The Agenda

A Battery Breakthrough?

Might the Envia rechargeable battery, with an energy density of  400 Watt-hours per kilogram, pave towards viable all-electric automobiles? Jamais Cascio offers a skeptical note:


Most standard automobiles have an average internal combustion engine efficiency of around 20% — that is, of the energy available in the fuel, about 20% is eventually translated into motive force. So that 12,000 Wh/kg is effectively ”only” 2,400 Wh/kg.

Electric motors, conversely, are extremely efficient at translating available energy into motive force; at 90%, that 400 Wh/kg Envia battery is still effectively 360 Wh/kg.

So a gasoline engine system 6.67x better than the Envia, not 30x better. The difference isn’t as gobsmacking, but it’s still significant, and remains a reminder of just how far battery technology has yet to evolve.

The Envia is, as Cascio makes clear, a significant improvement on its predecessors, but that won’t be good enough ti displace conventional gasoline engine systems for a years yet. And of course gasoline engine systems won’t sit still.


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