[_wmd]

Don't forget that electrical grid transmission losses cause massive efficiency problems before centrally generated power ever reaches that car charging point -- on the order of 30% or more, and conversion from AC to DC at the charging port may account for another 10-30%. (Made up numbers, but they're in well within range IIRC)

I don't think it follows that just because we have historically centralized power generation, this was obviously due to efficiency. For example, centralization of management, investment, pollution control, logistical (fuel delivery), safety (nuclear) and reliability concerns seem far more obvious to me, although I don't doubt there could be an efficiency benefit to large-scale generation, I've just never heard of it.

[kw71]

> conversion from AC to DC at the charging port may account for another 10-30%

Simple rectification has not so much loss, I think you are thinking about low voltage DC power supplies, and I think that chargers for large, high voltage battery piles are likely to be happy with rectified (maybe doubled) mains supply.

The low voltage supply is first rectifying the input, then using an inverter to generate high frequency AC, then rectifying and filtering this to give a DC output.

[londons_explore]

Large AC -> DC conversion has to do this too.

The simple "diode" rectification is no longer acceptable due to harmonics put on the AC side causing grid stability problems and emitted radio interference.