Study finds that aluminum reduces electric vehicle cost against steel counterpart for same targeted range
07 January 2013
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| The study task design steps. Source: fka. Click to enlarge. |
A recent study found that an aluminum electric vehicle can cost up to €635 (US$829) less than that its steel counterpart despite the higher cost of aluminum, given equivalent range targets. The study, conducted by Forschungsgesellschaft Kraftfahrwesen mbH Aachen (fka) for the European Aluminium Association (EAA) and the International Aluminum Institute (IAI), found that any additional cost of building a car with aluminum is more than offset by the cost savings that can be made on the battery pack, since a lighter car needs less battery capacity to drive the same distance.
A C-segment crash reference vehicle (Volkswagen Golf) with steel unibody and internal combustion engine served as the basis for this study. The mass and crashworthiness properties of this vehicle were analyzed in four Euro NCAP and FMVSS 301 high-speed load cases, serving as the crash reference within the project. One of the requirements was that electric vehicles (steel-based or aluminium-based) should at least be as safe as the crash reference vehicle.
The fka team first converted the conventional vehicle into an EV—the original steel unibody structure was conserved, with only minor changes made in order to adapt the structure to hold and protect the battery pack.
The next step was the conversion of that EV to a full aluminium space frame electric vehicle. The shape of the outer skin of the vehicle was kept identical to that of steel vehicles.
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| Various manufacturing methods used in the aluminum design. (blue: sheet, green: extrusion, red: casting) Source: fka. Click to enlarge. |
While keeping to the crash standards, the fka team determined that the weight of the total body structure could be reduced by 162 kg (357 lbs) compared to the electric reference steel-unibody. As a secondary effect, the battery system capacity could be downsized by 3.3 kWh while still maintaining an intended driving range of 200 km (124 miles). This also means an additional weight reduction of 25 kg (55 lbs)—assuming battery technology projected to be available in 2015—making the aluminium electric vehicle in total 187 kg (412 lbs) lighter than the steel electric vehicle.
The fka team then calculated aluminum lightweighting could be carried out, at a production volume of 100,000 vehicles per year, of €1,015 (US$1,324) per vehicle. Assuming energy-specific year 2015 battery system costs of €500/kWh (US$652/kWh), the reduction in total battery system costs is €1,650 (US$2,152).
If we compare the additional costs of the lightweight design with the reduction in battery system costs, it can be concluded that the benefits obtained from lower battery costs more than outweigh the additional costs for the lightweight aluminium vehicle. With the assumptions made in this report, the total cost of the aluminium electric vehicle is €635 [US$829] lower than for the steel electric vehicle.
—“Investigation of the Trade-off Between Lightweight and Battery Cost for an Aluminium-intensive Electric Vehicle”
Life cycle analyses of the full-steel and the full-aluminium electric vehicles found that the aluminium electric vehicle emits 1.5 tons of greenhouse gases less over its complete cradle to cradle life-cycle, including production, a driving distance of 150,000 km, and recycling. The carbon footprint of the production of the aluminium electric vehicle, including the end of life recycling benefits as recommended in ISO 14044 standards, is lower than that of the steel electric vehicle. Further, the aluminium electric vehicle also consumes less energy during the use phase. Thus, the researchers concluded, whatever the mileage distance over the vehicle life time, the aluminium vehicles is always less intensive in term of GHG emission and energy use.
Excluding recycling, the break-even point at which the carbon footprint of the aluminium electric vehicle is lower than that of the steel vehicle occurs at a mileage of 47,000 km (29,204 miles).
Resources
$500/kwh for batteries in 2015?
Surely should be more like $3-400.
OTOH at 25kgs for 3.3kwh they are assuming an energy density at the pack level of 131Wh/kg, way higher than that today in the Nissan Leaf or Volt at around 80Wh/kg.
Posted by: Davemart | 07 January 2013 at 02:55 AM
This is very interesting.
Manufacturers of electrified vehicles should have been using much light materials such as aluminum and various composites to further reduce the size of the e-storage units, increase e-range and reduce cost.
Steel, Coal and Oil lobbies will react.
Posted by: HarveyD | 07 January 2013 at 07:32 AM
Maybe some of past ten years of battery breakthroughs will be commercialized.
In any case, full EVs may need to stand economically without tax credits before the next President - esp. if oil firm "accounting" credits continue.
