Join OGE on the path to climate neutrality!

Carbon, C, is also known as the atom of life. It is in DNA and in half of our food – chemistry knows of 200,000 compounds in the world without carbon and 20 million with it. It is found in many compounds (including frequently as CO₂) and performs multiple functions: It is used to generate heat and power, as an aid in process technology (e.g. in steel production), and as a basic material in the manufacturing of products such as pharmaceuticals or plastics.

Carbon dioxide, CO₂, occurs naturally in the air at a rate of 0.038%. CO₂ absorbs part of the heat given off by the earth and radiates it back to the earth, which is why it is one of the greenhouse gases. It is a non-toxic, neither flammable nor explosive gas, and is a natural by-product of cellular respiration in many living organisms. CO₂ is also released as dead organisms decay or through natural CO₂ sources, such as volcanic gases. It is also produced, however, through combustion of wood, coal, oil or gas due to the carbon they contain (C), which combines with oxygen (O₂).

Carbon monoxide, CO, is a flammable, toxic gas. Unlike CO₂, CO does not occur naturally in the atmosphere. It is formed by the incomplete combustion of coal, natural gas or oil. A low oxygen content and low temperatures lead to the formation of carbon monoxide during combustion, but it can be further burned to create CO₂ where there is a sufficient oxygen supply.

Unavoidable CO₂

Process-related CO₂ quantities result from the reaction itself and not through the use of the energy required for the process. In industry, these are considered unavoidable if their formation cannot be prevented despite optimisation of the production process or the product. This is the case when no alternative processes and no alternative products or resources are available to a sufficient extent for the same use case.

These currently include, for example, process-related CO₂ quantities from glass production, the chemical industry, lime and cement production, and electric arc furnaces in the steel industry.

Green or biogenic CO₂

Biogenic CO₂ is produced by the combustion or fermentation of biomass (organic material consisting of carbon, hydrogen and oxygen), such as wood. Combustion of biomass produces emissions that are considered CO₂-neutral because the carbon is produced from a neutral CO₂ cycle. Trees, for example, capture CO₂ from the air as they grow, but when the wood is burned it is released back into the air. The total volume of CO₂ in the atmosphere thus remains the same in this case. The use of biogenic CO₂ is climate-neutral under the same circumstances as the utilisation of biomass.

Grey and fossil CO₂

Fossil CO₂ occurs through the use of fossil carbon (e.g. coal or lime). The use of fossil CO₂ for manufacturing products in which the carbon is not permanently chemically bound (so-called long-lived products) is therefore not climate-neutral, because the CO₂ escapes into the atmosphere and contributes to climate change. A sensible circular economy is therefore all the more important here in order to reduce the further use of conventional fossil carbons.

CO₂ capture

CO₂ capture refers to the process of “capturing” CO₂ from the air, from biomass, or from industrial emissions. Here, for example, a technical process makes it possible to capture up to 90% of CO₂ emissions produced by industry.

CO₂ can be captured directly from the air by means of a special process known as Direct Air Capture.

CCS

The abbreviation CCS stands for Carbon Capture and Storage. Following the capture of CO₂ from the air, from industrial emissions, or from biomass, there are various processes for storing this CO₂, also known as sequestration. Here, a distinction is made between geological storage, where the CO₂ is stored underground in rock formations, in natural sinks such as peat, bogs, or forests that naturally sequester carbon, and permanent sequestration in long-lived products.

CCU

CCU, Carbon Capture and Utilization, refers to the subsequent use of CO₂ after CO₂ capture. In the long term, even in a climate-neutral system carbon or hydrocarbons will still be needed, for example for air and sea transport or for the chemical industry. Recycling of carbon-containing products as a raw material source is gaining immense importance in this context. Since not all products can be recycled, on the one hand, and on the other this would most likely cover only part of the demand, CCU measures will be necessary to meet the demand using CO₂ from the atmosphere as well as from unavoidable CO₂ sources.

CCUS

If CO₂ is first used after capture before being stored, this process is known as Carbon Capture, Utilization and Storage.