The Economist has an article this week on the energy efficiency and reliability-enhancing characteristics of intelligent appliances, with the catchy title of “fridges of the world, unite!”. They discuss the GridWise Olympic Peninsula Testbed project in which I participated, although they focus on the frequency control aspect of the project and not on the price-responsive capabilities of the devices.
The most advanced project is the brainchild of the American Department of Energy’s Pacific Northwest National Laboratory (PNNL). Last year it completed the first residential trial of its “Grid Friendly Appliance” controller–a small device that listens to the AC-frequency hum of the electricity supplied by the grid. If the hum goes a little flat, that indicates too much demand on the grid, so whenever a controller notices the American standard 60Hz grid frequency dipping to 59.95Hz (something that usually happens at least once a day) it shuts off the heating element in the appliance it is regulating for two minutes. If, at the end of that time, the grid is still unstable, the element stays off for another two minutes, and so on until a maximum of ten minutes have elapsed.
It then goes on to discuss a British firm, RLtec, which is making refrigerators with “Dynamic Demand” technology to enable them to adapt dynamically to even smaller fluctuations in grid conditions. They believe that in aggregate, even such minute responses can lead to meaningful improvements in efficiency.