Ancillary services are the behind-the-scenes grid functions — frequency regulation and operating reserves among them — that keep electricity supply and demand balanced second by second. They sit apart from the bulk energy that actually powers homes and businesses, and the grid can't run without them.
— Overview
Why this exists underneath every bill
You pay for electricity as energy: the kilowatt-hours that run your lights. But underneath those transactions there's a second, mostly invisible layer of services holding the system steady between them. That layer is ancillary services.
This guide covers what they are, the main types, why they matter more every year, how grid operators buy them, and how flexible loads — demand response included — now compete to provide them.
01 — Definition
Secondary in billing, essential in function
Ancillary means support for a primary activity. Secondary in billing, essential in function. In electricity, the primary product is energy, and ancillary services are the supporting functions that make delivering it reliable.
They aren't optional extras. Without them, grid frequency and voltage drift out of bounds within seconds and equipment starts tripping offline.
02 — Categories
Names vary by market; the functions don't
Grid operators buy several distinct ancillary services. The exact names vary by market, but they fall into a few core categories.
03 — Trend
Faster swings, less predictability
Electricity supply and demand have to match instantaneously, and grid frequency is the live readout of whether they do. As predictable thermal baseload retires and variable wind and solar grow, output swings faster and less predictably, so the system needs more fast, flexible response to stay balanced.
Ancillary services have become one of the fastest-growing parts of grid operations, and operators keep widening the set of resources allowed to provide them.
04 — Markets
Increasingly, on a five-minute clock
Grid operators run dedicated ancillary services markets alongside the wholesale energy market, and increasingly co-optimize the two so each resource is paid for whichever it can supply most valuably at a given moment.
ERCOT is the clearest recent example. On December 5, 2025, the Texas grid operator launched Real-Time Co-optimization plus Batteries (RTC+B), which prices energy and ancillary services together every five minutes using Ancillary Service Demand Curves (ASDCs).
The value of ancillary services now moves on a five-minute clock. The resources best positioned to capture it are the ones that can respond automatically and fast.
05 — Providers
Generators, batteries, and now, loads
Traditionally, large thermal generators supplied ancillary services as a byproduct of running. Two newer sources now compete with them: batteries provide fast, precise frequency response and reserves, and demand-side resources — controllable loads that can raise or lower their consumption on command — compete directly, because reducing demand is electrically equivalent to adding supply.
FERC Order 2222 requires U.S. wholesale markets to let aggregated distributed energy resources, including flexible loads, participate. That's what opened ancillary services to demand response at scale.
06 — The Fit
Speed, depth, and reliability
A controllable load provides an ancillary service by adjusting its own draw. When the grid is short, the load reduces consumption, which has the same balancing effect as a generator ramping up. How much that load is worth as an ancillary-service provider comes down to how fast it can move, how deeply, and how reliably.
A fully interruptible compute load scores high on all three. This is high-density computing, like Bitcoin mining, engineered to be fully curtailable. It can shed 100% of its draw within minutes and resume without penalty. So it's a strong, deterministic provider of reserves and fast response — it moves on command, with the certainty of a single dispatchable asset rather than the probabilistic average you get across thousands of small devices.
This is the asset class Type 3 turns into a dispatchable, verified grid resource.
Type 3 is the software-defined demand response infrastructure company that turns fully interruptible compute loads into a dispatchable, telemetry-verified grid resource. Read the Manifest →
07 — Coverage
Every operator, its own instrument
Every U.S. grid operator runs its own ancillary services products with its own names and rules. What they share: each is rewriting its rules to bring faster, more flexible resources — storage and demand response — into services once reserved for power plants.
Leans heavily on ancillary services and reserves for reliability, and now co-optimizes them in real time under RTC+B.
Procures regulation and reserves alongside its capacity market.
Procures regulation and reserves alongside its capacity market.
Runs regulation and reserve markets with performance-based pay.
Ref — FAQ
Ref — Glossary
See the full glossary in the Manifest
Ref — Sources