Enabling Technologies, Electric Grid

Demand Response Analysis

Demand Response (DR) used to be just Shed. Now there are four flavors.

Since 2015 CIEE has been assisting the California Public Utilities Commission in the analysis of the potential for demand response (DR) in California. As part of a continuing effort, CIEE is now managing a $5,000,000 prime contract. CIEE’s primary role is to identify and subcontract with researchers who can perform the work needed by the CPUC.

The work has already produced a major report by LBNL (see link below), which used high resolution energy consumption data to estimate the potential for demand response in California. The current research agenda includes examining the role of new types of demand response (see figure) in meeting the needs of the growing penetration renewable generation on the California grid.

Until recently, DR was focused on meeting system “peak capacity” requirements during periods of peak demand. The tool of choice was “Shed,” that is, reducing load during periods of high demand, which has historically been driven by the hottest days of the year.

California’s goal of further increasing renewable energy supply on the grid, and emerging technology for communications and load control, has created the need for new DR strategies. A major challenge is surplus energy in the middle of the day and large ramps in the net load as the sun sets—the now well-known “Duck Curve.” Another challenge is the fairly rapid fluctuation in supply from changes in wind speed or the availability of sunlight, which are layered on top of existing fluctuations in demand.

A key insight from LBNL’s DR Potential study was that, in addition to Shed, new DR strategies—“Shape,” “Shift” and “Shimmy”—were likely to be important in managing the grid in the future. The objectives of Shape and Shift are the same: shifting load in response to renewable energy availability. In the language of the Duck Curve, they move load from the Duck’s neck to the Duck’s belly. The difference is that Shape is structural and Shift is dispatched. That is, Shape shows up as more permanent changes in the load shape over a period of time that result from customers’ behavior change in response to rate schedules and Shift results when the load is controlled directly—either by CAISO or by a DR aggregator who mediates the relationship between customer loads and the energy market. Shed continues to be a valuable service, providing valuable peak load reductions to defer or avoid the need for costly grid upgrades, with possible future applications at local and neighborhood scale. Shimmy refers to fast DR that supports stability on the grid in response to wind and solar fluctuations.

Future work on this project will be guided by needs identified by the CPUC. The work may include acquisition and analysis of more recent utility data, deeper analysis of the potential for Shape and Shimmy, continuing improvements of the modeling infrastructure, more locationally granular analyses of DR potential, and DR strategies for handling contingencies.

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