On Sat, 17 Sep 2011 15:39:20 +0100, Peter Masson wrote:

"Andy Breen" wrote in message
...
On Sat, 17 Sep 2011 15:21:58 +0100, Peter Masson wrote:

"allantracy" wrote

The future for cars looks very bleak unless they can be persuaded to
run on electricity.

Though there was a steam car around a while ago how ironic would that
be?

Battery technology can never be made efficient,

Define the meaning you are picking for "efficient" in this context..

so even with nuclear or
other renewable generation of electricity, battery cars can never be
made efficient.

See above. What do you mean by this? Cost? Energy density? Charge
cycling efficiency? Lifespan? Charging time?

charge cycle efficiency. The other issues can in principle be overcome,
but the laws of physics will not let you charge and discharge a battery
without significant energy losses.

More chemistry than physics in a battery, surely. The physical
limitations apply equally to any stored-energy medium (and thus as much
to H2 tankage as power stations as batteries..) - you always get less out
than you put in.

OK, I'll grant you that heat dissipation can be an issue in charging
batteries, but the degree to which it's an issue depends on the type of
battery (thinking back, here, to discussions of heat issues in spacecraft
that couldn't depend on constant solar charging..).

The real question is - is charge cycle efficiency enough of a restrictive
factor. It's not like the alternatives don't have serious issues of their
own. Inductive charging or power supply is lossy, H2 is /really/ good at
leaking out of storage (and producing the stuff and compressing or
liquifying it are all monsterously lossy processes). Given that we (as a
planet) are not short of renewable electricity production potential, but
that most of it is inconveniently placed for current - and even more so
for likely - population concentrations, any "good enough" means of energy
storage is likely to be, well, "good enough".

--
Speaking for myself, and no-one but myself