The yearly average solar flux incident on a horizontal surface in the United States is about \(180 \mathrm{~W} / \mathrm{m}^{2}\). The average total energy demand in the United States is approximately 100 quads \(\left(100 \times 10^{18} \mathrm{~J}\right)\) per year. Assuming an average efficiency of PV cells of \(14 \%\) and a biomass conversion efficiency around \(1 \%\), estimate the percentage of land required to provide the energy of the country by these two renewable technologies. (The total land area of the United States is about \(9.2 \times 10^{6} \mathrm{~km}^{2}\).)