Changing when we use energy to fit the ‘duck curve’

January 9, 2018
By: Robert Sanders

Solar and wind energy production have ramped up to such an extent in California that for a few hours last year, nearly 40 percent of all energy in the state was supplied by renewables.

With this comes a problem, however: too much electricity from solar in the middle of the day, represented by the fat belly of the so-called duck curve, and a sharp drop-off in the evenings and mornings.

Berkeley Lab physicist Mary Ann Piette, a UC Berkeley alumna, wants to address this by changing when Californians use energy, taking advantage of the more abundant and cheaper energy at midday and reducing the demand, or load, at other times of the day, when energy is more expensive and more carbon-intensive.

Image of duck to illustrate the duck curve
The so-called duck curve illustrates the large renewable energy supply in the middle of the day (the belly), when solar production peaks, compared to evenings and mornings, when solar production goes away.

Appliances and cooling systems, for example, can receive automated signals and reduce or shift the timing of electricity use. Thermostats with “Rush Hour Rewards” cut air conditioning use after sunset when demand on the electrical grid peaks.

In her Cal Future Forum talk, Piette discussed how Berkeley Lab research has led to more energy-efficient appliances and building requirements. Now, as director of the Building Technology and Urban Systems Division and of the Demand Response Research Center at Berkeley Lab, she and her colleagues plan to develop technologies that let the state’s energy production and energy consumption talk to one another.