The power company also has for many years offered small rebates for allowing them to shut off selected appliances whenever they need to. There is a reciever attached to the appliance (usually water heater) that allows remote control. Large industrial users may also volunteer (or be forced) to have their power cut to a/c or specialized refrigeration if there is a need.
Google "electric load management"
Indeed, and some of those are indeed already the right sort of demand/load management, and I mention them on my page, but I'm proposing that in the UK/EU we should extend them to more domestic equipment, and to smarten up home computers to do things like bring forward sleep mode a little and screen dimming and the other things you mention when the grid is under strain almost as if they were on battery: never enough to be a severe nuisance to the end user, but enough to help keep the lights on without needing to keep a big inefficient generator on stand-by.
Rgds
Damon[ Parent ]