u&i GmbH - Carbon Dioxide

Carbon Dioxide

Carbon dioxide (CO₂) acts as a greenhouse gas in the earth's atmosphere and therefore contributes to global warming in the long term. In the current discussion about reducing these greenhouse gas emissions in order to achieve the goals of the Paris Agreement, carbon capture (CC) is considered to be of great importance. In future, CO₂ will no longer be seen as a waste product but as a raw material in a wide range of applications and will become part of the circular economy in order to reduce global CO₂ emissions.
Overall, the topic of carbon dioxide/CO₂ is in a state of flux. Markets are changing and new ones are emerging - as are technologies and process combinations. Against this background, the current lines of action and possibilities are presented in simplified form below and finally the terms most frequently used in this context are summarized and explained.
When capturing CO₂, a distinction can be made between direct capture from the atmosphere using direct air capture (DAC) and post-combustion capture (PCC) of CO₂ from the exhaust gas of power plants and other facilities.

In DAC technology, there are various processes such as amine scrubbing, absorption by sodium hydroxide or membrane separation to reduce the CO₂ concentration in the atmosphere by means of so-called geoengineering and slow down climate change mitigation. However, all of these methods have the disadvantage of very high capture costs. Therefore, when implementing CC to reduce greenhouse gases, direct capture at power plants tends to be considered. In order to reduce CO₂ emissions at power plants, various processes have been developed, which are roughly divided into three areas.

Pre-Combustion		Post-Combustion
The capture of CO₂ before the combustion process in the pre-combustion process is mainly used in gas and coal-fired power plants. In this process, carbon monoxide is converted to CO₂ by water vapor through a water-gas shift reaction and removed from the process before combustion.	One option for low-CO₂ energy generation is the so-called oxyfuel process, in which combustion is not carried out in an air atmosphere, but with pure oxygen. This means that the exhaust gas consists mainly of water vapor and CO₂ after exhaust gas purification. The difficulty of this process lies in the provision of pure oxygen and the associated process control. As the separation of the ambient air is complex, pure oxygen from an electrolysis plant can also be provided for this process.	The post-combustion process describes the extension of flue gas cleaning in a power plant by means of CO₂ separation in the flue gas that escapes. Similar adsorbents and absorbents are used here as in the DAC process.

The main difference between DAC and point source capture is the fact that the DAC process reduces the CO₂ content of the atmosphere. With point source capture, CO₂ neutrality of the plant is usually achieved through the integration of CC. However, this depends on the further handling of the CO₂ and can be considered in more detail in the context of a CO₂ balance, the creation of corporate carbon footprints or the creation of climate gas balances.

One possibility is storage (CCS - carbon capture and storage), for example through sequestration in pure form in depleted gas deposits or special rock strata, in order to remove some of the CO₂ emissions from the cycle. However, this is only the case for biogenic fuels, while the carbon balance for fossil CO₂ remains unchanged with the help of CC. However, as storage is heavily dependent on geographical conditions and the possibility of re-emission cannot be ruled out at the present time, research is also being carried out into the mineralization of CO₂. This process is analogous to natural rock formation and involves a lower risk. In addition to storage, the focus is also on the use of CO₂ (CCU - carbon capture and utilization). New products can be created in various processes by incorporating carbon dioxide. For example, the supply of CO₂ and Hydrogen in a Power to X plant offers the possibility of producing hydrocarbons from renewable sources. Further applications can be found in the chemical industry for the production of synthetic compounds, in urea production, in greenhouses or as a basis for building materials.

In this context, so-called Bioconversion Processes can be mentioned as a third and indirect way of using CO₂. These can be used to technically convert organic waste into stable carbon compounds (e.g. using pyrolysis or HTC). This biochar / biochar is more difficult for microorganisms to access, so that further natural degradation to CO₂ is interrupted. By introducing the charcoal into the soil, CO₂ is removed from the atmosphere in the long term, while at the same time plant growth and the binding of CO₂ by means of photosynthesis can be promoted. These processes are often referred to as BCR (Biochar Carbon Removal).

