I have this in my home. I don't think it's been used at all this year, but last summer it was on multiple occasions.
How it works (in my area at least) copied from your linked site. Essentially, radio signal.
> If the demand for electricity escalates to a critical point, a "system emergency" or "peak alert" is announced, and Alliant willl turn on the radio signal that activates the switch on your air conditioner. The receiver will be activated to cycle the outdoor cooling unit according to the program option you elected.
How it works (in my area at least) copied from your linked site. Essentially, radio signal.
> If the demand for electricity escalates to a critical point, a "system emergency" or "peak alert" is announced, and Alliant willl turn on the radio signal that activates the switch on your air conditioner. The receiver will be activated to cycle the outdoor cooling unit according to the program option you elected.