Grid power is hard. Even with local generation failovers for air and ground safety systems, Heathrow is massive and uses a lot of power (1-2MWh/day). It's hard to route around that sort of demand.
I don't disagree that this is something that shouldn't happen, but that's what we say for almost every preventable grid failure. I think this is a national inconvenience rather than a security issue though. There are short-term alternatives which will be used.
It's 3 orders of magnitude more: 1-2GWh/day.
https://www.heathrow.com/content/dam/heathrow/web/common/doc...
The 2022 version of that sustainability report puts their annual bought in electricity at 272,610 MWh, 747 MWh per day.
My wonky maths aside, it's amazing how much energy they've saved. In your link, the switch to LEDs alone saw a 20% total power reduction. I'm sure I've seen electric vehicles there so I'm surprised this number is still apparently in freefall. Perhaps they're doing more local generation (eg) PV
That number doesn't seem that high, compared to a single high-speed train running at about 300kph or above. Or lets say all of the London Tube/DLR.
Seems like nothing, actually.
[0] https://www.bloomberg.com/opinion/articles/2025-03-21/heathr...
[1] I know precisely nothing about power consumption of large systems but dividing the annual figure by 365 seems plausible.
The point I was stumbling to try and make was that Heathrow is dense. Just under a GWh a day delivered to a 1200ha site isn't going to get a natural diversity of supply, especially compared to a rail system does.