Carbon capture technologies
There is currently one class of technology which is currently the benchmark for a large-scale capture of CO2: wet-chemical washing processes with the aid of strong alkaline solutions, in particular, so-called “amine scrubbing”. Wet-chemical processes involve diverting an exhaust stream through a so-called absorber solution. The CO2 contained in the exhaust stream is then absorbed by the molecules of the absorber solution and separated from the remaining exhaust stream. In the case of amine scrubbing, this absorbing mixture is based on a solution of amines.
The term catalysis defines the act of influencing a chemical reaction with the aid of a catalyst, with the goal of initiating a reaction, accelerating a reaction or reducing the necessary energy for a reaction, as well as causing specific reaction processes. For CCU processes, breakthroughs in catalysis research were essential. They made first processes feasible and/or energetically sensible, thus enabling further processing on the inert material CO₂.
Circular economy/(Closed loop) recycling management/German Life-Cycle Resource Management Act (Kreislaufwirtschaftsgesetz)/Recycling (Closed loop)
Recycling management defines a concept of leading resources that are completely utilised in production into further utilisation. Recycling processes are part of this concept, but are also supplemented by other forms of further use, such as cascade utilisation. In this study, both terms are used: (closed loop) recycling management stands for the conception of the objectives while recycling is a concrete process on the way to this. The European Guidelines for dealing with waste were determined by law in the German Life-Cycle Resource Management Act (KrWG) in 2012.
Delay of emissions
After a particular period of time, the used CO2 will be emitted again. Depending on the lifetime of the respective CCU product, the CO2 can be stored for days or weeks (e.g. synthetic fuels), years (e.g. polymers) or decades or centuries (e.g. cement).
Life Cycle Assessment/ecological balance/life cycle analysis
A Life Cycle Assessment or LCA is a systematic analysis of the possible effects on the environment of a production process of an interim or end product. Ideally, this analysis should include the complete lifetime of a product (“cradle to grave”) or up to the point in time of the finished manufacture of an (interim) product (“cradle to gate”). For CCU products, this means, in particular, the inclusion of all of the processes upstream and downstream from the actual CCU core process, in order to make a holistic assessment of the possible effects on the environment possible.
Permanent storage/binding of CO2
Permanent storage here refers to a duration of more than 1000 years.
Savings potential/emission savings
It must be considered that the evaluation for usable CO2 emissions are not to be considered equal with actual saved CO2 emissions, since all conversion technologies also require energy. For each individual CO2 utilisation technology, it is therefore necessary to determine the potential for CO2 savings individually – this can be higher or lower than the amount of CO2 which can be used. It is even possible that an increase in emissions will occur.
Synthetic fuels/energy carriers
Generally, it is also feasible to use carbon dioxide as a raw material in order to manufacture energy carriers. It is possible, for example, to produce the following energy carriers from CO2 by means of diverse processes:
- liquid fuels such as methanol, diesel
- gaseous fuels such as methane/synthetic gas.
Such energy carriers can directly serve the mobility sector or could find future use as energy storage, in order to use peaks in the generation of renewable energies.
- Dechema study: Low carbon energy and feedstock for the European chemical industry.
- Preliminary results booklet of the funding measure CO2Plus of the Federal Ministry of Education and Research (BMBF) [only available in German]: CO2Plus – Stoffliche Nutzung von CO2 zur Verbreiterung der Rohstoffbasis
- Circle chart