Example:
15 metric horsepower-hour = 0.000011 GW*h
1 metric horsepower-hour = 7.354988e-7 GW*h | 1 GW*h = 1359621.617304 metric horsepower-hour
Conversion Steps:
15 × (2647795.5 / 3.6e+12) = 0.000011032