[HN Gopher] Electric ferry uses a long extension cord [video]
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Electric ferry uses a long extension cord [video]
Author : zdw
Score : 159 points
Date : 2022-11-15 16:42 UTC (1 days ago)
(HTM) web link (www.youtube.com)
(TXT) w3m dump (www.youtube.com)
| MichaelCollins wrote:
| Did anybody else know this would be a Tom Scott video before
| clicking it? He always finds the oddest most interesting things
| to show off.
| Aardwolf wrote:
| Yes! I expected "this is going to be a Tom Scott video" before
| clicking the link. He has a niche in interesting esoteric
| infrastructure.
| daneel_w wrote:
| Sort of common in the nordics. We have lots of them in Sweden,
| the self-service type for short crossings to sparsely populated
| islands, but the power cable usually drives a winch attached to a
| steel cable.
| zwieback wrote:
| We have 3 electrical ferries in Oregon crossing the Willamette
| but they use 3 overhead wires to deliver 3phase AC. Works great
| for short hops.
| pinot wrote:
| https://img.atlasobscura.com/dmMEj9y780YXqaTupI_kf8Iin74JjtD...
|
| For example, the Canby ferry
| todd3834 wrote:
| This is pretty cool. I wonder what the effort would have been to
| instead have a battery charging / swapping process on one end. It
| would still be clean energy, charged on shore. I'm sure the
| batteries wouldn't be super light but you could have them in
| modules and you could engineer solutions for moving them.
|
| Perhaps for situations where it isn't already cable guided this
| is still a practical approach. I'm pretty ignorant when it comes
| to the weight of the batteries and how much energy they can
| provide + etc... but if my Tesla is any indicator it doesn't seem
| too hard vs managing that cable back and forth
| Thlom wrote:
| Around a quarter of the ferry crossings in Norway are
| electrified. Usually there's one or two electric ferries and
| one diesel ferry. They charge while unloading and loading and
| during the night when there's fewer crossings. Before they had
| to take breaks during the day to charge, but now days I think
| they run all day.
| todd3834 wrote:
| The batteries could even be attached cars themselves so moving
| them on and off would be really simple
| hawski wrote:
| Or with a thicker cable they could charge cars while they
| cross the channel.
| [deleted]
| chowells wrote:
| Rechargeable batteries are not 100% efficient. I'd put good
| odds on this system being cheaper.
| bentcorner wrote:
| The captain said they use 150-200kwh a day, which would be
| around 2-3 EV batteries' worth (Model S has a 100kwh battery).
| That's split up between 88 trips, so there's plenty of
| opportunity to swap batteries.
|
| So they could probably have some kind of battery system but I'm
| guessing since it's already "tethered" with a line just to
| cross, stringing an electrical cable was already easy to do and
| has simpler logistics than managing batteries.
| Epa095 wrote:
| For those interested in this, there is also a quite large battery
| powered ferry operating in Norway.
|
| >The Basto Electric is 139.2-metre-long and 21-metre-wide and was
| built by the Turkish Sefine Shipyard and has room for 600
| passengers and 200 cars or 24 trucks.
|
| >Basto Electric uses batteries with a capacity of 4.3 MWh. The
| fast-charging system has a capacity of 9 MW.
|
| https://www.electrive.com/2021/03/02/worlds-largest-electric...
| Thlom wrote:
| Around a quarter of all ferry connections in Norway have been
| electrified. Often there's one electric and one regular diesel
| ferry operating in tandem. Basto Electric is still the biggest
| one though.
| mstade wrote:
| While not fully electric, there's also the Color Line ferry
| operating between Sandefjord and Stromstad[0]. I happened it
| be in town for its inaugural voyage and it turned out to be a
| quaint little trip. As far as I understand it though, they
| more or less only run on electric power when navigating out
| of port, and back to diesel when at see and arriving.
| Enjoyable trip nonetheless!
|
| [0]: https://www.colorline.com/sandefjord-stroemstad/color-
| hybrid
| mywacaday wrote:
| While Norway is to be admired I find it difficult to see
| their experience as applicable to the rest of the world when
| they have a 1.19 Trillion wealth fund which equates to over
| 22 million per person in Norway.
| throwayyy479087 wrote:
| America invented the airplane then went to the moon. We
| started every large tech company. We essentially created or
| popularized everything that defines the modern era.
