From: B.Hamilton@irl.cri.nz (Bruce Hamilton)
Subject: Re: Electric Car Batteries?
Date: Sun, 27 Aug 1995 17:20:15 GMT
In article <email@example.com>
Carlo Izzo <izzo> writes:
>I have a question: what is the reason why electric car batteries
> are less polluting than combustion of fossil fuels? Where are
> the exhausted batteries dumped (or are they eternal)?
I've no wish to get into any protracted debates about this, so
I'll provide some references and you can decide for yourself.
Basically EVs have two problems, one is that current
economically-viable batteries don't have the specific energy
of gasoline. Gasoline = 12,000 Wh/kg ( excluding weight of
fuel tank), Pb/H+ = 25-40Wh/kg, Na/S = 80-85Wh/kg. Batteries
also can only stand a limited number of recharges ( Pb/H+ =
400-700 cycles, Na/S = 800-900 cycles), and currently the US
Advanced Battery Consortium has set mid-tern goals of
80Wh/kg, 600 cycles and calendar life of 5 years, and long
term goals of 200 Wh/kg, 1000 cycles and 10 year life.
The second problem is that over 80% of US electricity is
derived from the combustion of fossil fuels, consequently
it is important that the final efficiency of the Power Station
to EV is greater than that of oil well to ICV. The oil to ICV
has always been so cheap that little thought has gone into
efficiency, except from the point of meeting emissions
targets. There has been little attempt to address the
concept of using a 1000kg vehicle to carry a 100kg person,
as the public like "solid" vehicles - just in case they meet
another large vehicle.
So most of the research into EVs has focussed on getting
the most from the batteries, but as an interim measure EV
proponents have moved towards Hybrids, which contain a
small IC engine running very efficiently, as a supplement
to a much smaller battery. Pb/H+ batteries are still cheaper
than alternative and some of the alternatives ( Cd ) have
environmental problems of their own.
Now to answer your question, when all the various parameters
are considered various agencies and researchers come up with
reports that have totally different conclusions.
The most recently discussed research is a report in Science
( v.268 p.995 (1995)) that found EVs will probably use lead/acid
batteries, and thus cound be responsible for 60 times the lead
pollution caused by vehicles burning leaded gasoline ( 1.34g/km
for batteries using newly mined lead, compared to 0.022g/km
for leaded fuel ). Obviously most occurs away from the vehicle
at the battery manufacturing/recycling facilities, but mitigation
costs could significantly increase the cost of Pb/H+.
For an overview of the battery problem,I'd recommend
"Advanced batteries for electric vehicles"
G.L.Henriksen, W.H.DeLuca, D.R.Vissers
ChemTech November 1994 p32-38
Other good articles include:
"Check the tyres and charge her up"
New Scientist 15 April 1995 p.32-35
"Battery and Electric Vehicle Update"
Automotive Engineering September 1992 p.17-25
" Electric Vehicles: Getting the Lead Out"
Mechanical Engineering December 1991 p.36-41
IEEE Spectrum November 1992 p.18-24,93-101.
IEEE Spectrum July 1995 p.16-31.
" Electric Cars: will they work?, and who will buy them?
Business Week 30 May 1994 p.36-42
From: B.Hamilton@irl.cri.nz (Bruce Hamilton)
Subject: Re: Electric Car Batteries Breakthrough
Date: Fri, 8 Sep 1995 20:08:36 GMT
In article <firstname.lastname@example.org>
email@example.com (Will Stewart ) writes:
>In <...> firstname.lastname@example.org (Robert Ward) writes:
>>There has been a lot of technical discussion in this thread which is
>>very interesting. I wanted to point out that there are new batteries
>>that have been invented by Energy Conversion Devices of Troy, MI that
>>give a GM Impact a range of over 200 miles, recharge to 60% in 15
>>minutes, are fully recyclable and last 100,000 miles.
