[HN Gopher] Bring back hydrogen lifting gas
___________________________________________________________________
Bring back hydrogen lifting gas
Author : harporoeder
Score : 135 points
Date : 2021-08-09 17:50 UTC (5 hours ago)
(HTM) web link (www.thecgo.org)
(TXT) w3m dump (www.thecgo.org)
| fsckboy wrote:
| this article reads like the "a world without zinc!" school
| documentary spoof subplot on the Simpson's
| https://www.youtube.com/watch?v=U1iCZpFMYd0
|
| and the spat He... no, that's helium... She has with helium and
| in favor of hydrogen overshadows the more interesting suggestion
| at the end, that airships might make a lot of sense for cargo
| transportation. I wish the article made that case better!
| joefigura wrote:
| Interesting piece! I think the article makes some good points,
| but I don't think that helium is the reason that airships have
| failed to find use cases. The benefits of hydrogen do not change
| the fundamentals of the business case. Hydrogen's cheaper, but
| even using helium the lifting gas is <20% of the operating cost
| of the airship. The hangar, cost of the vehicle, and maintenance
| are all more impactful than the cost of the lifting gas.
|
| The bigger hurdle that airship startups have faced is the upfront
| cost of developing a new vehicle with a many ton payload.
| Projects trying to build very large airships have so far to get a
| vehicle to market, because of the amount of capital it requires
| and the lack of a strong, specific commercial case (Hybrid Air
| Vehicles, Cargolifter, Lockheed's Hybrid Airships). Changing the
| lifting gas to hydrogen does not address those challenges. But
| airships are certainly underutilized - I'm optimistic for their
| future!
| CuriouslyC wrote:
| One nice feature of hydrogen is that you can use it for lift and
| also for fuel (and it has good energy density).
|
| I've been wondering for a while if hydrogen airships couldn't
| make flying cars a reality. It seems like a hybrid jet/zeppelin
| could find a sweet spot in terms of performance and
| sustainability.
| jandrese wrote:
| The necessary bulk of the airship for human transportation is a
| serious crimp in the practicality of such a solution.
| Technology can't make the bag small enough because it is
| limited by physics.
|
| Even if we could build ultra-rigid and outrageously light bags
| that could have all of the air pumped out for a vacuum you
| still need a fairly large balloon to carry people. One person
| would displace 70 meter^3 of air, not counting anything else.
| That's not going to fit in your driveway.
| kozak wrote:
| I've been thinking of it the same way since I learned that helium
| is a non-renewable fossil resource. Once it's gone, it's gone.
| aeternum wrote:
| Only on earth. Helium is the 2nd most abundant element in the
| universe.
| Xylakant wrote:
| You'll have a hard time extracting it from the sun, though.
| [deleted]
| bena wrote:
| But an easier time from the Moon. The Moon's soil is
| apparently lousy with Helium.
|
| There was a movie named Moon about a decade back where that
| was the main character's job, helium mining on the Moon.
|
| That's not to say it would be easy, but it's closer than
| the Sun. Because it _is_ everywhere.
|
| In the various Star Trek shows, ships are made with
| something called "Bussard collectors" which basically scoop
| up particles like helium and hydrogen from space for use in
| the ship.
|
| Obviously both of those example are fiction. We don't have
| the capability to mine on the Moon or catch elements free
| floating in space. But those fictions are based on the fact
| that those elements are that abundant.
| perl4ever wrote:
| >"Bussard collectors"
|
| I think I read somewhere that despite this being a
| science fiction trope forever, there may not be a region
| between "too thin to produce net power" and "thick enough
| to blow up a spaceship at relativistic speeds". And in
| practice, the interstellar medium turned out to be the
| former, too thin.
|
| In fact, I'm not sure but what someone may have
| calculated drag would exceed power generated, regardless
| of density.
| aeternum wrote:
| Length contraction should also increase the apparent
| density for a ship travelling at relativistic speeds.
| Stevvo wrote:
| The Busard collectors in Star Trek are based on a real
| theoretical design; The Busard ramjet. I can't comment on
| its feasiblilty, but it would've actually captured
| elements free floating in space.
| skannamalai wrote:
| as an aside: a "fossil" resource implies the feedstock is
| decayed organic matter. Trapped helium is finite, but it's much
| more like a metal or ore than oil, LNG, or coal, which all were
| formed from living things under time and pressure.
| zabzonk wrote:
| > I learned that helium is a non-renewable fossil resource
|
| It is renewed, by radioactive decay within the Earth, but very,
| very slowly.
| nradov wrote:
| Helium is sort of renewable in that it's continuously produced
| by radioactive decay underground. That will continue
| effectively forever. But we're using the easily accessible
| helium far faster than it's being produced. Much of the helium
| we capture as part of natural gas extraction is totally wasted,
| just vented into the atmosphere.
| jandrese wrote:
| As we necessarily transition away from fossil fuels we also
| transition away from our primary source of helium.
| xphos wrote:
| So like I think the claim about the thermite coating could be
| wrong. That is my only concern you can't have the ship burst into
| flames in a minute. I don't know the truth of the hindenburg but
| it does seem like you could mitigate the flammability risk under
| good conditions but like security also comes to mind what if
| these things get hijacked. Like they do move slow but are
| basically a moving ball of death if they light on fire.
|
| https://www.airships.net/hindenburg/disaster/myths/
| csours wrote:
| I thought the bigger safety problem with lighter than air travel
| was weather? As in, anything less than perfect surface conditions
| may result in disaster when you go to moor the aircraft.
| FabHK wrote:
| TLDR:
|
| > With modern engineering standards, there is no doubt that
| hydrogen could be made a safe lifting gas.
