Ditch the Batteries: Off-Grid Compressed Air Energy Storage • Hacker News Board

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

#121

Post by ballenf » Thu, May 24, 2018, 3:48 PM UTC

Davertron wrote: post #105

linsomniac wrote: post #58

Earlier quoted context omitted.

Back in the late 1800s, city planners met to try to come up with some plan for dealing with "the manure problem". Large cities couldn't handle the amount of manure produced by the horses in the city. They ended the meeting early, because they couldn't come up with any sort of plan. Then cars came along and they were all like "Yay! The pollution problem is solved!" I too wonder what the impact of so many lithium batte…

https://www.youtube.com/watch?v=b9gnvZLkewg

(That's the silicon valley clip explaining the London manure problem being solved by the replacement of horses with cars.)

Maybe it's just me, but not a fan of bare links unless the URL is descriptive.

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

#122

Post by microcolonel » Thu, May 24, 2018, 3:49 PM UTC

throwaway5752 wrote: post #113

dwyerm wrote: post #89

Earlier quoted context omitted.

> it's a fairly energetic explosion So is a lithium battery explosion. So is a gasoline explosion. So is a flour mill explosion. So is a wind turbine explosion. Energy is energy, and losing control of energy is never great, no matter where it comes from. So while I catch your meaning, it might be better to phrase it with respect to how controllable that energy is. From what I know of flywheel storage, the problem mos…

I would disagree with you slightly. Energy is not totally fungible. I can punch you in the face or shoot you with a gamma ray (edit: though of course, I would never do either), and it would have very different effects, potentially. Same for a fastball vs a small caliber weapon. Heat, light, and kinetic energy are important distinctions - particularly when you have a bunch of 30k flywheels in close proximity and one o…

> that's a bit easier to manage/less likely to cascade.

What gives you that impression? Seems to me that it explodes if you contain it, and if you don't contain it, it can spout jets of thermal energy at virtually any angle. With flywheels you need to arrest it in bulk heavy objects that don't tend to sustain fire. That seems a lot simpler to me.

The bigger problems with flywheels are cost of manufacture and (depending on the technology used) efficiency for overnight storage.

> I thought the trend in flywheels was magnetic suspension and removing mechanical linkages? Admittedly I haven't kept up.

IIRC flywheels with limited motion gimbals (to reduce the tolerances on the wheel) are becoming more popular, still magnetic bearings.

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

#123

Post by johnbrodie » Thu, May 24, 2018, 3:51 PM UTC

tonyedgecombe wrote: post #6

imeron wrote: post #4

Earlier quoted context omitted.

And Bosch uses compressed air to keep motorcycles on track (experimental tech) https://www.youtube.com/watch?v=3ERowrZJyfw

If you could point them backwards for a little extra thrust ...

Modern supersports are pushing ~200hp, no need for the extra weight that would generate the thrust.

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

#124

Post by bluGill » Thu, May 24, 2018, 3:54 PM UTC

jandrese wrote: post #98

agumonkey wrote: post #66

Earlier quoted context omitted.

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

This doesn't make sense at all. High pressure water can be dangerous for sure, but water based energy storage doesn't use high pressure... It's all about pumping the water uphill and then letting the water flow back down through the pump to recover the energy. At worst your house gets flooded because the containment vessel failed. Worst case with compressed air is a total disintegration of the tank, the room it's in,…

Water is pressurized. The pressure is a function of gravity and depth, but that is still a lot of pressure.

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

#125

Post by Tobba_ » Thu, May 24, 2018, 3:54 PM UTC

ajuc wrote: post #74

jandrese wrote: post #62

Earlier quoted context omitted.

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

Any kind of high-density energy storage is basically a bomb. If you charge or discharge Lithium polymer or lithuium ion batteries "wrong" they explode too. I wouldn't want to be near a flywheel that stores 360 Wh of energy when it breaks.

Not necessarily, 1.3MJ (360 Wh; but screw that unit) of diesel isn't much of an explosive under normal circumstances. It really depends on the maximum power output under normal operation, and whether it can occur uncontrollably.

