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Because physics

July 7, 2017

There’s a tendency, common to us all, to become so enamored of what we want that we ignore the inconvenience that is reality. So it is with electric vehicles. The Silicon Graybeard takes a look (click here to see his post) at Volvo’s stated intention to focus on electric vehicles and discontinue development of internal combustion vehicles as of 2019.

The biggest inconvenience, as I see it, is simply this: batteries simply don’t have the energy density of gasoline. Silicon Graybeard puts it this way:

“battery makers are desperately trying to figure out how to reach a specific energy of 450 Wh/kg (Watt-hours per kilogram), gasoline already offers 12,000 Wh/kg. One horsepower is 750 W, so turning Watt hours to Horsepower hours, batteries give 0.6 HP*h per kg, while gasoline offers 16 HP*h/kg. Either way of looking at it, gas has over 26 times the energy density.”

That seems pretty consistent with what I remember from back when I thought I wanted to be an engineer.

One can argue that is because there hasn’t been enough incentive for research, that the market hasn’t been given a reason to push for the research and that we just need more players in the battery development field and all will be solved, but that seems at odds with reality and its ugly little face. Battery research is slow and is not, at least right now, comparable to the research and speed of development we’ve seen in some other areas. Silicon Graybeard, again:

“I don’t think the solution to the battery problems lies in competition and more players, Mr. Samuelsson; I think you need new physics or perhaps a new universe. There is no such thing as “Moore’s Law of Batteries”; this is more an exercise in physics and chemistry than clever manufacturing. While I’d never recommend betting against “clever”, there’s no methodical process at work like there was in the semiconductor industry during the heyday of Moore’s Law. To borrow a quote from that linked post on electric cars and batteries:
Battery research is slow compared to the semiconductor “internet speed” we’re used to. Think of how a battery works: two different materials give and take electrons at a voltage potential determined by the way the universe was put together. All of the simple combinations have been tried and new ones are being researched daily. The limits, though, are imposed by the universe. In semiconductor work, the same materials are always worked on, the techniques for putting down dopants and photoresistive masks is all that changes.”

I’m a big believer in the power of the free market to bring about change far faster than government mandate and interference. That said, once again this seems to be consistent with what my engineering education taught me long ago. The free market can overcome a lot of things. Physics isn’t one of those.


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  1. Having played in that world a ‘bit’ doing technology development, there is NO quick fix/breakthrough that is going to magically get the ratio up to anywhere approaching gasoline. Also, the weight. manufacturing, and disposal costs are NOT decreasing at the predicted (wishful) rates. Volvo will have to keep going with gasoline engines, or fold as a manufacturer.

    • Yep. Breakthroughs are neither common nor subject to time tables. They occur when they occur, if they occur at all. Banking on one (as Volvo seems to be doing) is a less-than-sound business policy.

      • Volvo has just made themselves immaterial as a car company… sigh

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