As soon as the sorbents collect CO2, the particles travel up to the top of the adsorber column, about six meters in height. From there, they flow down through a heated desorber, and deliver their CO2 load.

Anew air capture technology, developed by the University of Twente, in the Netherlands, captures CO2 from atmospheric air in a cheap and efficient way, they claim. The CO2, in turn, is used by the researchers for growing microalgae.

The new unit was designed to capture 500 grams of CO2 from air per day. It uses ambient air and, for one kilo of CO2, about 1400 cubic meters of air are needed.

To achieve their goal, the U of Twente researchers use solid particles – sorbents – for capturing CO2. When they don’t have a “load” yet, the particles enter an air flow, going through the setup with a low pressure drop. As soon as they collect CO2, the particles travel up to the top of the adsorber column, about six meters in height. From there, they flow down through a heated desorber, and deliver their CO2 load. After that, the sorbents enter a new cycle of collecting and release of CO2.

The CO2 rich gas goes to the algae reservoir. Although cooling down and heating require energy, the net energy consumption of the capture unit is low. The energy costs, of about 75 euro per 1000 kilograms of CO2 are competitive at the current market. The unit is flexible, isn’t dependent on industrial plants for collecting CO2 and can be used anywhere in the world, according to project leader Dr. Wim Brilman.

Another application of the technology could be in storing energy from solar or wind energy. Storage is one of the main challenges in the energy transition. Using CO2 from air, together with hydrogen, it is possible to produce methane (natural gas) for home use. In this way, energy is stored without the need for batteries: the excess energy from sun or wind is used for producing the gas. It is an attractive “closed cycle” approach, in which the boiler no longer has CO2 exhaust. This approach is currently being tested in a housing complex in Rozenburg, Netherlands.

The Sustainable Process Technology group of the University of Twente participated in the European MIRACLES (Multi-product Integrated bioRefinery of Algae; miraclesproject.eu ) programme, aimed at developing “specialties” based on algae. This project, financed by the Seventh Framework programme of the European Union, was presented in Brussels 17-18 October during the “Algae Biorefineries for Europe – Towards a Sustainable Economy” congress, algaebiorefineryconference.eu/

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