Across North America homes have massive tanks of hot water regardless of the outside temperature or other concerns. The energy cost to heat all this water is immense and not only can we reduce this cost we can use the water itself to power homes. The basic idea is to convert the temperature change in water into energy and vice versa to have the water tanks function has batteries. The coolest thing about this idea is that it’s not even a new one.
Here’s how it works. The heat pump water heater is like a refrigerator running in reverse. Instead of taking heat out of the unit (cooling) and dumping it into the nearby room air, the heat pump water heater dumps heat from the air around it into the water. This is vastly more efficient than heating water in the old way, with a high-wattage electric coil.
There is actually a little-known tradition, going back to the late 1930s, of electric companies managing water heaters to avoid short-squeezes on the grid during times of peak consumption. Because water can be kept hot so long, consumers don’t even notice. Originally this was done with timers, later via radio signals, and today through the cloud. And, thanks to smart meters that track energy use by the minute, demand-shifts can be very precisely targeted and valued. Water heaters, reborn as big thermal batteries, are an excellent means by which lots of clean power can be strategically banked for later use. Hundreds of thousands of water heaters have already been quietly hooked up this way. This is just the tip of the potential iceberg.