While Mr Ward is to be commended for putting a disclaimer on his
original post, and asking for comments, Will has frantically clutched
this straw. If he had bothered to read the references provided he
would have found in "Energizing the Batteries for Electric Cars"
( L.O'Connor IEEE Spectrum. July 1993 p.73-75 ) that Ovonics claimed
$5,000-$6,000 cost in quantities of over 10,000, that it can power the
Impact up to 240 miles, can power a vehicle more than 120,000
miles, and can be 60% recharged in 15 minutes, and "virtually all of its
energy recharges in 60 minutes". Their nickel metal hydride battery
was developed using a $18.5 million contract with the US Advanced
Battery Consortium, which then gave them a further $1.4 million in
April 1993 to supply evaluation batteries to Ford, Chrysler and GM.
They claimed a specific energy of 80 Wh/kg and $200/kWh, with the
ability to reach 150 Wh/kg.
For the curious, the Ovonics battery owes its performance to an
carefully-engineered negative electrode. The electrode is a metal hydride,
an alloy that easily absorbs hydrogen. The positive electrode is nickel
hydroxide, and the current-carrying electrolyte is potassium hydroxide.
Water in the aqueous electrolyte splits into hydrogen and hydroxyl ions
when the battery charges. The hydrogen is absorbed into the negative
electrode - which then converts from metal to metal hydride. At the same
time, hydroxyl ions react at the positive electrode and are converted from
nickel hydroxide to nickel oxyhydroxide. During discharge, hydrogen
leaves the electrode to form water and release an electron... The unique
aspect of the Ovonics battery is the mixed-metal-matrix negative electrode
( V,Ni,Cr,Zr,Co,Mn,Al and Fe ) which does not dissolve, fracture, or
recrystallise during charging and discharging.
So why hasn't this wonder battery created a breakthough in EVs, well
if WIll had read another of the references he might not have rushed to
create a thread with this title.
Type Manufact. Model Weight Capacity Specific Energy Peak Life Van
Energy Density Power Cycles Range
kg Ah Wh/kg W/L W/kg km
Na/S ABB B-11 253 238 81 83 152 592 246
Na/S CSPL BP-Mk3 29.2 292 79 123 90 795 240
Ni/Cd SAFT STM5-200 24.5 214 55 104 175 1018 163
Ni/MH Ovonics H-Cell 0.628 28 55 152 175 505 155
Zn/Br SEA ZBB5/48 81 126 79 56 40 334 149
Ni/Fe EP NIF200 25 203 51 118 99 918 139
Pb/H+ Sonn. 6V160 31.5 184 36 92 91 370 82
Pb/H+ CEVS 3ET205 32.8 185 33 78 68 149 75
Various footnotes and qualified omitted, the weights looke strange,
but I haven't time to clarify from the text.
They used the Federal simplifies urban driving schedule and a IDSEP
( improved dual-shaft electric propulsion) van - details in the
reference "Advanced batteries for electric vehicles" G.L.Henriksen,
W.H.DeLuca, D.R.Vissers. ChemTech. November 1994 p.32-38.
Note the 55 Wh/kg versus the 80 claimed above, note also the
superior performance of other batteries, but then remember that
ECD has Robert Stempel ( ran a small car company in Detroit :-) ) to
help with selling the product to GM..
>This is much more than I had expected. 100,000 miles will
>significantly improve the battery replacement time and the recharge
>rate exceeds the target of 50% in 90 minutes. Are these lead acid
Refer above. Basically, even with the NMH batteries the Impact is
not ecomonically competitive with a current ICV, much less one of
the more frugal ICVs that will appear in 1997.
>Is the range predicated on a particular driving profile?
Commonly known as London milk trolley acceleration profile and
the housewives pram pushing urban cycle. The GM Impact ( as does any
EV ) range plummets as speed or acceleration are pushed, GM quotes
50-70 miles for the Impact on the EPA city cycle and 70-90 for the
highway cycle, with the lower figures being for less frugal drivers
( or frugal drivers who forget they aren't in an ICV and turn on the
heating or air conditioning). It is governed at 75mph, and is only a
two seater ( adding another seat would reduce the range by 20% ).
The Impact does have a range of 250 miles at 25mph for those who
can stand the stress of high speed driving...