generator control panels, and also the exhaust system mounted on actual trailers that are road worthy and easily transportable. This allows the TM2500 to maintain residual value at the end of a particular plant term or short leasing period.
TM2500 aeroderivative gas turbine package
Ease of installation
Based on the modularized configuration, both the TM2500 and LM2500 gas turbine packages are prewired, prefabricated, and pre-commissioned as much as possible in the factory to reduce the amount of site installation works. This includes flushing of lubrication oil systems, point to point wiring tests, and also engine pre-alignment procedures. This reduces schedule risk and site material costs, which are traditionally the main two drivers leading to project delays. The risk of configuration interface errors is also greatly reduced, as most systems are already pre-engineered and pre-connected and commissioned prior to the gas turbine package being delivered to site.
The gas turbine packages are also delivered with receptacle wiring interconnectors between the main pre-fabricated trailers and skids, to allow for quick plug and play interconnections. Access ways and ladders and platforms can also be pre-engineered and delivered specifically for critical access points of the gas turbine package.
Engine changeouts can be conducted within a 72 hour window by having a spare engine available on site, or via an engine lease subscription with GE in which provides a customer access to lease engines within the GE Services fleet. This enables a gas turbine to be replaced within an extremely short time frame, which allows high plant availability levels to be maintained.
See how the TM2500 gives you power in hours
Five minute fast start
Both the LM2500XPRESS and TM2500 gas turbines are capable of starting from cold iron, to full load within 5 minutes. The GE aeroderivative gas turbine range is capable of fast starts without any standby auxiliary load requirements. This is mainly due to the inherent characteristic of a LM2500 gas turbine which is a derivative of an aircraft engine, engineered for high cycling, and immediate high thrust applications.
Figure 8 – 5 minute start profile of a GE LM2500 gas turbine
Why can aeros start up so quickly? Because they’re derived from aircraft engines, helping planes achieve close to 300 daily starts and stops!
The LM2500XPRESS and TM2500 gas turbine packages have multiple fuel capability on both Dry Low Emissions (DLE) and Single Annular Combustor (SAC) options. The SAC option can handle a higher variety of fuels including Coke Oven Gas, LPG (100% propane or 100% Butane) and a variety of low BTU fuels. The DLE combustor can handle both gas and distillate fuels while meeting World Bank Guideline emissions limits without any water injection required.
LM2500XPRESS Gas Turbine
The LM2500 gas turbine has two combustor options, a Wet Low Emissions and a Dry Low Emissions. Both options comply with 25 ppm NOx @ 15% O2, and 25 ppm CO @ 15% O2 requirements. The LM2500 DLE combustor also has the option of meeting 15 ppm NOx @ 15% O2 emissions levels.
In Australian, a drive towards lower emissions has been a key energy initiative. Having the ability to meet lower, best in class emissions levels is an added advantage in future proofing a power plant in which emissions criteria may change within the 10-15 year timeframe.
There are currently more than 2,460 units of the LM2500 gas turbine family that have been shipped with a total of more than 92 million operation hours. The LM2500, and more generally the GE aeroderivative gas turbine fleet, has achieved its high reliability and availability levels based on its stringent preventative maintenance regime and also engine lease program. This allows for engines to be replaced as quickly as within a 72 hour window, allowing continued operation whilst the customers engine is being repaired or upgraded during planned outages.
See where the TM2500 has made its global mark
Part load operation
The LM2500XPRESS and TM2500 solutions are capable of operating down to minimum load (down to 10%) without restriction on load profiles as a consequence. Compared to alternative technologies such as reciprocating engines, in which restrictions would apply when operating below particular load setpoints, after which higher load operation is required to avoid slobbering effects, the LM2500XPRESS and TM2500 gas turbines are able to be parked at any load setpoint without suffering from any such consequences.
What feature of aeros would benefit your business most?
- Fast start
- Fuel flexibility
- Ease of installation
- Lowered emissions
Aeroderivative gas turbines
AERODERIVATIVE TURBINES: 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).
The LM2500XPRESS/TM2500 HES solution is one of the most flexible grid firming solutions available today.
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.
Capitalizing on alternative revenue streams
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.
Transportation and lifting
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