Posted by: kelly | 07 January 2013 at 07:34 AM
It shows that battery powered cars are so energy starved that lightweighting makes sense.
ICE vehicles have so much power they do not need it (as badly).
However, the same benefit accrues to all cars, ICE or BEV, so it is worth investigating, especially in Europe and Japan where gasoline is > $8 / US gallon.
They are doing it using high tensile strength steel as well as Aluminium.
Posted by: mahonj | 07 January 2013 at 07:46 AM
Tesla is aluminum, they saved enough weight to make a difference. It remains to be seen if the cost of aluminum versus batteries makes this true years from now.
Posted by: SJC | 07 January 2013 at 08:23 AM
Time to resurrect the East German Trabant and convert it to an EV.
Posted by: Mannstein | 07 January 2013 at 08:44 AM
Davemart,
It's worse than that even as they were assuming 500 Euros ~$625/kWh.
Still, I'm all for the lightweighting, but they should do it with eyes open to real costs. By 2015, pack level cost have got to be closer to $300-$350 or we're wasting our time.
Posted by: DaveD | 07 January 2013 at 10:41 AM
Dave:
The 24kw Leaf battery, LiMn, has an energy density of 141 kwh/kg; We have tried to get the cost of a replacement from Nissan; but, since the Leaf is still under warranty, they have not been forthcoming with the information. That will change when the three year warranty runs out and they will need to announce the cost.
The Leaf weights about 3300 lbs and includes a hood and doors, not the rear hatch, that are made of aluminum. Nissan has modified the Japanese 2013 model to reduce the weight by 175 lbs...a fair start and it has resulted in a slight increase in range. But, not a major breakthrough by any means.
Nissan is rumored to have major announcements for the U.S. model in January...I have been hoping for at lease an incremental increase in battery capacity.
One of the days I believe the car will pass the "Ladson Test" of a true 100 miles range at a steady 65 mph.
Posted by: Lad | 07 January 2013 at 12:07 PM
As a rule of thumb, city range is constrained by weight, and highway range by aerodynamics.
Given a reasonably open road (a rarity in some parts, I know), you will spend 15 seconds accelerating the car's mass to cruising speed, and the rest of your trip fighting wind resistance. Energy use is directly proportional to Cd: a drag coefficient of .30 requires 50% more energy to move through the air compared to one of .20.
The question then becomes: do you want a 100 mile range in the city, on the highway, or both? The first will require a small, light car which probably won't have great highway range. The second is easier to accomplish with a sleek but heavier car such as the Tesla.
Posted by: Bernard | 07 January 2013 at 02:12 PM
The interesting thing from this article is that an aluminum structure is $1300, perhaps also exaggerated like the other numbers. Bring it on, cars today are overweight and it affects the stop and go city economy. The upcoming Ford F150 promises big weight savings by using aluminum.
Nissan is being prodded to release the cost of replacement batteries, perhaps in a few months.. they are being coy because they know it will be used against them by EV haters. The three Volt internal battery modules are around $7500 or so.
Posted by: Herm | 07 January 2013 at 02:30 PM
The €635 ($872) savings is for the production of the car. There is no specific mention of the operational savings in the article but with 3.3 kWh less of battery capacity that does not need to be charged up for 750 cycles at, say, 80% DoD, the energy savings would be in the 2,000 kWh range or €500 ($687), based on ~€0.25 (~35¢) per kWh cost of residential electricity in Germany.
The avoided emissions from 2,000 kWh would account for about half of the ̏1.5 tons of greenhouse gases less over its complete cradle to cradle life-cycle, including production, a driving distance of 150,000 km, and recycling. ʺ
Posted by: NorthernPiker | 07 January 2013 at 08:43 PM
Smash an aluminum can between your hands (or against your forehead). Then try steel. Case closed.
Posted by: Larzen | 07 January 2013 at 09:33 PM
Future five passenger BEVs with resilient molded re-enforced plastic body on aluminum alloy frame + composite wheels etc and 600+ Wh/Kg batteries should weight less than 1000 Km, have 500+ Km e-range and cost no more than $25,000 (2012$) if mass produced in the right place.
Posted by: HarveyD | 08 January 2013 at 10:14 AM
correction...1000 Km should read 1000 Kg......
