You flip the light switch, and the lights come on. Your fridge stays operational 24/7, and in the summer, your a/c unit might be set to high for months on end. Here in the States, we have grown so accustomed to constant, reliable electricity from our grid that it raises concerns when we lose power for more than a couple of minutes. For many of us, our energy consumption isn’t something we actively consider unless we’re looking at utility bills, but if we stop to think about it, we realize that our energy demands are constantly changing, and accordingly, so must our supply in the form of energy generation. This leads us to a puzzle: in an industry where demand and production are variable, but the supply of product (electricity) must necessarily flow instantly and continuously, how does a supplier (utility) forecast its needs, and how can it reliably respond to situations where demand is higher than anticipated?

As it turns out, overall energy usage follows a predictable 24-hour cycle, which can be explained in the arc of people’s typical daily routines. In the early hours of the morning, when people are sleeping, energy usage is at its lowest, rising around 6 am when people start their morning rituals. Energy usage steadily climbs and crests around noon, staying high through the evening before tapering off around 10 pm, when people begin to wind down for the night. Despite individual habits, weather events, and occasional spikes, this pattern has remained relatively consistent for decades. This trend benefits utilities and energy companies who can plan ‘baseload’ energy generation to a reasonable degree of accuracy by analyzing seasonal historical data, weather trends, and grid infrastructure tolerances.

Average Seasonal Baseload Trend Lines

So, what happens in events where consumer demand outstrips projections? Despite the best-laid plans, these events commonly occur in summer and winter months when energy-intensive HVAC units are blasting. Rather than rolling blackouts, utilities and energy companies commonly rely on ‘peaker power plants’ to bridge the gap between actual demand and the available baseload energy supplied from continuously operating power plants. Peaker plants, named so because they are typically only fired up when energy demands are at peak levels, are expensive to operate (reflected in higher energy bills in the summer and winter months), and most commonly rely on fossil fuels such as oil or natural gas. Due to their reliance on fossil fuels, and their inefficient ‘ramp up’ periods, it has been estimated that these plants emit between 2-3 times the emissions of a continuously operating power plant. Nationwide, peaker plants account for about 60 million tons of atmospheric CO2 annually. Phasing out peaker plant usage has been a longstanding cause for many climate-minded advocacy groups, but how do we get there without crippling our grid in times of high demand, and how does renewable energy fit into the picture?

Nationwide Peaker Plant Distribution

Let’s change gears for a second. Close your eyes and picture a duck. No, not Daffy or Donald, but the kind you might find when walking by a pond in the park. Picture the silhouette of the top of this duck when it is bobbing along in water with its legs below the surface: long, raised feathered tail curving down into a streamlined body, which rises with its neck and arches at its beak. Now imagine a single line starting from the end of its tail, following its bodyline up along the top of its head, and ending at the tip of its beak. With a bit of imagination, you might imagine this line as two peaks (tip and tail) with a long, slightly depressing valley in the middle. You now have yourself a ‘Duck Curve’.

In recent years, this 2-peaked curve line has been used by the energy industry to describe the impacts of solar energy generation on daily baseload energy demands. Tumbling costs and increased efficiency have made solar installations an attractive investment over the past few decades; in 2022 solar generation accounted for nearly 136 gigawatts of energy in the United States, enough energy to power 24 million homes. 

The Duck Curve

Like energy demands over the course of a day, solar generation follows a typical pattern that correlates to daylight hours. In the early hours of the morning, production is nil. At daybreak, solar energy production begins, rising with the sun to peak at noon then gradually decreasing as the sun sets before ceasing at dusk. Now that we have our energy usage trendline curve, and we can predict to a reasonable degree our baseload energy demands, we can use this information to analyze how solar energy production will affect utility energy demands throughout the day.

To understand how solar energy generation affects utility energy demands and baseloads, think back to our duck curve. As people begin their morning rituals before the sun is high in the sky, our first peak occurs. As the sun continues to climb, solar panels kick into gear, providing a  distributed (not from a power plant) source of energy.  This solar power decreases demand from the grid, creating our duck’s back. As the afternoon progresses, the sun starts to go down, and as a result, solar energy production slows.  Our second peak of energy demand occurs at sunset as most customers must now rely on utility energy for their electricity needs. As people settle in for the night, energy usage declines, giving us our beak. There you have it, our mighty duck!

What can we learn from these trends, and how can we use this information to try and ‘flatten’ the duck curve? Part 2 of this article will explore how emergent technology, infrastructure upgrades, information management, and progressive policy can be leveraged to create a stronger, more resilient grid that will lower emissions and energy bills while creating a pathway to desist from carbon-intensive peaker plants. Stay tuned, you’re in for a quacking good time! (I’m sorry, I had to throw at least one in)

Sources: 

Peaker Plants: https://www.cleanegroup.org/wp-content/uploads/The-Peaker-Problem.pd

Solar Energy Adoption: https://www.marketwatch.com/guides/solar/solar-energy-statistics/#:~:text=Solar%20power%20has%20grown%20at,Energy%20Industries%20Association%20(SEIA).