The dark cloud hanging over electric vehicles in the wake of recent Chevy Volt fires may not lift, no matter how much engineers to do improve EV safety. That's because they're up against the gating factor of battery pack cost.
Experts say rising concerns over safety are going to make it tougher for engineers to dramatically cut the costs of lithium-ion battery packs. Already, General Motors is reportedly considering a redesign of its lithium-ion battery pack to help prevent damage during a collision.
"We just don't know how much lower we can go in terms of price," says Donald Sadoway, a battery expert and the John F. Elliott Professor of Materials Chemistry at Massachusetts Institute of Technology. "It's not as if we can stand on the shoulders of all the work that's been done on cellphone and laptop batteries up to now. Laptop batteries don't have to be crashworthy."
The Chevy Volt battery pack caught fire three weeks after a crash test damaged it.
Photo courtesy of GM.
The National Highway Traffic Safety Administration said one Volt fire occurred after a side crash test was performed on it in May. During the test, the vehicle's battery was damaged, and a coolant line was ruptured. The fire occurred three weeks later. Three similar tests in November did not result in fires, though one damaged battery did emit sparks and smoke, the agency said.
Experts are confident that current cooling systems, coupled with improved crashworthiness, will keep electric cars safe. "We will learn how to better deal with the safety issues," says Elton Cairns, a professor of chemical and biomolecular engineering at the University of California-Berkeley and a designer of fuel cells for the Gemini spacecraft program during the 1960s. "After all, any battery that can fit on a vehicle stores much less energy than a tank of gas."
Still, the concern is that lithium-ion batteries are already too costly, and that new safety measures will prevent them from dropping significantly in cost, even as economies of scale kick in. Today about half of the cost of an EV battery pack lies in its "non-cell" portion, according to the National Research Council, and that number could go up if crashworthiness becomes a big issue.
Gasoline, and battery packs both represent stored energy, which must somehow be rendered 'safe' in a crash. Amazing strides have been made in gasoline technology, yet firery car crashes still occur. There will be similar occurances with battery technology. The question is, how safe is safe. Will we accept one fire in a hundred, a thousand, or a million or more crashes ?
A protocol needs to be established to drain the charge from damaged battery packs, just as capacitors are discharged to return them to safe voltage levels.
I believe that the issue here is weigth. There are other options in lithium ion technology, like Lithium Iron Phosphate, but they have 70 to 80% of the cappacity of the usual Lithium-Cobalt batteries. They are a lot safer, withstanding higher temperatures, and they do not burst in flames when short circuited. But the weight kills them for use in cars. They are very common in light vehicles, like bikes or motorcycles. Maybe it's a question of time...
Yes, there's still a fear factor associated with hydrogen. I still remember the Hindenburg and the hydrogen bombs used in Japan. Hydrogen still carries the fear factor people still carry about nuclear power. It's going to blowup and destroy us all.
Perception and related actions are an interesting thing. As long as these things continue to be bigger than life and out of proportion in our minds, use is going to be limited.
I find it interesting how the human mind finds it acceptable and doesn't impact our behaviors when 18,000 people are killed by drunk drivers and 100,000 people are killed because of incorrect hospital drug dispensing or contracted infections each year and they readily drive to hospital visits, but when a couple of batteries catch fire in a controlled crash test, or a dozen floor mats get stuck under an accelerator peddle, we refuse to buy that car.
With all of the press about EVs, I had the impression that technology was sound and that EVs were the future. It seemed it was just a matter of scale and volume before prices would come down to a level that would make these vehicles affordable. Your recent articles are penetrating that myth a bit, Chuck.
@jhankwitz: Actually, neither of the bombs dropped on Japan during World War II was a hydrogen bomb. The first hydrogen bomb (the Teller-Ulam design) was tested by the U.S. in 1952. And the fusion fuel used in hydrogen bombs is either deuterium or tritium (or a mixture of the two), rather than ordinary hydrogen.
As far as the Hindenberg disaster (which I think more people today remember from the cover of the first Led Zeppelin album rather than the actual event, which took place in 1937), there has been debate about the exact role which hydrogen played.
That being said, you're right that perception and reality are often two different things. This is particularly true when it comes to safety and risk. Studies have repeatedly shown that our brains react much more strongly to unfamiliar risks than to familar risks, even if the familar event is much more likely. A now-classic example is the decision of many people to drive rather than flying after the September 11 attacks. Since driving is actually much more dangerous than flying, it's believed that this may have lead to about 1000 additional fatalities.
In any case, the same thing which makes hydrogen relatively safe also makes it a relatively poor fuel: its energy density is low compared to batteries, and especially compared to gasoline.
In the words of a friend who worked in this industry, COST. Think the Volt is high priced? Fuel cell vehicles would be even more so. You can't get past the high material cost.
Storage of hydrogen in a dense form at low pressure is possible, but again costly and heavy.
There are many Li-ion chemistries. The various chemistries have widely ranging properties including inherent safety. Some have known issues with safety and some don't. The ones that do have issues tend to be those that can store the most energy and are tricky to charge quickly. People that use them also tend to run the cells from 80% charged to 20% charged to avoid either overcharge or undercharge which can shorten life or ruin the battery.
The Li-ion chemistries that don't have safety issues tend to not store nearly as much energy but can be charged and discharged extremely quickly and can be run from full charge to full discharge.
Chevy went with a chemistry that had safety issues.
So when reporting always specify the Li-ion chemistry involved so that the whole technology doesn't get a bad rep because of a few.
And I'm old enough to remember the Pinto gas tank problem. Gasoline is extremely dangerous and all that stands between safety and disaster is a fraction of a millimeter of steel or a couple millimeters of plastic. A friend of mine lost a daughter when someone T-boned his station wagon and the gas incinerated her.
The biggest issue with the chemistry that Chevy is using is to predict the delayed reaction.
And the other more imminent issue with battery power is training emergency responders in dealing with the potentially deadly orange wires after a crash.
My opinion exactly... Were people able to consider the electric car on a par with post WWII tech, at the start of post war competition and population mobilty, comparing electric would be easier.. Also Moores law in electronics raises expectations for improvments in other technologies unrealistically. AS for battery weight, I would gladly trade my 1264 pound lead acid pack in for a 600 pound lithium pack if it didn't mean handing over my $10 K to a foriegn government's company. Having converted rather recently, in 2003, never to turn back to gas, it's harder every day to understand why the US is still clinging to such a 20th century technology. Imagine YOUR laptop on AAA batteries!
Take a look at that picture of a Li-Ion battery pack and then visualize a gas tank. That alone should kill any fantasy about batteries being a substitute for combustible liquids. In terms of motive power, the Chevy Volt's battery pack is equal to about ONE gallon of gasoline, and look at all the complexity it takes to make it even that good. I might also add that a gas tank doesn't wear out, and is trivial to recycle.
In defense of battery packs, though, the real standard of crash safety should be whether they're as safe as gas tanks. If they don't cause dangerous fires any more readily than 20 gallons of gas, that should be good enough. I realize that we live in a litigious society and anything new and mildly dangerous is bound to attract lawsuits that things that are old and highly dangerous never would. If electricity and gasoline were invented today, the public would never be allowed access to either of them.
I think Chuck's earlier comment about gasoline-powered vehicles' performance giving us higher expectations, combined with visualeyes' comment about higher expectations that Moore's Law has given us in all technologies, are worth thinking about. I've always found it interesting that many have treated Moore's Law not as the simple observation it originally was when Moore made it, but as a prediction and even a prescription about what we should do with technology and what it should do for us.
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