Sensitivity of Emissions Estimation to Generation Dispatch Ordering in GridPIQ

The variable operating cost of electric generators and operational constraints determine the generator dispatch order, i.e. the order in which generator units are operated (or "dispatched") to meet electrical demand. Due to decreases in the cost of natural gas and increases in the penetration of non-dispatchable generation, some of the traditional paradigms regarding dispatch order are changing. Although it is a fair assumption that emissions consequences will be changed by the order in which power plants are dispatched, there has been little research to find out the extent of this change. In this paper, the Grid Project Impact Quantification tool (GridPIQ) has been used to investigate the sensitivity of emissions estimates to the dispatch order of the generating units based on their operational characteristics and fuel types. By making different underlying assumptions about generation dispatch across different regions in the United States and then calculating the impacts of the same grid projects, this analysis provides insight into how dispatch ordering drives regional CO
₂
, SO
₂
and NO
_x
emissions.