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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 clea

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.

tokenadult 12y ago
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.
- maxerickson 12y ago
  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 http://en.wikipedia.org/wiki/File:Energy_density.svg Lithium ion batteries are barely on it.
NickM 12y ago
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.
- MiguelHudnandez 12y ago
  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?)
  - JoeAltmaier 12y ago
    The energy density of hydrogen might be very small? So inefficient to store and move around.
cschwarm 12y ago
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 http://phys.org/news85074285.html [2] http://cleantechnica.com/2014/12/01/fuel-cell-economics-vs-batteries/ http://cleantechnica.com/2014/12/01/fuel-cell-economics-vs-b...
mrbabbage 12y ago
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 http://en.wikipedia.org/wiki/Energy_density
aidenn0 12y ago
Downside to hydrogen is that it's either created from hydrocarbons, or has a very poor cycle efficiency.

tokenadult 12y ago

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.

maxerickson 12y ago
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 http://en.wikipedia.org/wiki/File:Energy_density.svg Lithium ion batteries are barely on it.

NickM 12y ago

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.

MiguelHudnandez 12y ago
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?)
- JoeAltmaier 12y ago
  The energy density of hydrogen might be very small? So inefficient to store and move around.

cschwarm 12y ago

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 http://phys.org/news85074285.html [2] http://cleantechnica.com/2014/12/01/fuel-cell-economics-vs-batteries/ http://cleantechnica.com/2014/12/01/fuel-cell-economics-vs-b...

mrbabbage 12y ago

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

aidenn0 12y ago

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