Power plants are familiar with using continuous emissions monitoring systems (CEMS) to monitor pollutants, but these devices also may be able to measure heat rate—which could be handy for future compliance with the Clean Power Plan.

Continuous emissions monitoring systems (CEMS) are used to monitor power plant flue gas emissions as a means to comply with federal and state air emission standards. Through various methods, they determine the concentration and amount of key emissions, including nitrogen oxides, sulfur dioxide, carbon monoxide, carbon dioxide (CO₂), hydrogen chloride, particulate matter, mercury, and volatile organic compounds (Figure 1).

1. A continuous emissions monitoring system. Courtesy: EPRI

CEMS are required in all U.S. fossil-fired plants greater than 25 MW. They are a mature technology, and most have been widely used for more than 20 years.

The CEMS data provides an official record of the key power plant flue gas emissions. In the U.S., this data is reported to the Environmental Protection Agency (EPA).…

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