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Comment by skywhopper | Hacker News Reader

Batteries are one of those technology bottlenecks that will pay off in a huge way when and if someone can create a major leap that allows a 10x or 100x improvement in capacity, cost, efficiency, whatever. For computing, for transportation, for general energy usage, for third-world development, a better battery will reap enormous societal benefits. It's amazing how far Li-Ion cells have progressed, but we need more and better yet still. I'm glad to see someone is pouring huge resources into this problem. Hopefully Musk is not the only one.

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Straubel actually suggests that a massive leap in cost/efficiency may not needed due to the large market size:

"Mr Straubel counters. “They don’t understand the tight linkage between cost and volume. We’re at this crossing-point where a small reduction in cost is going to result in a ridiculously big increase in volume, because the auto industry is so big."

A downward spiral as it were, but in this case, a positive one.

Unfortunately batteries require advancements in chemistry, materials engineering, and manufacturing processes... all in sync. While there might be capacity for a 10x improvement at some point, it's far more likely that progress will continue to happen in smaller jumps, as decent improvements are made in each of those three elements.

The major leap happened, and it is Li-Ion technology. It improved by magnitudes on any important metric over previous battery technology.

Are you sure about that? I don't recall my battery life increasing by "magnitudes" when li-ion became widespread.

See this graph of energy density over time:

http://electronicdesign.com/site-files/electronicdesign.com/...

from http://electronicdesign.com/power/here-comes-electric-propul...

Where does Li-ion plateau on that chart? The two preceding technologies (NiMH, NiCd) also "doubled every ten years" until they didn't.

The plateau seems to happen once a technology is no longer the winner, and research moves on to the next.

That's because product designers used the improved performance to reduce package volume and weight.

You clearly never used a NiCd camcorder.

I'm guessing Li-ion batteries were always the battery tech used in smartphones, so it might have been harder to notice. I know once I put some Li-ion AA batteries in an old camera I realized I may never need to replace those batteries again.

What about hydrogen? Because of the energy required to isolate hydrogen it's hard to consider it a true "energy source". But as a dense, portable source of clean energy it seems like it could be poised to trounce existing battery technology. The only problem, of course, being the explodey thing.

The hydrogen fuel chain is very inefficient [1]. Building up a fuelling infrastructure would very expensive compared to a fast charger network, by about a factor of 5 to 10. The fuel itself is still rather expensive [2].

Only a few Japanese and Korean car companies are pushing the fuel cell. Car companies in Europe are rather reluctant about it, including Renault and VW.

[1] http://phys.org/news85074285.html

[2] http://cleantechnica.com/2014/12/01/fuel-cell-economics-vs-b...

Describing hydrogen as "dense" is a bit fraught. It is very dense on a joules per kilogram basis, but it is sparse on a kilograms per liter or joules per liter basis. And the design constraint in cars is the volume of the tank, not the weight of hydrogen it carries.

From wikipedia, compressed hydrogen (690 bar at 15°C) has 3x the specific energy (MJ / kg) but 1/8 the energy density (MJ / L) versus gasoline.

http://en.wikipedia.org/wiki/Energy_density

The biggest obstacle to using li-ion for stationary storage is not density. It doesn't really matter if the batteries weigh a ton if you're never going to move them. And hydrogen is roughly on par with batteries in terms of energy/volume.

Cost and efficiency are much bigger factors. Batteries completely destroy hydrogen in both of these measures.

I think the downside for hydrogen storage is the inefficiency of electrolysis. Last time I looked at it, you lose about 50% of the energy when making hydrogen. The plus side is that the fuel cell side is very efficient.

It'd be practical to have hydrogen split from water at a large scale at solar farms or at existing power plants, and delivered to homes as backup power. (like propane?)

The energy density of hydrogen might be very small? So inefficient to store and move around.

In what sense is hydrogen more "dense" than most current battery technologies in storing energy? By volume? By mass? I thought that several battery technologies are already better than (economically) stored hydrogen for storing energy, but I would be delighted to see some participant here on Hacker News "show the work" to compare storage of electrical energy through different means and discuss the trade-offs.

Per unit mass. Here's a handy chart of chemical energy density (which I guess ignores containment and conversion):

http://en.wikipedia.org/wiki/File:Energy_density.svg

Lithium ion batteries are barely on it.

Downside to hydrogen is that it's either created from hydrocarbons, or has a very poor cycle efficiency.

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