Duck curve

Methods for coping with the rapid increase in demand at sunset reflected in the duck curve, which becomes more serious as the penetration of solar generation grows, include:[9]

• Installing more dispatchable generation
• Over sizing DC rating compared to AC rating of the solar power plant than installing BESS for storing peak generation from solar power plant.[10]
• Orienting some solar collectors toward the west to maximize generation near sunset.[11]
• Energy storage[11] including:
  • Pumped-storage hydroelectricity
  • Battery storage power stations
  • Solar thermal energy with thermal energy storage
  • Ice storage air conditioning
  • Use of batteries in electric vehicles for temporary storage (vehicle-to-grid)[12]
  • Power-to-X
• Energy demand management, including:
  • Transitioning to more efficient lighting systems, such as compact fluorescent and LED lighting
  • Time-of-use pricing (TOU) and real-time pricing
  • Smart grid technology
  • Electric power transmission from the west where the sun is shining to the east where the sun is low

A major challenge is deploying mitigating capacity at a rate that keeps up with the growth of solar energy production. The effects of the duck curve have happened faster than anticipated.[13]

Sources of electricity generation in California in 2020. Because these graphs do not display energy demand, they are not Duck Cuvres themselves, but demonstrate daily and seasonal variation in power production.

  Natural gas

  Solar power

The California Independent System Operator (CAISO) has been monitoring and analyzing the Duck Curve and its future expectations for about a half a century now and their biggest finding is the growing gap between morning and evening hours prices relative to midday hours prices.[1] According to their last study, the U.S. Energy Information Administration, found that the wholesale energy market prices over the past six months during the 5 p.m. to 8 p.m. period (the “neck” of the duck) have increased to $60 per megawatt-hour, compared to about $35 per megawatt-hour in the same time frame in 2016.[3] However, on the other side they have measured a drastic decrease in the midday prices, nearing $15 per megawatt-hour.[3] These high peaks and deep valleys are only showing continued trends of going further apart making this Duck Curve even more prevalent as renewable energy production continues to grow.[4]

A crucial part of this curve comes from the Net Load ("the difference between expected load and anticipated electricity production from the range of renewable energy sources").[3] In certain times of the year (namely Spring and Summer), the curves create a “belly” appearance in the midday that then drastically increases portraying an “arch” similar to the neck of a duck, consequently the name “The Duck Chart.[14]” During the midday, large amounts of solar energy are created, which partially contributes to lower demand for additional electricity.[15] Increasing battery storage can mitigate the issues of solar abundance during the day. When excess solar energy is stored during the day and used in the evening, the price disparity between inexpensive midday and expensive evening energy can be reduced. Enough total solar technology exists to power the world, but there is a current lack of infrastructure to store solar energy for later use.[7] An oversupply of energy during low demand coupled with a lack of supply during high demand explains the large disparity between midday and evening energy prices.