Economic and energetic analysis of capturing CO2 from ambient air.

Capturing carbon dioxide from the atmosphere ("air capture") in an industrial process has been proposed as an option for stabilizing global CO(2) concentrations. Published analyses suggest these air capture systems may cost a few hundred dollars per tonne of CO(2), making it cost competitive with mainstream CO(2) mitigation options like renewable energy, nuclear power, and carbon dioxide capture and storage from large CO(2) emitting point sources. We investigate the thermodynamic efficiencies of commercial separation systems as well as trace gas removal systems to better understand and constrain the energy requirements and costs of these air capture systems.

The immobility of CO(2) in marine sediments beneath 1500 meters of water.

Injecting liquid CO(2) into deep-sea sediments below ca. 3 km of seawater has been suggested for the permanent storage of anthropogenic CO(2). At the pressures and temperature found below 3 km of seawater, CO(2) becomes denser than seawater and so is likely to remain permanently sequestered in the sediment.

Electrochemical acceleration of chemical weathering as an energetically feasible approach to mitigating anthropogenic climate change.

We describe an approach to CO2 capture and storage from the atmosphere that involves enhancing the solubility of CO2 in the ocean by a process equivalent to the natural silicate weathering reaction. HCl is electrochemically removed from the ocean and neutralized through reaction with silicate rocks. The increase in ocean alkalinity resulting from the removal of HCI causes atmospheric CO2 to dissolve into the ocean where it will be stored primarily as HCO3- without further acidifying the ocean.

Permanent carbon dioxide storage in deep-sea sediments.

Stabilizing the concentration of atmospheric CO(2) may require storing enormous quantities of captured anthropogenic CO(2) in near-permanent geologic reservoirs. Because of the subsurface temperature profile of terrestrial storage sites, CO(2) stored in these reservoirs is buoyant. As a result, a portion of the injected CO(2) can escape if the reservoir is not appropriately sealed.