Carbon tax is an important policy instrument to control greenhouse gases. How to design a suitable carbon tax rate is of significance for policy makers. This study aims to address this issue from a microeconomic perspective by exploring the decision behavior of a potential investor. A trinomial tree model based on real options theory is presented to evaluate carbon capture and storage (CCS) investment in coal‐fired power plants considering uncertain factors. The model is then applied to a case study and the main findings are as follows: (1) carbon tax policy will have a positive effect on the CCS investment. If the carbon price is not high enough to trigger CCS investment, a hybrid mechanism integrating carbon trading and carbon tax to stimulate CCS investment is required; (2) in applying the trinomial tree real options model, the optimal carbon tax rate should be 145.3 RMB/ton for supercritical pulverized coal (SCPC) (or 79.54 RMB/ton for integrated gasification combined cycle (IGCC)) plants under current market condition and at current technological levels; (3) the optimal carbon tax rate is sensitive to uncertainties. Specifically, the optimal tax rate depends largely on not only the cost of the CCS investment but also the portfolio of carbon price volatility and the initial carbon price level. These conclusions provide the theoretical foundations for decision making regarding CCS investment and related policy making. © 2018 Society of Chemical Industry and John Wiley & Sons, Ltd.

A two‐stage compound real options model is proposed to evaluate carbon capture and storage (CCS) investment decision making from the perspective of coal‐fired power plants, considering the phased nature of CCS technology. A newly built coal‐fired power plant is used as a case study for the application of the compound real options model. The results indicate that the compound real options approach has an advantage over both the traditional net present value (NPV) and single‐option method when handling multistage investments. Although the present carbon price level is not high enough to encourage CCS investment, the critical carbon price will decrease when considering the upside potential inherent in the CCS investment. Further analyses indicate that the timing of the second phase of a CCS project and other factors will also affect the critical carbon price and the value of a CCS investment. These findings will be useful for decision making associated with CCS investment, and related policy making in an uncertain environment. © 2018 Society of Chemical Industry and John Wiley & Sons, Ltd.