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Carbon dioxide Capture machine

Technical Specifications of the Outdoor Direct Air Capture of CO2 Unit from Soletair Power made for ZBT

Unrestricted burning of natural resources, deforestation, and competitive industrialization – ran parallelly for decades. These set off an alarming level of CO2 in the atmosphere. The effect of this can be seen with the increasingly changing weather phenomena – melting of glaciers, more frequent heatwaves, forest fires and droughts. It is terrifying to imagine what an even more dreary future might look like.

Scientists and policymakers agreed upon one solution: finding alternate ways to capture the atmospheric CO2 partly and achieving a net negative emission. Some very promising technologies emerged that can reduce the amount of CO2 released into the atmosphere such as CCS (Carbon Capture and Sequestration), BECCS (Bio-Energy with Carbon Capture and Storage) and DAC or Direct Air Capture.

Soletair Power is a Finnish direct air capture technology provider company that integrates DAC technology with buildings’ HVAC systems to remove CO₂ from the air, reduce overall emissions, and supply better air at work.

The 99.99% pure CO2 captured directly from the air, goes to a concrete manufacturing facility to be stored for a long time as concrete, or to a utilization facility that makes valuable products out of the CO2.

In 2021, Soletair Power demonstrated making fuel from thin air with Power-to-X at Expo 2020 Dubai.

What is direct air capture of CO2?

Direct Air Capture is a group of technologies that filters CO2 from the air or other low-concentration sources, e.g. building ventilation. The concentration of CO2 may vary from 400 ppm in ambient air to 1000-2000 ppm in building ventilation exhausts.

Traditional CCS (Carbon Capture and Storage) technologies focus primarily on capturing CO2 from concentrated point sources such as flue gases, effluents from biogas plants and other industrial processes. The concentration of CO2 is typically around 10-15% in flue gases and can be even higher in off-gases released from purifying or upgrading steps used in biological processes.

The significant difference in the concentration of CO2 between ambient air and point sources differentiates the design of DAC and other carbon capture units.

CO2 capture machine
Soletair Power Outdoor CO2 Capture Unit Direct Air Capture Plant made for German ZBT

Technical Specifications of Soletair Power’s DAC unit delivered to ZBT

Operating for 12 hours a day, Soletair Power’s ZBT Direct Air Capture unit can capture up to 21 kg of CO2 per day (running for 8 hours) at >98% purity, compressed to above 10 bar. The unit is housed in a 12 m × 2.4 m × 2.87 m container which is designed to limit the noise level to approximately 62 dB.

This unit uses weak base anion resin as the adsorbent for CO2 capture. We have tested the lifespan of this resin using a rapid multi-cycle-per-day test rig to ensure its capture performance and service life.

A large volume of air needs to be moved inside to capture the required amount of CO2. Using computational fluid dynamics (CFD), Soletair Power has designed a vessel that can hold the optimum amount of sorbent, and maintain the required airflow rates, while limiting the pressure drop to allow the use of conventional fans. To ensure uniform distribution of air inside the vessel, the geometry inside is made highly symmetric allowing uniform velocity even at large airflows.

To produce high-purity CO2, the Temperature Vacuum Swing Adsorption (TVSA) process is used. In the vacuum-swing step, the air inside the chamber is removed using vacuum pumps to achieve a vacuum level of below 100 mbar. In the temperature-swing step, the sorbents are heated below 90°C promoting the release of CO2 and water. Heating is accomplished using warm water flowing through specially designed heat transfer elements inside the vessel.

Due to the low-temperature level of operation of the system, several sources of heating can be used. In this project, purely electric heating of water in a hot water silo is used. In other projects, there were heat pumps, and in some cases, district heating plus boosters can also be used.

The gas collected from the vessel is a mixture of CO2 and water which is separated using various physical methods that lead to the condensation of water, leaving out dry CO2 as the product. This CO2 is collected using dry-vacuum pumps to eliminate oil contamination ensuring ease in downstream use of CO2. The product gas is stored in buffer tanks operating at up to 10 bar, from where gas boosters are employed to compress CO2 up to the pressure required by the customer.

Soletair Power’s Direct Air Capture system made for ZBT comes fully instrumented to ensure stable and safe operation. The customer can gather operational data from relevant process instruments. The container is also equipped with indoor air and product gas quality monitors, control units and several smoke detectors. The unit can be integrated into the customer’s system by using industrially relevant communication protocols.


Outdoor Carbon Dioxide Capture Unit
Process – Soletair Power Illustration 1 of ZBT Outdoor CO2 Capture Unit


Outdoor Carbon Dioxide Capture Unit
Process – Soletair Power Illustration 2 of ZBT Outdoor CO2 Capture Unit

Data-driven and scalable

Starting from the development of sorbent to the design of the vessel – all decisions are guided by extensive research and data gathered from experiments. The sorbent used at Soletair Power has been chosen after being subjected to long-duration cycles and undergoing a battery of tests. Active collaboration with local universities and research institutes ensured a proper understanding of the properties and limitations of the sorbent.

Extensive use of computational fluid dynamics modeling further substantiates the performance of the sorbent. Soletair Power employs design-of-experiment principles to ensure the vessels have the lowest pressure drop given the technical boundaries of the project.

Soletair Power is uncompromising in terms of quality assurance. The parts such as the pumps, sensors, and process valves used in the deliveries are top brands and obtained from reliable suppliers. The components undergo several technical checkpoints before being put into use.

The DAC units at Soletair Power follow a modular design principle allowing customers to install multiple units and assemble them on site. Customers may choose to get a unit with a large production capacity, or they can also get a regular unit and get add-on units later to increase the capacities of production.

[Drag to rotate] Soletair Power Outdoor CO2 Capture Unit’s 360-degree view

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CO2 removal machine
Finnish Company Soletair Power Capturing CO2 from the Air at ZBT Germany with Outdoor CO2 Capture Unit

About Soletair Power:

Soletair Power is a Finnish carbon capture technology provider company founded in 2016 that manufactures solutions for capturing CO2 directly from the air. The captured carbon dioxide is stored as long-lived products. Soletair Power is backed by technology giant Wärtsilä Corporation and secured 1.5 million euros as seed funding for playing a vital role toward a carbon-neutral future.

About Hydrogen and Fuel Cell Center ZBT:

ZBT is one of the leading research institutes in Europe for fuel cell and hydrogen technologies and a sought-after R&D partner in both European and national cutting-edge research as well as in industrial projects focusing on automotive applications and stationary power generation.

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