|
| Excuses are why infrastructure and politics here sucks. We
| should bully the federal government for their failure here,
| just like Biden bullied LGA into renovating
| transportgo wrote:
| It's actually $220,000 pr person.
| encoderer wrote:
| Sort of off topic but the war in Ukraine has brought to my
| attention that we actually fire missiles with giant miles-long
| extension cords. Missiles. With extension cords.
| sidewndr46 wrote:
| I think those are just for control & telemetry. The actual
| missile has a battery on it usually.
| hnlmorg wrote:
| Anyone got a source for this? I'd be interested to learn more
| modeless wrote:
| https://en.wikipedia.org/wiki/Wire-guided_missile
|
| I think the TOW missile is the most prominent example.
| adwww wrote:
| MILAN is very slightly older and probably just as widely
| used - especially out of US.
| nuccy wrote:
| Those are wire-guided missiles, usually used to destroy tanks
| and other armed vehicles. The length of the wire is just few
| kilometers. The wire is needed to actually tell the rocket
| where to steer [1].
|
| More modern approach to anti-tank missiles are those with
| lasers being used for highlighting the target [2], while the
| missile has a battery and a camera to find the spot. The
| other approach is to do on-the-fly image recognition [3].
|
| Edit: interesting fact: DART space craft sent by NASA to hit
| an asteroid used a missile derived technology to recognize
| the image and steer itself into the target, since direct
| control from Earth was not possible due to communication lag
| [4] (also try googling "dart mission" to see google's doodle
| on the topic).
|
| 1. https://en.wikipedia.org/wiki/Wire-guided_missile
|
| 2. https://en.wikipedia.org/wiki/Laser-guided_bomb
|
| 3. https://en.wikipedia.org/wiki/FGM-148_Javelin
|
| 4. https://www.nasa.gov/press-release/nasa-confirms-dart-
| missio...
| stavros wrote:
| Wait, what? Why?
| NwtnsMthd wrote:
| - Can't be jammed
|
| - Simple
|
| - No radio frequency indication of an incoming missile.
|
| There must be other reasons as well.
| stavros wrote:
| I agree with the first and last point, but reliably
| unrolling a 4km wire while going 500 kmh cannot be simple.
| MarkMarine wrote:
| They seem to work quite effectively, I've never seen a
| TOW fail. Downside is you need to maintain visual
| guidance of the missile through it's whole flight path.
| SketchySeaBeast wrote:
| I'm envision that classic "look down and see a pile of
| rope unspooling around your leg right before you
| disappear out of frame" shtick.
| supergeek wrote:
| Anyone involved in RC aircraft will gladly tell you that
| getting a stable radio link for video and control past
| 4km is anything but simple.
|
| Even a basic analog video signal is orders of magnitude
| more data than what you'd be transmitting in a phone
| call.
| encoderer wrote:
| Isn't it crazy how much effort we still spend as a race
| trying to kill each other.
| jedc wrote:
| Also torpedos (for example, from submarines)
| simon_000666 wrote:
| Cool - another option could be beaming power to the ferry using
| microwaves, millimeter waves or lasers. The power transfer
| efficiency would be lower but saves the cable complexity and
| slacking/maintenance.
| MarkMarine wrote:
| I think the losses on both sides of that invisible death ray
| would be more complex than a long extension cord.
| jguimont wrote:
| For those mega cargo ships, why is civil nuclear power vessels
| are not a thing? Seems they would massively reduce the footprint
| while providing better clearner power.
| coryrc wrote:
| Because they don't pay for pollution.
| Gwypaas wrote:
| Because it's all about cost. Those 400m container ships are ran
| by a low cost crew of 15-25 with some 3rd party maintenance
| personnel sprinkled in. Try fitting a more expensive fuel and
| more maintenance into that. On top of all safety concerns.
|
| For ocean crossing vessels they are more closely looking at
| e-fuels and hydrogen since that gives the same benefitd at
| cheaper cost with not a too large change in the shore side
| infrastructure.
| Markoff wrote:
| https://youtube.com/watch?v=cYj4F_cyiJI
| mediaman wrote:
| Servicing marine nuclear reactor units requires very special
| skills and is expensive. So is the initial capital cost.
| Servicing large marine diesel systems uses labor that is much
| more available globally.
