ENERGY In 2015, it is estimated that the United States used about 51,000 quadrillion thermal units. If U. S. energy consumption increases at a rate of about 0.6% annually, what amount of energy will the United States use in 2020? a) 52, 448.47 Q b) 52, 548.47 Q c) 52, 648.47 Q d) 54, 748.47 Q