Not Your Father’s Water Heater

The home water heater, often forgotten as it sits in a dark corner of the basement doing its primary job – heating the home’s water – has emerged on the scene in Washington.

Last month PJM, along with a group of electric industry organizations, suggested ways to modify a federal rule that limits the size of residential electric water heaters to 55 gallons. The rule has the unintended consequence of removing electric water heaters as reliably available energy storage.

The U.S. Department of Energy is reviewing a rule change that would allow water heaterssteffes-water-heater
larger than 55 gallons that are used in grid-interactive water heater programs – which are most effective using tanks greater than 55 gallons. Grid-interactive water heaters are defined as water heaters capable of receiving a real-time signal from a grid operator, electric utility or other energy services company to control the way in which water is heated.

In addition to the joint comments, PJM’s separate comments to the DOE noted that advances in technology, grid integration of demand response and new market structures place new value on energy storage – all of them developments that had not matured when the DOE’s original rule was put into place.

PJM, working with the Steffes Corporation, has demonstrated the value of grid interactive water heaters serving as a fast-responding resource to providing ancillary services such as frequency control to the transmission grid.

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