The idea behind the system is simple, yet innovative: four high-performance wind turbines linked to a pumped storage power station are set to use a combination between wind power and hydropower to generate electricity staring in 2018, thus ensuring flexible power supply for the 12,000 inhabitants in the town of Gaildorf in Baden-Württemberg, Germany. Besides renewable energy generation, energy storage and feeding electricity into the grid are current issues which local authorities and utilities need to address. Engineer, initiator and product developer Alexander Schechner has closely examined this need for a unique storage technology and launched a singular energy project, the Gaildorf natural energy storage plant. The world's first system of this type links wind turbines with a pumped storage plant and a lower reservoir in a valley. Any excess wind energy not required when produced is used to pump water upwards and the water is then channelled down to the turbines in the power plant when electricity is needed.
Combined wind and hydro-power
To allow wind and water to work together perfectly, four wind turbine towers began to emerge on the Limpurg Hills above the Kocher Valley in April 2016. With a total height of up to 240 metres, these towers are among the highest in the world to date. Planned and constructed by Max Bögl, the wind turbines will achieve hub heights between 158 and 178 metres, feature a rotor diameter of 137 metres and produce a total output of 13.6 megawatts. The genius of this system is that, whereas conventional pumped storage power plants feature just one upper and one lower reservoir, the upper reservoir in the Gaildorf project is effectively divided into four small ones which are directly integrated into the wind turbines.
Tower base as a water tank
Four metres high and almost 17 metres in diameter, water tanks are being built on the conventional ring-shaped bases of the wind energy towers. These active reservoirs are constructed using a modular tubbing structure consisting of four segments, which each form an individual ring and come together to create massive pedestal foundations. Normally used in tunnel construction, these components are being produced in the prefabricated component works in Sengenthal and have been arriving at the construction site since August. The upper encasement on the active reservoirs constitutes another ring-shaped foundation, into which the time-tested Max Bögl Hybrid Tower System made of steel and pre-stressed concrete is screwed in a vertical position.
Increased wind harvesting
The pedestal foundations themselves are placed in outside reservoirs, 63 metres in diameter, which are filled with water up to 13 metres deep and can thus store most of the water. Together with these upstream passive reservoirs, the tank foundations beneath the wind energy towers can hold about 160,000 cubic metres of water. The active reservoirs elevate the turbines' foundations, thus increasing the hub height of the rotors up to 40 metres, boosting power generation from wind energy by up to 25 percent.
Use of the latest technologies
A pressure pipe connects the wind energy towers with one another and with the lower reservoir 200 metres below in the valley. Measuring 400 by 150 metres, the water reservoir at the pump storage power station will also feature as an attractively landscaped body of water for leisure activities. The decidedly innovative high-pressure pipeline with an operating pressure of 30 bar was specially developed and needed to be designed with a suitable laying technique right from the preparation stage of the project. The new technique enables the pressure pipe to be laid at an unprecedented speed and greatly reduces the necessary intervention on the landscape. These were all good reasons to submit the concept to the German Patent and Trade Mark Office (DPMA) in Munich for patenting.
World's fastest pumped storage system
A state-of-the-art pumped storage power station is emerging between the wind farm and the water reservoir in the valley. If the wind turbines deliver more power than needed, the water is pumped from the lower reservoir and into the wind turbine tower tanks and the passive reservoirs surrounding them. If there is a lull in the wind or more electricity is needed, the water stored in the towers is channelled down into the valley to the power station, where it drives three pump turbines, also newly developed for the project. Made by Voith Hydro, the turbines have been devised to start delivering full power of up to 16 megawatts within a mere 30 seconds. The power station's electricity storage capacity is designed to hold 70 megawatt hours.
Environmentally friendly electricity generation and storage
The advantage of this ingenious pilot system is not only that excess electricity produced from renewable sources can be stored locally at short notice without needing to diminish energy production. Besides decentralised, sustainable electricity generation without CO² emissions, the innovative technology also delivers the flexibility required for future energy systems. The German Federal Ministry for the Environment, Nature Conservation, Building and Nuclear Safety (BMUB) was also impressed by its capabilities and decided to help fund the project with 7,150,000 euros from its environmental innovation programme.