| expazl wrote:
| With this setup I wonder why even have the motor on the ship?
| It's using an extension cord to get power to the ship so it can
| pull on the wire guides, but you might as well just have put the
| engine pulling the wire on the shore and have a "dumb" platform
| in place of the boat.
| AdamJacobMuller wrote:
| The wire would need to be parallel to the water at just above
| or below it and would always obstruct other traffic. This
| arrangement allows the wire to fall onto the seabed so ships
| can easily pass in front of and behind the ship, given
| reasonable clearances.
| TheRealPomax wrote:
| You want the engine in a place where the people who need to
| control it, or even kill it in an emergency, can feel what the
| engine's doing, and have control over that engine.
| willcipriano wrote:
| If I was in Hollywood I'd call Tom Scott and give him whatever he
| needs to make whatever he wants. Imagine something like a long
| form road trip documentary, stopping in at interesting places and
| doing interesting things but with the pull and budget of a studio
| behind him.
| DaiPlusPlus wrote:
| > If I was in Hollywood...
|
| Hollywood essentially destroys almost everything it touches:
| the people that invest in film production insist on maximising
| their RoI at the cost of petty things like artistic integrity,
| historical accuracy, and such.
|
| I enjoy independent video producers ("creators" is the term
| now, I gather?) on YouTube (and Vimeo, etc) like Tom Scott
| precisely because _it isn 't_ Hollywood.
| yreg wrote:
| What does he need the pull and budget of a studio for?
| adamparsons wrote:
| He has mentioned a few times now that he struggles with
| developing ideas and script writing, and is essentially
| bottlenecking his pipeline. I'd imagine a well picked writing
| team that doesn't lose sight of what makes his content great
| would be welcome, but also I don't doubt over the years he's
| explored this at length already
| willcipriano wrote:
| My grandparents made a documentary years ago[0], they started
| on their own and interviewed the family but once HBO got
| involved in the project they were able to do things like get
| into the courtroom for a parole hearing. Few people would
| talk to them, but the same people would bend over backwards
| for HBO.
|
| [0]https://m.imdb.com/title/tt1024663/
| paxys wrote:
| There is a long line of very popular YouTube stars who have
| tried to transition to making more "mainstream" entertainment
| content (TV, movies) and have failed spectacularly. Large
| YouTube channels have fine tuned all aspects of their
| production to be surfaced by YouTube algorithms and consumed by
| YouTube audiences. Making engaging content for Netflix/HBO or a
| movie theater is a completely different problem.
| MarcelOlsz wrote:
| Just upload it on YouTube. Problem solved.
| adamparsons wrote:
| Yeah whenever I've seen a favourite creator put up an out-
| of-place piece of long form content, it sometimes even gets
| a calendar entry so I can give it my full attention later
| dredmorbius wrote:
| Electrified marine transport is an interesting challenge, though
| there are a few options available.
|
| Notably, canal and river traffic _can_ rely on electric traction
| provided by onshore "mules".
|
| _That_ terminology is borrowed from the original practice of
| having mules haul barges along canals, _and_ reveals the immense
| enhancement in efficiency of water-borne transport. A single mule
| _might_ haul a cart weighing a tonne or so across level land (and
| far less climbing any sort of grade). The same mule could haul a
| barge on a flat and still canal carrying 20--40 tonnes of cargo
| or passengers.
|
| For passengers, the comfort of canal travel (no jostles, bumps,
| or broken axles as with a coach) was an immense improvement. The
| effect of the Erie Canal, a four-foot-deep (1.2 m) ditch from the
| Hudson river to Lake Erie was immense in opening up the US
| interior in 1825. Further, canals and their locks mean that the
| work of lifting (or lowering) cargo is done by the "roadbed) (the
| river) itself. In the case of the Erie Canal, 172m (565 ft) of
| elevation gain in net.
| Someone wrote:
| > That terminology is borrowed from the original practice of
| having mules haul barges along canals
|
| The Panama Canal has mechanical mules, but they are only used
| to keep ships on course, not to propel ships
| (https://en.wikipedia.org/wiki/Panama_Canal_locks#Mules)
|
| Disadvantages of towing are that it requires a towpath
| alongside the water, that overtaking is difficult, and that
| making tight turns can be difficult (the puller always pulls
| the ship closer to the canal or river shore, requiring the use
| of the ship's rudder to keep it on track. In tight turns, the
| pull direction is closer to orthogonal to the shore, requiring
| more rudder)
|
| Because of these, I think battery-powered ships with container-
| sized batteries that can easily be swapped may be a better
| solution.
