The full dimensions of the challenge become apparent when these numbers are translated to a specific case. The following case study may serve to illustrate the point. About 50 jumbo jets leave Frankfurt Airport every day, each loaded with 130 tons of kerosene. If replaced on a 1 : 1 energy base by 50 tons of liquid hydrogen, the daily needs would be 2500 tons or 36 000 m3
of the cryogenic liquid, enough to fill 18 Olympic-size swimming pools. Every day 22 500 tons of water would have to be electrolyzed. The continuous output of eight 1-GW powerplants would be required for electrolysis, liquefaction, and transport of hydrogen. If all 550 planes leaving the airport were converted to hydrogen, the entire water consumption of Frankfurt (650 000 inhabitants) and the output of 25 full-size power plants would be needed to meet the hydrogen demand of air planes leaving just one airport in Germany.
For hydrogen derived from fossil hydrocarbons, the availability of water and the safe sequestration of CO2 may pose serious problems, not because of inadequate technology, but with respect to logistics, infrastructure, costs, safety, and energy consumption. To fuel the 50 jumbo jets with hydrogen, about 7500 tons of coal and 11 250 tons of water are needed daily and 27 500 tons of carbon dioxide must be liquefied for transport, shipped to a suitable disposal site (perhaps in the deep waters of the mid-Atlantic) and safely deposited. The significant energy needs for hydrogen liquefaction and transport are the same for any source of hydrogen. Fueling the 50 jumbo jets at Frankfurt airport is only an insignificant part of a hydrogen economy. Has the magnitude of the task been recognized?