Fontina Petrakopoulou
1
e-mail: f.petrakopoulou@iet.tu-berlin.de
George Tsatsaronis
Tatiana Morosuk
Institute for Energy Engineering,
Technische Universität Berlin,
Marchstraße 18, Berlin 10587, Germany
Exergoeconomic Analysis of an
Advanced Zero Emission Plant
In this paper, an advanced zero emission plant using oxy-fuel combustion is presented
and compared with a reference plant (a) without CO
2
capture and (b) with CO
2
capture
via chemical absorption. A variation of the oxy-fuel plant with a lower CO
2
capture
percentage (85%) is also presented, in order to (1) evaluate the influence of CO
2
capture
on the overall performance and cost of the plant and (2) enable comparison at the
plant-level with the conventional method for CO
2
capture: chemical absorption with
monoethanolamine. Selected results of an advanced exergetic analysis are also briefly
presented to provide an overview of further development of evaluation methodologies, as
well as deeper insight into power plant design. When compared with the reference case,
the oxy-fuel plants with 100% and 85% CO
2
captures suffer only a relatively small
decrease in efficiency, essentially due to their more efficient combustion processes that
make up for the additional thermodynamic inefficiencies and energy requirements. Invest-
ment cost estimates show that the membrane used for the oxygen production in the
oxy-fuel plants is the most expensive component. If less expensive materials can be used
for the mixed conducting membrane reactor used in the plants, the overall plant expen-
ditures can be significantly reduced. Using the results of the exergoeconomic analysis, the
components with the higher influence on the overall plant are revealed and possible
changes to improve the plants are suggested. Design modifications that can lead to
further decreases in the costs of electricity and CO
2
capture, are discussed in detail.
Overall, the calculated cost of electricity and the cost of avoided CO
2
from the oxy-fuel
plants are calculated to be competitive with those of chemical absorption.
DOI: 10.1115/1.4003641
Keywords: CO
2
capture, combined cycle, advanced zero emission plant, exergetic
analysis, exergoeconomic analysis
1 Introduction
The capture of CO
2
in power plants is a measure suggested to
help mitigate the greenhouse effect associated with the use of
fossil fuels in the energy sector. Various methods to facilitate the
capture of carbon dioxide have been proposed in recent years.
One approach to reduce the energy demand and simplify the CO
2
separation process is to perform combustion with pure oxygen
oxy-fuel combustion or oxy-combustion. When the combustion
process is carried out with pure oxygen, the combustion products
consist mainly of carbon dioxide and water vapor. In this way, the
energy demand to separate the CO
2
is decreased and the main
energy expense is related to the oxygen production and CO
2
com-
pression unit.
Although, currently, oxy-fuel concepts present implementation
obstacles related to technological limitations 1,2, studies, such
as this one, prove these concepts as promising procedures with
respect to their efficiency and their relatively low CO
2
capture
cost. Many different concepts that incorporate oxy-fuel technol-
ogy have been presented in literature, e.g., 3. One of the most
efficient methods is presented here.
In order to decrease the cost and energy penalty associated with
the implementation of an air separation unit ASU in oxy-fuel
combustion plants, oxygen ion transport membranes have been
introduced. The power plant analyzed in this paper is an advanced
zero emission plant AZEP and it incorporates such a membrane.
The development of the concept was examined in a trans--
European consortium and was initiated in a European project 4.
It was estimated that the technology would be available for ex-
ploitation five to seven years after completion of the first phase of
the project. However, with the exception of some publications
through 2007, no information about current activities based on the
AZEP project has been made available 3–7. Data used to simu-
late the plants in the present study are derived from small-scale or
theoretical studies presented in Refs. 3–7 and the results are,
therefore, associated with relatively high uncertainties.
The AZEP uses a mixed conducting membrane MCM reactor
to separate the oxygen necessary for the combustion process and it
performs with approximately 100% capture of the produced CO
2
AZEP 100. A variation of the AZEP that performs with CO
2
capture close to 85% AZEP 85 is also discussed here. This varia-
tion is used to overcome the temperature limitation related to the
operation of the membrane of the plant and to allow the evalua-
tion of possible economic trade-offs between CO
2
capture and
plant efficiency. The operation and structure of the plants are
based on a reference plant without CO
2
capture. The comparison
of the plants is performed with an exergoeconomic analysis 8,
which constitutes a combination of an exergetic analysis with eco-
nomic principles. The exergoeconomic analysis provides informa-
tion on how the structure and the operation of each plant compo-
nent should be modified, in order to achieve a more cost efficient
operation of the overall plant. Costs related to exergy destruction
and investment are calculated and compared. Selected results of
an advanced exergetic analysis are also briefly presented to pro-
vide an overview and deeper insight into the design and the im-
provement potential of the power plant.
This paper is part of a comprehensive study analyzing different
concepts of CO
2
capture from power plants.
1
Corresponding author.
Contributed by the Power Division of ASME for publication in the JOURNAL OF
ENGINEERING FOR GAS TURBINES AND POWER. Manuscript received May 4, 2010; final
manuscript received January 12, 2011; published online May 13, 2011. Assoc. Editor:
Paolo Chiesa.
Journal of Engineering for Gas Turbines and Power NOVEMBER 2011, Vol. 133 / 113001-1
Copyright © 2011 by ASME
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