Integration of direct air capture and biomethanation for decentralized fuel production

The development of energy-efficient CCU technologies is of outmost important for our society to reduce global warming. New technologies should achieve a cost-effective capture of CO2 and conversion into carbon-neutral fuels/chemicals by using renewables. In this context, an emerging strategy is direct air capture (DAC), i.e. technologies aiming to capture CO2 directly from ambient air. However, current DAC technologies are still highly energy demanding, and therefore uneconomical on large scale.

The aim of this project is to develop an energy-efficient process based on DAC and mixed culture biomethanation. The project requires the development and integration of three main steps:

1. Direct air capture. Capture of CO2 from air will be achieved via adsorption in solid sorbents (ion exchange resins) in combination with intermittent desorption with an alkaline solution. In this way, CO2 is extracted in the form of bicarbonate/carbonate salts in aqueous solution

2. Electrochemical desorption. An electrochemical system will allow the simultaneous regeneration of the spent alkaline sorbent and desorption of high-purity (>96%) CO2 gas. This step operates at ambient temperature and pressure, so it does not require excessive heat, but only (renewable) electricity as energy input

3. Biomethanation. A membrane bioreactor will be developed based on autotrophic microorganisms for methanogenesis from the captured CO2 and renewable H2. The bioreactor does not need any additional feedstock, thus it will be not limited by the availability of biomass for its operation.

The final goal is to achieve the simultaneous capture of CO2 from ambient air and production of renewable methane.