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

#126

Post by mabbo » Thu, May 24, 2018, 3:55 PM UTC

newman8r wrote: post #3

An added benefit is you could power your air-tools with something like this without having to convert to electrical energy. As a former off-gridder, that's actually a really big plus. Another non conventional way to store energy is using gravity power modules (example: http://www.gravitypower.net/ ) Storing hydrogen from electrolysis via solar panels also sounds interesting. Basically once your batteries are charged…

A lot of modern automation works this way. Conveyance systems with pop-up diverts make this satisfying hiss noise as they do their work- all powered by compressed air coming from a huge tank in the parking lot.

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

#127

Post by g8oz » Thu, May 24, 2018, 3:57 PM UTC

leblancfg wrote: post #119

g8oz wrote: post #77

Also interesting is hydraulic energy storage. Any entrepreneurs want to take a shot with this system? http://license.umn.edu/technologies/z07054_hydraulic-energy-...

>Hydraulic energy storage systems store energy by compressing air similar to a battery storing energy in an electric circuit. Wait, did you read the article? :)

Hydraulic systems and compressed air systems are usually regarded as separate things. Maybe the distinction is a bit arbitrary and the former can be regarded as a subset of the latter but there you go. edit: Google says hydraulic transmits power through fluid, compressed air through air/gas.

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

#128

Post by newman8r » Thu, May 24, 2018, 3:58 PM UTC

jandrese wrote: post #111

oori wrote: post #48

Earlier quoted context omitted.

"sealing off caves" - would love to see, or hear the facts. Specifically, about safety of the pressure "chamber".

I think it is more typically done with old mines. Natural caves are far more complex systems and there are environmental concerns.

you're right - it looks like the caverns being used for experimentation are the result of solution mining for salt.

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

#129

Post by throwaway5752 » Thu, May 24, 2018, 3:59 PM UTC

microcolonel wrote: post #122

throwaway5752 wrote: post #113

Earlier quoted context omitted.

I would disagree with you slightly. Energy is not totally fungible. I can punch you in the face or shoot you with a gamma ray (edit: though of course, I would never do either), and it would have very different effects, potentially. Same for a fastball vs a small caliber weapon. Heat, light, and kinetic energy are important distinctions - particularly when you have a bunch of 30k flywheels in close proximity and one o…

> that's a bit easier to manage/less likely to cascade. What gives you that impression? Seems to me that it explodes if you contain it, and if you don't contain it, it can spout jets of thermal energy at virtually any angle. With flywheels you need to arrest it in bulk heavy objects that don't tend to sustain fire. That seems a lot simpler to me. The bigger problems with flywheels are cost of manufacture and (dependi…

What gives you that impression?

Insulation is cheap, effective, and very compact. And it's easy to transfer heat quickly, also (either via injecting lots of cold extinguisher or flush lots of hot oxidizing gas)?

Cool, thanks for the update on flywheels. I ... am not trying to create a false dilemna, here. Fuel cells for stranded methane deposits are great. Flywheels have outstanding responsiveness and energy density. Li / compressed air / pumped water et al scale well. They all fit into a more resilient grid storage strategy that permits a transition to periodic sources of input from non-renewable base load.

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

#130

Post by hinkley » Thu, May 24, 2018, 4:02 PM UTC

bdamm wrote: post #92

3pt14159 wrote: post #85

Earlier quoted context omitted.

The core insight for me was when Musk talked about how little the cost of Li mattered in the unit economics of Li batteries. It was something like 3% of the cost. The rest of it was mostly manufacturing costs. With so much room for improvements at scale and so many potential applications, it seemed like a sure winner.

That's a very useful insight. My "aha" moment came during a lecture given by DARPA at PARC about 5 years ago, outlining how wasteful current battery technology is in terms of density entirely because of safety requirements. They had at the time over a dozen different research projects on ways to improve density by changing how safety is achieved. It is only a matter of time until some of them get to market, and in fa…

There’s a kind of Moore’s law in batteries, but the multiplier looks more like inflation than 2x.

Any tech that falls outside of the growth curve seems to run into issues with production or cost that delay it until it fits under the curve. Something cheaper and easier gets picked first.

The first modern EVs had lead acid batteries. More sophisticated than your starter battery, sure, but lead acid all the same. Which is why Tesla was a big deal. We talked about LiPo for something like fifteen years before it showed up in consumer electronics, and then they started catching on fire.

All of this stuff is painfully slow. The big story in EVs is how crazy efficient the motors can get. A company I used to follow (whose name is escaping me now) had a motor that was 95% efficient in its sweet spot. They had scaled up the design to 100 HP.