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Ditch the Batteries: Off-Grid Compressed Air Energy Storage

lowtechmagazine.com

61–70 of 238 posts

Re: Ditch the Batteries: Off-Grid Compressed Air Energy Storage

#62
post #31

> However, to store 360 Wh of potential electrical energy, the system requires a storage reservoir of 18 m3, the size of a small room measuring 3x3x2 metres. The authors note that “although the tank size appears very large, it still makes sense for applications in rural areas”. This would light a home for an hour, with LED bulbs and careful usage. And all it requires is a room-sized storage tank. So if I wanted somet…

For home use you also have to consider that you're basically making a bomb every time you store energy in the thing.

Re: Ditch the Batteries: Off-Grid Compressed Air Energy Storage

#63

Earlier quoted context omitted.

My knowledge of physics is very basic and practical engineering is zero, but storing hydrogen in compressed tanks always seem very impractical to me. It's the most freaking volatile element in the universe. And atomic hydrogen reacts with pretty much anything. Leakage and corrosion. From my armchair perspective, storying it in chemical bonds (like nature does) makes a lot more sense.

The bigger deal is how easily hydrogen leaks. H2 is small enough to squeeze through tiny holes in rubber or plastic gaskets. It's fine in a car, but keeping it in big tanks for months is something else. At least when it leaks it floats away rather than collect on the floor looking for a reason to ignite.

And, Hydrogen embrittlement makes the tanks fail prematurely. (http://www.corrosionclinic.com/types_of_corrosion/hydrogen_e...)

Re: Ditch the Batteries: Off-Grid Compressed Air Energy Storage

#65
post #39
post #31

> However, to store 360 Wh of potential electrical energy, the system requires a storage reservoir of 18 m3, the size of a small room measuring 3x3x2 metres. The authors note that “although the tank size appears very large, it still makes sense for applications in rural areas”. This would light a home for an hour, with LED bulbs and careful usage. And all it requires is a room-sized storage tank. So if I wanted somet…

I thought this too, but read the rest of the article. Spoiler alert: State of the art is 30x better

I picture Rick Moranis operating a large space-based vacuum cleaner.

Re: Ditch the Batteries: Off-Grid Compressed Air Energy Storage

#66
post #31

> However, to store 360 Wh of potential electrical energy, the system requires a storage reservoir of 18 m3, the size of a small room measuring 3x3x2 metres. The authors note that “although the tank size appears very large, it still makes sense for applications in rural areas”. This would light a home for an hour, with LED bulbs and careful usage. And all it requires is a room-sized storage tank. So if I wanted somet…

For home use you also have to consider that you're basically making a bomb every time you store energy in the thing.

few mechanical engineer~ youtubers said so many times; compressed gas seems less dangerous than water but compression is terribly dangerous

Re: Ditch the Batteries: Off-Grid Compressed Air Energy Storage

#67
Isn't there a loss in efficiency due to heat? Compressing air heats it up, which is lost (this is the basic principle behind refrigeration, though it doesn't use air). And then there's the loss in converting this PE back into electricity. Are these losses less than what's lost in LiON cells?

Re: Ditch the Batteries: Off-Grid Compressed Air Energy Storage

#68

Hold on... So if you take a Tesla, remove the batteries, remove the electro engine, and replace that with a trivial compressed air based pneumatic motor it would be more eco friendly, more powerful and have a higher autonomy ?

Unfortunately there are downsides, but compressed air vehicles are already a thing.

https://en.wikipedia.org/wiki/Compressed-air_vehicle

https://en.wikipedia.org/wiki/Compressed_air_car

Re: Ditch the Batteries: Off-Grid Compressed Air Energy Storage

#69
post #9

Volvo diesel cars avoid turbo lag by storing compressed air. Not very relevant but interesting nevertheless https://www.roadandtrack.com/new-cars/car-technology/news/a2...

ABS braking does the opposite: a vacuum is stored that's used to release the brakes in short bursts.

Modern (post 1990-something) ABS has its own pump.

Air brakes on trucks run in reverse. Compressed air releases spring pressure therefore releasing the brake.

Re: Ditch the Batteries: Off-Grid Compressed Air Energy Storage

#70

Hold on... So if you take a Tesla, remove the batteries, remove the electro engine, and replace that with a trivial compressed air based pneumatic motor it would be more eco friendly, more powerful and have a higher autonomy ?

From https://en.wikipedia.org/wiki/Compressed_air_car#Disadvantag...

- A 2005 study demonstrated that cars running on lithium-ion batteries out-perform both compressed air and fuel cell vehicles more than threefold at the same speeds.

- A 2009 University of Berkeley Research Letter found that "Even under highly optimistic assumptions the compressed-air car is significantly less efficient than a battery electric vehicle and produces more greenhouse gas emissions than a conventional gas-powered car with a coal intensive power mix."

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