EDITOR: | December 18th, 2015 | 12 Comments

Nixon and Dr. Schlachter on the “No Moore’s Law for Batteries” debate.

| December 18, 2015 | 12 Comments
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Note from the Publisher: Due to interest from our audience, this article, which was originally published on May 22, 2015 has been republished.

In my last column published earlier this week titled Electric Dreams’ and Moore’s Law for Batteries, I would like to start by thanking Dr. Fred Schlachter for making time to comment in detail on my previous column with the following:

Thanks for mentioning my opinion piece from April 2013 Proceedings of the National Academy of Sciences, the title of which is “No Moore’s Law for Batteries.” The Editors removed the quotes I had placed around “Moore’s Law'” This “law” is an empirical finding which has become a self-fulfilling prophecy, rather than a law of nature, such as the Second Law of Thermodynamics.

Let me remind the reader that “Moore’s Law” behavior is exponential, evidenced by a straight line on a semi-log plot, or, in popular vernacular, doubling over many time periods with the same time period for each doubling (as, for example, doubling every two years for the past forty years). Simply doubling over some time period is NOT exponential, it is simply doubling. Doubling over several time periods (the same time period in each period) is required to demonstrate exponential behavior. At least four or five time periods are necessary, not just one or two.

As I made clear in my article, the exponential increase of computer power over a long period of time is due to advances in lithography and technology, and has no fundamental meaning, nor is an exponential increase to be expected in any other area of technology. In fact, ongoing improvements in processors will slow and eventually stop as feature sizes approach atomic dimensions, if heat dissipation does not stop improvement before that limit is reached.

There is absolutely no reason to expect the specific energy of batteries to increase in any regular fashion. Indeed, most improvement in battery performance has come about from changing chemistry rather than from ongoing improvement within a given chemistry, which has been incremental. I believe this is the “different time scales” referred to by the author. There has been improvement in battery specific energy from lead-acid through nickel-metal-hydride to the present leader, lithium-ion chemistry. Improvement, however, has been far from “doubling every 22 years.” The first sentence of the reference provided by the author, Zu and Li (2011), is as follows: “The average increase in the rate of the energy density of secondary batteries has been about 3% in the past 60 years.” This statement indicates that the specific energy of batteries has not quite doubled in the past 60 years.

A recent EPRI report [Arshad Mansoor, EPRI, January 1, 2013] shows specific energy data from 1860 through the present, over five battery technologies. This report shows a doubling of specific energy over a 60-year period, roughly consistent with Zu and Li.  This is far indeed from doubling many time periods of 22 years.

I leave it to the author to show data with specific energy doubling over several 22-year periods, which would indicate exponential growth (a “Moore’s Law” behavior). I maintain my view that there is no multi-period doubling of the specific energy of batteries, which would indicate exponential growth.

I suggest that particular care be used in citing Zu and Li. Figure 1 shows development of primary batteries (batteries which are not rechargeable), thus not relevant to transportation or many other applications. Figure 2 shows development of secondary (rechargeable) batteries, but includes data for Na/S and other batteries which are far from ready for use in the real world, as there are major issues to their implementation. Thus the most reliable quote from the paper is in the abstract: “The average increase in the rate of the energy density of secondary batteries has been about 3% in the past 60 years.”

Given the need to show at least 4 or 5 periods of improvement in specific energy density, and taking 60 years as an approximate doubling time (the real doubling time is greater than 60 years), something like 240-300 years of doubling every 60 years would be required to show exponential growth. This is longer than the time since the first useful battery, lead-acid, was first invented.

Thus there is no evidence at all that there is a “Moore’s Law” for batteries, as I stated in my 2013 paper, over any time period since practical batteries were first invented.

I’ll eat a bit of humble pie before moving to further thoughts on battery technology and transport, here goes…

I accept your comprehensive reply that there is no “Moore’s law” for batteries and I’ll retract my statement to the contrary unreservedly. I had also assumed the readership to be an informed audience that understood the empirical nature of “Moore’s law”. Your description of it as a self-fulfilling prophecy rather than a fundamental law of nature has admirable clarity that I should have employed.

