QUAD

unit of energy equal to a quadrillion (1015) British thermal units (BTU). The quad is a convenient unit for describing national and world energy resources. One quad is also equal to 293 billion (109) kilowatt hours, or, for fuels of average heating values, 183,000,000 barrels of petroleum, 38,500,000 tons of coal, or 980,000,000,000 (1012) cubic feet of natural gas.