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Designing – and insuring – the future

When nature not only generates electricity but also stores it. Insurance solutions for an energy project that connects wind turbines with a pumped-storage plant. By Benjamin Rohloff, HDI Risk Consulting

The Gaildorf water battery is being built in a hilly wooded area near Stuttgart in southern Germany. The special feature is that electricity is being produced using renewable energies and stored depending on demand. This is being achieved for the first time by combining wind turbines and a pumped-storage power plant.

It is a pilot project for which several construction and erection all-risks policies were necessary as well as technical support for risks. This project provides a good insight into how industrial insurers always have to be prepared to adopt new pathways when innovative customers want to be supplied with equally innovative and tailor-made insurance solutions. This applies in particular for industrial projects from the area of renewable energies.

The water battery in Baden-Württemberg is without parallel. In the range of hills near the town of Gaildorf, our policyholder is currently constructing the third out of a total of four wind turbines. The rotors have a diameter of 137 metres and they will produce up to 14 megawatt (MW) of electricity from wind power. Of course, this is not exactly new territory.

However, at the same time a pumped-storage plant is being constructed in the nearby valley through which the “Kocher” river flows. This power plant is being connected to the four wind turbines by a penstock pipeline. The idea is that the electricity produced by the wind turbines will be fed into the public electricity grid. When there is an oversupply and consequently a correspondingly low electricity price, the electricity is not fed into the grid. Instead, the energy is consumed by the power plant pumping the water up to the wind turbines.

Reservoirs are being built in the foundations of the wind turbines to store the water. As a result, the tower gains an additional 40 metres in height. This increases the efficiency of the wind turbines. However, at the same time the project posed some very special challenges for the construction works. The crane had to be positioned as close as possible to the wind turbine in order to install the rotor at this altitude. Our policyholder developed a crane rucksack specifically for this purpose. This is a platform on the reservoir that allows the crane to be set up.

The technology is protected by a high plateau during flooding

What happens when the electricity supply falls while the demand remains the same and the price increases accordingly? The power plant then switches from pump to turbine operation. The turbines are driven by the flowing water so that electricity is generated.

The key advantage: Thanks to water storage, renewable energies can also be used on still days when there is little wind.

The water circuit is regulated using another reservoir which is located in the valley near the pumped-storage plant. The powerhouse plant has currently been set up on the right-hand bank of the “Kocher”. The water storage for the power plant is being constructed on the left-hand side of the river. At the same time, this lower reservoir is being used as a flood plain when the river floods. This is intended to prevent the river flooding its banks uncontrollably when the water is high.

The statistics indicate that flooding is likely to occur once every ten years. Water levels are therefore measured daily so that the site can be cleared when defined thresholds are reached. All technical plant and equipment can then be protected on a plateau. This was set up on our recommendation as part of our risk consultancy. Successful cooperation of this type requires permanent openness and trust on the part of all the participants. This is the only way in which safety recommendations made by our risk engineers can be communicated and then implemented during the construction works.

In spite of the innovative nature of this project, the construction and erection all-risks cover has already been used in a lot of other projects by this policyholder. The cover was simply split into three areas for improved transparency. The first two phases are already being realised while the wind turbines and the hydropower plant are being erected. The third phase is still at the planning stage: erection of the pressure pipelines which will be used to transport the water volumes. This pipeline might be described as the main artery of the project. A new automated laying procedure is being used for this phase in which the pipes are welded together and underpinned with liquid soil so that they can be laid uniformly.

Prototype including the cover “go into series production”

The objective is for this prototype to go into series production if there is sufficient demand, and it can then be manufactured within the space of one year. The construction company will market the water battery together with the participation of a cooperation partner.

At the same time, an appropriate standardised insurance cover needs to be developed for the water battery so that this modern renewable energy project will also have good protection in the future if it goes into series production – irrespective of where such plants are constructed in the future. From my perspective, covering key risks in industrial projects of this type is both a challenge and a motivation for industrial insurers. Adopting this approach is the only way in which pioneering projects can be implemented and taken forward at the same time.

This article was first published by Insurance Day, London. Publication on this website by courtesy of Insurance Day (