You were quite right to pick up on the fact that simply doubling over a few time periods is not exponential growth.

Regarding the 22 year doubling period, I’ll happily share how that was derived from the Zu and Li (2011) paper. I do also take note of the care you advise in citing this paper. I’m very interested that you see the energy density increasing over significantly longer timescales (60 years rather than 22) and the EPRI report is certainly something I’ll pay attention to. Perhaps we can correspond outside of this column. My motivation here is continuous learning.

Enough humble pie.

This has made me think a bit more, and I’d welcome further views

We do agree that battery technology development is not progressing at an impressive pace in terms of the amount of energy a battery can store and release from a given volume or mass from the point of view of energy storage for transport.

If batteries are used for energy storage in transport they will have to be rather large and heavy devices and this is not going to change unless some unexpected breakthrough takes us all by surprise.

Given this limitation, it would seem that electric vehicles of the future have two possible lines of development:

  1. One could be to make batteries that can charge rapidly and frequently. This implies a well-distributed infrastructure of charging points built into the road network. My guess is that batteries with this capability need to have a very large surface area and a structural design that allows fast access to this surface to accept and release the charge.
  2. The other alternative for electric vehicles would be to store the energy in another form that has a high energy density and convert this to electricity on board the vehicle.

Many of the automobile manufacturers are already producing hybrid cars with gasoline or diesel engines that power on board electric generators. I am more aware of these types of vehicles on the road than electric vehicle charging points so perhaps this indicates the likely development path for electric vehicles of the future. I’d be interested in your thoughts too…


Editor:

Adrian Nixon began his career as a scientist and is a Chartered Chemist and Member of the Royal Society of Chemistry. As a scientist and ... <Read more about Adrian Nixon>


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Comments

  • Dr. Fred Schlachter

    I would like to thank Adrian Nixon for his kind followup to my comments. I have been told that I can be persuasive…

    I have comments of course about your recent suggestions, and in fact about energy resources and their applicability to transportation, which topics are at the heart of my energy interests. In another life I was an atomic physicist doing basic research on the structure of matter.

    Rather than responding piecemeal I suggest we talk offline. You can reach me by email at fsschlachter@gmail.com. This email address is not confidential as it is easily found by a google search on my name.

    May 22, 2015 - 6:28 PM

  • NGS

    Hi,
    One factor not considered in the energy density (per mass) comparison is the mass of the system required to convert that energy to vehicle motion. EV engines are smaller and lighter than internal combustion engines and their associated components (radiator, cooling fluid, lubricating oil, etc.). This lessens to a small degree the ~50:1 fuel (liquid:battery) energy density advantage of conventional hydrocarbon fuel.

    May 22, 2015 - 6:58 PM

  • Geobob

    Energy density is a good place to start. Applied to the entire power supply chain, it shows you that natural gas and hydrocarbons (45-55 MJ/kg) are more efficient than coal (25-35 MJ/kg), which is better than wood, wind, or solar (some physicists have worked out the energy density of wind and solar, although as a mere geologist I can’t follow all of the math). Wind, solar and biofuels are politically-correct, feel-good energy sources that are unreliable and put very little juice onto the grid. No off-the-shelf energy source compares with nuclear: U-235 nuclear fuel has a whopping energy density of 77 MILLION MJ/kg and no greenhouse gases. You get even more efficient with THORIUM, which doesn’t need enrichment like U-nukes and is impractical for weapons. Th molten salt nuclear reactors were pioneered in 1950s-1960s by Alvin Weinberg et al at Oak Ridge, but Nixon favored uranium because it fed into the Cold War arms race. That was then, and now there are no defensible excuses to avoid nuclear power, which in spite of Fukushima, Chernobyl, etc remains a safe, efficient and zero greenhouse gas option. Modern designs are tsunami-, earthquake- and Homer Simpson-proof.

