A real heavyweight in the energy transition is on its way to Ireland. On 14 April the world’s largest flywheel left the Siemens Energy factory in Muelheim, Germany, and is now on its way to the Moneypoint power station located in Southwest Ireland.

The 177 tonne flywheel will complete the synchronous condenser based grid stabilisation plant that Siemens Energy is currently developing at ESB’s Moneypoint site. It is intended to play a key role in transforming Moneypoint, a coal-fired power plant, into a green energy hub and in strengthening the stability and resilience of the Irish grid.

Travelling by sea, the flywheel will be first transported onto a barge from the factory in Muelheim, via the river Rhine, to Rotterdam. From there a vessel will ship it to Foynes in midwest Ireland, where it will be loaded onto a barge and sailed to the construction site.

This kind of storage device plays an important part in providing the inertia traditionally supplied by the rotating generators in conventional power systems.

Wind and solar power plants do not provide inertia because they are not operated at grid frequency. In synchronous condenser plants, a conventional generator provides, in addition to reactive power compensation, the necessary inertia for grid stabilisation with its rotating mass.

In the Irish grid stabilisation plant, the flywheel is attached to the phase shifter. At a negative pressure close to perfect vacuum, it can rotate in its chamber at 3000 rpm and can thus briefly provide the stored rotational energy as electricity. This flywheel can multiply the inertia that the grid stabilisation system can currently provide by a factor of 6.8. It will be the first plant of its kind in Ireland.