Has Israeli firm cracked electric car angst ?
mo at ccr.org
Sun Sep 2 23:36:27 CDT 2012
that is hardly the first time the battery swapping idea occurred to anyone.
the article explains one reason it hasn't been tried before - they've
burned through a billion dollars getting it this far and the market required to make
it economical is not remotely a sure thing.
the other issue not mentioned but apparent "between the lines" is that the
target geographies are extremely dense and/or compact. that has everything to
do with how many battery swap stations are required. the density in almost all
of the US makes for needing a MASSIVE LOT of swap stations.
they do get big points, however, for the 115 mile range. that makes a lot more
sense than the stupid 43 mile "average commute" number tossed around.
I also suspect the average commute speed in Israel is less than the US, too,
which helps the range.
just read an article about a chap with one of the new BMW 3- series pure electrics.
he took part in a track day where a number of different pure electrics ran. some were
designed as race cars and they were astonishingly fast. what left him quite badly surprised
is how quickly the batteries in the BMW went into over temp protection. being driven hard,
within 3-4 minutes he was getting overtaken by a Nissan Leaf because the liquid cooling
system could not deal with the heat produced by discharge rate. between the morning
and afternoon sessions the batteries cooled enough to give him a couple of additional
minutes of BMW-worthy performance, but soon, the Nissan Leaf, also being driven
flat-out started gaining on him as the power controls rolled-back the grunt.
one other approach to the "change the batteries" model which certainly seems to
have much better deployment economics as well as range is the "flow battery".
Flowbats use two liquids which flow through an ion exchange chamber (rather
like a fuel cell in some ways) and current is produced. the discharged chemicals come
out the other end and are stored because the can be recharged almost indefinitely.
the size of the tanks determine the KwH capacity.
a Flowbat vehicle would use a "filling station" where the depleted solutions would be
pumped out and the charged solutions would be topped-up. the filling station
would then recharge the spent solutions and store them to fill another vehicle.
the station would need some inventory, but not the massive fuel deliveries
needed currently. more interestingly, a station could chose whatever power
source they like for the recharging. a filling station in a remote area might
use solar PV to recharge the solutions and could conceivably be unmanned.
this can dramatically lower the operating cost of widely distributed filling stations.
the big wrinkle in this is the chemistry. the classic Flowbats use solutions which
are not very friendly. they are aqueous, and while that's better than molten sodium
and sulphur, they can still be quite nasty. there are groups working aggressively
on alternative chemistries which are much less nasty, but any system still has to
deal with the energy density problem - KWh per kilogram.
Hydrocarbons happen to be an insanely efficient way to store energy with an
energy density which is essentially unrivaled at room temperature. anything that
uses water to carry the energy carriers in solution is starting at a huge disadvantage.
we know Flowbats are likely to have bright future in stationary applications.
whether they can make the grade for (some?) vehicles is still TBD.
Sent from my iPad so please excuse the jammy fingers.
On Sep 2, 2012, at 4:25 PM, Andre Kesteloot <andre.kesteloot at verizon.net> wrote:
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