Measurements, abbreviations, and acronyms.

Measurements, abbreviations, and acronyms used in this subpart and subparts BB through II are defined as follows: Btu—British thermal unit. CO 2 —carbon dioxide H 2 O—water Hg—mercury hr—hour kW—kilowatt electrical kWh—kilowatt hour lb—pound mmBtu—million Btu MWe—megawatt electrical MWh—megawatt hour NO X —nitrogen oxides O2—oxygen ppm—parts per million scfh—standard cubic feet per hour SO 2 —sulfur dioxide yr—year [71 FR 25381, Apr. 28, 2006]