The Naturstromspeicher Gaildorf is a natural energy storage plant that combines a 160 000 cubic metre pumped storage hydro-electric power station with a wind farm that consists of four large towers that double as a water reservoir. Reportedly, it is the first plant of its kind in the world. In late September Voith signed a contract to deliver the pump turbines for this special project. The three reversible Francis machines with a total output of 16 MW will be a core element in the plant.
The principle behind the operation of the plant is simple. If there is a surplus of power, the pumped storage power station switches to pumping mode, moving water from a lower reservoir to the higher storage located in the wind towers. If the demand for electricity in the grid rises, water is released from the upper basin to the bottom via a penstock and causes the pump turbines to move. Within a few seconds, electricity is generated and fed back into the electricity grid.
The combined tower/reservoirs confer an additional benefit – they make it possible to increase hub height by an additional 40 m, increasing power generation from wind energy by as much as 25%.
As well as supplying the hydro turbines Voith has contributed to the project development by adapting the Francis turbines to the unusual behaviour of the long pipe run and the long penstock.
The project marks a major step forward in using renewable energy sources to balance power demand and supply fluctuations because the combined wind and hydro power plant will act as a fast-response grid stabilisation resource.
Modern pumped storage systems need only thirty seconds to start up from a standstill and in the event of a blackout, such plants can support and control the complex grid restoration process due its unique black start ability.