The 1MW/1.3MWh battery, supplied by specialist Younicos, will store energy produced from the world's first commercial floating offshore wind project and feed it into the UK's grid when it is needed.
Younicos produced the two three-metre modular battery containers that are placed at the project's onshore substation in Peterhead, Scotland.
Speaking at Windpower Monthly's floating offshore wind forum on 28 June, Sebastian Bringsvaerd, Equinor's head of the Hywind project, said the battery was "an important milestone" for the wind industry.
"It really shows how floating wind can be at the forefront of driving renewables," Bringsvaerd told delegates.
The battery project took two years "from idea to reality" and could serve to tackle the problem of variable generation, he added.
"We want to teach the battery when to hold back and store electricity, and when to send power to the grid, thus increasing the value of the power.
"It will be really exciting to see how we can develop the combined battery and software solution and make Batwind as smart as possible," said Bringsvaerd.
The £3 million (€3.4 million) Batwind project is also backed by United Arab Emirates-based renewables investor Masdar, following a deal in January 2018.
Equinor described the storage project as "a battery with a brain". It hopes, through data input and digitalisation, the system will learn when to store energy, and when to supply to the grid.
"Digitalisation is a key driver here. The more we feed Batwind's power management system with data, the smarter it gets.
"In addition, Batwind can be utilised for other renewable energy sources, including solar and onshore wind. We believe this will expand the market for all renewable energy sources," Bringsvaerd said.
Since being commissioned in September 2017, the Hywind Scotland project has achieved a capacity factor of 48-60% — on a par with many bottom-fixed offshore wind projects.
This will help to "convince the market that floating offshore wind has no disadvantage", Bringsvaerd told delegates at the forum.