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Show PRE-COMBUSTION REMOVAL OF CARBON DIOXIDE FROM HYDROCARBON-FUELED POWER PLANTS Y. Mori, S.M. Masutani, G.C. Nihous, L.A. Vega, Pacific International Center for High Technology Research Honolulu, HI 96813, U.S.A. and C.M. Kinoshita,~ ) Hawaii Natural Energy Institute University of Hawaii (ilt Manoa Honolulu, HI 96822, U.S.A. I ABSTRACf PAPER NO.14 The desire to reduce carbon dioxide emissions from industrial furnaces that burn hydrocarbon fuels poses new challenges in the design of combustion systems. The present study examines a concept based largely on existing technologies that has the potential to reduce significantly carbon dioxide emissions from large-scale, stationary combustors. Unlike most measures proposed previously that call for the removal of carbon dioxide from post-flame gases, here, carbon is removed from the fuel as carbon dioxide prior to combustion via oxidation with superheated steam on a catalyst followed by preferential absorption into a recyclable liquid solvent or by staged phase transformations of the carbon dioxide. The resultant gas stream, comprised primarily of hydrogen, is burned in place of the original fuel. Containment of the extracted carbon dioxide is accomplished by liquefaction and discharge into the deep ocean where local conditions prevent it from resurfacing and escaping into the atmosphere. A thermoeconomic analysis of a 5()() MW methane-fired, steam power plant fitted with the pre-combustion carbon dioxide removal system indicates moderate cost and energy expenditures. INTRODUCTION Carbon dioxide is one of a number of "greenhouse" gas species which, with increasing concentration, has been blamed for elevated global temperatures. Even though the technical community has not reached consensus over whether climatic changes have already begun as a result of increased concentrations of greenhouse gases, the potential environmental consequences of such warming have spurred the development of various strategies to control the level of these gases in the atmosphere. National policies to limit anthropogenic (man-made) carbon dioxide released into the atmosphere currently do not exist; however, such regulation probably will be enacted in the near future in Europe and, possibly, in Japan. It is likely that initial restrictions will be directed at electrical utilities and similar energy-intensive industries that burn fossil fuels because of the potential this sector has to significantly reduce the level of carbon dioxide in the atmosphere and the relative ease of monitoring the compliance of such highly-localized sources. In anticipation of such regulation, appropriate strategies and technologies must be devised to reduce carbon dioxide emissions from combustion systems with minimum economic burden. Strategies to reduce the level of carbon dioxide in the atmosphere include: (1) energy conservation; (2) preferential use of energy sources that release less net carbon dioxide into the atmosphere than fossil fuels (e.g., nuclear power or biofuels); (3) biological uptake (i.e., cultivation of terrestrial or marine plants that, via photosynthesis, remove carbon dioxide from the 1 |
