Red and yellow alerts: what May 2023 taught about availability

The Luzon grid went to red alert on several days in early May 2023, with yellow alerts around them, when a string of forced outages at large plants met the hottest weeks of the year. Some distribution areas saw rotating cuts of an hour or two. The Visayas had its own alerts the same month. Nothing failed catastrophically; the margin simply ran out.

Compiled in September 2026 from the releases of the time, with the revisions the agencies have published since. Nothing here is a forecast.

What an alert is

The system operator declares a yellow alert when the reserve falls below the size of the largest unit on line, and a red alert when the reserve is gone and load has to be shed. The alerts of May 2023 were the result of ageing coal and gas plants tripping in the same fortnight, on a grid whose peak had grown faster than its dependable capacity since the pandemic.

The arithmetic of an hour

For a factory the alert is not a headline but a spreadsheet. A line that stops loses its output for the hour and, for a process with a start-up, for several more. A cold-chain plant loses product. A mill with a boiler on grid-fed pumps loses steam. The cost of an hour is specific to the site and is usually far larger than the electricity that would have been bought in it.

What the plants with their own generation did

They ran. A sugar mill with a bagasse boiler and a turbine, a rice mill with a husk-fired unit, a food plant with a biogas engine: each kept its process on its own steam and its own power and, in some cases, exported into a grid that was paying the price cap for it. The alerts were the first time in a decade that self-generation had been an availability decision rather than a cost decision.

What followed

The alerts of 2023 returned in April 2024, with El Niño behind them, and the market operator's reserve market opened in between. The lesson did not change: a site that needs steam and power at 2 p.m. on a May afternoon needs to own the plant that makes them, or to accept the hour.

If your site runs a fuel-fired boiler or produces an organic residue, an energy and waste audit puts your own numbers against this. Tell us about your site and an engineer replies with the data we need. The figures behind each quarter are in the quarterly market brief.