5 Ways to Flatten the Duck Curve with GIS

Posted to Esri in the Digital Utility Group
Bill Meehan's picture
Director, Utility Solutions Esri

William (Bill) Meehan is the Director of Utility Solutions for Esri. He is responsible for business development and marketing Esri’s geospatial technology to global electric and gas utilities.A...

  • Member since 2002
  • 195 items added with 231,594 views
  • May 27, 2020

Utility operating people have been creating demand curves for decades. A demand curve shows the use of electricity over the course of each day. As you would expect, demand rises with the sun. As people wake up and factories gear up, the electricity usage increases until it reaches a peak late in the afternoon. As the first shift shuts down and people leave their jobs, the demand gradually falls off.  As people arrive home, they crank up their air-conditioners, turn on their lights, and flick on the TV. Demand shoots up again.  

In the past utilities would schedule power supply to mirror customer behavior. As demand for power increased over the day, the utility would add more power. As demand decreased, utilities would shut plants down. 

Before solar.

The Duck Curve - California’s One Day Demand Curve
(Source – California Independent System Operator)

The fastest growing segment of new energy is solar. In some regions (California, Hawaii and Germany) solar supplies nearly all the electricity to customers for part of the day. That’s the good news. The bad news is that they are variable and can’t be turned on whenever we want. That’s unlike regular power plants. Utilities can turn them on and off. It is difficult and very expensive to turn on and off some large plants.  And utilities hate to do this.

In areas with lots of solar, utilities can’t mirror their supplies to meet the customer.  Instead the utility supply curve looks like a duck. It follows customer demand in the mornings, but as the sun gets stronger, solar takes over. The utility supply drops quickly. But just as fast as the sun goes down, the utilities must quickly ramp up their supply with conventional generation.

This situation is shown the picture created by California Independent System Operation (CAISO) - the famous duck curve.

If there is too much solar and utilities don’t want to shut down their big plants, that creates a big problem. It’s called over generation. So far, the solution is to turn off the free, clean and cheap solar.

The National Energy Renewable Lab (NREL) suggested two approaches. Fatten the duck. Flatten the duck.  Fattening the duck means making the duck’s belly even fatter. Utilities do this by figuring out how to make it easer and cheaper to turn on and off large power plants that normally run all the time. I won’t cover that here. The other approach is to flatten the curve by moving demand from the head of the duck to the belly.  That’s where GIS comes in.

Five ways to flatten the duck:

  1. Crush the duck’s head – energy efficiency

Mapping energy efficiency by location boosts utilities incentive programs to willing customers.  Utilities have been using GIS to do this for years. GIS provides insight into the greatest opportunities for conservation and energy management programs.  They gain insight into where they get the best return for the incentives.

  1. Put the duck on a diet – demand response

In the old days, utilities put practices in place to encourage customers to stop using electricity during peak times. That used to happen during hot sunny summer middays.  Now they must do the reverse. They must encourage customers to move usage from the late afternoon/early evening hours during the rapid rise in usage to the mid-day, during the peak of solar.  Using spatial technology, utilities can map where to best apply demand response. Esri’s Tapestry data set can pinpoint where to establish incentives to control all kinds of loads, from air-conditioning to pool pumps to refrigeration units.

  1. Pad the duck’s belly- storage

Storing electricity during the periods of excess generation is one of the best ways to use every ounce of clean, free electricity. Spatial technologies find ways to locate and design storage systems that are compatible with network operations. ArcGIS’s new Utility Network has advanced tracing capabilities to facilitate the rapid and widespread use of storage into the network.  Storage can take many forms from batteries to air conditioning with built in ice-like storage facilities. Here again, utilities can leverage demographic data to target the right customers.

  1. Go west young duck - transmission

Horace Greeley was credited with the expression of “Go West Young Man”. As we move from one region to another, the duck curve shifts in time. By adding more interconnections, utilities can expand solar generation time. GIS can model solar resources. It can determine the best location for transmission ties. It can even help utilities build real time market pricing into highly valuable solar resources that flatten the late afternoon ramp time.

  1. Break the duck’s back – diversity

The duck’s back is a problem. The steeper the back, the faster that utilities must convert from solar to some other form of generation.  One way to ease that transition is to apply other generation resources during that critical time. These can distributed energy resources that are relatively clean but not all renewable, such as natural gas micro-turbines, small scale wind energy resources and electric vehicle to grid resources.  GIS can be used to site, plan, and discover the best location to optimize the breaking of the duck’s back.

It’s hard to think about anything but Covid-19 these days. As we move into a new world of increased residential and decreased commercial electrical demand, we may find additional opportunities to reshape the way we respond to the duck.  The conventional wisdom about customer electric demand will be different. As customer behavior changes, GIS will be there to model it.

For more information on how GIS can add value to electric utilities, download our free e-book.

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Matt Chester's picture
Matt Chester on May 28, 2020

I love focusing on these five different tools as all parts to create a holistic solution (though the duck analogy breaks down for me when you tell me to crush his head!). So often you'll hear criticism that energy efficiency isn't enough or that demand response is no silver bullet, but when we have all these options as tools in our toolbox then can together create real change towards solving the problem. Sometimes it's not about the silver bullet, but attacking from all angles and chipping away. 

Eric Van Orden's picture
Eric Van Orden on Jun 8, 2020

Thanks, Bill. I like how these are broken out. EE and DR make a lot of sense, especially when targeting customers. I see the suggestion to use demographic and lifestyle information from ESRI. What about real-time endpoint consumption data? 

I created a scrolling image to show visualizations of the duck curve, plotted on a map, with endpoints in Copper Labs Utility Portal. Targeted demand response is a function within the portal (see the "Create Event" button). But, I'm mostly sharing this to show morning and afternoon demand date in a neighborhood with a high penetration of solar and the segmentation between all solar and solar & non-solar. Image 1 & 2 were from June 6th, 2020 and Image 3 & 4 were from June 5th, 2020

  • Image 1) About 200+ homes with and without solar, backfeeding onto the grid in the morning. 
  • Image 2) About 200+ homes with and without solar, quickly demanding more energy in the afternoon, which was flattened.
  • Image 3) Only homes with solar, showing a big duck curve and backfeeding in the morning. 
  • Image 4) Only homes with solar, showing a big duck curve and quickly demand more energy in the afternoon. 

Real-world, real-time duck curve

Click here if the image doesn't scroll/animate -

Matt Chester's picture
Matt Chester on Jun 8, 2020

Really cool visualization, Eric-- would love to see more investigations like this into these topics. Much to be learned from the treasure trove of data

Mark Howitt's picture
Mark Howitt on Jun 8, 2020

Thanks for this post. The duck is so big that all the 5 options are needed. The fifth (diversity) will help greatly The fourth (transmission) tends to break down when neighbouring states have similar surpluses or deficiencies - and the timing of their production and demand will always be similar; therefore the full loas must be taken by options 1-3. But 1 (efficiency) and 2 (demand response) will only ever be a small fraction of the need. So the heavy lifting needs to be done by 3 (storage. And this has to be larger-scale and longer-duration than batteries; CAES is the most cost-effective, long-lived and (adiabatic versions like most efficient over their lives.

There's another challenge: inertia and related aspects of grid stability, which CAES can provide but wind, solar, interconnectors, demand-side response and batteries cannot. Last August's black-outs in the UK (1 million people left in the dark, and many railways knocked out at rush hour!) proved that pseudo-inertia has reaction times, which means that they can never be as effective as real inertia which is always-on and which would have prevented those black-outs.

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