Carbon in Energy

How can energy be produced efficiently? How can it best be stored? How can we use it in a resource-friendly way? Questions about energy are questions about the future.

These are the most urgent questions of our time and carbon holds promising answers. Whether for generating, storing or using energy, the materials and solutions provided by SGL Group are used in all of these areas.

In our global production and technology network, knowledge and ideas flow between countries, between continents, and between people. Because, after all, the development of sound innovations for energy technology involves teamwork. It is a task for many creative minds, all of which have something in common – a passion for carbon.

Solar energy

0% percentages of energy produced by photovoltaics worldwide in 2030 0%
reduction of CO2 with photovoltaics in 2030

Solar: Smart materials and concepts for photovoltaics

Innovative materials and concepts are required to make solar energy usable. One of these materials is isostatic graphite. With the right know-how, it can be turned into various parts. This specialty graphite is used wherever the technical properties of other materials are not sufficient – for instance in the production of silicon monocrystals, the most important raw material in photovoltaics.

Even at very high process temperatures, graphite remains solid far beyond the melting point of silicon. Ist high purity and low solubility in silicon enables the manufacturing of high performance solar cells with very little contamination.

We supply the photovoltaic industry with graphite and carbon products along the entire supply chain. And the company has impressive expertise in other areas, such as customized process technology and system solutions, such as recycling units. With this unit, highly corrosive hydrogen chloride gas (HCl) can be recovered from waste acid and fed back into the process. This reduces the HCl consumption by 30 percent, eliminates the need for a complex disposal of waste acid, and reduces process costs significantly.

The recycling unit consists of over 25 components, such as heat exchangers, columns, and pumps made of corrosion-resistant graphite and polytetrafluoroethylene (PTFE).

Heat exchangers for heating systems

 Home heating systems consume a lot of energy. The right technology and the right material could save a lot of this energy. Graphite heat exchangers provide such solutions. They enable to use the heat contained in the waste gas of a heating system: In the graphite heat exchanger water cools down the flue gas and thereby heats up itself. Is the flue gas cooled down below the dew point, the steam contained in the flue gas condenses to water. This condensation process puts additional heat to the cooling water.

The energy absorbed by the water is completely transferred to the heating circuit. The high heat conductivity of graphite and its resistance to corrosion against acidic condensates within the flue gas results in a more efficient use of the energy carrier by up to 20 percent.

Largest Graphite Plate Heat Exchanger

Plate heat exchangers allow a considerable higher energy utilization compared to traditional designs like annular groove-, block- or shell&tube heat exchanger. A main requirement of our customers has been the development of larger graphite plate heat exchanger to be able to process higher flow rates. This would extend the range of applications.

The largest graphite plate heat exchanger in the world has been developed and is now available through our cooperation partner Alfa Laval. The new model provides flow rates of more than 250 m3/h. Its main field of use is heating or cooling of liquid corrosive substances e.g. in chemical processes.

Energy efficiency in architecture

Thanks to rising energy costs, the threat of climate change, and environmental policy requirements, efficient energy concepts for construction and refurbishment are in demand as never before. Heating, cooling, and ventilation use the most energy in a high-rise building.

The Deutsche Bank has recognized this problem and modernized its headquarters in Frankfurt/Germany from the ground up. The two towers are among the most environmentally-friendly skyscrapers in the world. They use 67 percent less energy for heating and cooling. About 10,000 radiant ceiling elements with ECOPHIT® graphite lightweight panels made by SGL Group were installed on the room ceilings.

This surface heating and cooling system utilizes the retention capacity of concrete and the benefits of a natural material: graphite distributes heat and cold quickly and evenly over a surface.

The thermal exchange takes place with water, which flows through the pipe meanders that are directly pressed into the lightweight graphite panels.
These tight connections significantly increase the efficiency of the radiant ceiling elements. The result is one single system for heating and cooling that saves a large amount of energy. Planners and architects are also delighted by another benefit - more design flexibility. In the Deutsche Bank building, the flat modules enabled a ceiling height of 3 meters – 35 centimeters higher than before.

Along with panels, SGL Group’s specialty graphite product portfolio for construction and HVAC applications also boasts foils, granulates, and powder. The source material is always pure natural graphite from which we produce expanded graphite. As a natural material, this graphite is also completely recyclable.

Latent heat storage with graphite

Latent heat accumulators use the energy created in phase transition. So-called phase change materials (PCM) are used. These are, for instance, salts, paraffins or water, which at their melting points take up or give off heat without changing their own temperature.

By combination of graphite and PCM composites can be generated which have a heat conductivity up to 100 times higher than a pure PCM. Those can be used to create compact heat storage systems which are suitable for diverse applications, ranging from industrial processes and solar-power plants to the air-conditioning of buildings and vehicles. In industrial processes, these easily integrable units can regenerate over 90 percent of waste heat.

Flow batteries store renewable energy

Solar modules supply power when the sun shines, and wind turbines when the wind blows. This means that energy storage is necessary so that energy is available when needed, even when there is a lull in the wind or in the middle of the night. Redox-Flow batteries provide the solution. They can store larger amounts of electricity, have a longer operating life, and are very robust. Because of its electric conductivity and its chemical stability, graphite is used in many advanced battery systems.


SGL Group supplies two core components for flow batteries. The SIGRACELL® bipolar carbon and graphite felt, a porous electrode material, enables efficient charging and discharging of the battery. And SIGRACELL® bipolar plates of expanded natural graphite provide for low internal resistance of the system. Our materials are also used in other battery systems like for example in sodium-nickel cells and in the new lead storage batteries.