The costs of producing wind energy and solar energy have fallen steadily in recent years. Also the costs of storage solutions such as lithium-ion batteries continued to fall steadily. This leads to very interesting questions:
What opportunities does this price trend offer for the combination of wind turbines with an integrated storage solution?
Storage Solution Requirements
If one assumes that the future electricity market will consist mainly of renewable energies and that conventional energy production will be the minority, it follows that the storage capacities of the entire electricity market will also have to increase. This is due, for example, to the fact that electricity consumers do not always consume electricity when there are many renewable energies on the electricity market.
Only if the economic value of a storage facility on the electricity market is given will the network participants also build these storage systems and make them available to the electricity grid.
In order to understand more precisely what storage capacity requirements will arise, it is necessary to analyse the temporal application areas of electricity storage more precisely.
In general, these storages can be divided into different timeframes:
- Milliseconds: Restart of the grid
- Seconds: Freqency regulation
- Minutes: Reserves
- Hours: Peak Shaving
- 10-360 Hours: Weather Changes
- Months: Seasonal Storage
For simplicity's sake, we will limit this article to the example of peak shaving and weather-related fluctuations, although Li-Ion batteries can also be used to regulate the frequency of the grid.Quelle: Stanford Webinar
Peak Shaving of the "Californian Duck Curve"
The "Californian Duck Curve" is a popular example to describe the problem of daily fluctuations in energy consumption. The curve owes its name to its duck-like shape. In the morning, many people who just get up and start their morning routine need a lot more electricity. While the electricity consumption then drops slightly beyond the day and finally rises strongly again in the evening after work.
This cycle is unfortunately anti-cyclical to solar energy, which provides the most energy in the midday hours.
At most locations, wind energy is independent of the time of day but rather randomly dependent on the weather.
At noon there is therefore a risk of overproduction of electricity, whereas at night there is a risk of underproduction.
These differences can exceed 10,000 MW.
Electricity consumption in Germany
In Germany, too, electricity consumption during the day is mostly similar to the Californian "duck curve".
The light blue area shows how electricity from pumped storage plants is fed into the grid at these times in order to meet current electricity demand.
Beginning with January 26, there is also an increased production of electricity from wind (light green). This has led to a reduction in electricity production from lignite and hard coal.
The course over a few days is a good example of the demanding requirements placed on the grid by renewable energies, which unfortunately are not always available.Quelle
Electricity price in Germany
The short-term overproduction from wind energy described above ultimately leads to an electricity export from Germany (negative output) and at the same time to a drop in the electricity price in Germany (light blue curve) to up to 0€/MW.
The regular fluctuations of the electricity price at the morning and evening times are also noticeable. Quelle
Opportunities for wind energy
In a subsidy-free electricity market, the dilemma arises that the price of electricity is usually low when there is a lot of wind blowing.
If the electricity could be stored and made available to the grid again at times when the demand is particularly high and thus the electricity price is usually high, great economic potential would arise. Storing the energy would also mean that wind turbines would have to be switched off less frequently due to grid overloads.
The above examples show that in times of high electricity production by wind the electricity price drops to almost 0 €/MW. If the electricity were to be stored instead of fed into the grid and fed back into the grid on days with less wind or at times of day with higher demand, the storage facility would make it possible to sell the electricity at a price up to 3 to 150 times higher.
The investment costs and efficiency losses of a Li-Ion battery storage would be far exceeded in a free electricity market with an intelligent control system.