    May 24, 2015 - 2:16 PM

  • Chris Donaghue

    I agree thorium should be used instead of uranium in reactors. And scarcity of bio-fuels and competition with food are real concerns. But with biodiesel, only small amounts can have larger effects. The cetane number of biodiesel is so much higher than petrol-diesel that adding only 5% to petrol-diesel lowers GHG’s by 17%, and increases lubricity by 20%. As a result this fuel is being mandated in the US, Canada, Europe and more. It doesn’t need to compete with food, as one of the best sources is coconut oil. Coconuts are mostly consumed for their milk because it’s easier to poke a hole than crack them. Millions of coconuts lie discarded all over the tropics with their meat rotting, that could have been turned into biodiesel. Biodiesel has exponential and compounding effects on petroleum. Many things have lower emissions, but nothing else can lower the emissions of petroleum.

    May 27, 2015 - 2:14 PM

  • Fred

    People have been brainwashed on global warming. Of course mankind can affect the climate. But, during the last million years, the earth has been in ice age conditions 90% of the time. If the current interglacial warm period lasts only as long as the last one, we have only 2000 more years before the ice sheets start advancing again. The ides of March.

    I think it’s great that particulate and chemical pollution should be limited. CO2? Maybe it will get us an extra few thousand years before the ice sheets descend upon the world again.

    May 27, 2015 - 7:42 PM

  • Dr. Fred Schlachter

    Everyone is entitled to his/her opinion. However, it is rather clear at present that CO2 in the atmosphere and global temperature rise are correlated, and causality is likely. Note that both have been increasing since the industrial revolution, short on the time scale of ice ages. Of course this alone does not prove causality….however….it is likely IMHO that increasing CO2 in the atmosphere is causing temperature increase….with all its ups and downs.

    June 10, 2015 - 4:59 PM

  • Fred

    Glaciers have been melting for the last 10,000 or 15,000 years. If the history of the last few million years is any guide, they’ll start forming again within the next few thousand years. I wish that CO2 had the potency of water vapor as a greenhouse gas, to prevent this from happening.

    Geologists consider the current times to be a geologically brief warm period wedged between the severe cold periods of the ice age. Geologists actually view current times as being an ice age, it’s just that we get occasional 15,000 year warm spells. The 15,000 years is almost up.

    I wish Al Gore had taken a bunch of geology courses, so we wouldn’t be in a rush to head in the wrong direction.

    June 10, 2015 - 9:22 PM

  • Kjetil Kjernsmo

    All,

    I just found this thread, and it is extremely interesting. I recently bought an electric vehicle, specifically a Renault Zoe. Also, I live in Norway, where the infrastructure is already being developed rapidly. I also have the possibility to charge in my garage, at least at 11 kW, but possibly up to 22 kW. Now, I’m charging at 3.3 kW at home though.

    I feel that I’ve seen a revolution, and it is not just the Tesla (my neighbour has a Model S P85D), it is also the Renault Zoe. When driving an EV, the first thing you notice is that you can get the torque you need when you need it. I’ve been driving with manual shift for most of my cars and become fairly good at it. I could get thrust if I planned for it and shifted at exactly the right time. With automatic shift, it takes a couple of seconds before it is there, but then, why bother, when you can have an electric engine? Also, EVs perform much better on steep, icy roads.

    But the main thing you notice is how the occasional visit to a gas station is not just a minor inconvenience, you start wondering how you could put up with that. I’m not driving my car for very long, but my neighbor is, and to have a break every few hours to charge is not problematic. I tend to think that the inconveniences of gas stations are underestimated, but on the other hand, the desire for the battery to have the same energy density as fossil fuels is uncalled for (if for no other reason than the engines are not very efficient).

