In April 2025, Spain and Portugal were suddenly swallowed by darkness. Tens of millions lost power in an instant; hospital emergency rooms ran on backup generators; subways stopped, traffic lights went black. People spent a long night in anxiety and confusion before the cause was identified. On that day we were reminded, in our bodies, how impossible it is to last even a single day without electricity.
So who, exactly, holds up the power grid that supports our lives in such fine detail? Everyone knows that power plants generate electricity. Very few have heard of “ancillary services” — the work that gets the electricity safely into the outlet at your house. Making electricity matters; so does delivering it reliably, and the second job requires equally advanced technology and equally meticulous institutional design. Ancillary services are exactly that second job — the hidden backbone of the power grid.
Electricity is a peculiar form of energy: the moment it is produced, it must be consumed. Supply and demand must match without a margin of error; the instant they diverge, frequency wavers, and at worst the result is a mass blackout. Ancillary services are the invisible safety net that holds this balance in real time. Frequency control, voltage regulation, restoring the grid after an outage — all of this falls inside the category. Until recently, the role belonged mainly to large thermal and hydro power plants. Switching plants on and off, tuning the flow of power moment to moment, was the traditional face of ancillary services.
The problem is the world has been changing fast. Coal and gas plants, with their heavy rotating mass, carry inertia that naturally absorbs frequency shocks. Solar and wind, connecting to the grid through inverters, have none of this physical inertia. As the share of renewables rises, the grid becomes more easily destabilized by small disturbances — the so-called “low-inertia grid” problem. The reason ancillary services have moved, in the carbon-neutral era, from a supporting role to the heart of grid operation lies exactly here. Expanding renewables is not simply swapping one generation source for another. It demands a fundamental redesign of the entire ancillary-services system, and that’s worth remembering.
The world is moving quickly to respond. Ireland began the DS3 program (Delivering a Secure, Sustainable Electricity System) in 2011, requiring batteries and wind turbines to detect frequency anomalies and respond within two seconds. The result: Ireland now supplies up to 75 percent of its electricity from renewables while maintaining grid stability. The UK built a system of daily auctions to procure these services from batteries and electric vehicles, and Japan went so far as to create a dedicated reserve product for handling forecast errors in solar and wind. A role that had been the exclusive province of power plants has been thrown open to every participant in the market.
One technology in particular is worth watching. Vehicle-to-Grid (V2G) uses the batteries of parked electric vehicles directly for grid stabilization. In a Danish pilot, a single EV participating in this service earned roughly $1,200 in annual revenue. The era in which home batteries, smart refrigerators, and even factory equipment contribute to balancing the grid is already in front of us. People who used to only consume energy are becoming producers — and reliable members of the safety net. The shift is well beyond a technology demonstration; it is opening a whole new horizon of energy democracy.
Innovation in ancillary services is not a purely technical question. Depending on how the institutions and markets are designed, consumers and businesses alike can become active participants in protecting the grid. In the future grid, where renewables are the main act, ancillary services must be more important and more varied than ever before. A future in which electric vehicles, batteries, and smart appliances all become true partners in grid stability — preparing for that future, carefully, starting now, is the most important task on our energy-policy desk.