| joak wrote:
| Small fusion generators.
|
| TAE, helion energy and ZAP energy are 3 well founded companies
| (combined $1B+) aiming at building ~50MW generators based on
| non-tokamak fusion.
|
| The generators are small enough to fit on a truck and could
| easily power the biggest container ships.
| dtgriscom wrote:
| "are small enough" => "would be small enough"
| dredmorbius wrote:
| If you've got the ability to build fusion generators, you've
| got the ability to create carbon-neutral analogues of
| existing fuels.
|
| You've also got that ability _without_ nuclear inputs, from
| conventional renewables (solar, wind, geothermal).
|
| Those fuels can be far cleaner than bunker fuel, and a diesel
| or kerosene analogue burning in a well-tuned ICE or turbine
| would have limited negative effects. The marine-propulsion
| pollutants of most significant concern, aside from (fossil)
| CO2 are particulate, NOx, and SOx emissions.
|
| All are far more prevalent with heavier fuels, and are
| concentrated largely along shipping lanes far out to sea,
| other than at ports. These tend to settle out / mitigate
| reasonably quickly, and I believe their long-term ecological
| impacts are fairly minimal.
|
| The problems with nuclear marine propulsion are many, not the
| least of which are the 100--200 shipwrecks logged every
| decade or so, though you can add to that risks of piracy or
| terrorism involving nuclear propulsion. Keep in mind that
| present commercial fleets are on the order of _eight
| thousand_ vessels. We 've had experience with only about four
| _hundred_ nuclear-powered vessels, virtually all military
| ships, of which about 170 are presently operational. The
| exceptions are three demonstration commercial vessels, the
| _Otto Hahn_ , _Savannah_ , and _Mutsu_ , all of which failed
| to prove feasible, and a handful of Soviet-era icebreakers,
| now operated by Russia.
|
| Fusion itself remains both technically and economically
| infeasable for any foreseeable future.
|
| <https://old.reddit.com/r/dredmorbius/comments/3c52ll/shippin
| ...>
| js2 wrote:
| This is the origin of the term towpath:
|
| https://en.wikipedia.org/wiki/Towpath
| azepoi wrote:
| https://en.wikipedia.org/wiki/Chain_boat_navigation
|
| Not a new idea: Chevaux electriques, meaning "Electric horses"
| (electric towpath tractors, halage=tow).
|
| https://de.wikipedia.org/wiki/Treideln#/media/Datei:Courchel...
|
| https://de.wikipedia.org/wiki/Treidellokomotive
|
| http://ronfleur.centerblog.net/6408563-halage-des-peniches-p...
|
| https://www.ronquieres.org/le-village-de-ronquieres/vieilles...
| (last image bottom right)
|
| http://www.traitsensavoie.fr/spip.php?article308
|
| http://www.traitsensavoie.fr/IMG/jpg/cheval_electrique_bethu...
|
| http://papidema.fr/traction_vn_extra.php#chevaux-elec
| dredmorbius wrote:
| _Not a new idea..._
|
| FWIW: I wasn't claiming that.
| tpmx wrote:
| I think this ferry between Helsingborg (Sweden) and Helsingor
| (Denmark) does it in the coolest way. Since 2018 the ferry has
| been running on batteries. Whenever it docks into any of the two
| ports, an ABB robot connects the charging cable.
|
| One real cool thing here is that they have gotten it to work for
| 4 full years in a northern climate. That means a lot of extreme
| weather edge cases.
|
| https://youtu.be/l93i87pZWhY?t=13
| tjoff wrote:
| When I clicked on this I thought, why not just have a cable-
| guided ferry instead? (Which already is a common thing) I assumed
| they'd have to make maneuvers not possible with a cable. But it
| already is?!
|
| Then why not just tug the cable instead, much better efficiency
| then propellers.
|
| Edit: ok, it is. Though what I've seen is that the motors are
| pulled from shore rather than on the boat. Which seems simpler,
| but this is maybe easier to retrofit.
