Comparing post-combustion CO2 capture operation at retrofitted coal-fired power plants in the Texas and Great Britain electric grids
Date
2011-04-07Metadata
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This work analyses the carbon dioxide (CO2) capture system operation within the Electric Reliability
Council of Texas (ERCOT) and Great Britain (GB) electric grids using a previously developed
first-order hourly electricity dispatch and pricing model. The grids are compared in their 2006
configuration with the addition of coal-based CO2 capture retrofits and emissions penalties from 0 to
100 US dollars per metric ton of CO2 (USD/tCO2). CO2 capture flexibility is investigated by
comparing inflexible CO2 capture systems to flexible ones that can choose between full- and zero-load
CO2 capture depending on which operating mode has lower costs or higher profits. Comparing these
two grids is interesting because they have similar installed capacity and peak demand, and both are
isolated electricity systems with competitive wholesale electricity markets. However, differences in
capacity mix, demand patterns, and fuel markets produce diverging behaviours of CO2 capture at
coal-fired power plants. Coal-fired facilities are primarily base load in ERCOT for a large range of CO2
prices but are comparably later in the dispatch order in GB and consequently often supply intermediate
load. As a result, the ability to capture CO2 is more important for ensuring dispatch of coal-fired
facilities in GB than in ERCOT when CO2 prices are high. In GB, higher overall coal prices mean that
CO2 prices must be slightly higher than in ERCOT before the emissions savings of CO2 capture offset
capture energy costs. However, once CO2 capture is economical, operating CO2 capture on half the
coal fleet in each grid achieves greater emissions reductions in GB because the total coal-based
capacity is 6 GW greater than in ERCOT. The market characteristics studied suggest greater
opportunity for flexible CO2 capture to improve operating profits in ERCOT, but profit improvements
can be offset by a flexibility cost penalty.
Department
Description
Stuart Cohen is with UT Austin, Hannah Chalmers is with University of Edinburgh, Michael Webber is with UT Austin, and Carey King is with UT Austin
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