    I cannot challenge you on the timescale of doubling of battery density, I can only note that the original Nissan Leaf had a battery pack of 24 kWh, but the 2016 model year has a pack of 30 kWh. If this creates the same expectancy as Moore’s law do, then, the effect of that will be that people will be wary about the second hand prices of fossil fuel cars. Since an EV is such a superior product to a fossil fuel car, once you can expect the range to increase, people will buy those once they get familiar with them.

    If there is another doubling of energy density, then a Tesla type car will have a practical range of 600 km, and a Zoe will have 300 km. Those are based on my real-world experience. This could also translate into smaller battery packs and thus lower prices, in addition to the effects of economy of scale. At that point, EVs become a very realistic choice, and the expectancy of doubling the range will be a killer for fossil fuel car prices. I suppose it is really hard to have another doubling, but it is not needed, fossil fuel cars will be killed by the expectancy of continued range extensions.

    Therefore, car manufacturers that aren’t investing in EVs now, are in my opinion betting that it’ll take a looong time for that doubling to happen.

    So, since this is a forum for investors, I suppose the question to ask is “when should we start shorting their stocks?” 😉

    I don’t know yet if my next car purchase to replace my aging 4WD will be a Volvo XC90 Twin Engine or a Tesla Model X, but I’m never going to buy a pure fossil fuel car again, PHEVs may be a good choice up to the next doubling, but probably not beyond that.

    December 18, 2015 - 8:01 AM

  • Alvarita

    I’d love to know what percentage of “experts” and scientists who beat the man-made global warming drum are government funded. Just like the space cadets talking about colonizing Mars in the near future, the global warming crowd is engulfed in a serious conflict of interest cloud. One decent volcano eruption could skew the data significantly. It’s akin to inflation numbers that fail to include food and fuel in the calculations. Otherwise known as misleading and absurd. As for Al Gore, he needed something as a follow-up to his ridiculous lock box idea that solidified his place among the most infamous snake oil salesmen of all time.

    December 18, 2015 - 10:46 AM

  • Kjetil Kjernsmo

    Climate science involves some very sophisticated physics, chemistry and data analytics. Each and every one of those publicly funded scientists could have increased their paycheck by at least 50% if they went to industry, and the industry is screaming for their knowledge. There’s even a buzzword for it: “Data Science”.

    There is plenty to be skeptical about with climate science, but to be a skeptic means that you actually understand philosophy of science.

    Moreover, this is a debate about the whether there exists evidence for fitting an exponential curve to the time-series of energy density of batteries. Then, it is my proposition, that it if does, then if not the days, at least the years of the fossil fuel cars are numbered, due to that EVs are superior in most other respects than range.

    December 18, 2015 - 3:11 PM

  • Alvarita

    Buzzwords and a dollar won’t get you a subway ride. Even the most sophisticated analysis and science based on a sampling of around 150 years out of billions that this planet has been around is highly suspect. People are so reluctant to admit what they don’t know, especially scientists(and doctors). That’s why malpractice insurance is so high. As for all publically funded scientists being able to easily secure industry employment for a 50% raise, that’s an opinion based on what? Scientists employed in the private sector have a much higher bar. They are usually required to produce something other than theories or they get the boot. Big difference. My father worked for Bell Labs which at the time hired the top 2 percent of the brightest young scientists in the world. They typically had an initial 2 to 3 year contract and a practically unlimited budget to actually produce something useful or they got shown the door.

    December 18, 2015 - 4:54 PM

  • Lok Chong

    With consensus on the need to tackle ‘climate change’ it is a safe bet that demand for lithium will skyrocket. Same for commercialisation of graphene for enhancing power storage. Bought a lithium play that has a processing plant in an Argentina’s dried salt lake. It went up 34% since October. Same for Sarah Resources that will soon become biggest producer of spherical coated graphite for lithium-ion batters for use by EV and ‘powerwall’ batteries for homes. So there is a lot of good investing in the supply chain whether or not Moore’s Law applies or not.

    December 19, 2015 - 6:07 AM

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