| distrill wrote:
| I have to admit, it sounds a lot crazier before you learn that
| there are already cables running along the channel that the boat
| uses. This also means that this can't generalize outside of
| channels that already have cabled crossings.
|
| Given that constraint, I wonder about operating these ferries
| more like a ski lift then. If we're already stringing cables
| across the channel might it make more sense to keep them on shore
| away from the water?
| newpavlov wrote:
| Why not simply pull the ferry using the steel cables? In other
| words, put traction systems on both riversides and move the ferry
| using them. It even should be more efficient than a propeller-
| based propulsion system.
| matsur wrote:
| The ferry in the video uses cable based propulsion.
| bbstats wrote:
| This is why hn needs a downvote button LOL
| javawizard wrote:
| HN has one, it's just only accessible to those who have
| reached a karma threshold (501 I believe).
| javawizard wrote:
| It pulls itself along the cables rather than using a
| propeller, yes, but the motor that's doing the pulling is on
| the ferry rather than on the shore.
|
| To answer GP's question: I don't know, but given that this
| was a retrofit of an existing diesel-powered ferry I could
| guess that this was the cheaper way of doing it.
| nippoo wrote:
| Yes, but the propulsion is on the boat rather than at
| shoreside like OP suggested (ie the cables are static)
| [deleted]
| w-ll wrote:
| So it doesnt have a cable spanning the river all the time.
| newpavlov wrote:
| But it does have two cables spanning the river all the time.
| IIUC they get relaxed when ferry does not move and sink to
| the bottom to allow other ships to pass.
| clouddrover wrote:
| They say the ferry uses 150-200 kWh a day. If those numbers are
| right that wouldn't be a very big battery pack. The Hummer EV,
| for example, has a 212 kWh usable pack:
|
| https://www.youtube.com/watch?v=ORKuZxrFr6A
|
| https://www.youtube.com/watch?v=F9IUOR8lG3E
|
| Still, it's a cabled ferry anyhow so also having a power cable
| makes sense.
| oh_sigh wrote:
| Notably, this ferry is driven on a chain which crossed the
| channel already.
|
| I suspect they would have gone for batteries if the route wasn't
| already anchored in
| ok_dad wrote:
| Yea, they only use 150-200 kWh per day, that's not a lot of
| batteries to store on a large ship like that (it's like ~5-10
| EVs worth of batteries maybe? not the whole car, just the
| batteries!), even if you couldn't charge between sailings
| (which you could). I think it was probably a cost thing, too,
| as this system with a cable is probably way cheaper than
| batteries.
|
| edit: I was trying to reinforce here that, although this
| application could easily have used batteries due to the low
| energy needed per day, it didn't because there was a better
| solution due to the pre-existing cable infrastructure.
| Certainly this cable method isn't useful for most ferries, and
| most ferries will be traveling further and faster and require
| way more batteries.
| karamanolev wrote:
| They use so little because the use the (steel) cable for
| traction (as I understand it) and not water. If they had to
| use a propeller in the water to cross a river, the
| consumption would be much more.
|
| So in essence, there's symbiosis between electricity and
| running a cable-guided ferry. Otherwise you'd need more
| energy, therefore bigger batteries, etc.
| rz2k wrote:
| When he mentioned the steel cable, I wondered why they
| don't use an arrangement more like cable cars. It sounded
| like it is in case they break loose during a storm or
| emergency, so it useful to have the engine on board along
| with the back up generators.
|
| Are the cables actually used for traction, or just a
| countermeasure against having to fight the cross current?
| ricksunny wrote:
| I was also wondering this, you beat me to asking. If
| there is precedent for two cables why not connect them to
| make a long narrow loop of them like on a ski-lift; place
| an electric-powered winch on one end and an idler on the
| other?
|
| Was neat to see the video, and I'm sure they have their
| reasons.
| matsemann wrote:
| One reason may be that the cable sinks to the ground,
| which makes it possible for other boats to cross. If it
| was like a ski lift, the cable had to be more tensioned I
| guess, thus obstructing?
| ok_dad wrote:
| Yea, they pull themselves along the cable. The commenter
| above you was correct, it is way more efficient than
| props, plus it's way more efficient for high currents
| like this river. My comment was simply that they _could_
| have used batteries, but for this particular application
| a cable was perfect. I was reinforcing that this was a
| great confluence of constraints that enabled this.
