In the face of existing international provisions limiting the emissions of greenhouse gases, primarily carbon
dioxide, it is necessary to introduce solutions that will allow the production of electricity from coal
with high efficiency and low emissions. Oxy-combustion systems integrated with carbon capture and
storage (CCS) installations may prove to be such a solution.
This paper presents the main results from a thermodynamic analysis of a supercritical unit operating in
oxy-combustion technology, fueled with pulverized coal with a power output of 460 MW. The parameters
of the live steam in the analyzed system are 600 C/30 MPa. To perform the numerical analyses, models
of the individual components were built, including an oxygen production installation (ASU), a boiler, a
steam cycle and a flue gas conditioning system (CPU). The models were built in the commercial programs
GateCycle and Aspen and then integrated into the Excel environment.
In this paper, different structures for an integrated oxy-type system were analyzed and compared. The
auxiliary power rates were determined for individual technological installations of the oxy-combustion
power plant. The highest value of this indicator, in the range between 15.65% and 19.10% was calculated
for the cryogenic ASU. The total value of this index for the whole installation reaches as high as 35% for
the base case. The use of waste heat from the interstage cooling of compressors in the air separation
installation and flue gas conditioning system was considered as the methods of counteracting the
efficiency decrease resulting from the introduction of ASU and CPU. The proposed configurations and
optimization allow a significant reduction of the auxiliary power of the considered unit. In consequence,
the efficiency decrease was reduced by approximately 3.5% points.
An economic analysis of the different structures of the oxy-fuel system and the reference air-fired
power plant was also conducted using a newly developed computational algorithm built in the Excel
environment. The algorithm uses a Break Even Point (BEP) method, focusing mainly on determining a
break-even price of electricity. It was found that about the profitability of this investment will mainly
decide the price of emission allowances. For the assumptions made, the oxy-combustion power plant will
be economically comparable with a reference plant without carbon dioxide capture when the price of
allowances would be between 34 and 41 €/tonne. A sensitivity analysis concerning the influence of
selected components of the cash flows on the break-even price of electricity was also performed. The
main results of the calculations are presented in the paper.