This work describes an analysis of the techno-economic performance of CCGT’s with an advanced membrane concept and compares this with MEA postcombustion capture. The analysis is undertaken at part-load (off-design) conditions to mimic realistic power plant dispatch. It integrates the part-load performance of operating points from minimal stable load to maximum continuous rating into weighted single techno-economic performance indicators that allow comparing the performance of CCS technologies under more realistic conditions than full load.@en

This work compares the part load techno-economic performance of CO₂ capture from a combined cycle gas turbine (CCGT) using a membrane configuration with selective CO₂ recycle and using monoethanolamine (MEA) solvent, under the assumption of flexible power plant dispatch. This is the first time that the techno-economic performance of CO₂ capture technologies is compared assuming a flexible dispatch profile, and the assessment was done using a comprehensive, new, part load assessment approach. Analyzing the part load performance of CO₂ capture and storage (CCS) technologies is relevant because of significant changes in our power systems, dramatically reducing the utilization of thermal power plants. The technical performance of the configurations with and without CCS was simulated at steady state, at operating points between maximum continuous rating (100% gas turbine loading) and minimum stable load (35% gas turbine loading). The performance at these operating points was then aggregated into weighted averages to produce single performance indicators (specific CO₂ intensity, specific primary energy per tonne of CO₂ avoided (SPECCA), and levelized cost of electricity (LCOE)) over the dispatch profile of the power plant. The technical performance of the MEA configuration was favorable over the membrane configuration over the whole CCGT loading range. The MEA SPECCA increased from 3.02 GJ/(t of CO₂) at 100% GT loading to 3.65 GJ/(t of CO₂) at 35% GT loading; the membrane SPECCA increased from 3.35 to 4.20 GJ/(t of CO₂). The higher SPECCA of the membrane configuration is caused by the reduced gas turbine efficiency, due to the selective recycling of CO₂ to the GT. When equal GT efficiency was assumed for combustion with normal air and with CO₂ enriched air, the membranes' technical performance was comparable with that of MEA. The capital costs of the CCGT with membrane configuration were 35% higher than the CCGT with MEA configuration. That, and the 6 year replacement frequency of the membranes, led the membrane LCOE to be 10 €/(MW h) higher than the MEA LCOE, when calculated with the part load approach. The membrane LCOE was 8 €/(MW h) higher when a full load was assumed. The new part load approach proved instrumental in highlighting performance (differences) at flexible dispatch conditions and aggregating those into easy to understand performance indicators.

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An integrated energetic evaluation has been performed of a reference coal-fired power plant, a power plant with an advanced MEA-based post-combustion CO₂ capture plant, and a power plant with a capture plant using concentrated piperazine (PZ) and high-pressure flash regeneration. This comparison shows that using a MEA-based capture plant reduces the net electric efficiency from 44.6% to 35.5%, while the PZ-based capture plant reduces it to 37.4%, corresponding to an efficiency penalty of only 7.2%.

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Extensive research efforts have been applied to obtain more efficient and less cost-intensive absorption-based processes and solvent systems for CO₂capture during the last 15-20 years. High concentratedaqueous solutions of piperazine (PZ) have been suggested as a good replacement for the current bench-mark solvent mono-ethanolamine (MEA). So far, the research on concentrated PZ solutions has mainlyfocused on the development and evaluation of various configurations for the post-combustion CO₂cap-ture process. The present paper studies the integration of a configuration based on high-pressure flashregeneration with the upstream power plant. The main focus is on the overall energy performance, but aqualitative analysis of the effect of flexible operation is added as this is important for the optimization ofthe total plant. A power plant integrated with the optimal PZ-based capture plant is found to have a netelectric efficiency of 37.4%, which is 7.2% less than the reference power plant without CO₂capture. Theefficiency penalty when using an MEA-based capture plant including lean-vapour compression is 9.1%.

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