Confusion about Power Plant Cost in IECM11.5

[Fan Chen]

IECM is a very useful platform to help us analyze the technical cost issues of coal-fired power plants.In the process of studying IECM recently, I have discovered an interesting phenomenon, but I am not sure about the cause of this phenomenon.

Therefore, I am seeking your advice and hope to receive your professional response. I used IECM11.5 to construct different types of coal-fired power plants,

including PC, PC-CCS, Oxyfuel, IGCC, and IGCC-CCS. In the cost analysis of these power plants, I found that in the Overall plant cost section of

IGCC and IGCC-CCS, the Variable O&M (M $/yr) indicator of Power Block was negative, resulting in a negative Total O&M (M $/yr) value.

This phenomenon confuses me and I don't quite understand why the value is negative, and what is the economic meaning behind it? Meanwhile,

this phenomenon did not occur in PC and Oxyfuel power plants.

Unfortunately, I have reviewed relevant literature and have not found any effective explanations. Therefore, I am sending you an email in the hope

of receiving your reply (I sent the interface of IGCC-CCS in the form of pictures).

In addition, I learned through browsing tutorial videos that unlike carbon capture, IECM considers carbon transportation and carbon storage in CCS systems

as Variable O&M Costs. Does this mean that when analyzing the capital costs of configuring CCS power plants, there is no need to consider the capital costs of

carbon transportation and carbon storage, and only focus on changes in the overall O&M costs of the power plant? Because it has already been included in the

calculation as Variable O&M Cost. I have this speculation because I found that Total Capital Cost in the Overall Plant does not include carbon transportation and storage,

but it does include carbon transportation and storage in the Overall Plant Cost and Cost Summary. I am not sure if my ideas are accurate, so I am looking forward to receiving a professional response from your team, which will be crucial for my research work.

[Karen Kietzke, Programmer, IECM]

In an IGCC plant, the cost of fuel is assigned to the gasifier rather than the power block, so the only variable O&M cost for the power block is a possible credit for power used by other plant components. If there is such a credit, it is shown as a negative cost. The O&M cost result screens for the individual components provide more details as to what is included.

Carbon transportation and storage are considered to be annual costs because we do not treat them as part of the plant. The plant is assumed to be paying for transport and storage as services, so while T&S capital costs will be included in the cost of those services, which would be part of the plant's O&M cost, there is no associated capital cost to the plant. Does that answer your question?