Available Technology

Carbon Dioxide Capture at a Reduced Cost IB-2614

Scientists at Berkeley Lab have developed a method that reduces the expense of capturing carbon dioxide generated by the combustion of fossil fuels. This technology would allow power plants and the chemical and cement industries to better sequester carbon dioxide and reduce the associated expenses passed on to consumers. The method uses novel promoters that kinetically favor the reactions for CO2 absorption and solvent regeneration. The absorber uses an aqueous alkali carbonate, such as potassium carbonate (K2CO3). When the CO2 reacts with this in the presence of a promoter, a slurry of potassium bicarbonate (KHCO3) is formed. This slurry is then transported to a regenerator, where another promoter is used to accelerate the production of concentrated CO2 for sequestration and regenerate the K2CO3 for reuse in the absorber. The energy required in the regeneration step is predicted to be at least 40% less than that in state-of-the-art monoethanolamine (MEA) systems. The lower energy requirement results from the decrease in the regeneration temperature due to the use of reaction promoters and the production of a slurry rather than an aqueous solution for regeneration. A slurry, with its comparatively low water content, consumes much less sensible and latent heat in the stripping process. The lower regeneration temperatures mean that waste heat, which is normally too low to drive regeneration of amine solvents, can be used for this process. The lower temperatures also have the benefit of reducing the loss of reagents to side reactions, thereby increasing efficiency and decreasing equipment corrosion. Alternatively, the temperature can be deliberately elevated to accelerate solvent regeneration kinetics, decreasing the regenerator size requirement and reducing capital costs. One of the most expensive operating costs for carbon capture and sequestration systems is the energy demand for concentrating CO2 and compressing it into a supercritical liquid for transport. This expense is estimated to equal about 25%-35% of the power produced from an existing coal-fired power plant using MEA. The new Berkeley Lab system greatly decreases this expense and reduces other problems associated with regenerating solvents at high temperatures.
Lower energy requirement - Lower regenerator capital cost - Less reagent loss - Less equipment corrosion
Internal Laboratory Ref #: 
Patent Status: 
Patent pending. Available for licensing or collaborative research.
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