I knew that you would find the following interesting - taken from "How The World Really Works" A scientist's guide to our past, present and future, by Vaclav Smil.
How soon will we fly intercontinentally on a wide-bodied jet powered by batteries? News headlines assure us that the future of flight is electric - touchingly ignoring the huge gap between the energy density of kerosene burned by turbofans and today's best lithium-ion (Li-ion) batteries that would be aboard these hypothetically electric planes. Turbofan engines powering jetliners burn fuel whose energy density is 46 megajoules per kilogram (that's nearly 12,000 watt-hours per kilogram), converting chemical to thermal and kinetic energy - while today's best Li-ion batteries supply less than 300 Wh/kg, more than a 40 fold difference. Admittedly, electric motors are roughly twice as efficient energy converters as gas turbines and hence the effective energy gap is "only" about 20 fold. But during the past 30 years the maximum energy of batteries has roughly tripled and even if it were to triple that again densities would still be well below 3,000 Wh/kg in 2050 - falling far short of taking a wide-bodied plane from New York to Tokyo or from Paris to Singapore, something we have been doing for decades with kerosene-fueled Boeings and Airbuses.
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