Waiting for Superbatteries
Arthur T Knackerbracket writes:
They are still a long way from matching the energy density of liquid fuel:
The era of large steam-powered ocean liners began during the latter half of the 19th century, when wood was still the world's dominant fuel. But no liners fired their boilers with wood: There would have been too little space left for passengers and cargo. Soft wood, such as spruce or pine, packs less than 10 megajoules per liter, whereas bituminous coal has 2.5 times as much energy by volume and at least twice as much by mass. By comparison, gasoline has 34 MJ/L and diesel about 38 MJ/L.
But in a world that aspires to leave behind all fuels (except hydrogen or maybe ammonia) and to electrify everything, the preferred measure of stored energy density is watt-hours per liter. By this metric, air-dried wood contains about 3,500 Wh/L, good steam coal around 6,500, gasoline 9,600, aviation kerosene 10,300, and natural gas (methane) merely 9.7-less than 1/1,000 the density of kerosene.
How do batteries compare with the fuels they are to displace? [...] The best energy density now commercially available in very large quantities for lithium-ion batteries is at 750 Wh/L, which is widely seen in electric cars. In 2020 Panasonic promised it would reach about 850 Wh/L by 2025 (and do so without the expensive cobalt). Eventually, the company aims to reach a 1,000-Wh/L product.
[...] There is a long way to go before batteries rival the energy density of liquid fuels. Over the past 50 years, the highest energy density of mass-produced batteries has roughly quintupled, from less than 150 to more than 700 Wh/L. But even if that trend continues for the next 50 years, we would still see top densities of about 3,500 Wh/L, no more than a third that of kerosene. The wait for superbatteries ready to power intercontinental flight may not be over by even 2070.
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