FINAL TOPICAL REPORT FOR NOVEL SYSTEMS SEQUESTERING AND UTILIZATION OF CO2

Atmospheric CO{sub 2} concentrations are increasing by about 0.5% each year, and there is serious concern that this will cause adverse climate change via the ''greenhouse effect.'' The principal sources of the increase are the utilization of fossil fuels and the deforestation of land. The capture of CO{sub 2} from flue gas or process streams has been demonstrated using chemical absorption with an ethanolamine solvent. However, the cost of releasing the CO{sub 2} by thermal stripping and recovering the solvent is very high, resulting in an energy penalty of 27% to 37 %, depending on the type of power plant (1). Alternatives that would result in energy penalties of 15% have been investigated. Sequestering schemes for CO{sub 2} produced from fossil fuels conversion to energy in utility plants could instead yield useful polymer products. Relatively concentrated CO{sub 2} by-product streams from fermentation of cellulose to fuel ethanol will also be available for conversion to useful polymers. As shown in Figure 1, this project offers two opportunities for mitigating the emission of CO{sub 2} to the atmosphere, depending on the source configuration and economic feasibility of the proposed processes: CO{sub 2} in a conventional utility-produced flue gas could be sequestered to form a reactive monomer using an amine (such as ethanolamine) that reacts with an aldehyde to form an amine intermediate, which subsequently copolymerizes with the CO{sub 2} to give a copolyurethane. Using a tertiary amine to trap the CO{sub 2} is also proposed. In this case the tertiary ammonium carbonate is reacted with the aldehyde to form the copolycarbonate, regenerating the tertiary amine. In an alternate scheme, a concentrated CO{sub 2} stream from an advanced energy system could be directly polymerized with aldehyde and catalyst to Polymer 2. Sources of concentrated CO{sub 2} include the water-gas shift reaction in an IGCC (integrated gasification combined-cycle) device, fermentation, a fuel cell anode gas, or oxygen-fired combustion. Significant sequestration of CO{sub 2} would be accomplished if large amounts could be efficiently and economically converted to stable and useful products that would pay for the processing. If the CO{sub 2} is stored rather than converted to a useful product, the cost of sequestering must be extremely low. If CO{sub 2} is to be utilized as a chemical feedstock, the allowable process cost can be higher, but only high-volume commodity chemical products could sequester a significant amount of CO{sub 2}. Large volumes of inexpensive CO{sub 2}-derived polymers could be utilized for enhanced oil recovery, structural thermoplastic resins, and ion-exchange applications. Economic success is better achieved with the availability of a very inexpensive aldehyde or derivative mine. To provide this component inexpensively, a novel photosystem is proposed such that CO{sub 2} is also converted to the desired copolymer feedstock