In part 3 of a 3-part blog series, Bob Bellis answers important questions about gas plant flexibility.
When we talk about dispatchable load range, what we mean is the ability for your equipment to reach “higher highs” and “lower lows”—as well as faster ramp rates up or down between these two load extremes—all while continuing to run reliably, and in emissions compliance. Expanded dispatchable load range is key to helping ensure grid reliability as grid operators continue to add more and more non-dispatchable renewable generation to their grids.
In addition, the risk of grid emergencies and upsets in grid frequency are becoming more common since non-dispatchable, low inertia renewable power sources make up more grid capacity than ever before, and extreme weather events are happening more frequently.
As an example, let’s look at what happened in Texas in 2021, when the state was hit with an unprecedented winter storm that caused many conventional power plants and renewable energy generators to go offline, prompting Electric Reliability Council of Texas (ERCOT) to cut electricity to millions of residents to protect the grid from complete collapse. This event served as a catalyst for grid operators to incentivize power providers to invest in upgrades to better manage emergency situations, and for power providers themselves to investigate options for both surviving and responding to grid emergencies.
In this blog, we will talk about strategies to improve dispatchable load range, as well as to better survive and respond to grid emergencies, from the power provider’s perspective:
- We’ll spend the majority of the blog talking about short-term, lower cost quick hitters that you can implement before the next peak season.
- We’ll also touch on long-term upgrades that require a year or two of planning, a significant financial investment, and potentially a scheduled multi-week outage to install.
Short-term solutions:
Peak fire
Peak fire solutions enable turbines to deliver incremental output above and beyond the normal baseload level for a short time, as there is a tradeoff of both increased wear and tear and increased emissions. However, this tradeoff may be worthwhile in grid emergencies and/or to financially take greater advantage of high-power prices in periods of high-power demand. Peak fire provides the flexibility for generators to make this tradeoff decision on the fly based on their own economics.
GE Vernova has multiple peak fire offerings, including Robust Extended Peak for F-class gas turbines. As our most sophisticated peak fire offering, Robust Extended Peak leverages OpFlex Enhanced Transient Stability (ETS) and AutoTune software to manage turbine and combustor operability. This solution enables the highest possible firing temperature increase and therefore greatest output increase at any ambient condition. Output increases of as much as +4 to +5% are possible. Robust Extended Peak can also be configured to operate to the maximum possible output while holding a user set emissions level. Simpler versions of variable peak capability are also available to provide increased output capability on older units with older controls and/or software.
We also have digital solutions to help with peak fire, including GE Vernova Electrification Software’s Capacity Trader software, which significantly increases the revenue stream potential from peak fire operation while actively managing the maintenance impact. This is accomplished by a combination of control software to “bank” peak fire maintenance credits during part load operation and decision support software to identify when peak fire operation is recommended to be used (e.g., for high profit opportunities in deregulated markets or to help reduce energy imbalance costs in regulated markets). This has been very beneficial for our customer Competitive Power Ventures (CPV), which has been able to increase its use of peak fire at its gas plants by 10x without impacting maintenance intervals.
For more information on our peak offerings, visit our OpFlex website
Trip avoidance
Trip Avoidance software modernizes a unit’s software to our latest and greatest library standards, much like the software a customer would get when purchasing a new unit. This software has rationalized protection logic which is the result of studying the logic from a customer perspective.
The concept here is that not all gas turbine operation events need to result in a protective action, such as a trip which causes the unit to no longer generate power. From a customer’s perspective, if the event doesn’t pose a safety or equipment damage risk, there’s no reason to trip, and so the revised protection logic might change the trip to an alarm to allow continued operation and therefore continued generation of reliable power.
Building on the concept of trip avoidance software, GE Vernova is exploring further capabilities to allow gas turbine operators to suspend certain operational constraints (like emissions limits, maximum temperatures, pressures, etc.) for short durations during declared emergencies—and even for rare short-term commercial opportunities, like when power prices are very high. As noted earlier, the potential for grid emergencies appears to be increasing, making the need to explore changes to operational limits more urgent.
Sliding fuel pressure
This solution is a good option to improve tolerance to low pipeline gas pressure, which can happen, for example, during a cold winter storm when gas is being diverted away from power generation to support residential home heating. Being able to keep a power plant running when less gas is available helps support reliable production, and both better enables your plant to survive grid emergencies and continue to earn revenue.
Ramp rate
Ramp rate refers to the rate at which the gas turbine’s power output can be increased or decreased over a period of time. How fast a gas turbine can ramp up and down is critical for grid stability and system reliability because it helps enable the integration of more and more renewable energy sources onto the grid. Turbines with higher ramp rates can be more flexible and agile to better adapt to changing operating conditions, which helps enhances overall performance and economics.
Hydrogen
All the offerings we have for natural gas can help with plant flexibility, and we’re doing the same with hydrogen. Our goal with gradually switching over to hydrogen as a fuel source for gas turbines is to maintain—or even expand on—the flexibility we can currently deliver when burning natural gas. Explore all our hydrogen solutions here.
Liquid fuel
For customers running their 7F gas turbines on liquid fuel because of a lack of available gas, GE Vernova’s liquid fuel (LF) system reliability upgrade helps resolve common pain points many 7F gas turbine operators face, resulting in greater efficiency, safety and reliability. With improvement options for simple cycle and peaking units, as well as combined-cycle plants, the LF system improvements help address issues such as failed starts, capacity shortfall and cost of weekly maintenance.
Long-term solutions:
We’ve talked about some of the shorter-term solutions we can offer for dispatchable load range and improved reliability for emergency operations, but there are some key strategic, long-term solutions as well, like Axial Fuel Staging (AFS) and Advanced Gas Path (AGP).
AFS
Implementing AFS can help you stay online and avoid the wear and tear of shutdown/startup cycling by significantly lowering the minimum load at which the gas turbine can operate while maintaining emissions compliance. The result is an expanded emissions compliant operating range with reduced emissions and reduced maintenance costs. For 7F gas turbines, AFS can improve emissions-compliant operation down to as low as 25% GT load, vs. ~40% today. Learn more about AFS here.
AGP
Whether added to the AFS upgrade or done standalone, our AGP upgrade offerings can increase the top end of the emissions-compliant load range of your 7F gas turbine, and enable increased capacity. Explore GE Vernova’s AGP Flex, Peaker, Standard and Tech upgrades. With AGP, you can increase your gas turbine output by up to 12%, improve your heat rate by up to as much as -2.5%, and extend your hot gas path intervals to 32K factored fired hours (FFH) or 1250 Factored Fired Starts (FFS).
