Quote:
Originally Posted by Bicycle Bob
If heat is needed, storing it makes sense. The secondary steam engine has been an obvious option for a century, but steam engines are only efficient with a much higher temperature difference, so they would dissipate most of any remaining heat.
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No, not necessarily. While modern batteries have poor energy density compared to gasoline, they're still way lighter and more compact than hauling a water heater tank around in your Prius. The other thing to think about is, in a hybrid car, you ALREADY have a storage mechanism - the batteries - built in. All you have to do is build the steam generator and add a heat exchanger to condense the steam back into water.
As for the efficiency of the steam generator, so what if it's not as efficient as a modern steam plant? You're recovering waste heat anyway, so anything you get back is a win. I would think that the reason they don't already have this technology on hybrid cars has more to do with weight, complexity, packaging and safety than thermal efficiency.