One proposed fusion reaction combines lithium 3Li6 (6.015 u) with deuterium 1H2 (2.014 u) to give helium 2He4 (4.003 u): 1H2 + 3Li6 ----> 22He4. How many kilograms of lithium would be needed to supply the energy needs of one household for a year, estimated to be 4.70 x 1010 J?