What are DUCK CURVES, really?

Along with the green development in the power system, a new concept has emerged, namely “duck curves”. The presence and absence of the sun in the sky not only dictate when you can sunbathe on the beach, but also have a significant impact on the production patterns of the power system. These curves throw a curveball at our traditional ways of managing the power grid as both production and consumption now have to adapt to ensure the stability of the energy system.

Duck Curve

In the energy sector, a new term has begun to be used, namely duck curve. A duck curve represents a specific challenge for the power system that arises when the production of solar power exceeds demand for electricity during the daytime and then rapidly decreases when the sun sets. The production of electricity from solar power, which is entirely dependent on the availability of the sun, is simply not adjusted or synchronized with electricity consumption, creating a graphical curve for the production requirement from other energy sources resembling a duck, see the image below. The high demand in the morning and evening represents the head and tail of the duck, while the lower demand in the middle of the day represents the body. This poses a challenge for the system operator, which in Sweden is Svenska Kraftnät, and the power system as a whole, which must quickly increase the production of other energy sources to meet the high demand at 6 PM.

Synergy. 2020. Everything you need to know about the Duck Curve

The major challenge with duck curves is that grid operators must manage these rapid fluctuations in solar power production to ensure that the grid remains stable and that demand is always met by available electricity production. Thus, rapid and substantial ramping up and down of other energy sources are required to quickly balance the system. Failure to handle these variations effectively can lead to disruptions in the grid and, in the worst case, a system collapse.

To balance duck curves and minimize their impact on the power system, the use of other energy sources that can be adjusted quickly is often required, which in Sweden is hydropower that has more adjustable production. It’s however not optimal to only rely on hydropower to fix the problem as hydropower is less effective during the spring as they need to fill up their massive reservoirs after the winter and are therefore more restricted during these periods. By developing and implementing innovative technologies and strategies, duck curves can be effectively managed, and the opportunities with solar power in the power system can be fully utilized. 

A problem

The occurrence of duck curves is a relatively new phenomenon in the energy sector, arising with the significant expansion of weather-based energy sources such as solar power. This is especially evident in Germany, where solar power accounted for 60 TWh in 2023, or approximately 14% of the electricity mix, most of which was produced during the summer. For a period, solar power accounted for as much as 68% of all electricity production in the country, which is a lot considering that this electricity production must later be compensated by other energy sources when the sun sets.

So why is this a problem for other countries like Sweden? Well, it’s because Europe has a strongly interconnected electricity system across borders, which means that at times, Sweden receives Germany’s duck curve through imports. Germany is a large country, with a gigantic population compared to Sweden, which means that the duck curve has a greater impact.

The duck curve is a problem in itself. In an electricity system, production should attempt to mimic consumption, which should be the driving force. But the fact of the matter is that Sweden’s becoming increasingly dependent on energy sources that cannot or have difficulty in adjusting their production according to electricity demand. Nuclear power is incredibly expensive to adjust according to consumption, solar power depends solely on the presence of the sun, and wind power depends on how much the wind blows. Electricity prices can even become negative on a very sunny and windy day. So, the production of electricity is so high in comparison to the consumption that you’re actually getting paid to consume.

Frequency Regulation

Balancing the grid is a delicate dance of increasing and decreasing other energy sources to compensate for varying electricity consumption and production. Too much or too little, and you risk power outages or wasting valuable energy. It wasn’t long ago that Svenska Kraftnät came out appealing for more actors to offer frequency regulation, especially downward regulation ahead of a tough period. Downward regulation means that there is an excess of electricity production compared to consumption, so either power plants need to produce less or someone needs to consume more. Upward regulation on the other hand is the opposite where energy needs to be supplied to the grid in order to stabilize it by either increased production or a reduction in consumption.

Peak Energy’s Solution

The world needs green electricity production in the future, and solar power and wind power will play a crucial role in this development. What’s really needed is new innovation that increases the flexibility of the electricity system through energy storage. Thus, solar power production can be adapted to society’s demand by storing excess production during the day until it’s needed more during the evening peak consumption. This would not only smooth out demand and reduce dependence on other energy sources after sunset but also optimize the use of solar power. Excess production will then be seen as a strength rather than a burden for Svenska Kraftnät to fix, and the duck curve will disappear.

Peak Energy is a part of the solution. We can use your electric car, more specifically the battery, to help the grid and Svenska Kraftnät overcome the “duck curve” by participating in frequency regulation. Not only upward regulation like FCR-D up, but also the downward regulation requested by Svenska Kraftnät. Energy storage will play a central role in Sweden’s future electricity system, and society should use its batteries efficiently to benefit everyone. By using the battery in the electric car when it’s parked and not in use, we cannot only help the grid remain stable, but also be compensated for the assistance. This is one of many activities that Peak Energy does to provide the cheapest and best charging possible, beyond regular smart charging.

Peak Energy offers:

  • Grid assistance: Helps the grid with duck curve by selling various reserves, including the downward regulation that’s desperately needed.
  • Cheaper charging: Through a combination of frequency regulation and smarter “smart charging”, you get the cheapest and most efficient charging.
  • Control: You gain more control over your car’s charging.
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