Hydrogen technology: Global Observer

Demand for unmanned aerial vehicles is soaring and companies are racing to produce systems that fly higher for longer periods and can carry heavier payloads. AeroVironment Inc.'s Global Observer can fly at around 20 000 m for as long as a week and provide 4000-km radius coverage. Global Observer runs on liquid hydrogen fuel, which has an energy density that is 3.5 to 4 times that of fossil fuels. The aircraft could be flown high above an approaching hurricane for weather monitoring.