What Is a Balancing Authority?

A balancing authority is the organisation responsible for keeping electricity supply and demand in balance across a defined area of the North American grid. It forecasts demand, schedules and instructs generators, measures the power flowing across its borders with neighbouring areas, and corrects any mismatch in real time. There are around sixty of them covering the lower 48 states, and they are the reason hourly data for American grids is available at all.

The job in one sentence

Within its own footprint, a balancing authority must make generation plus net imports equal demand plus losses, continuously.

Everything else follows from that. It needs a demand forecast for tomorrow and for the next hour. It needs generators under instruction, or a market that produces the same result. It needs metering on every line crossing its boundary, because power flowing in or out counts towards the balance exactly as local generation does. And it needs reserves it can call on when the forecast is wrong or a plant trips off.

The control room watches a single number that captures how well it is doing, comparing actual flows across the borders and actual frequency against what was scheduled. Persistent error in that number is a reliability problem, and performance against it is measured and reported.

Where the boundaries come from

Balancing authority areas are historic. Most began as the control areas of vertically integrated utilities that owned generation, transmission and the local wires, and their edges still trace those old service territories. That is why the map looks nothing like a map of states.

You will find large areas covering many states, for example PJM across thirteen states and the District of Columbia, alongside small ones covering a single city utility or a single federal dam project. Some are single companies, such as Southern Company’s area in the southeast. Some, such as the Bonneville Power Administration in the northwest, market power from federal hydroelectric dams. Our full list is on the grid zones page, and there is a national summary at our United States page.

Three separate alternating current systems make up the continental grid: the Eastern Interconnection, the Western Interconnection, and Texas. Balancing authorities inside one interconnection are synchronised with each other and can exchange power freely, subject to the capacity of the lines. Power moves between interconnections only through a small number of direct current links.

How they differ from ISOs and RTOs

This is where the vocabulary gets confusing, because the terms describe different things and one organisation can be several of them at once.

Balancing authority is a reliability role. It is defined by the continent’s reliability standards, and whoever holds it is accountable for the second by second balance in that area.

Independent system operator and regional transmission organisation are market and transmission roles. An ISO or RTO runs the wholesale markets for a region, dispatches generation across many separate utilities on a least cost basis, manages access to transmission that it does not own, and plans expansion of that transmission. The distinction between the two terms is largely one of scope and history rather than function.

In practice every American ISO and RTO is also the balancing authority for its region, so CAISO in California both runs the market and keeps the balance. The reverse is not true. Most balancing authorities are not ISOs: they are utilities that balance their own area without running a market at all, buying and selling with neighbours through bilateral contracts instead.

The consequence for anyone reading the data is that the areas are not comparable in kind. One row in a table may be a multi state market covering tens of millions of people, and the next may be a single municipal utility.

Where the hourly numbers come from

Balancing authorities report their operating data to the US Energy Information Administration, which publishes it in a public hourly dataset covering demand, the day ahead demand forecast, net generation, generation broken down by energy source, and the interchange with each neighbouring area. This is the basis of every grid zone page on this site.

A few things are worth knowing before you read those numbers closely.

• The figures are operational, not audited statistics. They are the operator’s own meter readings and estimates, and they are revised.
• Different quantities arrive with different delays. Demand is close to real time. Generation by fuel arrives later, and the detailed flows between neighbouring areas later still.
• Demand and generation are not the same series. An area that imports heavily will show demand well above its own generation, and an exporter the reverse.
• Net generation can include negative values for a fuel, most often where pumped storage or batteries are consuming power to charge.

Our methodology page explains how we handle these points, and why operator data is always kept separate from the annual statistics we publish for countries.

Why the concept matters outside North America

Every synchronised grid in the world needs the balancing function, but few other places use this name or divide the responsibility so finely. In Europe the equivalent role sits with transmission system operators, usually one per country, and markets are organised around bidding zones rather than control areas. In most other countries a single national operator does the job.

North America is unusual in having so many balancing authorities within one synchronised system, and unusual again in publishing their hourly numbers openly. That combination is why the United States gives a more detailed public picture of an operating grid than almost anywhere else.