Siemens Energy: World’s largest flywheel shipped

Siemens Energy said the world’s largest flywheel has left its factory in Muelheim, Germany, and is on its way to Ireland’s Moneypoint power station.

The 177-ton flywheel will complete the synchronous condenser, a grid stabilization plant, that Siemens Energy is currently developing at ESB’s Moneypoint site. The technology will 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.

Siemens Energy’s grid stabilizer technology to help Irish grid exceed renewables penetration limit. (Image: Siemens)

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

Due to the shift in renewables, the grid increasingly lacks inertia which previously was provided by the rotating masses of the generators and the turbines from the fossil-based power generation, Siemens said. These rotating masses play an important role in the grid: If electricity demand and supply get out of balance, the frequency drops. Rotating masses store a high amount of energy, that can compensate this drop in a blink of an eye and long enough so that the operators can initiate appropriate measures to feed in energy into the system.

Wind and solar power plants do not provide inertia because they are not operated at grid frequency. That is where the synchronous condenser come into play. In synchronous condenser plants, a conventional generator provides, in addition to reactive power compensation, the necessary inertia for grid stabilization with its rotating masses. In the Irish grid stabilization plant, the flywheel is additionally attached to the phase shifter. At a negative pressure close to perfect vacuum, it can rotate in its chamber at 3000 rotations per minute and can thus briefly provide the stored rotational energy. The flywheel can thus multiply the inertia that the grid stabilization system can provide by a factor of 6.8. It will be the first plant of its kind in Ireland. Commissioning of the new plant is planned for mid-2022.

Siemens Energy will deliver the synchronous condenser system, providing engineering, procurement, and construction. Key components are a control system that optimally fits to the overlaying grid automation system, a synchronous generator with circuit-breaker and a flywheel. In addition, Siemens Energy will provide preventive maintenance for 10 years with remote diagnostics. The synchronous condenser will, in turn, help management of Ireland’s transmission system with a reduced dispatch of fossil fuel plant under constraints and reduced costs of transmission operations.

“Synchronous condensers are an important building block for mastering the transition to climate-neutral, CO2-free power generation,” says Beatrix Natter, Executive Vice President Transmission at Siemens Energy. “We are proud that ESB has chosen us to build the first system of this kind in Ireland. Our solution will provide the maximum possible inertia and reactive power to stabilize the Irish grid, helping the country press ahead with its ambitious plans for the expansion of renewable energies.”

Siemens said that with the rising share of renewable power and the shutdowns of conventional plants, synchronous condensers are playing an increasingly important role in the grid. By means of the rotating mass of a conventional generator, the solution adjusts conditions on the transmission grid, provides the necessary inertia to support the grid frequency and short-circuit contribution while also providing or absorbing reactive power. In addition, synchronous condensers can diversify revenue for owners and operators while providing an important cash flow contribution.