51–60 of 88 posts
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Something that requires 1,221 F (660.3 C) doesn't seem like something you would want to sit on or pump without serious protection.
Slurry, not molten. This (aluminium powder suspended in a liquid) was considered as a rocket fuel at one point.
So I've posted this before, but aluminum smelting is just plain old too hard for this to be as cheap as batteries. I mean, it's great if you're Alcoa, an aluminium smelter, but let's take a look at bulk prices: Aluminium costs $1.80/kg: http://www.indexmundi.com/commodities/?commodity=aluminum Alumina, the product of the aluminium-air reaction, costs ~$0.45/kg: http://www.indexmundi.com/en/commodities/minerals/bauxit…
The idea is it's a backup battery instead of a backup gasoline engine. Being "nearly as expensive as gasoline" could still be a win because it could be used in electric vehicles without having to add a backup generator engine. Also it could have other benefits like being safer (less combustible), producing fewer emissions on the road, and weighing less than gas. That said, I'm not saying I'm believer in this tech
metal-air batteries (fuel cells), rechargeable and not, is the future. Having comparable to gasoline energy density, yet higher efficiency - 60-90% vs. 30% of gasoline, it will transform cars and especially planes (subsonic ones). You can imagine that it is absolutely not an issue to replace a 100Kg spent aluminum fuel cell block on a small plane at airport. It would also be better than gas turbine for bigger commerc…
There are still renewable / sustainable liquid fuel options, though. Among the most interesting to me in recent months is the US Naval Research Lab's work on seawater-based Fischer-Tropsch fuel synthesis (SFTFS).
It uses electrical energy (from an external source: nuclear or OTEC in the NRL's scheme, solar, wind, geothermal, or other sources could also be substituted). The net efficiency is no better than 60% (the energy cost of electrolysis), my suspicion is that it will be around 50%, for a round-trip return of around 15-20% based on thermal engine applications (higher for electrical generation, lower for internal combustion).
But what this gives you is a sustainable, renewable, carbon-neutral source of energy-dense, highly-versatile liquid fuels.
I seriously doubt metal-air batteries will work for serious air transport.
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It's not reversible in the car, but it is reversible in an aluminum smelter. The power cell is turning the metal into aluminum oxide, which is (mostly) how we find Al in its ore form. So once you burn it out, it gets shipped back to Alcoa and they treat it like some nice clean ore and shortly turn it back into metallic Al. Which is not entirely energy-cheap, but at current prices of less than $1/lb isn't too bad. You…
with that definition of recycling even gasoline is recyclable in plants :)
I hate being a naysayer - this is cool technology - but the energy economics won't work out for metal-air batteries if they're used as the main power source. Recharging a metal-air battery is grossly inefficient, and a big part of the advantage with electric cars is that they use less energy in every step of the process except initial manufacturing. This means that the general economics of metal-air batteries will no…
Huh, the article addresses this issue pretty directly -- did you read it? Because the car would still rely on its regular rechargable lithium-ion battery most of the time and would switch to the aluminum-air battery as a backup only if the lithium-ion battery ran out, and because most car trips are 50 kilometres or less, Alcoa estimates the aluminum-air batteries would only need to be changed about once a year.
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Huh, the article addresses this issue pretty directly -- did you read it? Because the car would still rely on its regular rechargable lithium-ion battery most of the time and would switch to the aluminum-air battery as a backup only if the lithium-ion battery ran out, and because most car trips are 50 kilometres or less, Alcoa estimates the aluminum-air batteries would only need to be changed about once a year.
Yes but then you are hauling around an extra 100kg of unused batteries for 95% of your trips.
Think how much lighter the Volt would be with no gasoline engine!
And they also don't mention if you can choose how much to lug around. Maybe I think I'll only need 500 miles of extra range a year and I can carry around a pack half the size? I'd do that, even in the fast-charge plentiful northwest. It would be nice to have the freedom to skip a station and make some time instead.
Doesn't aluminum smelting use crazy amounts of electricity and emit significant greenhouse gases? So not only would we be doing that, we'd also have to ship these 220 lb modules back to the smelters every 1,000 miles? Is there anybody advocating for this besides aluminum smelters?
Read article. The smelter they are using is hydroelectric and the 1000 miles air battery range is only used on long journeys as mostly the car runs on lithium.
Al2O3 + carbon => Al + CO2
Edit: I can only guess that the down votes are for not providing a source? Here you go:
http://en.wikipedia.org/wiki/Aluminium_smelting
It doesn't matter if the smelter runs on fairy dust or hippie juice. Reducing aluminum oxide to aluminum produces CO2 no matter the energy source.
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It's highly recyclable. Aluminium oxide (the result of the reaction in the battery) is one of the feedstocks for industrial aluminium smelting. Recyclable isn't necessarily the same as 'efficient' or 'a good idea' though. It's energy intensive (haven't checked the efficiency of 'recharging'), and additionally has, as a byproduct, massive amounts of CO2 even before considering CO2 emitted in generating the electricity…
This particular smelter uses hydroelectric power, mentioned in the article.
I hate being a naysayer - this is cool technology - but the energy economics won't work out for metal-air batteries if they're used as the main power source. Recharging a metal-air battery is grossly inefficient, and a big part of the advantage with electric cars is that they use less energy in every step of the process except initial manufacturing. This means that the general economics of metal-air batteries will no…
The most important part for me for electric cars is the simpler power-train system which is less likely to break... which is why i would never buy an hybrid that has both systems.
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>If the CO2 emitted from the battery's materials came from the atmosphere in the first place, this will be a closed cycle and won't increase global CO2 levels. The carbon emissions of aluminum smelting come from the carbon electrodes in the electrolytic cell-- you're essentially burning them to pull the oxygen atoms off the aluminum oxide molecule. http://en.wikipedia.org/wiki/Aluminium_smelting Carbon electrodes use…
Carbon electrodes used in industrial processes are generally formed from processed coal and mineral graphite: the fossiliest of the fossil fuels. Again, there's no fundamental reason why this must be the case. You could theoretically produce synthetic bulk carbon from atmospheric CO2 using the Bosch process, ( http://en.wikipedia.org/wiki/Bosch_reaction ) at incredible cost per kilogram of carbon produced, which woul…
The logic isn't circular. Rather, you're conflating multiple independent processes. Even if we did have a commercially viable way to capture atmospheric co2 and turn it back into carbon that still doesn't mean we should then burn the carbon to make batteries. We could also bury it, and use normal rechargeable batteries.