How TenneT's BESS Project Will Transform the Netherlands' Grid

The Netherlands has one of the most congested electricity grids in Europe. This is not a minor inconvenience — it's a structural chokepoint that has been actively slowing down renewable energy projects, forcing developers onto waiting lists that stretch years into the future. Now, a contract signed between Dutch transmission system operator TenneT and developer Green Energy Storage (GES) is testing a genuinely new approach to the problem.

The project is called Sequoia. It's a 200MW/800MWh battery energy storage system located in North Brabant, and it's not just another large battery getting bolted onto the grid. What makes it significant is the legal and commercial architecture surrounding it — a combination of contract types that TenneT says makes Sequoia the first controllable congestion mitigator on its high-voltage network.

That distinction matters more than it might initially appear.

A New Kind of Grid Contract

The agreement between TenneT and GES involves two overlapping instruments. The first is a time-bound transmission right (TDTR) — a flexible connection agreement that gives TSO customers access to so-called "residual capacity" on the grid during off-peak hours. Think of it as a conditional grid access pass: you can use the connection, but only when the highway isn't already full.

The second instrument is a capacity control contract (CSC), which goes a step further. Under a CSC, GES doesn't just agree to operate within residual capacity — it actively adjusts Sequoia's electricity consumption or feed-in during congested periods at TenneT's direct request, in exchange for a fee. Where the TDTR defines when the battery can operate, the CSC gives TenneT a lever to pull in real time.

Together, these two contracts transform Sequoia from a passive grid participant into an active congestion management tool that TenneT can dispatch on demand. This is the first time this combination has been deployed on the Dutch high-voltage grid, and it represents a meaningful step beyond what previous flexible connection agreements have accomplished.

It's also worth understanding what Sequoia would likely do anyway. A battery earning revenue from energy arbitrage will naturally charge when renewable production is high (prices low) and discharge when demand peaks (prices high) — exactly the behavior that relieves congestion. The difference here is that this behavior is contractually guaranteed and directly controllable by the operator. For a TSO managing a stressed grid, that guarantee is far more useful than hoping market incentives align with grid needs at the right moment.

What This Unlocks for Renewables

North Brabant sits in one of the most constrained parts of the Dutch grid. Renewable developers in the region have been stuck in an interconnection queue, unable to come online because the local grid simply can't absorb more capacity during peak production hours. Sequoia directly addresses that by absorbing excess energy when renewable output is highest, freeing up headroom for other generators.

TenneT has stated explicitly that Sequoia could help renewable projects currently sitting in the queue come online earlier than currently planned. The mechanism is straightforward: by making part of Sequoia's grid capacity available to other projects, it effectively creates room that didn't exist before. TenneT is conducting a revised grid congestion study for North Brabant this autumn, and the results — which will account for Sequoia's contribution — will determine which waiting-list projects benefit and on what timeline.

For developers who have been watching their projects stall while financing costs accumulate, that revised study could be the difference between a viable project and a dead one.

The battery energy storage system market in the Netherlands has been watching this dynamic play out for years. A 2024 analysis from Aurora Energy Research found that non-firm agreement connections and time-weighted tariffs could substantially improve BESS project economics in the Netherlands. Developer LC Energy went further, stating flatly that without flexible connection agreements, no large-scale storage project could have reached financial close in the country. Not everyone agreed — executives at SemperPower were more skeptical about the real-world benefits — but the market's subsequent behavior is telling. Following the regulatory reforms enabling these agreements, Dutch grid-scale storage saw a surge of large-scale BESS financing and construction activity across 2024 and 2025.

Sequoia is the next iteration of that evolution. Earlier flexible agreements gave developers a path to connection. This one gives TenneT active control over a 200MW asset during congestion events. That's a different level of grid management capability.

The Regulatory Foundation That Made This Possible

None of this would exist without a specific regulatory decision made by the Netherlands Authority for Consumers and Markets (ACM). Last year, the ACM authorized network operators to offer customers special contracts for residual grid capacity — the foundational permission that makes both the TDTR and CSC instruments legally viable.

That regulatory clearance did something else too: it established a prioritization framework that gives projects operating under these agreements priority on the interconnection waiting list. Sequoia is benefiting directly — GES expects to commission the project in 2027, a timeline that would be significantly harder to achieve without priority queue placement.

This regulatory model is gaining traction beyond the Netherlands. German TSOs and DSOs are increasingly offering flexible connection agreements to storage and industrial customers, though the German experience also illustrates the tradeoffs. Flexible connections can constrain a project's revenue stack if operators are frequently called to curtail or adjust output. Developers need to model these operational constraints carefully — a project that gets built faster but earns less over its lifetime may not pencil out better than one that waits for a firm connection.

The broader regulatory lesson from the Dutch experience is that grid operators don't need to solve congestion entirely before enabling new connections — they need the right contractual tools to manage assets dynamically once they're online.

That's a meaningful reframe. Traditional grid planning assumes you build enough capacity first, then connect new load and generation. The TDTR/CSC model inverts part of that logic: connect the assets that can help manage congestion, give operators control over them, and use them to create space for the next wave of renewables.

What Comes Next

Giga Storage already claimed a first with its time-limited grid usage contract with TenneT in 2024. Sequoia represents a second generation of that thinking — more sophisticated, more operationally integrated, and more directly tied to TenneT's real-time congestion management capabilities.

The autumn congestion study for North Brabant will be the first real test of how much headroom Sequoia actually creates. If the numbers support a meaningful acceleration of queued renewable projects, expect TenneT to move quickly toward replicating this model in other congested regions. The Netherlands has several.

For developers sitting on projects in the interconnection queue, the immediate action is straightforward: understand whether your project sits in a region where Sequoia's capacity relief could change your timeline, and engage with TenneT's study process this autumn. The results won't be academic — they'll determine who gets to build and when.

The Dutch grid congestion crisis didn't emerge overnight, and it won't be solved by a single 800MWh battery. But Sequoia is demonstrating that the right combination of technology, contracts, and regulation can turn a storage asset into genuine infrastructure — not just a revenue-seeking machine, but a grid management tool that creates space for everything else to follow.

[INTERNAL LINK: TenneT's role in renewable energy]

[INTERNAL LINK: The future of battery energy storage]

[INTERNAL LINK: Regulatory changes in the Netherlands]

EDITOR NOTES

• Consider cutting the paragraph discussing the skepticism from SemperPower for brevity.
• Ensure that the internal links are relevant and lead to appropriate content on the blog.