Use of battery storage

Raw grinding serves to crush the most important cement raw materials limestone and clay (or their natural mixture limestone marl). The resulting raw meal is then burned in a kiln at temperatures of around 1,450°C to produce what is known as cement clinker. This in turn is finely ground in cement mills after cooling and storage in silos.⁷

In 2020, 33 integrated cement plants with raw grinding and clinker burning process and 21 cement grinding plants without their own clinker production were in operation in Germany.¹⁰ An integrated cement plant has an average of 3.8 cement mills and a raw mill, while a cement grinding plant has only 2.4 cement mills. Each individual mill has a power consumption of around 3 MW (raw mill) or 2 MW (cement mill). If the electricity consumption for kiln, transport and other purposes is added, the average annual electricity consumption is 90.7 GWh for an integrated cement plant and 42.4 GWh for a cement grinding plant (own calculation according to ⁹).

Cement plants are thus among the large industrial consumers of electricity that place a high demand on the power grid, especially when consumption fluctuates. In view of this, the legislator has created incentives in the Electricity Grid Charges Ordinance (StromNEV) for grid-serving plant operation. One of the cases regulated here is "intensive grid use": if a large consumer has an annual electricity demand of more than 10 GWh and at the same time at least 7,000 annual hours of use, it can be exempted from up to 80 % of the grid charges, as the electricity grid is less burdened by the more even consumption.^11,12

The first condition for reduced grid charges - an electricity demand of over 10 GWh - is easily met by cement plants, but the second condition is not. In fact, the average annual usage is around 5,000 hours (own calculation and estimate from ⁹). This is where battery storage comes into play. With their help, the power consumption of the cement plant can be "distributed" over 7,000 hours or more to serve the grid: During ongoing production, part of the electricity demand is covered by the battery, which is recharged during production breaks.

Performance requirements

The energy-intensive cement industry has a special role to play in improving the integration capacity of renewable energies. To date, the discussion has been dominated by technical flexibility potentials, which involve achieving a temporal shift in energy demand by shutting down production plants.^9,13 Battery storage systems have the potential to significantly expand these flexibility options. In order to ensure investment security, they must have a pronounced longevity, which should be oriented to the operating time of the production plants.

The sheer size of the storage units required also makes multiple-use applications economically interesting, which can only be developed if the battery storage unit also has sufficient fast-charging capability.

In principle, the energy storage systems used should also meet high sustainability standards - not least because this is rightly demanded in the political and public debate on the energy transition.