Ostrand 200
A 200 MW, 400 MWh battery beside a retired coal plant.
Energised
11 days early
Size
200 MW, 400 MWh
Location
Ostrand, North Sea coast, Germany
My role
Principal engineer, electrical and controls
Team
11 engineers, 70 people on site at peak
Duration
19 months, 2024 to 2025
01
The situation
Ostrand is a small port town whose coal plant shut in 2021. The plant left behind a 380 kV grid connection and a cleared yard. Tidemark bought the site to build a 200 MW, 400 MWh battery there. It is the larger of the company's two sites, and by far the biggest the team had ever energised.
The grid operator gave us one fixed energisation window, tied to a planned outage on the old plant’s line. If we missed it, the next slot was five months away. The design was only half done when I joined in February 2024, and the main transformers had a lead time of 14 months.
02
What I did
I took ownership of the electrical and controls design and froze the main circuit diagram in my first six weeks. Every later change had to come to me with a reason in writing. I wrote the energisation plan myself, as 186 numbered steps, and walked it on site with the grid operator's engineer before any cable was live.
I split the site into four 50 MW blocks so we could test each block while the next one was still being built. Factory tests for the transformers and inverters were witnessed by my own engineers and not left to the vendor. Faults found in the factory cost us hours. The same faults found on site would have cost weeks.
03
What changed
We energised the grid connection 11 days ahead of the contract date, in March 2025. All four blocks were trading within a month of that. The grid compliance tests passed on the first submission. The site logged 126,000 working hours over the build with no lost-time incident.
The block by block method is now Tidemark’s standard for any site above 100 MW. The energisation plan became a template, and two of my engineers have since written their own for the second site. What I remember best is how calm the control room was on the day. Nobody had to improvise.
400 MWh
Storage capacity energised
200 MW for two hours
11 days
Ahead of the energisation date
Against the contract date
0
Lost-time incidents
126,000 site hours
“Linnea's plan had 186 steps and we followed every one. It was the least dramatic energisation day I have worked on, and I mean that as praise.”
Tomas Wieland
Site Manager, Tidemark Energy