Carbon Capture Overview
Government research funding initially emphasizing pre-combustion (CO2 capture from syngas) has led to the realization that less-glamorous post-combustion (flue gas scrubbing) most likely represents the best option for timely, cost-effective Carbon Capture and Storage (CCS) in the immediate future. A better understanding of capture costs resulting from the renewed interest in post-combustion has prompted the U.S. Government to increase the acceptable target for increased cost of energy required for flue gas scrubbing from 20% in 2006 to 35% today, highlighting the importance of advancing the current technology. While acid gas removal from process streams using alkanolamines is a mature technology, flue gas scrubbing presents many new challenges still not adequately met on the scale necessary for GHG abatement. In addition to discussing those challenges, this paper reviews (1) flue-gas scrubbing facilities installed over the past 30+ years for commercial purposes such as EOR, urea manufacture, soda ash manufacture and food processing, and (2) current status of innovative technologies employing, for example, sterically hindered amines and aqueous ammonia. While the GHG contribution of sulphur recovery activities is arguably insignificant, potential monetary CO2 reduction incentives will likely improve the economics of reducing incineration fuel by simple, established means as discussed.
CO2 capture by aqueous amines and aqueous ammonia–A Comparison
This paper presents the results of ASPEN simulations of a carbon-dioxide (CO2) removal and recovery plant that captures CO2 from a 500 MWe (net) conventional coal-fired power plant flue gas stream. At a constant CO2 recovery rate of 86.5% by weight, the performance of aqueous ammonia solution as an alternative to various aqueous amino solvents (MEA, AMP and MDEA) is compared in terms of the process scenarios, solvent loadings and overall energy consumption. The overall mass transfer co-efficient and CO2 loading data generated for aqueous ammonia solutions using a laboratory scale wetted wall gas-liquid contactor are also presented. 
 
The ASPEN simulation results in conjunction with the laboratory data show, that capturing CO2 from coal-fired power plant flue gas, using aqueous ammonia solvent, will require ammonia concentration no more than 5% by weight and absorber temperature 10 ∘C or lower, if the vapor phase ammonia losses are to be contained and the precipitation of ammonium bi-carbonate in the absorber is to be avoided. Under such an operating scenario, the aqueous ammonia based CO2 capture process has overall energy requirement comparable to the conventional 30% by weight aqueous MEA based process. The ASPEN results further show that 30% by weight AMP based process has the lowest overall energy requirement among the solvents considered in this paper.
Oxyfuel combustion for coal-fired power generation with CO2 capture—Opportunities and challenges
Publisher Summary This chapter illustrates that the increased carbon dioxide level in the atmosphere is the dominating contributor to increased global warming. Carbon dioxide is emitted to the atmosphere through combustion of fossil fuels in power plants, automotive engines, for industrial use and for heating purposes. The world is currently depending on the use of fossil fuels for its energy supply, and will continue to be so for a long time yet to come, due to the abundant sources of in particular bituminous coal and lignite. Small-scale renewable electricity production is available on the market today, but the cost of avoiding CO2 emissions through renewable is at present very high. It discusses oxyfuel recycle combustion is a highly interesting option for lignite-based power generation with CO2 capture, due to the possibility to use advanced steam technology, reduce the boiler size and cost and to design a zero-emission power plant. This technology, also poses engineering challenges in the areas of combustion and heat transfer, boiler design, boiler materials, energy-efficient oxygen production, and flue gas processing. The overall challenge is to design a robust plant that has a sufficiently low total cost of electricity so that it is interesting to build, but it must also have a sufficiently low variable cost of electricity so that it will be put in operation as a base load plant once it is built.