Cement
With CO2 emissions in the gigatonnes range, cement production makes a very significant contribution to global greenhouse gas emissions. A large proportion of the emissions are due to the chemical process of lime burning, while only around 12 % are attributable to the electrical energy required for production. Nevertheless, cement plants are among the largest industrial consumers of electricity. As such, they pose specific challenges for the energy transition. Battery storage systems enable companies to obtain the electricity they need in a way that serves the grid, i.e. adapted to fluctuating availabilities. Multiple use of the storage systems also opens up economically attractive options for the cement plants, such as participation in the market for balancing energy.
References
Relevance of this field of application
Cement is the world's most widely used material, with production of 4.1 billion tonnes (2019). China alone accounts for 2.3 billion tonnes. The second-largest producer is India, with a production of 320 million tonnes, while Germany (2020) ranks twelfth with 35.5 million tonnes.1,2
The CO2 emissions associated with cement production are immense: they are estimated at 2.3 to over 3 billion tonnes per year, which corresponds to a share of 6 to 8 % of global emissions. Only the CO2 emissions of China and the USA (and, depending on the calculation, India) are higher than those of the cement industry.3,4,5,6
With regard to the cement production process, three main sources of emissions can be distinguished: During the production of burnt lime, one of the main components of cement, CO2 chemically split off from the raw material limestone ("deacidification"). These so-called process-related emissions account for around 50-60% of total CO2 emissions, depending on the estimate. A further 25-35% is due to the use of fuels required to heat the kiln. Electrical energy accounts for only 11-13 %.2,3,6,7
Although electricity-related CO2 emissions only account for a comparatively small proportion of total emissions, the electricity demand of the cement industry is nevertheless quite considerable: in 2020, an average of 109.4 kWh of electrical energy was used to produce one tonne of cement in Germany. With a total production of 35.5 million tonnes, this results in an energy input of 3.88 billion kWh - which corresponds to a share of 0.8 % of Germany's net electricity consumption.2,8 Most of this is accounted for by the comminution processes raw grinding (20 % or 776 million kWh) and cement grinding (45 % or 1.75 billion kWh).9
The electrical energy required to produce one tonne of cement has increased in Germany in recent years and is expected to rise further in the future. This is due to the increasing demand for high-performance cements with fine grinding.2
1 The European Cement Association (Cembureau, Hrsg.) (2021): Activity Report 2020.
Link ↗ (accessed 20.12.2021).
2 Verein Deutscher Zementwerke VDZ (Hrsg.) (2021): Umweltdaten der deutschen Zementindustrie 2020.
Link ↗ (accessed 20.12.2021).
3 Hasanbeigi, Ali (2021): Global Cement Industry's GHG Emissions.
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4 Wikipedia (2021): Zement.
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5 Global Carbon Atlas (2021).
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6 WWF (2019): Klimaschutz in der Beton- und Zementindustrie. Hintergrund und Handlungsoptionen.
Link ↗ (accessed 20.12.2021).
7 Verein Deutscher Zementwerke VDZ (Hrsg.) (2017): Umwelt-Produktdeklaration nach ISO 14025 und EN 15804. Zement.
Link ↗ (accessed 20.12.2021).
8 AG Energiebilanzen (2021): Auswertungstabellen zur Energiebilanz Deutschland. Daten für die Jahre von 1990 bis 2020.
Link ↗ (accessed 20.12.2021).
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.
9 Ausfelder, Florian; Seitz, Antje; von Roon, Serafin (Hrsg.) (2019): Flexibilitätsoptionen in der Grundstoffindustrie. Methodik, Potenziale, Hemmnisse.
Link ↗ (accessed 20.12.2021).
10 Verein Deutscher Zementwerke VDZ (2021): Zementwerke in Deutschland.
Link ↗ (accessed 20.12.2021).
11 Bundesministerium der Justiz und für Verbraucherschutz (2021): Verordnung über die Entgelte für den Zugang zu Elektrizitätsversorgungsnetzen (Stromnetzentgeltverordnung - StromNEV). § 19 Sonderformen der Netznutzung.
Link ↗ (accessed 20.12.2021).
12 Dusseldorp, Marc; Heinz, Sebastian; Lange, Christopher; Pohl, Sebastian (2021): Rightsizing – aber richtig! Auslegung von Batteriespeichern für mehr Nachhaltigkeit in der Energiewende.
Link ↗ (accessed 20.12.2021).
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.
13 Gruber, Anna-Maria (2017): Zeitlich und regional aufgelöstes industrielles Lastflexibilisierungspotenzial als Beitrag zur Integration Erneuerbarer Energien.
Link ↗ (accessed 20.12.2021).
Market outlook
The use of battery storage represents an attractive, legally regulated option for large consumers to drastically reduce the grid fees they have to pay. Assuming that an integrated cement plant wants to increase its annual usage hours from 4,850 to 7,000, a battery storage system with a capacity of 58 MWh is required for this purpose. A cement grinding plant needs a 40 MWh capacity storage for the same purpose. If all 54 cement plants in Germany were equipped with such battery storage systems, the market potential for this alone would be around 2.75 GWh.