Water Heater Energy Storage: “Inefficient” Electric Heaters May Have Role in Smart Grid
December 18, 2012
Germany apparently still has 1.4 million electric heaters spread across roughly 40 million households, putting the percentage of electric heating at around 3.5 percent. Nonetheless, RWE estimates that these electric heaters could add the equivalent of around 10 gigawatts of pumped storage – equivalent to an eighth of peak German power capacity and a sixth of peak demand on a normal workday.
The approach will only make sense, however, if the heaters are not only used to store power at night, but quite the opposite – to store excess renewable electricity during the day. Going forward, the problem Germany faces is not a lack of demand for power at night, but excess solar power during the day.
While this option marks a fundamental break with environmentalists’ previous focus on more efficient heating systems, the renewables community is increasingly praising electric heaters as a way of allowing more renewables to be installed.
The Bonneville Power Administration (BPA) is recruiting one hundred homeowners in Washington for an experiment on how to store surplus wind energy. The BPA is testing a promising smart-grid concept that would use residential water heaters to help manage the fluctuations of wind energy generation.
The project will address two problems experienced on the grid: shortage of power during peak times and surges of power during windy periods, when the energy isn’t needed.
While homeowners will be able to override the control device at any time, it’s unlikely that they would even notice a change in temperature.
The water heaters in effect become energy storage devices — turning on to absorb excess power and shutting down when demand ramps up —leveling out the peaks and valleys of energy use. Benefits include:
- no need for expensive and toxic battery storage
- no need for fossil fuel burning power plants to fill in low wind energy gaps
- water heaters provide distributed storage, avoiding point loads on grid
- smart water heaters can be manufactured economically, for just a few dollars more.