Posted by: HarveyD | 08 January 2013 at 10:17 AM
@lad:
http://en.wikipedia.org/wiki/Nissan_Leaf
'The battery and control module together weigh 300 kilograms (660 lb) and the specific energy of the cells is 140 W·h/kg.[32] Each battery pack costs Nissan an estimated US$18,000 (as of May 2010).[33][34]'
That comes to the 80Wh/kg for the battery pack that I quoted.
Density at cell level is a whole different ball game.
AFAIK the weight would scale against the total battery pack weight rather than that of the cells, but perhaps that notion is in error.
Nissan have kind of given a battery replacement cost, that of the modules, which ties in with Wiki's costs.
I think their difficulty is that there is no subsidy for replacement batteries, so if not quite at those elevated levels, might be more than anyone will be prepared to pay on a three year old car.
In my view the problem is the manganese lithium chemistry with no cooling.
As Musk predicted it is not good enough.
Most of the other battery electric cars with the possible exception of the iMiEV have far better battery chemistries and cooling systems and are unlikely to degrade so fast.
Posted by: Davemart | 08 January 2013 at 01:50 PM
>>>"Smash an aluminum can between your hands (or against your forehead). Then try steel. Case closed."
Weight an aluminum can, and then weight a steel or iron food can, and then see how much % weight saving you can achieve. I'd bet the aluminum can is 1/5th the weight of the steel can. Case closed.
Just ask Boeing, Cessna, Lockheed, Grumman, Douglas, North American, Martin, etc...as to why planes are made of aluminum and last for decades, and not from steel.
Posted by: Roger Pham | 08 January 2013 at 04:38 PM
The study, was conducted for the European Aluminium Association (EAA) and the International Aluminum Institute (IAI).
The aluminum industry has ALWAYS said aluminum was better for frames, bodies, suspension, and engines - ALWAYS.
But few were buying.
Aluminum frames and bodies are virtually non-existent (too costly) in economical production cars - do you really think the auto makers of the world have not thought of this and run the numbers over and over and over?
Of course they have - but aluminum is generally not affordable for major parts.
Do you think they have not noticed that MPG has become very important? "Oh Gee, when did we have to start putting MPG ratings on the window sticker?"
Do you think auto makers are unaware that airplanes are made of aluminum?
Just ask Ford, Toyota, GM, Honda, Fiat, Mercedes, Chrysler and BMW (and even Tesla, Porsche and Audi) why autos have generally been made of steel for decades, and not from (so far, too expensive) aluminum.
Posted by: ToppaTom | 08 January 2013 at 11:30 PM
@TT,
Aluminum is increasingly used in cars. Once upon a time, engines are made of cast iron and steel, now engines are all aluminum. The hood and brakes of Priuses are made of aluminum. Increasing number of suspension components are made of aluminum. Of course, when fuel was cheap, nobody cared about MPG's, only about purchasing cost. Now, fuel is expensive, and weight-saving makes sense.
The new high-strength steel is also promising and has demonstrated a lot of weight saving. So, the contest goes on, and the consumers and the environment win!
Posted by: Roger Pham | 11 January 2013 at 11:16 PM
Why would you advocate aluminum for frames, bodies and engines when titanium is superior?
Cost?
Of course aluminum is increasingly used in cars, and MANY, but not all engines are aluminum - and aluminum frames and bodies are rare.
Once upon a time, ALL engines, including the pistons were made of cast iron or steel.
First pistons went to aluminum when it made economic sense and then many engine blocks and heads went to aluminum.
Much of this happened many years ago.
The hood of the Expedition went to aluminum in 1989.
So what?
Weight-saving ALWAYS made sense; only somewhat more so now - but then and now there must be a cost tradeoff - not a kindergarten-teacher knee jerk revelation that all cars should be converted to use a full aluminum space frame and to not do so is evil or indicates mental defect.
Posted by: ToppaTom | 12 January 2013 at 10:36 AM
There is a current (medium and long term) surplus of Aluminum and the price has dropped from $1.50/lb to under $1/lb in the last 24 months or so.
As the aircraft industry and others move to more and more use of composites and new large aluminum plants go on line, the surplus will continue and price may drop even further.
At that low price, aluminum becomes competitive with steel for many car parts. All cars will gain with the use of more aluminum components, special the electrified units.
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