Saturday, October 25, 2008

Golf carts no more

As both an ardent fan of F1 racing and student of alternative energy, the recent article in New Scientist on electric cars took my immediate fancy. The main feature of the article was the Tesla roadster prototype funded by some Californian whiz who had made masses of money doing something else. Although there are shades of the Monty Python line, "...made a cool 4 million in vanadium and sank it all into diesel powered nuns..." (Editor's note: the internet is an amazing thing: I enter diesel powered nuns into Google, every academic's best friend, to check the accuracy, and get 76,200 hits; and there's even a blog of the name "dieselpowerednuns."), initial results are certainly impressive from the performance perspective; while massive questions of cost and practicality remain.

Time was when the electric car was a tiny, nasty little box with absolutely no performance and even less range; it was as if it were necessary to carry around a long cable so it could plugged in every few miles to recharge. It's not the first car to have changed the image, but the Tesla blows it out of the water, with its blinding acceleration and claimed top speed of 200 mph apparently limited internally. I don't recall the range but for sure it is far superior to yesterday's golf carts. So what is the difference? All in the battery. The Tesla derives its awesome power from a lithium battery that weighs in at a mind-blowing 450 kg. Lithium batteries are the wunderkind of modern batteries, since lithium combines very low atomic mass with very high reduction potential (the bit that makes the voltage). So they combine low mass with high energy density unparalleled by other competing battery technologies. As a side note, the SSCP is not slow to point out that he worked on lithium batteries back in his youth at Exxon. That was the era of the first oil crisis.

The amazing thing about the Tesla power plant is that the size of the battery far exceeds anything I have been familiar with. The lithium battery powering this laptop as I type weighs maybe 100 grams. It would also cost be about $150 to replace unless I buy one from some disreputable place on eBay. Two issues with lithium batteries are safety and cost. I already alluded to the latter. Little wonder then that the Tesla would set you back $100,000. At that price it is hardly the answer to all our transportation issues; but to be fair to the developer, he does say that the Tesla is a kind of marketing vehicle and that "future products" would emphasize lower-performance, mass-production type cars.

The safety issue represents a longer term problem perhaps. Most people have heard about, or seen pictures of, laptops spontaneously bursting into flames. Imagine that happening on an airplane with an armed marshal sat in the row behind you. My understanding was that the size of the lithium battery was limited by this safety concern. Imagine the conflagration that would ensue if a 450 kg battery (4,000 times larger than the laptop battery) went off. An earlier lithium-powered car made by Volvo (also a high-performance sex machine) used hundreds of tiny cells. Evidently things have moved on.

Looking down the road there are other things to be concerned about. So, if each existing automobile, not to mention the millions more that will appear in places like India, China and Brazil, uses a lithium battery like the one in the Tesla, that means a lot of lithium. At a stroke we will have moved from concerns about peak oil to concerns about peak lithium. In all probability, the latter will be an even more massive problem. And then supply issues will negatively impact prices and so on.

Then what about the recharging? Although the Tesla emits no carbon in its travels, other than that emitted by the driver, the production of electricity to recharge the battery currently does. Although calculations show that, apparently, the carbon footprint of electrical power generation is lower than that of fossil-fuel-powered cars, it is far from zero. So, to some degree, the carbon problem is simply moved somewhere else by the Tesla. Then of course there is the irritating charging time.

The developer is disdainful of the fuel cell approach; but at least the latter requires no long charge times; nor does it hold the owner hostage to the cost of lithium. Of course fuel cell technology will require a hydrogen infrastructure, which is still in its infancy; and that is probably a stretch.

Still, all-in-all, interesting times in electrical transportation.


Anonymous said...

Thought you might be interested in this link to some articles about lithium availability and alternatives for light-weight, high-energy-density battery alternatives:

Respectfully yours,


Aylwin Forbes said...

So, I wonder who might that "anonymous" DWK be?

Anyway, thank you for the references. Although I haven't read in detail, the answer is clear in the executive summary: there isn't enough lithium to sustain widespread vehicle use, and the depletion rate of lithium in those circumstances would exceed that of oil currently. The report goes on to mention other batteries based on more abundant materials, with which I am unfamiliar. Plenty of reading for an autumnal afternoon.