A Preliminary Techno-Economic Analysis on the Calcium Looping Process with Simultaneous Capture of CO2 and SO2 from a Coal-Based Combustion Power Plant

Antonio Coppola,Fabrizio Scala

doi:10.3390/en13092176

Abstract

The increase of capital investments and operation and maintenance (O&M) costs represents a current limitation to the diffusion of carbon capture systems for the clean combustion of fossil fuels. However, post-combustion systems, such as calcium looping (CaL), for CO2 capture from flue gas are the most attractive carbon capture systems since they can be installed at new plants and retrofitted into existing power plants. This work investigates the pros and cons of employing a calcium looping system for CO2 capture and also as a desulphurization unit. A preliminary techno-economic analysis was carried out comparing a base case consisting of a coal-based power plant of about 550MWe with a desulphurization unit (Case 1), the same plant but with a CaL system added for CO2 capture (Case 2), or the same plant but with a CaL system for simultaneous capture of CO2 and SO2 and the removal of the desulphurization unit (Case 3). Case 2 resulted in a 67% increase of capital investment with respect to the benchmark case, while the increase was lower (48%) in Case 3. In terms of O&M costs, the most important item was represented by the yearly maintenance cost of the desulphurization unit. In fact, in Case 3, a reduction of O&M costs of about 8% was observed with respect to Case 2.

Highlights

Energy from coal accounts for about 30% of the total global energy supply, as reported in the IEA World Energy Outlook [1]
The hypotheses assumed in this analysis are that the nominal electrical power of the plant will not be less than 400 MWe and the expected CO2 capture will be greater than 90%
Case was a power plant without the wet scrubber and with used for it is sufficient at 22.5 €/t CO2

Summary

Introduction

Energy from coal accounts for about 30% of the total global energy supply, as reported in the IEA World Energy Outlook [1]. The endothermicity of the calcination reaction can be sustained by the combustion of an auxiliary (and cheap) fuel under oxy-combustion mode with pure oxygen provided by an ancillary air separation unit (ASU) Another recently proposed possibility, which is still in an early research stage, is based on the combination of the calciner with a concentrated solar power system [11,12]. SO2 emissions are regulated in all countries, and the coal power plants are equipped with flue gas desulphurization devices in order to decrease the SO2 concentration to below the permitted limits This abatement is carried out in situ in the combustion chamber in the case of fluidized bed (FB) boilers, while wet scrubbers are typically used in the case of pulverized fuel (PF) boilers. This study had two objectives: The first was to evaluate the advantages and disadvantages of carrying out desulfurization upstream or simultaneously with the capture of CO2 ; the second was to evaluate on the basis of current and future/possible European laws on greenhouse gas emissions the possibility of adding a CaL unit to an already existing plant using alternative strategies

Description of Plant Configurations

Estimation of Plant Capital Costs

Levelized cost and avoided

Findings

Discussion and Conclusions