Hydrogen vs. Battery

[GoTslaGo]

Ok, not a car, but interesting:

A $5.25 Million Self-Powered Hydrogen Boat Has Set Off on a 6-Year Trip Around the World

Quote:

The 100-foot-long vessel primarily utilizes sun or wind energy during the day. At night, it harnesses a reservoir of hydrogen that the boat itself produces through electrolysis of the salt water. The team behind the Energy Observer has dubbed the project "the first hydrogen ship around the world."

End quote.

Normally I complain about using water for fuel. But here, since it's a boat, surrounded by water... not going to complain.

 

[BluestarE3]

Ok, not a car, but interesting:

A $5.25 Million Self-Powered Hydrogen Boat Has Set Off on a 6-Year Trip Around the World

Quote:

The 100-foot-long vessel primarily utilizes sun or wind energy during the day. At night, it harnesses a reservoir of hydrogen that the boat itself produces through electrolysis of the salt water. The team behind the Energy Observer has dubbed the project "the first hydrogen ship around the world."

End quote.

Normally I complain about using water for fuel. But here, since it's a boat, surrounded by water... not going to complain.

Would having on-board hydrogen gas help the boat stay afloat?

 

[JohnSnowNW]

Ok, not a car, but interesting:

A $5.25 Million Self-Powered Hydrogen Boat Has Set Off on a 6-Year Trip Around the World

Quote:

The 100-foot-long vessel primarily utilizes sun or wind energy during the day. At night, it harnesses a reservoir of hydrogen that the boat itself produces through electrolysis of the salt water. The team behind the Energy Observer has dubbed the project "the first hydrogen ship around the world."

End quote.

Normally I complain about using water for fuel. But here, since it's a boat, surrounded by water... not going to complain.

If they're using part of the energy they harness during the day to produce hydrogen, it seem like they'd have enough to store in batteries instead...and it'd be considerably more efficient.

 

[GoTslaGo]

If they're using part of the energy they harness during the day to produce hydrogen, it seem like they'd have enough to store in batteries instead...and it'd be considerably more efficient.

Looks like it was a former racing boat, so presumably it doesn't have a lot of capacity and space. Thus storing fuel for overnight use as hydrogen does kind of make sense (since as @BluestarE3 pointed out it may also make the boat more buoyant). Interesting!

 

[JohnSnowNW]

Looks like it was a former racing boat, so presumably it doesn't have a lot of capacity and space. Thus storing fuel for overnight use as hydrogen does kind of make sense (since as @BluestarE3 pointed out it may also make the boat more buoyant). Interesting!

Right, but how much does it actually produce? I'd wager not a whole lot. So, you would assume that you'd likewise not need that many batteries on board to equal the same amount of energy.

The article is a bit light on the details.

 

[GoTslaGo]

Right, but how much does it actually produce? I'd wager not a whole lot. So, you would assume that you'd likewise not need that many batteries on board to equal the same amount of energy.

The article is a bit light on the details.

Definitely true. Since it's a racing boat I can't imagine that it would produce or store that much either. Maybe next iteration they should try with batteries for comparison since they already would have done it with hydrogen.

I think with batteries they probably could have gone with a larger boat/ship with a combo of solar and wind. Thinking about it, a decent size area of a tanker/ship is the engine. Imagine if that was all battery and you had those rotating motors that a lot of newer cruise ships have. Set up the same top half with solar coverage and wind turbines... that would be cool.

 

[JohnSnowNW]

Definitely true. Since it's a racing boat I can't imagine that it would produce or store that much either. Maybe next iteration they should try with batteries for comparison since they already would have done it with hydrogen.

For me it's more to do with the excess energy they might have from solar and wind after powering the boat during the day. So, they're using excess solar/wind energy to split sea water, then presumably compressing it (because I'm not sure how else you could store and then pump through a Fuel Cell). So, they've already taken the excess solar energy and expended a certain amount on two processes that are not required with batteries. Then they take this H2 and put it into a fuel cell that is less than 60% efficient.

I mean, just how much energy have they wasted there?

You'd only need as many batteries on board as the hydrogen tanks store, minus ~40%.

 

[ItsNotAboutTheMoney]

For me it's more to do with the excess energy they might have from solar and wind after powering the boat during the day. So, they're using excess solar/wind energy to split sea water, then presumably compressing it (because I'm not sure how else you could store and then pump through a Fuel Cell). So, they've already taken the excess solar energy and expended a certain amount on two processes that are not required with batteries. Then they take this H2 and put it into a fuel cell that is less than 60% efficient.

I mean, just how much energy have they wasted there?

You'd only need as many batteries on board as the hydrogen tanks store, minus ~40%.

However, using a battery doesn't generate water.

 

[JohnSnowNW]

However, using a battery doesn't generate water.

Quite true, though Toyota claims the water isn't potable in the Mirai. It could be a simple process to make it drinkable, but I haven't really looked into it.

 

[Jeff N]

Quite true, though Toyota claims the water isn't potable in the Mirai. It could be a simple process to make it drinkable, but I haven't really looked into it.

It's also well-understood how to make fresh water from ocean water on boats through filtering and reverse osmosis. The units cost around $2,500 and can make about 4 gallons of fresh water in 2.5 hours on 100 Wh of electricity.

