Answer:
4396 days
Explanation:
1 BTU =1055.06 Joules
total energy stored in fuel = 15 * [tex]10^{12}[/tex] * 1055.06 = 1.58259 * [tex]10^{16}[/tex] J
Total energy converted is 12% of this so 0.12 * 1.58259 * [tex]10^{16}[/tex] J = 1.899108 * [tex]10^{15}[/tex] J
Daily demand = 5 MW same as 5MJ/s for 24hours (notice units are seconds)
Daily demand in terms of joules is 5 * [tex]10^{6}[/tex] J * 24 hours * 60 min * 60 sec = 4.32 * [tex]10^{11}[/tex] J
So the fuel will be consumed in 1.899108 * [tex]10^{15}[/tex] J / 4.32 * [tex]10^{11}[/tex] J = 4396.08 or 4396 days