| algo_trader wrote:
| I really dont think so.
|
| There are just crossing 500m at 2-3 knots several times a
| day.
|
| This is basically less than a semi rolling resistance which
| is maybe 1/5kwh/km?
|
| EDIT: even so, x10 batteries 2mwh are still very reasonable
| for a boat which cycle daily
| brink wrote:
| > it's like ~5-10 EVs worth of batteries maybe? not the whole
| car, just the batteries!
|
| Batteries are heavy, batteries need recharging, batteries can
| explode, batteries wear out, batteries cost a lot to
| replace.. or you can have a cable that might snag, but
| probably won't if you keep tension on it.
| dredmorbius wrote:
| And batteries in marine environments age much more quickly
| than those in dry-land applications. Salt loves anodes and
| cathodes.
| yafbum wrote:
| Also safety, I'd guess. Fire has much worse consequences on
| ships than on land...
| rz2k wrote:
| Furthermore you could charge them during the middle of the
| day and at night, and use the batteries during morning and
| evening commutes, which is pretty ideal.
|
| As for the additional mass and displacement, the video
| mentions boats having to push water out of the way, but water
| also fills in behind the boat, so there isn't as much
| physical work involved as it sounds like.
| ortusdux wrote:
| The Ford F150 Lightning comes with either 98kWh or 131kWh of
| batteries depending on the package.
| hathawsh wrote:
| Wait a minute... in theory, there could be a ferry that
| depends on power from an electric vehicle driven onto the
| ferry. That would solve the logistics problem of moving
| heavy batteries on and off the ship. The ferry could
| initially use consumer vehicles and switch to customized
| vehicles when the economics make sense.
| l1tany11 wrote:
| Some teslas have 100kwh batteries. The Hummer EV has ~200kwh
| battery. Depending on how much extra capacity is needed to
| optimize for longevity of the pack, and charging, it might be
| far less than 10 cars worth of batteries. Potentially as
| little as 1.
|
| Makes you think that there might be quite a few river ferries
| that could be converted quite economically.
| martinmunk wrote:
| Worth noting is, the subtitles said "The ferry uses, each
| day, about 150-200 kWh" whereas the speaker said "the ferry
| uses today between 150 and 200kW". I'm guessing Tom Scott had
| him clarify later, but the units, and what could be assumed
| to be a timeframe or not, is not the same.
| hnlmorg wrote:
| I found this video about another type of crossing using a cable:
|
| https://youtube.com/watch?v=OW24yLHmC20
| rmason wrote:
| I've ridden on one of those boats when I was in Basel. It was
| incredibly calming to cross the river with no noise from a
| motor.
|
| There are also I think five different cable cars in the
| immediate Basel area that offer some incredible views as well.
| hnlmorg wrote:
| You've now convinced me that I need to Basel :)
| gpvos wrote:
| There is a link below the video to a Wikipedia article with
| similar ferries all over the world.
| rmason wrote:
| Though I am a big fan of Elon Musk's Boring company I think his
| used of modified Tesla's to transport people in the tunnels isn't
| the best idea.
|
| The old streetcars, like in Detroit, used to attach to an
| overhead wire to power themselves. I think you could have normal
| train cars using this method. In other words use the electric
| grid as opposed to batteries. I can't imagine a battery fire in
| an enclosed area like a tunnel.
|
| Much better than NYC's subway using a live third rail which I
| believe has killed more people falling on to the tracks than the
| trains themselves.
| mikeyouse wrote:
| These are super common - all of SFs MUNI system is built using
| the overhead wires -- batteries in the individual cars are
| interesting because there's a ton of cost involved in
| electrifying the entire length of the tunnel to deliver as much
| power as a train needs. All of the substations, the physical
| electrical cables themselves, etc add a ton of cost to
| tunneling projects and long-term wear items that will require
| endless maintenance that often shuts down the lines.
|
| Building a dumb cheap concrete tunnel and leaving the expensive
| parts in the cars themselves could be a very cost effective
| method of urban transport. Though I think the "use Teslas" is a
| dumb addition since a purpose built train car similar to the
| airport shuttles at Denver would be much more efficient and
| handicap accessible.
| tshaddox wrote:
| To clarify, the light rail (Muni Metro) and electrified bus
| lines use overhead 600 volt DC, but most of the bus lines are
| not electrified.
