Techno-economic evaluation of oxy-combustion coal-fired power plants

Abstract

Increasing attention is being paid to the oxy-combustion technique of coal-fired power plants because CO 2 produced from fossil fuel combustion can be captured and sequestrated by it. However, there are many questions about the economic properties of the oxy-combustion technique. In this paper, a detailed techno-economic evaluation study was performed on three typical power plants (2 × 300 MW subcritical, 2 × 600 MW supercritical, 2 × 1000 MW ultra supercritical), as conventional air fired and oxycombustion options in China, by utilizing the authoritative data published in 2010 for the design of coal-fired power plants. Techno-economic evaluation models were set up and costs of electricity generation, CO 2 avoidance costs as well as CO 2 capture costs, were calculated. Moreover, the effects of CO 2 tax and CO 2 sale price on the economic characteristics of oxy-combustion power plants were also considered. Finally, a sensitivity analysis for parameters such as coal sample, coal price, air separation unit price, flue gas treatment unit price, CO 2 capture efficiency, as well as the air excess factor was conducted. The results revealed that: (1) because the oxy-combustion technique has advantages in thermal efficiency, desulfurization efficiency and denitration efficiency, oxy-combustion power plants will reach the economic properties of conventional air fired power plants if, (a) the CO 2 emission is taxed and the high purity CO 2 product can be sold, or (b) there are some policy preferences in financing and coal price for oxy-combustion power plants, or (c) the power consumption and cost of air separation units and flue gas treatment units can be reduced; (2) from subcritical plants to supercritical and finally ultra-supercritical plants, the economics are improving, regardless of whether they are conventional air fired power plants or oxy-combustion power plants.oxy-combustion, CO 2 emission control, techno-economics, sensitivity analysis, CO 2 tax, CO 2 sale, cost of electricity Citation:Xiong J, Zhao H B, Zheng C G. Techno-economic evaluation of oxy-combustion coal-fired power plants.

Comprehensive investigation of process characteristics for oxy-steam combustion power plants

“…3 and Table 5. Detailed cost calculation method has been described in the previous study [21] and key information for completing this analysis is also presented in Appendix B and C. As shown in Fig. 3, similar cost distribution for oxy-steam combustion and oxy-CO 2 combustion is gained, which the main cost results from fuel and depreciation.…”

“…On account of detailed assumptions and techno-economic analysis can be referred to the previous studies [21][22][23][24][25] for the base case, some crucial hypotheses for cost calculation of oxy-steam combustion are established as below. (1) Different from desulfurization method used in Ref.…”

“…(1) Different from desulfurization method used in Ref. [21] for oxy-CO 2 combustion, wet FGD with 95% efficiency is considered in this study. (2) As unit size can be reduced by 40% because less amount of overall flow rate is required in oxy-steam combustion [2,8], six-tenths rule [19,26], which allows to estimate cost of an equipment or plant at a given capacity or size to be calculate when cost of the same equipment or plant at a different capacity or size is known, is employed here to calculate the total investment cost of the whole base power plant for oxysteam combustion.…”

“…And investment cost of heat exchanger for heating recycled water is not considered here, but it affects little on economic assessment results since it accounts quite small proportion in that of whole power plant. (3) The cost of ASU is calculated according to oxygen requirement in oxy-steam combustion power plant whilst the cost of CPU is assumed to be 2.5% of the total investment cost of the whole base power plant [21]. (4) Simulation results elaborated in Section 3 are used as values of net power output and CO 2 recovery rate for computing cost of electricity, CO 2 avoidance cost and CO 2 capture cost.…”

“…(6) Other parameters and assumptions are equivalent to that stated in Ref. [21] for techno-economic cost estimation of oxy-CO 2 combustion power plant. (7) The data for calculation are mainly based on the book ''Reference costing indexes in quota design for coal-fired power plant projects (2009 levels)'' published by the China Power Engineering Consulting Group Corporation [27] and related Refs.…”