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Ditch the Batteries: Off-Grid Compressed Air Energy Storage (2018)

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Re: Ditch the Batteries: Off-Grid Compressed Air Energy Storage (2018)

#81

Post by jandrese »

atrus wrote: post #66
jandrese wrote: post #59

I'm not a fan of this personally. Compressed air is dangerous. A full tank is basically a bomb. While we have the technology to make this safe, it has to be regularly inspected. If your homeowner slacks on the inspections they could come home one day to discover their energy storage has turned itself into a crater and flattened all nearby structures. One thing to consider is that the heat generated by compressing the…

I mean, doesn't any big energy storage device become essentially a bomb? Batteries have some pretty impressive failure modes. As do large tanks of fuel. Even piped in energy sources can be dangerous as well. How many houses have literally exploded over a leaking gas line? Or burnt down due to faulty wiring? Large amounts of energy stored in an area is inherently dangerous, no matter the form.

People talk about batteries "exploding", but really they're just burning fast. An air tank explosion however will decimate everything nearby. Even small SCUBA tanks can release a tremendous amount of energy when they go, which is why they are typically refilled inside of water baths.

Re: Ditch the Batteries: Off-Grid Compressed Air Energy Storage (2018)

#82

Post by jandrese »

wil421 wrote: post #73
jandrese wrote: post #59

I'm not a fan of this personally. Compressed air is dangerous. A full tank is basically a bomb. While we have the technology to make this safe, it has to be regularly inspected. If your homeowner slacks on the inspections they could come home one day to discover their energy storage has turned itself into a crater and flattened all nearby structures. One thing to consider is that the heat generated by compressing the…

How is compressed air any different from houses with large natural gas tanks? My father in law bought a house with some property and no gas like. The tank is like 20+ years old and it’s filled every few years.

Compressed air is way more dangerous than liquid fuel. Liquid fuel needs oxygen to burn, so it is slow to start and prone to starving itself. All compressed air needs is an undetected defect in the tank and it will turn into heavy knives flying at supersonic speed.

Re: Ditch the Batteries: Off-Grid Compressed Air Energy Storage (2018)

#83

Post by jfengel »

therockspush wrote: post #56
ortusdux wrote: post #23

Earlier quoted context omitted.

I've been obsessed with technology that skirts religious laws for a while now. Whole house pneumatic systems to run $800 dollar non-electric blenders. Elevators that spend the sabbath atomically opening on each floor. Automatic timers to complete forbidden circuits. I would love to spend an hour or two with a rabbinical scholar. Does walking in front of a motion senor complete a circuit? Are you allowed to ask an AI…

This stuff cracks me up. Do they think Hashem is up there looking down, thinking "Good one guys. You got me there. I thought I had all my bases covered. I'll save you some extra latkes when you get here." Someone help me understand why some folks treat this stuff like a tax loophole.

It's more a matter of community than of trying to get one over on God. The identity is "We are the people who follow these rules," and in particular, "others are those who don't". Compare it to Western revulsion at people who eat insects or dogs, even though they're as nutritious and safe as anything we eat.

The rules come from God because Jews consider themselves a chosen people. They don't particularly want you to follow those rules or concern yourself with the mechanics of them, because they're not about you. The fact that it doesn't make sense is perfectly fine.

Interpreting those rules in a modern context is every bit as arcane and arbitrary as the rules were in the first place. The important part is that they come to a conclusion and follow them together. That cements the society as a group.

It doesn't really matter what God thinks, either. If God had a contrary opinion, He'd say so. There is, for that matter, a famous story about rabbis coming to a conclusion that God explicitly sends messages against, but is pleased that they have used their reason.

The Jews put a lot more weight on community and a lot less on trying to please their deity by following the rules. It just so happens that the rules really are both things.

Re: Ditch the Batteries: Off-Grid Compressed Air Energy Storage (2018)

#84

Post by jfengel »

grawprog wrote: post #57
diego_moita wrote: post #11

Slightly of-topic: compressed air is the preferred source of power for the tools of Amish people, since their religion doesn't allow them to use electricity or internal combustion engines. https://www.cottagecraftworks.com/home-goods/self-sufficient...

I personally think compressed air tools are underrated. I worked at a shop that used a lot of compressed air powered 'things'. We had a bunch of air powered hand tools that out performed electric equivalents by a fair bit. Most of the larger machines, though mostly electrically driven, had major components that were air powered and required a compressor. The force and energy available through natural physical process…

Conversely, I spent some time at a physical therapy gym that used compressed air for resistance instead of metal plates. It was a lot quieter than any other gym I've ever been to, just a gentle whoosh instead of clang-clang-clang.

