Why are some generators required to be on the grid quickly?
The requirement for generators to get on the grid quickly has been driven by the advent of renewables. Primarily, the reason is to have backup power available for quick dispatch to support grids that already have a number of renewables operating. In particular, renewables like solar and wind have a tendency to drop off quickly. Due to that, it’s important to have a fast-acting backup energy supply available. Gas turbines are the primary means of doing that.
The increase in renewable energy over the last 20 years has increased the need for this type of support. In the 1990s, renewables represented only about 3.5 gigawatts (GW) on the grid. In 2020 it went to 120 GW of renewables. With the increase in renewable energy comes greater opportunities for instability on the grid. We need more units to pick up the lost load when the sun sets or the wind stops blowing. That’s the opportunity for owners of gas turbines to offer this type of support to the grid.
What are the basic requirements for a gas generator to be considered “Fast Start”?
Generators have to come on within a certain period of time to provide capacity. The requirement to be considered “fast start” varies by market. Regulatory bodies establish standards for all entities within each market.
Is there a set of criteria or a regulating document that sets these standards?
It varies by the market and regulatory body. As a practical matter, that means you have to meet criteria to get your unit synced or fully loaded within a certain amount of time. ERCOT and a number of other regulatory bodies require providers to be on full load within ten minutes. On the other hand, PGM requires that units be online within 15 minutes. Yet, as more renewables join the grid and as technology improves, the criteria for “fast start” and what you can get paid for will change.
What markets in the US are considered “Fast Start”?
Fast Start markets have the greatest amount of renewables and greatest exposure to fluctuation in energy generation. Leading markets right now are ERCOT (Texas), PGM, and Western regions such as CALISO. All of these markets are making efforts to provide opportunities for operators to make their units Fast Start.
Why are some markets in need of Fast Start generation over others?
Markets with a greater percent of renewables, particularly wind, are in need of Fast Start generation. Iowa is the state with the greatest percentage of renewables with about 50% of its energy generated by wind. ERCOT in Texas has the highest amount of total wind generating capacity (20 GW), which is 20% of its total generation capacity. Those markets are considered for Fast Start for these reasons. Additionally, as steam plants and coal plants are phased off the grid, markets that traditionally relied on them will also seek fast start capabilities.
What type of generators are best suited for “Fast Start” duty?
The simple answer is the generators that get loaded and synced the fastest. Traditionally, that is aero engines because they are lighter and start-up faster. Beyond that, simple cycle units lend themselves better to Fast Start duty because unlike combined cycle, they don’t have a heat cycle requirement. Older, simpler units are also viable candidates because they have simple combustion systems and start-up cycles. A lot can be done to make these units Fast Start ready without affecting the maintenance factors on the unit. Next would be DLN machines with simple systems. Combined cycle and complex DLN units are the final options for Fast Start as they don’t offer as much ease in making upgrades.
What can you do to your existing asset to see if it is suitable for “Fast Start” service?
The first step is to understand your market and their requirements around Fast Start Service. Baseline your unit against those current regulations, including times for purge, fire, acceleration, synchronization, load, and total time. It’s important to baseline your unit against the original design, not where it is at currently (if you’ve made upgrades, for example). Once you understand your unit’s suitability, you can determine the modifications it needs and whether it will meet the final criteria. From there, you can offer the unit as a Fast Start option and make revenue.
What types of modifications can be done to gas turbines to compete in the “Fast Start” markets?
Modifications that can be undertaken on any gas turbine are driven by the current start-up and loading capabilities and process for the gas turbine. Essentially, anything you can do to shorten the start-up process is important. Generally, that means any steps you can take to remove delays and start the unit rotating after initiation, accelerate the firing time, eliminate waits or any other form of delays.There are a number of different benefits and costs for each of these upgrades. TTS can assist you in understanding your needs and what steps are most cost effective and beneficial to getting your unit to Fast Start ready.
Which modifications provide the most decrease in startup time?
These modifications are driven by the unit and manufacturer’s requirements, but generally reducing the loading times for synchronization. The next best modification to decrease startup is to look at any purge time you can reduce to what is the minimum required for safe operation. Or you can eliminate the purge time by modifying your gas delivery system to gain a purge credit. This is one of the most beneficial in terms of reducing time, but depending on the steps you need to take, there could be hardware costs to modifying your liquid or gas fuel system to accommodate purge credit requirements. The next best thing is to eliminate any waits, warm-ups, or stays in the unit’s ignition process.
Fire on the fly is a cost effective controls modification that reduces all of those times. Updating the loading time is usually achieved with simple software modifications that don’t require a major capital investment.
Take Your Unit from Vintage to Fast Start Ready with TTS.
These updates and modifications should all be looked at on a case-by-case basis to determine the best outcome for your unit. At TTS, we don’t look at all units as the same. Our team will provide a custom consultation on your unit and help you determine the best modifications that will take your unit from vintage to Fast Start ready. Getting units up and running is not only necessary for grid stability, but for your own revenue goals. That’s our promise at TTS.