Measurements, abbreviations, and acronyms used in this subpart are defined as follows:

Btu—British thermal unit CO2—carbon dioxide CSAPR—Cross-State Air Pollution Rule H2O—water hr—hour kWh—kilowatt-hour lb—pound mmBtu—million Btu MWe—megawatt electrical MWh—megawatt-hour NOX—nitrogen oxides O2—oxygen ppm—parts per million scfh—standard cubic feet per hour SIP—State implementation plan SO2—sulfur dioxide TR—Transport Rule yr—year [76 FR 48379, Aug. 8, 2011, as amended at 81 FR 74605, Oct. 26, 2016]