[adwww]

This is actually a big potential for a smart grid - turning on or off demand from things like fridges and ovens in response to the grid frequency changing.

If the grid is very slightly over 50hz it means demand exceeds supply and vice versa.

By automatically switching off the pump on thousands of fridges for a few seconds, networks would require less generation capacity on standby - saving $$$ and CO2.

Of course, like you say, this would leave potential for this to be used in reverse to destabilise an entire grid.

[jaywalk]

> If the grid is very slightly over 50hz it means demand exceeds supply and vice versa.

Not to be too pedantic, but it's actually the opposite. Frequency drops as demand goes up, which requires more supply to compensate. This is because the generators physically spin more slowly as they are put under more load.

[adwww]

thanks, I knew I should have googled to check...

Also occurs to me that it's 60hz in North America, but point roughly remains!