[HN Gopher] Human-powered air-compressor and energy storage system
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Human-powered air-compressor and energy storage system
Author : surprisetalk
Score : 46 points
Date : 2023-07-15 17:26 UTC (1 days ago)
(HTM) web link (solar.lowtechmagazine.com)
(TXT) w3m dump (solar.lowtechmagazine.com)
| umtksa wrote:
| did same thing but smaller scale to use with usb powered devices
| https://www.youtube.com/watch?v=fMBtU3irxLo
| maxerickson wrote:
| Article is wrong about energy. Gonna keep getting cheaper. For
| instance, that's the long term trend:
|
| https://www.usinflationcalculator.com/inflation/electricity-...
|
| Reliability is a little less of a given, but it's not
| unreasonable to expect grid operators to seek to continue making
| profits.
| debbiedowner wrote:
| Used in foiling boats in America's cup and similar races.
| n40487171 wrote:
| I believe those use a hydraulic accumulator system rather than
| compressed air.
| KennyBlanken wrote:
| Guess what's on the other side of the membrane or piston in a
| hydraulic accumulator?
| gotts wrote:
| I'm far from foiling boats would you mind explaining why are
| these compressors human powered and not gas/battery powered?
| Is it something from racing code?
| BrentOzar wrote:
| Racing code - America's Cup races prohibit stored energy
| aboard the boat, for example. Exceptions are made for
| certain springs, valves, and batteries for electronics.
| bombela wrote:
| What a refreshingly clean, quick to load website. I would have
| done without the email popup. But I can forgive that. If I trust
| the footer, the server is solar powered in Barcelona.
| ReactiveJelly wrote:
| It does load fast, but I'm pretty sure the ditherpunk aesthetic
| is bogus. Byte for byte, JPEGs should beat dithered PNGs /
| GIFs, and they never proved that the end-to-end costs of JPEG
| encoding and decoding are worse than dithering. It just looks
| distinct.
| pwg wrote:
| > I would have done without the email popup.
|
| With uBlockOrigin blocking all Javascript by default, there is
| no "email popup".
| karaterobot wrote:
| > The process of filling the empty tanks to 100 psi takes 5-10
| pedaling sessions per day for roughly a week.
|
| The main thing I wanted to know from this article is how much
| peddling it takes to keep the tank filled, and I don't feel like
| he answered that: how long is a peddling session? If it's 5
| minutes, that's about four and a half hours of peddling to fill
| the tank. If it's 15 minutes, that's about 13 hours. And how
| often does he empty the tank? How long does it take just to keep
| it topped up in an average week? Details, man! He must know this
| if he uses the thing.
| KennyBlanken wrote:
| The hint is in him having a 7hp (quite powerful) compressor
| that apparently runs enough to be running up his electric bill.
|
| I'm perplexed by the comment about "empty tanks." In these
| systems the tank is almost never empty because pneumatic tools
| are pretty useless below a certain pressure; you can't just use
| them until they're empty. The impact guns I've used became
| tonka toys around 40 psi or so, if that.
|
| The compressor might get shut off for the night, and sure,
| there are some air leaks - but the next morning when the shop
| opens, it's not empty.
|
| Maybe the reason this dude's compressor is eating him out of
| house and home is because he's got a bunch of leaks he isn't
| addressing...
| anon84873628 wrote:
| Huh? Nowhere does the author suggest that the electric
| powered system was "eating him out of house and home". The
| motivation here was clearly resiliency and creativity. He
| also mentions the importance of addressing leaks too.
|
| "Empty tanks" is probably just shorthand for "pressure too
| low to run the tools".
| brnt wrote:
| I love lowtechmag, but it's almost a rule they are economical
| with details too, and often to hide a (pretty obvious)
| compromise that not everyone would be willing to make.
| antisthenes wrote:
| The extremely obvious compromise is that you need to have a
| high-PSI air tank on hand as well as a donor bike. The donor
| bike can probably be gotten for very cheap or free, but the
| tank...
|
| I looked at the prices of 80-gal 200 PSI rated tanks online,
| and the conclusion is...not great.
|
| It's going to run you roughly $1000, for which you can
| realistically buy a whole set of cordless battery powered
| tools AND an outlet-powered air compressor on top of that.
| tspike wrote:
| The point is that this solution works without access to
| electricity and is resilient to the loss of industrial
| supply chains
| sp332 wrote:
| How are you going to make an air tank that can handle 200
| PSI without industrial supply chains?
| littlestymaar wrote:
| > I looked at the prices of 80-gal 200 PSI rated tanks
| online, and the conclusion is...not great.
|
| Or you can get a bunch of empty propane tanks for a few
| bucks and call it a day...
| juujian wrote:
| Also, I'm curious whether it takes more energy to fill the
| tanks from 60 to 80 psi vs 80 to 100 psi. Filling the tank
| until its full is not really a useful metric, would be more
| interesting to learn how much pedaling continuous operation
| requires.
| function_seven wrote:
| I think it's harder to go 80-100 than it is from 60-80.
|
| I'm both cases, you need to stuff the same volume of
| additional air into the tank, but in the 80-100 case, the
| resistance to the stuffing is higher.
|
| At least I think that's how it works. Assuming spherical cows
| and an ideal gas.