In addition to BCR, another widely used approach is BECCS (Bioenergy Carbon Capture and Storage). This aims to capture and store (CCS) or utilize (CCU) the CO₂ from bioenergy applications.

The following overview provides a summary of the most common terms and abbreviations:

BCR - Biochar Carbon Removal

The Biochar Carbon Removal process is based on the thermal process of pyrolysis. Organic material is treated in the absence of oxygen and at elevated temperatures. Some of the carbon is then in the form of biochar, which is usually difficult for microorganisms to break down. If the biochar produced is introduced into the soil, this is referred to as biochar carbon removal - an active form of carbon deposition.

BECCS - Bioenergy with Carbon Capture and Storage

Bioenergy with Carbon Capture and Storage (BECCS) is a combination of a biomass power plant and various CC processes. The energy is extracted and used from the biomass in combustion processes, fermentation, pyrolysis or other conversion processes. The resulting waste gases and residues are cleaned of carbon dioxide using CC processes, and the CO₂ is stored accordingly or used further.

CC - Carbon Capture

Carbon Capture refers to the process of extracting CO₂ from the ambient air or an exhaust air stream. Technologies are differentiated according to their place of application and the downstream use of the carbon dioxide. CO₂ capture directly from the atmosphere (Direct Air Capture, DAC), capture directly after a CO₂ emitter (Post-Combustion Capture, PCC), storage of the captured CO₂ in existing storage facilities (Carbon Capture and Storage, CCS) and general use of the CO₂ after capture (Carbon Capture and Utilization, CCU).

CCF - Corporate Carbon Footprint

The Corporate Carbon Footprint (CCF) enables companies to measure their total greenhouse gas (GHG) emissions. All GHG emissions from the company's various activities are recorded, including direct emissions from fuels and indirect emissions from energy supply as well as upstream and downstream activities in the value chain. The CCF can serve as the basis for developing a climate strategy.

CCS - Carbon Capture and Storage

Carbon Capture and Storage (CCS) bedient sich in der Regel der Technologien der Direct Air Capture (DAC) oder Post-Combustion Capture (PCC). Bei DAC wird CO₂ direkt aus der Atmosphäre entnommen, während PCC das CO₂ nach der Verbrennung von Brennstoffen abfängt.
Das mit diesen Verfahren abgeschiedene CO₂ kann entweder als Gas behälterlos in unterirdische Speicher gepresst werden, wie zum Beispiel alte Erdgas- oder Erdöllagerstätten. Dies wird als geologische Speicherung bezeichnet. Alternativ kann das CO₂ auch mineralisiert werden, indem es chemisch in feste Mineralien umgewandelt wird. Diese mineralisierten Produkte können dann in alten Bergwerken oder anderen geeigneten geologischen Formationen gelagert werden.
Beide Methoden dienen dazu, das abgeschiedene CO₂ sicher und dauerhaft zu speichern und so zur Reduzierung der Treibhausgasemissionen beizutragen.

CCU - Carbon Capture and utilization

Carbon capture and utilization (CCU) uses similar technologies to CCS processes, but the focus here is not on storing or storing the captured CO₂. Instead, the captured CO₂ is used as a raw material for other uses, for example in chemical processes.
In contrast to CCS, the CO₂ is not permanently removed from the cycle in CCU, but is released back into the atmosphere for later use. CCU processes therefore have no direct climate protection effect, as the CO₂ is ultimately released again. However, a certain climate-protecting effect can be achieved by substituting primary raw materials with the captured CO₂.
CCU technology has the potential to reduce the use of fossil resources and thus indirectly contribute to reducing greenhouse gas emissions.

CSRD - Corporate Sustainability Reporting Directive

The Corporate Sustainability Reporting Directive (CSRD) is an EU directive that obliges companies to expand their reporting to include relevant ESG criteria. It specifies what must be reported. To understand the abbreviation CSRD, you should first read the explanations of the European Green Deal, ESRS and ESG.

DAC - Direct Air Capture

Direct Air Capture (DAC) refers to the direct removal of carbon dioxide (CO₂) from the atmosphere. There are various technologies that can be used for this process, such as amine scrubbing, absorption by sodium hydroxide or membrane separation.
In DAC, air is taken from the atmosphere and passed through these technologies to capture the CO₂. The result is pure CO₂ and low-CO₂ atmospheric air.

