Capture-ready power plants : options, technologies and economics

Abstract

A plant can be considered to be capture-ready if, at some point in the future it can be retrofitted for carbon capture and sequestration and still be economical to operate. The concept of capture-ready is not a specific plant design; rather it is a spectrum of investments and design decisions that a plant owner might undertake during the design and construction of a plant. Power plant owners and policymakers are interested in capture-ready plants because they may offer relatively low cost opportunities to bridge the gap between current coal-fired generation technologies without CO2 capture to future plants that may be built from the start to capture CO2, and reduce the risks of possible future regulations of CO2 emissions. This thesis explores the design options, technologies and costs of capture-ready coal-fired power plants. The first part of the thesis outlines the two major designs that are being considered for construction in the near-term - pulverized coal (PC) and integrated gasification/combined cycle (IGCC). It details the steps that are necessary to retrofit each of these plants for CO2 capture and sequestration. Finally, for each technology, it provides a qualitative assessment of the steps that can be taken to reduce the costs and output de-rating of the plant after a retrofit.

(cont.) The second part of the thesis evaluates the lifetime (40 year) net present value (NPV) costs of plants with differing levels of pre-investment for CO2 capture. Three scenarios are evaluated - a baseline supercritical PC plant, a baseline IGCC plant and an IGCC plant with pre-investment for capture. This analysis evaluates each technology option under a range of CO2 tax scenarios and determines the most economical choice and year of retrofit. The results of this thesis show that a baseline PC plant is the most economical choice under low CO2 tax rates, and IGCC plants are preferable at higher tax rates. Little difference is seen in the lifetime NPV costs between the IGCC plants with and without pre-investment for CO2 capture. The third part of this thesis evaluates the concept of CO2 "lock-in". CO2 lock-in occurs when a newly built plant is so prohibitively expensive to retrofit for CO2 capture that it will never be retrofitted for capture, and offers no economic opportunity to reduce the CO2 emissions from the plant, besides shutting down or rebuilding. The results of this analysis show that IGCC plants are expected to have significantly lower lifetime CO2 emissions than a PC plant, given moderate (10-35 $/ton CO2) initial tax rates.

(cont.) Higher (above $40) or lower (below $7) initial tax rates do not result in significant differences in lifetime CO2 emissions from these plants. Little difference is seen in the lifetime CO2 emissions between the IGCC plants with and without pre-investment for CO2 capture.