 

[Cloxxki]

I wonder how hydrogen generation would compare to compressing air. The air tank would be big and propelling from air may not be as effficient, but the tech would be simple.
Here is what a quick google turned up Compressed air energy storage - Wikipedia
Hydrogen probably wins. Darnit.

 

[jkn]

Nano aluminium offers fuel cells on demand – just add water

Hopefully link works. Key points:

"The accidental discovery of a novel aluminium alloy that reacts with water in a highly unusual way may be the first step to reviving the struggling hydrogen economy.
...
Adding water to the mix produces aluminium oxide or hydroxide and hydrogen – lots of it. “Ours does it to nearly 100 per cent efficiency in less than 3 minutes,” says team leader Scott Grendahl. Moreover, the new material offers at least an order of magnitude more energy than lithium batteries of the same weight."

 

[miimura]

... the new material offers at least an order of magnitude more energy than lithium batteries of the same weight."

Sure. Once. How much energy does it take to produce the nano-structured material? How much energy (hydrogen) does it release? The story mentions military applications. It may make sense for that and possibly a range extender that is rarely used. However, you still have the expense and weight of a fuel cell to carry around for infrequent use. No thanks.

 

[stopcrazypp]

Nano aluminium offers fuel cells on demand – just add water

Hopefully link works. Key points:

"The accidental discovery of a novel aluminium alloy that reacts with water in a highly unusual way may be the first step to reviving the struggling hydrogen economy.
...
Adding water to the mix produces aluminium oxide or hydroxide and hydrogen – lots of it. “Ours does it to nearly 100 per cent efficiency in less than 3 minutes,” says team leader Scott Grendahl. Moreover, the new material offers at least an order of magnitude more energy than lithium batteries of the same weight."

Reads a lot like the metal hydride which was part of the "water car" hype years ago. It never reached anywhere close to commercial stage. The need to carry tanks of water, and the recycling of dispensed material probably doomed the concept.
Metal hydride fuel cell - Wikipedia

 

[JeffK]

Nano aluminium offers fuel cells on demand – just add water

Hopefully link works. Key points:

"The accidental discovery of a novel aluminium alloy that reacts with water in a highly unusual way may be the first step to reviving the struggling hydrogen economy.
...
Adding water to the mix produces aluminium oxide or hydroxide and hydrogen – lots of it. “Ours does it to nearly 100 per cent efficiency in less than 3 minutes,” says team leader Scott Grendahl. Moreover, the new material offers at least an order of magnitude more energy than lithium batteries of the same weight."

This idea has been around for over four decades. The 100% efficiency thing is a load of crap... plus the reaction is not sustainable.

 

[Yggdrasill]

First you have to make the aluminium, that takes around 12 kWh/kg. The aluminium stores 8.1 kWh, so if the process is 100% efficient, you get out 8.1 kWh/kg. Then you run it though a fuel cell with 60% efficiency and end up with 4.9 kWh that can be used to propel the car.

The efficiency, wall to drive unit, is under 41%, while the efficiency for a battery is over 85%, potentially as high as 95%.

And that's if the process is 100% efficient, which it isn't.

 

[jkn]

Idea is old, but it has not worked before this. I understood 100 % efficiency meant that 100% Al reacts with water. Of course this cannot replace batteries in most cases. In some situations high energy density of Al and easy storage makes this interesting.

 

[JeffK]

Idea is old, but it has not worked before this.

Really? Here's it working in 2013:

It's not a catalyst, you can't simply add more water and have the reation continue indefinitely. You'd have to carry both aluminum, the other metal material AND water. The cost of all this is more than the current price of gasoline.

A few approaches use gallium as part of the alloy... imagine accidently getting that on an exposed surface of your aluminum body panels.

 

[winfield100]

Really? Here's it working in 2013:

It's not a catalyst, you can't simply add more water and have the reation continue indefinitely. You'd have to carry both aluminum, the other metal material AND water. The cost of all this is more than the current price of gasoline.

A few approaches use gallium as part of the alloy... imagine accidently getting that on an exposed surface of your aluminum body panels.

oh, wow, they rediscovered how we used to make exploding Hydrogen fireball balloons 55 years ago,
a variation on NaOH + H20 + Al ==>>> very explosiive H2 + lots of heat + toxic stuff to clean up and get rid of

 

[jkn]

2013 US Air force lab Ohio: Nano particles of Al
2017 US Army lab Maryland:
"previous attempts to drive the reaction required high temperatures or catalysts, and were slow: obtaining the hydrogen took hours and was around 50 per cent efficient."
"Ours does it to nearly 100 per cent efficiency in less than 3 minutes,”

I guess efficient means that 100% of Al reacts.

Perhaps there is real progress, instead of "We have to publish to get money to continue".

Resulting Al oxide must be transported back to factory for 'recharging'. To me this seems best way for long term safe storage of hydrogen. So hydrogen will not replace batteries in most tasks.

But it is not useless. 100 kWh Tesla battery has 300(?) kg of cells. Rest is protection and cooling. 30 kg of Al alloy might give 100 kWh. If some task requires much more than 100 kWh, Al-H2 fuel cell would enable an EV to do it. So not for every day normal usage, but sometimes useful.