Category Archives: WECC

CAISO Time-of-Day Power Prices

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CAISO time-of-day power prices are changing.  The daily price profile now reflects a growing premium in the morning and evening hours,  The profile also includes a steeper price discount in the midday hours. The new time-of-day prices represent a market incentive: ramp power supply up or down more quickly on command.

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The Western EIM is Expanding

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The Western EIM (Energy Imbalance Market) is an interregional exchange that is gaining ground as CAISO adopts a larger share of renewable energy production.

What is the Western EIM?

Grid operators use the EIM’s advanced market systems to find the lowest-cost energy to serve real-time customer demand across a wide geographic area. EIM provides transparency on the status of multiple grids.

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The Renewable Energy “Duck Curve”

The California grid operator (CAISO) has a high of share of  renewable energy.  CAISO has adopted a mascot that sums up the challenge: the duck curve.

The chart at left presents the duck curve.  It shows net power load during the day.  CAISO defines net power as the difference between forecast load and expected power production.  In certain times, net load curves have a “belly” in the middle of the afternoon given a surge in solar power production.  The chart then shows a rapid ramp-up in net load – as much as 13 to 15 GWh – as solar production declines and demand accelerates in the early evening.

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