Building a more flexible energy system
Energy storage systems can help alleviate grid congestion in the Netherlands, says Koen Broess, board member of Energy Storage NL.
He sees it as part of his role to raise awareness among politicians and policymakers of the contribution energy storage can make to the electricity system.
“In the long term, investment in energy storage can prove economically advantageous.”
You work for S4 Energy in Amsterdam. What kind of company is it?
“S4 Energy is a European developer, owner and operator of battery energy storage systems. We currently have four systems in operation and are developing new systems at several other locations.
These new projects will be significantly larger and will connect directly to the transmission grid rather than the distribution grid. S4 Energy is active in the Netherlands, Germany and the United Kingdom.
As Director Contracting & Regulatory Affairs, I am involved in negotiating and concluding contracts with battery suppliers and other parties.
This is a young sector that is developing rapidly. Our current systems have only been in operation for a few years, yet newer systems already offer improved safety and higher energy density. The technology is developing quickly.”
You are also a board member of the trade association Energy Storage NL. Why do you do this alongside your day-to-day work?
“I have been on the board of Energy Storage NL for five years and have been involved in energy storage for a long time. In 2010, I joined the innovation team at KEMA [now DNV, ed.], which is how I became involved in the sector.
I have a technical background and was asked to join because of my knowledge of both regulation and technology.”
What kinds of companies does Energy Storage NL represent?
“It is a broad group. In addition to battery developers, our members include companies active in thermal and molecular storage. The organisation has more than 250 members. Several grid operators are members as well, because energy storage is an important part of the future energy system. Banks and energy companies are also represented.
Our membership therefore ranges from small, young companies to large, established organisations. We focus on both knowledge development and advocacy. The organisation is very active, with strong participation in working groups and good attendance at events.”
What is at the top of your agenda when it comes to advocacy?
“Many politicians and policymakers are not yet fully aware of what energy storage can contribute to alleviating grid congestion. There is still a knowledge gap, which is understandable given how young the sector is. It is important that policymakers understand the possibilities and the latest developments in energy storage.
For grid operators, the impact of energy storage on the electricity grid is understandably an important consideration. Our electricity system is more than a hundred years old. We need to take care of that infrastructure, so it is important to understand how energy storage technology interacts with it.
A recent study by local grid operators found that batteries can support the grid and help alleviate grid congestion. The study found no negative impact of the kind that had initially been feared.
That is important, because grid congestion is one of the Netherlands’ biggest infrastructure challenges. In some areas, hospitals, schools and factories can no longer obtain the grid connections they need.”
How can energy storage help address grid congestion?
“The contribution can be significant and can provide relief in the short term. Traditionally, grid congestion has been addressed by building additional infrastructure, such as electricity cables and higher-capacity substations. Today, energy storage can complement those measures by reducing pressure on the grid.
The electricity grid is only used to its full potential for part of the time, while pressure is concentrated during peak periods, particularly between 6 and 9 p.m. Batteries can help reduce loading during those periods, creating additional room to connect businesses and households.
However, batteries need to be used in a grid-friendly way: within the right frameworks, in the right manner and at the right times.”
How quickly can large-scale energy storage be deployed?
“A large-scale battery project can be built and commissioned within approximately 18 to 24 months after financial close. Such a project can have a power rating comparable to, or greater than, that of a gas-fired power plant up to around 500 MW.
An energy storage system can only discharge for a defined number of hours, but that can be sufficient to reduce peak loading on the grid. That is one of the ways storage can help relieve grid constraints.”
Grid congestion is also an issue in the Port of Rotterdam. Does energy storage offer opportunities there as well?
“I am aware of several initiatives in the port where energy storage is being actively considered. I also know that the Port of Rotterdam Authority is looking seriously at the potential role of storage.”
Do you also see opportunities for energy storage in industry?
“Definitely. In the United States, for example, there is a trend towards installing energy storage systems alongside data centres. Traditional data centres have a relatively constant electricity demand, while demand from newer data centres can be more variable. With energy storage, data centres can potentially operate with a smaller grid connection.
A further step would be to operate data centres independently from the grid, in combination with gas-fired generation, energy storage and potentially solar power.There is considerable discussion about data centres in the Netherlands. On the one hand, we want to reduce our dependence on foreign data infrastructure, but that means building data centres here.
Space is limited in the Netherlands, so this needs to be done efficiently, potentially in combination with energy storage, wind and solar generation. This can help minimise the impact on the electricity grid.”
Data centres are an industry, but I was referring more specifically to the existing chemical and petrochemical sectors.
“That is an interesting area. Electrification in those sectors is progressing slowly, and energy storage can play an important role there as well.
Deployment in these industrial sectors is still at an earlier stage than in stand-alone battery projects and data centres. Energy storage can also create economic value for industry. If companies want to expand, they can face very long waits for additional grid capacity and in some cases up to ten years.
Companies then effectively face two options: relocate production or make more efficient use of their existing grid connection. In some cases, energy storage can help them do the latter.”
How much energy storage capacity is currently installed in the Netherlands, and how quickly do you expect it to scale?
“There is still relatively little energy storage in the Netherlands, less than 1 GW. This includes both residential batteries and larger-scale systems.
By 2030, TenneT expects to need between 5 and 7 GW of flexibility, which will need to be provided through energy storage. That is achievable, but the conditions need to be right. Regulation can sometimes slow progress, so reaching that level will be challenging.
At Energy Storage NL, we favour a consensus-based approach. Grid operators and market participants can try to push solutions through independently, but that is unlikely to deliver the best outcome. We therefore prefer dialogue and cooperation to arrive at solutions that work for the wider energy system.”
Which emerging energy storage technologies do you see the most potential in?
“Batteries represent the largest category. Lithium-ion batteries are widely used today, and one of the next developments is sodium-ion battery technology. Sodium-based chemistries have the advantage that the underlying raw materials are widely available.
Five years ago, battery systems were often expected to have a lifespan of up to around fifteen years. In new projects, lifetimes of twenty-five years or more are now being considered.
Safety and energy density are improving as well. Higher energy density means less space is required, which is particularly relevant in a densely populated country such as the Netherlands.
That is a fundamental difference compared with many wind and solar projects, which generally require more land and have a greater visual footprint. We are also seeing established and newer technologies being combined. Eneco, for example, is installing battery storage alongside a gas-fired power plant.
Recently, an auction was held in the United Kingdom for a long-duration storage project involving a lithium-ion battery system with a 16-hour storage duration.
This illustrates how modular battery systems can also be deployed for longer-duration applications.”
What is your outlook for energy storage in the Netherlands?
“Energy storage will not only provide short-term support. It will become a structural part of the infrastructure required for our future energy system. Energy storage can help make electricity generated by wind and solar available when it is needed, including outside periods of generation.
In the Middle East, a decision was recently made to invest in a 1 GW data centre supplied by a 5 GW solar park in combination with a large energy storage system. The decision was not primarily driven by sustainability. It was the most financially attractive solution.
That may sound paradoxical, but it illustrates an important point. In Europe, we want to reduce our geopolitical dependencies and produce more of our energy domestically.
Investments in energy storage may appear significant today, but their long-term value should be considered in the context of the wider energy system. In the long term, these investments can prove economically advantageous.”
Who is Koen Broess?
Koen Broess studied biophysics at Wageningen University and spent fifteen years at DNV in a range of roles.
Since February 2026, he has been Director Contracting & Regulatory Affairs at S4 Energy.
He is also a board member of the trade association Energy Storage NL.
This article is published at Europoort Kringen.
