Question 1

A local taxi driver thinks that your system releases the CO₂ to the atmosphere without you knowing it. Have you considered this possibility?

Accepted Answer

The Carbonaide carbon dioxide curing process is based on a gas-tight system and circulation where CO₂ concentration is constantly monitored. CO₂ flow management and monitoring are at the core of our operations.

We at Carbonaide have spent a lot of time in development ensuring a gas-tight operating environment and leakage control for the system.

An important point of the system design is that the system chambers and the ducts above the chambers are under pressure during processing compared to the atmosphere. This means that in case of potential leakage, the flow would be outside in, from the surroundings to the chamber.

The Carbonaide system constantly monitors potential leakages during operation. This allows both quick reactions in case of potential leakages and measuring the amount of lost CO₂ in life-cycle analysis.

We follow two standards for controlling and testing system leakage:

1. EN 1507:2006 – Ventilation for buildings – Sheet metal air ducts with rectangular section – Requirements for strength and leakage

2. EN 15727:2011 – Ventilation for buildings – Ducts and ductwork components, leakage classification and testing.

Our specifications for chamber roof and wall structures and the main ducts are based on these standards, and our system tightness is better than class D (the best class) in the standards.

We also conduct tightness testing following the EN 15727 procedure.

Question 2

A member of our development team still claims that you must lose CO₂ when you open the doors. What happens during loading and unloading?

Accepted Answer

The Carbonaide system comes with a gas-tight door system and an advanced circulation system for the CO₂ in the chambers that ensure safe loading and unloading.For secure and safe loading and uploading, the curing chamber is divided into isolated chamber slots. Gas ducts connect the slots with each other, and the CO₂ flow between the chambers is controlled by special gas valves.When the specified curing time is reached in a slot and the products are ready to be unloaded, the remaining CO₂ in the space can be circulated into a chamber area that contains fresh concrete. Fresh concrete there mineralizes CO₂ very rapidly and empties the space with already hardened products from carbon dioxide. The door of the first chamber can then be safely opened for unloading and reloading.The CO₂ in the system is continuously recycled between the separated chamber slots according to the production cycles to enable uninterrupted operations.In addition, we have door subcontractors who can provide special gas-tight chamber doors that meet our specifications for permeability.To secure the permeability at the door, we have also created maintenance instructions for the operators. Following the maintenance routines for keeping the floor and track clean ensures sufficient sealing of the doors and the door-track seams.

Question 3

The boys at the pub say that CO₂ is dangerous for the people in the factory? Is this true?

Accepted Answer

Carbon dioxide is not a poisonous gas. It exists in the air we breathe all the time in low concentrations. It only becomes dangerous to humans when concentration levels are high. Carbonaide’s carbon curing process utilises a patented CO₂ management procedure to obtain high CO₂ exposure without high CO₂ concentrations.

Normal CO₂ level in fresh air is approximately 400 ppm (part per million) or 0.04% CO₂ in air by volume. Concentration levels causing severe symptoms to humans are around 5%, about 100 times higher than normal. Carbon dioxide is extremely dangerous to humans only after the concentration exceeds 10%.

The use of CO₂ in carbon dioxide curing can therefore only be dangerous, if the CO₂ concentration in the process is high. CO₂ levels should never surpass 5% in the operational areas.

The Carbonaide system has been designed so that it does not need high concentration of CO₂ inside the chamber, which means that even in the case of potential leaks, the working environment around the system is always safe. Carbonaide’s process CO₂ will never reach dangerous levels in the operational area.

Furthermore, the amount if CO₂ in the air at the premises is constantly monitored with several sensors that alert immediately if the CO₂ concentration rises. The alerts levels have been set so low that humans in the facilities should not get symptoms even in worst case leakage scenarios.

Question 4

My uncle who used to work in the concrete industry says that you must push the CO₂ in concrete with high pressure and to get it deep enough in the concrete. How do you make sure the gas does not leak?

Accepted Answer

We manage the risk in two ways: Firstly, Carbonaide’s carbon dioxide curing process never uses high pressure, and secondly, we have created a safety process where CO₂ is constantly managed and controlled with several protection layers.

Our intelligent patented carbon dioxide curing process ensures good CO₂ distribution in the chambers and does not need high pressure to achieve good carbonisation results, even with low concentrations of carbon dioxide.

It is true that high pressure would increase the risk of leakage from the system, which is why high operating pressures should be avoided in the process. Using CO₂ for concrete curing requires a gas-tight environment, and if the pressure were high, it would be more difficult to build a gas-tight system. This would also increase the cost of the system.

In the previous answer, we already explained that our system does not need dangerous CO₂ concentrations. In addition to the low concentration of CO₂, another big benefit of the Carbonaide carbon dioxide curing system is that our process is mostly under pressure compared to the surroundings, which means that any potential leakage would be outside in, towards the gas-tight curing chambers and away from the spaces around the chambers.

However, any chance of leakages must be minimized (we obviously don’t want to release CO₂ back to the atmosphere). We at Carbonaide have created a multilayer procedure to prevent any potential issue with gas leakages. The layered approach ensures that we can always protect both people and the environment while maintaining high product quality and process efficiency. The Carbonaide safety approach has four layers:

1. As previously mentioned, the first level of protection is that the process does not utilise high CO₂ concentrations.

2. The second level of safety is that the chambers mostly operate under pressure. Any potential leakage would be inwards, and CO₂ does not leak from the chambers to the operational areas.

3. The third layer of protection is that the process units are separated from the curing chambers. The liquid CO₂ is processed in a separate module, typically placed outside the factory building, preventing the liquid CO₂ from leaking into the facilities and causing an increase in the CO₂ concentration of the factory air.

4. Last safety level is that we continuously monitor the CO₂ levels in the operational areas and outside the curing chambers to detect any potential leakages.