Valuing Demand-Response Benefits In Eastern PJM

Fortnightly Magazine - March 2007

When summer heat waves cause electric demand to peak, they also often cause wholesale electricity prices to rise substantially above their average levels. However, since most electricity customers face retail rates that do not reflect this movement in wholesale market prices, they do not modify their consumption patterns, causing a significant drop in economic efficiency. The Energy Policy Act of 2005 calls upon states and utilities to evaluate and implement DR programs to mitigate this problem. California has initiated comprehensive regulatory proceedings about demand response, advanced metering, and dynamic pricing. Other states, including Hawaii, Idaho, Illinois, Missouri, and New Jersey, are conducting pilot programs with a variety of innovative demand response rates and technologies.

The Brattle Group has just completed a study of the value of demand response for the PJM Interconnection LLC (PJM) and the Mid-Atlantic Distributed Resources Initiative (MADRI). The objective of the study was to quantify market impacts and customer benefits that would result form a modest 3-percent reduction of peak loads during the top 20 five-hour blocks in the service areas of BGE, Delmarva, PECO, PEPCO, and PSEG. We used a simulation-based approach to quantify the market impact that the specified 3 percent load reductions would have brought about in 2005 and under a variety of alternative market conditions. We performed the analysis using the Dayzer market simulation model, which we calibrated to represent the PJM market using data provided by PJM and public sources. By comparing market simulations with and without curtailments, we obtained the following results:

• Curtailing 3 percent of each selected zone’s super-peak load, which reduces PJM’s peak load by 0.9 percent, yields an average energy market price reduction of $8 to $25 per megawatt-hour, or 5 to 8 percent on average, during the 133 to 152 hours in which curtailment occurs in at least one service area. The range in average impacts depends on market conditions. As shown in Figure 1, even these modest 3 percent load reductions can reduce market prices by $50 to $75 per megawatt-hour in some of the hours.

• Assuming all loads (either customers or their retail providers) are exposed to spot prices, the estimated price reductions could benefit non-curtailed loads in MADRI states by $57 million to $182 million per year. The potential energy market benefits to the entire PJM system amount to $65 million to $203 million per year. Producer surplus would decrease by a nearly equal amount.

• The market impact in each zone would be substantially smaller if it curtailed its load in isolation from the other zones. By the same token, the market impact would be larger if more than five zones implemented DR programs or if greater amounts of DR participation were achieved.

Our study also estimated benefits to DR program participants:

EES North America

• The energy market benefit that