Storing excess green power in large battery containers at wind and solar farms to get through windless and sunless periods. It seems so logical, but now only produces losses. Yet the Dutch company Alfen is going to enter the market with it. "We think that the most logical place for this type of battery is at solar and wind farms," he said.
The Dutch energy transition has a problem. By 2030, the government wants to generate 120 terawatt hours of electricity from solar and wind to reduce CO2 emissions by 55 percent. But new solar and wind farms cannot always be connected to the electricity grid because it is full and cannot handle the supply of green power on sunny and windy days. The electricity price is then often zero. If the SDE subsidy for wind and solar farms is abolished after 2025, they will suffer losses at such times and it will become less interesting to build them. The solution: batteries in large sea containers to temporarily store green power.
More green power
This is especially true for solar power, because it is only generated at limited times during the day and is mainly used in the evening, while at night it just blows through. A report by commissioned by RVO last year showed that with 5.5 gigawatts of battery storage, 7.5 gigawatts of additional solar farms could be connected to the existing grid. That's an additional 5 terawatts of green power per year. Enough for 2 million households and good for 1.6 to 2.2 million tons of CO2 reduction per year. Batteries of this kind accelerate the energy transition, because solar parks - this includes large flat roofs full of solar panels - with batteries can have a smaller connection to the grid and better distribute their power throughout the day. Businesses (sites) with batteries also benefit from a smaller connection and are able to use more of their own power instead of feeding it back to the grid. More solar farms can then also be connected when the grid is expanded. Unfortunately, these types of batteries are not currently profitable for developers.
You can in fact make money with a battery in several ways. For example, by supplying power at times when coal, gas and nuclear plants supply too little and storing power when too much power comes onto the market. In doing so, grid operators prevent grid congestion and imbalance on the grid. These types of batteries are called grid batteries. Such a business case is already profitable, according to CE Delft's research this year, because grid operators such as TenneT pay a fixed amount to deploy these batteries. However, they do not contribute to CO2 reduction because they do not provide additional green power.
Not throwing electricity away
Batteries that store surplus solar and wind power can later offer that power on the electricity market EPEX. That avoids having to throw away green power. In the case of solar farms, this does not seem to be profitable until 2030. Batteries used only for this purpose have an uneconomic top of 85,000 euros per megawatt of battery power until then, according to the study. In order to cash in on the environmental benefits of this, the government must therefore stimulate these types of batteries through subsidies (SDE++ for deferred delivery of power or an investment subsidy), reducing charges (lowering transportation costs), increasing the CO2 price of gray power or by offering cheap financing. As of January 1 this year, the double energy tax for storing power in batteries has already been , removing one of the barriers.
Another solution is temporary contracts with grid operators. For example, grid operators such as are entering into temporary contracts with solar farms with batteries. They agree, for example, that the farm will store solar power in the battery during the day and only supply it to the grid in the evening. This prevents grid congestion and allows a solar farm to be connected to the grid years earlier.
With wind farms, these types of batteries can never be made profitable, because they run for longer periods and require a very large, expensive battery to avoid throwing power away. Most battery capacity is also only used a few times a year.
Piling up business cases
"For all storage, you have to stack business cases," says Jasmijn Kleij innovation analyst smart energy systems at , which promotes energy innovations and collaboration within the top sector energy. "One business case is often not enough to make energy storage technology profitable."
Now, large-scale battery storage is mainly used against grid congestion and grid imbalance. National high-voltage grid operator Tennet already has 28 gigawatts of battery connection requests pending. The regional grid operators another 6 gigawatts, making a total of . A growth of 77 percent since last October. "Still, there is not really a business case for batteries at solar farms yet," Kleij notes. "Because if you want to use that to store power for countering grid congestion and imbalance, you have to reserve such a large part of your battery for that, that you don't have enough space left to trade on energy markets. With additional policies, such as the SDE++ for deferred delivery, that business case for batteries at solar farms can become more favorable and more solar farms can be built."
The Dutch company has been active in the energy market for 85 years. For example, it built its first transformer station in the 1960s. Today, the company also supplies charging points for electric vehicles. Evert Raaijen set up the energy storage branch in 2011. "That has now become booming business. The projects we do are bigger and bigger and increasingly go to the 20, 30 or 50 megawatt storage and in megawatt hours even more. Those are often containerized solutions," he says. The company has Shell, Eneco, Vattenfall, Uniper, Greenchoice, as well as Lidl as customers.
Alfen supplies batteries for all kinds of applications. At festivals, construction sites and outdoor events, they replace diesel generators. They provide balance to the grid, store excess solar and wind power, provide power to charging points and are used to trade on the power market. According to Raaijen, the traditional energy system has changed. In addition to power plants, wind and solar farms provide a lot of power, but it is variable and not always in stock and sometimes too much. Batteries are needed to store surpluses. "You can include these in your grid in all places, but we think the most logical place for these types of batteries is at solar and wind farms," he says.
Storing unused capacity
Linking batteries to solar and wind farms has several advantages, he says. They stabilize the grid, prevent grid congestion and lower the connection costs of farms to the grid. With batteries, solar and wind farms can form a local energy grid that provides local parties with enough power at any time. Alfen has already built several such island or microgrids in Europe, including in Finland. But the really big advantage lies in harnessing the unused capacity of solar and wind farms. The capacity of those farms is often much higher than the average capacity they currently supply to the grid. You can store that power in batteries. That can add up to 90 percent of solar power generated to 60 to 80 percent of wind power generated. "Those are significant numbers," says Raaijen.
During trade show Solar Solutions International, Alfen demonstrated its battery for solar and wind farms. The modular battery systems the company builds are rack-mounted. They start at 1 megawatt and can be expanded up to 100 megawatts, depending on what is needed. "The first project we built was a 5 megawatt project in Hungary. Nowadays, that's a small project for us," Raaijen says.