| nottorp wrote:
| > I think you could have normal train cars using this method.
| In other words use the electric grid as opposed to batteries.
|
| Like... most trains in Europe?
| TheLoafOfBread wrote:
| Subway makes perfect sense, except when you are CEO of a car
| company. Then they are your direct competitor and suboptimal
| solution of Tesla's in the tunnel is used instead.
| WaitWaitWha wrote:
| Electric trolleybus have been running in some cities pre-WWII
| [0].
|
| I have seen them in Budapest, Sao Paulo, and Malatya.
|
| [0]: https://en.wikipedia.org/wiki/Trolleybus
| bilsbie wrote:
| Thinking outside the box a bit I think there could be lots of
| applications for "long extension cords". Especially when you
| consider how light and thin a cord could be when you use high
| voltage.
| bloak wrote:
| I agree. What someone needs to invent is a good way of powering
| a tractor (or combine harvester) through an electric cable.
| adamjc wrote:
| I don't follow, how are high voltage cables able to be thinner
| than low voltage cables?
| mikeyouse wrote:
| The limiting capacity of an extension cord is the resistance
| it can carry - at high resistance the cord will basically
| catch on fire. High voltage can deliver much more power at
| lower resistance as compared to low voltage. The easy example
| is household power -- in the US, standard household
| electricity is 120v, so a common 14 gauge wire that can carry
| 12A at constant load would be able to deliver 1400 watts. If
| you use 240v, that same wire can deliver 2800 watts.
|
| To extend that to extension cords -- if your boat/tool or
| whatever needs 5kw of power, at household voltage of 120v,
| you'd need a #4 wire which weighs 1.3 lbs/10 ft. At 240V,
| you'd need a #10 wire which weighs 0.3 lbs/10 ft. At 360v,
| only a #14 wire which weighs 0.13 lbs/10 ft.
|
| So by tripling the voltage, you can cut down the weight of
| the cable by roughly 10x.
| Arrath wrote:
| While annoying to route around trees and a bit of a hazard
| considering the possibility of running the cord over, using a
| corded electric lawn mower worked passably well for a small
| yard.
| jakear wrote:
| Seems like ideal use case for a battery. Use 1/week max, rest
| of time plugged in. I had one at my house and it was perfect
| for my small-ish yard.
| muti wrote:
| This is an application where I find the old tech does a
| better job: push mowers.
|
| I recently replaced my mower with an old push mower [1],
| someone local restores them and sells them for a reasonable
| price (much less than anything new or even a petrol or
| electric second hand mower.
|
| It works so well I wouldn't go back unless I had more than
| about 200 sqm to mow. Modern push mowers are junk and put me
| off in the past, but the older ones are much heavier and
| better built. They cut grass cleaner than a rotary mower
| which is supposedly better for the grass too.
|
| [1]: trademe.tmcdn.co.nz/photoserver/full/1857940265.jpg
| jimjimjim wrote:
| yep, they are very light and maneuverable and not have a
| battery pack allows for more interesting designs. but I have
| run over the cord before. things went quiet for some reason.
| unwind wrote:
| There are rather big excavators/shovels as used in mining
| operations, for large-volume material handling, that are
| powered by a tether. I guess they don't nimble around much but
| rather stay in roughly the same spot, filling trucks to haul
| the rocks away for smelting/processing.
| algo_trader wrote:
| Do you have any experience with this ?
|
| Is it possible to have a 10KV x 100A power tether snaking
| around like this ?
|
| There is a whole basket of safety requirements which kick in
| with higher power scenarios
| MisterTea wrote:
| They do this with large mining machinery such as the drag
| lines and bucket wheel wheel excavators. They don't move very
| far so extension cords are acceptable.
|
| And in mining they run portable medium voltage wiring through
| the tunnels to baby substations. They even make plugs and
| sockets rated to 15kV or possibly to 35kV, the upper limit
| for "medium voltage" in NA.
|
| Obviously you aren't going around plugging these cables in
| like they're attached to a reading lamp. They are on
| disconnects or circuit breakers and the circuit is de-
| energized before connection or disconnection. Otherwise
| arcing would destroy the connector. A faulted circuit would
| cause an explosion on connection likely killing or severely
| injuring an operator.
|
| Electricians working on medium voltage circuits must have
| medium voltage training and certifications.
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