CO2 Solutions by Saipem
An introduction to CO2 Solutions by Saipem
CO2 Solutions by Saipem is a post-combustion CO2 capture technology based on solvent washing of the flue gas by means of a water-based solution containing potassium carbonate salt and an enzyme.
This technology has been developed over the past twenty years by Canadian scientists and engineers, and supported by the governments of Canada, the United States and the European Union. The patented process, demonstrated at an industrial scale, has reached the marketing stage (TRL8).
The enzyme is a proprietary strain of Carbonic Anhydrase (CA) enhanced for the application of CO2 capture through an exclusive directed evolution process. The CA enzyme significantly accelerates the conversion of CO2 into bicarbonate, during absorption, and the reverse reaction (bicarbonate to CO2) during solvent regeneration.
The enzyme is used at very low concentration and it is exceptionally selective to catalyze the reactions only with CO2.
Carbonic Anhydrase (CA) is present in all living organisms
CA catalyzes the interconversion between carbon dioxide and solution in tissue cells
The CA used in the CO2 Solutions process has been laboratory improved to enhance molecular stability
The main advantages of CO2 Solutions by Saipem
A high tolerance to flue gas impurities and to oxygen
The CO2 Solutions by Saipem is highly tolerant to flue gas contaminants, such as sulphur oxides (SOx) and nitrous oxides (NOx). In fact, in the presence of these contaminants, the solvent used in the CO2 Solutions technology is less prone to degradation compared to amines. In particular, SOx reacts almost completely with the potassium carbonate present in the solvent without impacting process performances, thereby reducing the amount of SOx emissions into the atmosphere.
Furthermore, the solvent is not affected by the presence of oxygen, making the technology suitable for the treatment of flue gases with a high oxygen content, such as from gas turbines.
Low complexity
The process is characterised by three simple steps:
1. The flue gas is initially conditioned and quenched prior to be sent to the core process,
2. The CO2 is absorbed by the enzyme in an absorption column,
3. The CO2 is released thanks to a stripping process into a regeneration column.
The enzyme
The enzyme is a proprietary strain of Carbonic Anhydrase (CA) that has been enhanced for the application of CO2 capture through an exclusive, directed evolution process. The CA enzyme significantly accelerates the conversation of CO2 into bicarbonate during absorption, and the reverse reaction (bicarbonate to CO2) during solvent regeneration.
The enzyme is used at a very low concentration, and it is exceptionally selective in only catalysing reactions with CO2.
Low-grade heat
CO2 Solutions by Saipem is also cost efficient, as it requires only low-grade waste heat.
Compared to other CO2 capture technologies, steam is not required for solvent regeneration, hot water is sufficient.
Consequently, such low temperatures allow the use of unconventional, low-grade heat sources to regenerate the solvent, thereby significantly reducing the costs of operation compared to other capture technologies.
Part of the heat necessary for solvent regeneration can be recovered from the hot flue, and additional possibilities of heat recovery can be identified on a case-by-case basis, considering the heat integration in the specific installation.
No toxic waste
This innovative enzymatic CO2 capture process utilises a non-toxic and non-volatile solvent that poses no danger to human health or to the environment. Therefore, the CO2 Solutions by Saipem technology has eliminated the toxicity of amine technologies.
Low corrosion and toxicity
Furthermore, compared to traditional amine technologies, the Saipem process is also more reliable, as the carbonates and enzymes, being low-corrosion substances, minimise the deterioration of equipment.
Standard equipment
Due to the low corrosion of the process streams, low-cost materials can be used. Moreover there are no proprietary items in the process equipment definition. Therefore, ordinary equipment that is easily available on the market can be used.
The resulting CO2 recovery efficiency is at the same level of amine-based technologies but with distinct advantages:
| Characteristics | Amines | K2CO3 | K2CO3 + Enzyme |
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No aerosol emissions |
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Non-volatile (no VOCs or HAPs) |
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Non-toxic |
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Oxidative stability |
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Low viscosity |
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Low corrosion |
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Limited flue gas polishing required |
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Low-grade residual heat used for solvent regeneration |
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Municipal grade water treatment |
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No sludge generated |
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High capture rate |
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