ESG - Environment, Social, Governance

The ESG criteria, which originate from the European Green Deal, are EU requirements. They set standards in the areas of Environment Social (social), (environmental) and Governance (corporate governance). Each of these areas contains further requirements and guidelines.

ESRS - European Sustainability Reporting Standards

The European Sustainability Reporting Standards (ESRS) are divided into the areas of environment, social affairs and corporate governance and prescribe how the requirements of the European Green Deal must be reported. The ESRS E1 standard is the first of five climate-specific standards under the title “Climate Change” and contains nine disclosure requirements (E1-1 to E1-9) that must be reported independently of a special materiality test. Unlike other parts of the CSRD, this standard is mandatory for (almost) all companies. ESRS E1-1 to E1-9 ultimately contain the three major steps towards climate neutrality: accounting, setting measurable targets and developing and implementing an action plan. In summary, the ESRS determines how reporting must be carried out.

European Green Deal

With the European Green Deal, the European Union has developed a comprehensive plan to make the EU the first climate-neutral continent. The EU Taxonomy and the CSRD, which many companies are already familiar with, play a key role in this. The ESG criteria in these directives set standards in various areas, with each area containing further specifications and guidelines.

GHG - Protokoll - Greenhouse Gas Protocol

The Greenhouse Gas (GHG) Protocol is an internationally recognized standard for reporting greenhouse gas emissions. It was developed by the World Resources Institute (WRI) and the World Business Council for Sustainable Development (WBCSD). The GHG Protocol comprises several guidelines and standards, including guidance on the PCF, CCF and Scope 1, 2 and 3.

GWP - Global Warming Potential

The Global Warming Potential (GWP) is an abbreviation that indicates how much heat a greenhouse gas traps in the atmosphere over a certain period of time (usually 100 years) compared to CO₂. By converting gases into CO₂ equivalents using the GWP, the effect of the individual gases on our climate can be compared.

PCC - Post-Combustion Capture

The process of post-combustion capture (PCC) describes the retrofitting of CO₂ capture technologies in existing power plants or other large CO₂ emitters. With PCC, CO₂ capture is installed in the exhaust gas stream after combustion in order to capture the CO₂ more efficiently at a higher concentration.
The technologies used in PCC are similar to those of Direct Air Capture (DAC), such as amine scrubbing or absorption by sodium hydroxide. Operating a PCC plant can significantly reduce the CO₂ emissions of a power plant.
However, it should be noted that the operation of a PCC plant can increase the fuel requirements of a power plant.

PCF - Product Carbon Footprint

The Product Carbon Footprint (PCF) is a measure of the total greenhouse gas emissions associated with the manufacture, transportation, use and disposal of a product or service. The PCF enables companies and consumers to compare the environmental impact of different products and make more environmentally friendly decisions.
The PCF usually takes into account various greenhouse gases such as carbon dioxide (CO₂), methane (CH₄) and nitrous oxide (N₂O), which are emitted throughout the life cycle of a product. This includes the extraction of raw materials, production, transportation, use and disposal of the product.
By calculating the PCF, companies can identify their emissions and take targeted measures to reduce their2 footprint. Consumers can use the PCF to choose more environmentally friendly products and reduce their own ecological footprint.

SDG - Sustainable Development Goals

The Sustainable Development Goals (SDGs) are 17 major goals that were adopted by the 193 member states of the United Nations in September 2015 as part of the 2030 Agenda for Sustainable Development. The abbreviation SDG stands for these goals. They have the overarching goal of achieving peace and prosperity for humanity, protecting the planet and ending poverty. The SDGs call on us to act accordingly and align ourselves with these goals.

We are happy to support you with the integration of a process into your planned plant as well as with the expansion of your existing plant.
Thanks to our expertise in the planning of incineration plants with flue gas cleaning, we can support you in all planning phases, from the initial idea and approval through to implementation and commissioning.
Are you considering whether it is worth expanding your plant? We would be happy to draw up a CO₂ Balance sheet for your current system and support you with the assessment.

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