More than four billion tonnes of cement are produced worldwide every year. In the process, the building material inevitably releases large quantities of the carbon dioxide bound in the lime. Cement manufacturers, such as CEMEX from Mexico, are meeting the gigantic challenge of decarbonizing the industry. A bottleneck in the development is lack of green hydrogen. The building materials manufacturer has now set ambitious targets for itself. The site in Rüdersdorf is to serve as a blueprint.

For production of green cement, it is not only the required energy that is a problem, since only one-third of the CO₂ emissions originate from the energy input. Two-thirds are intrinsic to the system. These are emissions that arise in the course of cement production itself. A cement produced with purely green energy still releases huge amounts of CO₂ during the production process. Businesses and researchers want to change this.

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Change for the climate also means changing cement to eco-cement. Various scientists are also working on this, among them the research institute Empa in Switzerland, which is developing a CO₂-negative magnesium-based cement. Building materials manufacturer CEMEX also wants to rapidly reduce its emissions. According to the company’s calculation, it is already releasing 35 percent less CO₂ than in 1990, Sergio Menendez states. He is president of CEMEX Europe, Middle East, Africa and Asia. By 2030, it should be 55 percent less in Europe, and the manufacturer wants to produce only CO₂-neutral concrete worldwide by 2050.

So far, however, there has been little demand for green products, CEMEX speaker Alexandra Decker laments. The company therefore has the idea of separating carbon dioxide from exhaust gas, storing it temporarily and then converting it together with H₂ into synthetic fuel. Thus providing a product that is planned for in advance and producible on demand. “This is another reason why we only want to use green hydrogen,” Decker assured H2-international.

CEMEX has specifically chosen to build electrolyzers at the location in Rüdersdorf so that it can supply the factory there with hydrogen from green electricity. In this way, H₂ that might be needed for other industries would also not be taken off the market. The construction would have to start in 2025/26 for the site to produce CO₂-free from 2030 onwards, Decker states.

The consortium Concrete Chemicals

In order to free not only cement production but also air traffic from CO₂, three companies founded the project consortium Concrete Chemicals. CEMEX, with 56,000 employees worldwide and its own locations in Germany; Sasol ecoFT, a subsidiary of chemical corporation Sasol; and Uckermark-based Enertrag plan to produce a sustainable aviation fuel that can also be used in cement production. For this, a power-to-liquid method (PtL) will come into use. CO₂ and H₂ are converted into syngas. The mixture of carbon monoxide and H₂ is then, with the aid of the Fischer-Tropsch process, converted into longer-chain hydrocarbons to produce e-kerosene.

The project in Rüdersdorf comprises two scaling levels. First, the hydrogen will be produced on site with electricity from regional renewable energy plants. In this first stage, 15,000 tonnes of e-kerosene are to be produced annually this way. For it, 100 tonnes of CO₂ per day are to be captured in Rüdersdorf, combined with 12 tonnes of H₂ per day and used for PtL production. In the second stage, larger quantities of H₂ are to be delivered by pipeline.

The green hydrogen will be generated as part of the IPCEI project Elektrolyse-Korridor Ostdeutschland (electrolysis corridor Eastern Germany) to build a capacity of 210 MW. This will enable the production of 35,000 tonnes of e-kerosene per year. This project also uses only renewable electricity for the production of 40 tonnes of green hydrogen per day, the consortium states, which requires that another 300 tonnes of CO₂ per day be sequestered.

The partner network Doing Hydrogen

Concrete Chemicals as well as Elektrolyse-Korridor Ostdeutschland are part of the IPCEI partnership project Doing Hydrogen. During construction of the pipeline from Rostock to Sachsen, all components of an H₂ value chain will be covered. The resulting transmission system is to be built by 2026, two-thirds by conversion of existing natural gas infrastructure and one-third by the construction of new complementary hydrogen lines. In this way, a starter grid with a total length of 475 kilometers will arise that connects production and use points in Mecklenburg-Vorpommern, Brandenburg, Sachsen, Sachsen-Anhalt and Berlin.

The e-kerosene is then also to be certified for use in aircraft, since no alternative propulsion systems in the aviation sector are in sight for the foreseeable future. Through PtL, fuel of exactly the same specifications as petroleum-based kerosene can be created. With this, no modification of the existing drive technologies is needed. The three companies want to meet the criteria for aviation fuel set out in the EU directive RED II. Fuel having the prescribed minimum percent of PtL kerosene to be blended can be achieved this way.

The market for e-kerosene

The EU proposal ReFuelEU Aviation represents a first step towards the decarbonization of air transport. At the same time, it should ensure the purchase of synthetic fuels such as e-kerosene. At EU level, the regulation includes a sub-quota of 0.7 percent synthetic fuel out of the required quota of sustainable fuels for year 2030. The quota is to rise to a minimum of 28 percent e-fuels by 2050. “In this way, demand is plannable and ensured,” states Enertrag speaker Matthias Philippi.

Furthermore, under the German fuel blending regulation (Beimischungsverordnung), the fuel for all aircraft refueling in Germany will need to contain at least 0.5 percent PtL kerosene starting as early as 2026, and 2 percent starting 2030. This should increase the share of renewable energy in the transport sector to 28 percent by 2030.

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