Innovative pilot project Uniper tests environmentally friendly large-scale power storage system at Staudinger site

Uniper is piloting an organic solid-flow battery based on CMBlu technology at its power plant near Hanau, not far from Frankfurt am Main. It has an output of 1 MW and a capacity of 1 MWh. What's special about the UniBlu project solution? The storage system uses sustainable materials that are recyclable and almost indefinitely available. Rather than metal ions, the solid-flow batteries instead use organic electrolytic liquids and solids. During operation, the liquids function as an "energy shuttle" and are pumped through the battery stack in a circuit. There, they pass the electrode that implements the charge transfer. The actual energy is stored in the tank, where the liquid electrolyte flows through the solid—in the form of a plastic granulate—and transfers the energy to it. As a result, the system also differs considerably from lithium-ion storage on a technical level, combining the ability of flow batteries to independently scale power and energy with the high energy density of solid-state batteries.

The benefits of future-oriented solid-flow storage can be seen in a number of areas. Since there is no risk of fire or explosion, the batteries offer a high level of safety. In addition, the materials used are highly sustainable, and the electrolytes can be fully recycled. The storage facilities therefore have a particularly small carbon footprint. Furthermore, no rare or conflict resources are required. The batteries are designed so that over 90% of the materials required for the manufacturing process can be sourced locally or regionally.

The CMBlu storage solution is modular in design and therefore offers high levels of scalability in power and capacity. The storage system currently being tested has a capacity of 1 MWh. However, looking toward a sustainable future, sizes from 50 to over 200 MWh are also conceivable. The solid-flow batteries leave a lot of room for maneuver and have no size limitation.

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Sustainable solutions put to the test

Construction of the project has already begun at the Staudinger site. So far, the transformer for the battery has been installed and is currently connected to the battery interfaces. The main intended purpose of the storage system in the power plant is to ensure the stability of the power grid and to compensate for seasonal fluctuations. This is particularly important when it comes to the use of renewable energies. Sustainable large-scale electricity storage systems will ensure the optimal provision of energy base load capacity in the future as well as offer opportunities for peak load capping per location or in companies, for example.

In the future, the new storage systems may play an important role in the overall system, so they first have to undergo a number of tests to prove their suitability, explains Innovation Manager and UniBlu Project Manager Thomas Pock: "For a start, we use a variety of test programs to test the technical reliability of the system. Here we are also concerned with the degradation of storage capacity." This ensures that all parameters still meet the requirements even after a specific number of storage cycles — power, efficiency and other technical parameters are examined closely. "In the medium-term, we test the capabilities of the battery system with regard to system services." One example of this is primary control power. Among other things, the system must deliver a specified power level within 30 seconds in order to pass the tests. "These checks allow us to determine which market channels the battery system is suitable for and can therefore be pre-qualified for," he explains.

As part of the pilot project, the tests are only carried out with reference to the power plant's own requirements. Of course, mains power is also available in addition to the supply from the battery. "This allows us to play with the parameters of the battery without having to do this on the actual grid," explains Nadine Schulte Pelkum. She is also an Innovation Manager and is responsible for electrical engineering in the UniBlu project.

The Staudinger power plant was ideally suited for the pilot project

"The biggest advantage of the Staudinger site is the proximity to our partner CMBlu. This is especially helpful for a pilot project," summarizes Nadine Schulte Pelkum. The infrastructure of the power plant is also ideally suited to the requirements of the project. After the first planning phase, the team decided not to build a separate hall for the storage system on the power plant site. This was unnecessary because the battery could be easily integrated into the existing buildings. "The storage facility is being installed in the pump building of block 1/2 at a height of 11 meters," said Thomas Pock. There were a number of benefits to this: Firstly, this allowed costs for constructing a hall to be saved. Secondly, it made compliance with the German Federal Water Act incredibly straightforward. No new hall meant no new required permits to apply, saving time on the project. However, integration with existing infrastructure makes implementation more complex.

A considerable amount of time is required to remove the cables and route new ones. Certain fire safety regulations also have to be followed. However, CMBlu and Uniper have overcome all of these challenges together and are planning to start commissioning the first two battery strings at the beginning of next year. Following the planned delivery of the electrolyte repository, all 12 strings are scheduled to go into operation in mid-2024.

The UniBlu pilot project is a pioneer for the further development and use of solid-flow technology. If the storage system is expanded following the project's completion, the sizable benefits of scalability will come to fruition. This is because, unlike conventional storage technologies such as lithium-ion, the only things required to expand the storage capacity of solid-flow batteries are more electrolyte liquids and solid granules. This also brings cost efficiency benefits over alternative storage technologies.

UniBlu is an important milestone in the breakthrough of solid-flow storage. In 2024, CMBlu is planning to construct a highly automated, high-capacity production facility to drive the adoption of these batteries. Uniper will be working closely with this ambitious company throughout and providing them with exclusive supply conditions.

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