This document discusses methods for estimating the costs of carbon capture and storage (CCS) in the coal, oil, and gas sectors. It outlines challenges in estimating incremental costs for CCS projects in these industries, including establishing appropriate reference cases and determining the net amount of avoided carbon dioxide emissions. The document also notes complications that arise in estimating how CCS would impact production costs and defining emission intensities for projects that coproduce heat, power, and other commodities.