Re: Ditch the Batteries: Off-Grid Compressed Air Energy Storage (2018)

#85

Post by jhayward »

aspenmayer wrote: post #68
jhayward wrote: post #67

Earlier quoted context omitted.

The flywheels GP refers to were homopolar generators [1]. They created an impressive current pulse, and extracted almost all the kinetic energy in less than one revolution. [1] https://en.wikipedia.org/wiki/Homopolar_generator

Like running an electromagnet in reverse to salvage current from a free-spinning motor? I’m trying to understand how the fields and forces interact.

There is a paper [1] published that documents one of the early 1980's designs they used.

[1] https://repositories.lib.utexas.edu/bitstream/handle/2152/30...

Re: Ditch the Batteries: Off-Grid Compressed Air Energy Storage (2018)

#86

Post by aidenn0 »

jhayward wrote: post #85
aspenmayer wrote: post #68

Earlier quoted context omitted.

Like running an electromagnet in reverse to salvage current from a free-spinning motor? I’m trying to understand how the fields and forces interact.

There is a paper [1] published that documents one of the early 1980's designs they used. [1] https://repositories.lib.utexas.edu/bitstream/handle/2152/30...

A different paper specifically mentioning the railgun shows a more traditional alternator design:

https://web.archive.org/web/20151017100843/http://www.utexas...

Re: Ditch the Batteries: Off-Grid Compressed Air Energy Storage (2018)

#87

Post by [deleted] »

darksaints wrote: post #20

While I'm a pretty big fan of low tech solutions, I'd just like to point out that electrochemical hydrogen compressors can basically already do this, but better. 80% round trip compression efficiency, up to 700 bar compression, no moving parts, and massively long lifetimes (in the 30-50 year range). The fact that the compression medium (hydrogen) is also an energy storage medium is just a cherry on top. It's just a m…

[deleted]

Re: Ditch the Batteries: Off-Grid Compressed Air Energy Storage (2018)

#88

Post by jhayward »

aidenn0 wrote: post #86
jhayward wrote: post #85

Earlier quoted context omitted.

There is a paper [1] published that documents one of the early 1980's designs they used. [1] https://repositories.lib.utexas.edu/bitstream/handle/2152/30...

A different paper specifically mentioning the railgun shows a more traditional alternator design: https://web.archive.org/web/20151017100843/http://www.utexas...

Yah, that's a railgun, but it's not what everyone around CEM called the railgun.

The difference being one between a .50 caliber machine gun and something that can sink a ship from 100km away.

I worked across the street from CEM at the time. Firing the railgun was a big deal. The mechanical stresses on the electrical systems were pretty severe.

The vast proportion of what UT CEM was doing in that era was with the big gun, for Navy and SDI type projects.

Re: Ditch the Batteries: Off-Grid Compressed Air Energy Storage (2018)

#89

Post by jacknews »

darksaints wrote: post #20

While I'm a pretty big fan of low tech solutions, I'd just like to point out that electrochemical hydrogen compressors can basically already do this, but better. 80% round trip compression efficiency, up to 700 bar compression, no moving parts, and massively long lifetimes (in the 30-50 year range). The fact that the compression medium (hydrogen) is also an energy storage medium is just a cherry on top. It's just a m…

This is a very interesting technology, and can be used with other gases too: https://www.sciencedirect.com/science/article/abs/pii/S01407...

Re: Ditch the Batteries: Off-Grid Compressed Air Energy Storage (2018)

#90

Post by jacknews »

DoingIsLearning wrote: post #63
darksaints wrote: post #20

While I'm a pretty big fan of low tech solutions, I'd just like to point out that electrochemical hydrogen compressors can basically already do this, but better. 80% round trip compression efficiency, up to 700 bar compression, no moving parts, and massively long lifetimes (in the 30-50 year range). The fact that the compression medium (hydrogen) is also an energy storage medium is just a cherry on top. It's just a m…

The advantage of a system as simple as compressed air, is that anyone with a minimal technical background and shop tools is able to maintain and minimally repair the compression system. An electro-chemical hydrogen conversion and compression vessel would have far more points of failure with far greater technical barriers to repair. The access to specialized spares in a remote location would also be a major issue. I a…

Indeed, compressed air seems ideal for hot humid climates (cool/dry air being a byproduct of discharge), which are are often quite low-tech.
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