Environmental Emissions

Environmental Emissions Picture Increasingly stringent environmental regulations have forced some utilities to move from an economic dispatch procedure to what is called environmental dispatch. In southern California, for example, generators are dispatched to minimize air pollution on very smoggy days even if it results in higher costs for generating electricity.

Generation plants are sometimes limited in their annual release of emissions by federal or state laws. Older plants may have lower generating costs but produce more emissions than newer plants. If the older plant is run purely on economic dispatch, it may reach its emissions limit well before the end of the allowed time period and have to be shut down until a new period starts. To prevent this from happening, the dispatchers operate more costly units with lower emissions during the non-peak times of the year and try to optimize the use of the older plant with higher emissions so that it is available during the times of the year it is needed most.