| oh_sigh wrote:
| If it takes 7hp(5200w) for 5m, let's say a person can do 100w,
| so they will take 52x as long, so 260m total. Broken up between
| 7 sessions a day for a week means each session is only 5
| minutes.
| tshanmu wrote:
| obligatory: fifteen million merits
| https://www.imdb.com/title/tt2089049/?ref_=ttep_ep2
| detourdog wrote:
| I just wish the article contained the duration of a bike session
| and the run time of 90 gallons at 100psi.
|
| Myabe its there and I missed it.
| woutgaze wrote:
| Nice setup although I remember that the efficiency of air tools
| is very low like around 1%. That's also why they get replaced a
| lot.
| KennyBlanken wrote:
| A massive amount of power is lost in air tools. They're also
| painfully loud, the hose is annoying in a variety of ways, and
| the air system in the shop is expensive to install and involves
| periodic maintenance.
|
| Most mechanics use battery tools these days. Impact drivers for
| all but the biggest stuff, with handheld drivers having enough
| torque to work on a lot of suspension components easily, and
| there are even electric ratchet drivers now with sufficient
| torque for a lot of smaller stuff under the hood that require
| little more space than a hand ratchet, and no room for swing
| needed.
|
| Battery tools are faster, quieter, easier to control. The
| system scales linearly in capacity, charging speed, etc. Add
| two mechanics to your shop where you're only using air? You're
| looking at thousands of dollars to upgrade a compressor, maybe
| a tank too.
|
| If you're concerned about still being a mechanic when you lose
| power, put a solar panel on the roof, attach it to a MPPT solar
| charger and a couple of car batteries you recycle from
| customers' cars, and have an inverter ready to switch on if you
| need it.
|
| What mechanic has the energy to pedal this thing just to work?
| What mechanic does so little work with their tools that the
| system can be infrequently refilled by a guy taking an hour or
| more to fill the tank?
|
| This is at best useful for a shadetree mechanic and the article
| is fetishizing low-tech BS with no practicality. Replacing a
| 7hp compressor that was chewing up his electric bill...with
| something he pedals? If it was chewing up his electric bill,
| then there's no way he could replace it by pedaling.
| DannyBee wrote:
| I mostly agree, but the first part is not universally true.
|
| My 30cfm compressor is 45db. Basically noiseless. You can
| easily have a normal conversation with it running. The air
| itself makes more noise than the compressor. It is happy with
| any duty cycle from 0-100%. Maintenance interval is about
| every 5 years. It produces oil free air. I can use it for
| breathing air (spray finishing) and not worry about things as
| much (I have proper gas sensors on that part anyway but it's
| nice to know i won't get poisoned by oil in some fashion)
|
| I pay for this in efficiency. A oil sealed rotary screw would
| be about 30% more efficient (maybe a little more) but have
| some carry over and be about 65db. Not hugely noisy but
| still.
|
| My pneumatic sanders have much lower vibration (30-40%), are
| quieter, smaller, weigh a lot less, and are essentially
| maintenance free. They can be repaired easily if I ever need
| to because they are very simple devices. The mechanism lends
| itself well to really good dust collection.
|
| As a result They are much nicer to use than even the nicest
| electric festool and mirka sanders (I have both). The
| electrics are massively improved over two decades ago but
| still.
|
| I don't woodwork or metalwork without mask or ear protection
| at all times so even if they were noisier I'd be fine.
|
| The air drops are set up to be convenient from anywhere in
| the shop.
|
| All that said, I do agree with the rest and the main point-
| for most people, battery is a better bet. I use what I do for
| convenience and comfort, not for cost or effectiveness.
|
| There are times using air is just a better way of doing that
| than batteries.
| KennyBlanken wrote:
| I was referring to the tools themselves being loud. It's
| not common for mechanics to be wearing ear protection, and
| air ratchets and impact guns are VERY loud.
|
| Air tools are not maintenance free. They all require oiling
| devices inline, or regularly being oiled, and that oil gets
| into the shop and coats everything; you're also breathing
| that shit into your lungs. That's why in a lot of
| mechanic's shops, everything is greasy. Pneumatic tool oil.
|
| You can buy a lot of batteries, tools, and chargers for the
| cost of installing a hard line air system. That still
| doesn't address the annoyance of the air hose, which is
| even worse than electrical cords - less flexible and
| heavier.
| mindslight wrote:
| I too had a hard time reading the article, with my own
| criticisms of what I'd do differently or details I wish
| they'd focus on. Replacing the need for electrical energy
| with the need for the chemical energy of food doesn't seem
| particularly great. An air compressor is still a
| technological device that relies on long supply chains, and
| keeping a few spare parts around doesn't count.
|
| But I try not to be too knee-jerk critical! Because I am glad
| someone is doing the work of trying experiments to look at
| outside the local maximum of our current technology.
|
| I'd think that an infrequently-used air compressor would be a
| fantastic place to use electricity from peak solar
| generation. That kind of thing seems closer to a
| sustainability local maximum than using human power.
| mrob wrote:
| >Replacing the need for electrical energy with the need for
| the chemical energy of food doesn't seem particularly
| great.
|
| Seeing as you need exercise anyway to stay healthy, it
| might as well be doing something useful.
| landemva wrote:
| I use both power sources, and have used a 3" electric impact
| on track jobs and it would get hot. Air tools don't get hot,
| which is great when it is repetitive wrenching.
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(page generated 2023-07-16 23:01 UTC)