|
| Disadvantages of hydrogen:
|
| * burns (but only with sufficient oxygen, eg a mixture of air and
| 4% up to 75% hydrogen)
|
| Advantages of hydrogen:
|
| * lifts 8% more than helium (per volume). Not a huge difference,
| but not trivial for an airship
|
| * costs 98.5% less than helium (!) (Airships have crashed because
| helium was too expensive to vent: safety valves on the _USS
| Shenandoah_ were capped, 14 crew members lost their lives.)
|
| > Airships are too slow for human travel
|
| Too slow for transportation, maybe. But leisure travel? Imagine a
| one week air safari from Kilimandjaro and the Serengeti to Kruger
| Park. It could be awesome.
|
| Edit to add:
|
| (Leisure air travel/Safari is my own pipe dream. The article
| suggests cargo):
|
| > If airships were to make a major comeback, it would be in cargo
| service.
|
| > Cargo airships would need to be big--bigger than the
| Hindenburg. [...] "'the lift-to-drag ratio, a critical parameter
| in aircraft performance, gets better as the airship gets bigger)
|
| > Ginormous airships require a lot of lifting gas--perhaps a
| million cubic meters
|
| > FAA has discouraged the return of the airship in the use case
| that makes the most sense
| dr_dshiv wrote:
| I completely agree with the leisure air travel scenario for
| airships. It would be incredible anywhere. Massive windows,
| tons of interior space, and quiet. Here is a deck I prepared
| luxury airships and opportunities for hydrogen airships:
|
| https://docs.google.com/presentation/d/1r6CPFJ1AX1ZULacguTf6...
| pitaj wrote:
| Airships are being investigated as a method of shipping to
| remote locations without ship, train, or truck access.
| R0b0t1 wrote:
| Airships would be good for freight. Far less carbon footprint
| than airplanes.
| throw37388 wrote:
| Source needed! Airships are quite inefficient, have high air
| drag and are slow.
|
| They are more comparable to ships, trains or cars. And here
| their inefficiency is very bad.
| himinlomax wrote:
| ... as long as you don't need that freight while the weather
| is even slightly bad.
| romwell wrote:
| Just like shipping things doesn't work because of storms,
| right?
| himinlomax wrote:
| Airships just don't work in strong winds, no need for a
| storm. And a plane can quickly move out of a hazardous
| location. An airship cannot move quickly.
| chrisco255 wrote:
| Is that true even if it has a large mass from cargo?
| jfk13 wrote:
| I suspect airships are much more vulnerable to bad
| weather than most other forms of transport.
| jvanderbot wrote:
| Well certainly that's an edge case. I don't know anything,
| honestly, but seems to me TFA is talking about wholesale
| distributor type cargo, not pizza deliveries. I guess
| waiting a day for a storm to pass doesn't kill anything,
| and airships can actually loiter in that time.
|
| I'm trying to think of a (non aquatic) case where rail is
| worse than airships though. If we were to invest in
| thousands of vehicles for distributing machinery, I'm
| guessing the average joe like me would vote rail. Unless
| we're talking going to a place where the infrastructure
| isn't good enough to support traditional delivery.
|
| For setting up a base in Greenland or the antarctic, I bet
| airships are really attractive. Or delivering bulk cargo to
| hawaii, perhaps.
| jcims wrote:
| One downside of rail is that new routes seem to always be
| decade long, multi-billion dollar projects.
| fanf2 wrote:
| Airships are better than trains at crossing the sea
| jvanderbot wrote:
| Sure, I was thinking any nation that wants to move cargo
| over the sea would use ships.
|
| So what conditions other than unestablished areas make
| airships better than sea ships?
| vineyardmike wrote:
| > I'm trying to think of a case where rail is worse than
| airships though
|
| You can ship non-standard cargo via air easier than rail
| if its wide. Eg. Moving a wide machinery, or parts to
| large construction project.
| outworlder wrote:
| If only we had a way to monitor the weather patterns in the
| entire globe and maybe even predict them...
| solarkraft wrote:
| Except they don't compete with planes, but with water ships.
| chrisco255 wrote:
| Except not really, as it's quite difficult to float a barge
| across a continent.
| aww_dang wrote:
| Especially for oversize or awkwardly shaped items.
| drivers99 wrote:
| That's what the article actually said. I think the parent
| post switched from summarizing to contributing their own
| thought instead.
| FabHK wrote:
| (you're right, I clarified)
| newsclues wrote:
| I've been thinking they are a good idea to help with
| overloaded ports, as they can pick up cargo cans and move
| them without any of the current bottlenecks.
| lb1lf wrote:
| -The airship would likely be the bottleneck; a 40ft
| shipping container may weigh anything up to approx. 30
| metric tons.
|
| You wouldn't be able to put many of those under an airship,
| hence you'd need a lot of rather space-hogging airships.
| newsclues wrote:
| But there are ships moored waiting for their turn for the
| cranes to unload.
|
| If you have swarms of these unloading, a few cans, it
| helps right?
|
| I'm sure it would be very handy for edge cases where only
| a few cans need to be offloaded at a specific port.
|
| You can also setup secondary drop off zones that avoid
| bottlenecks, like straight transfers from ship to train.
| manigandham wrote:
| Unlikely to help given how big and slow they are. These
| cargo ships carry thousands of containers.
| xphos wrote:
| Airships would probably be much fast than cargo ships
| though. Ships cut through the water at like maybe 30 mph
| in good conditions. Airships could easily keep as they
| are dealing with so much less drag. In the 1930 they
| moved at like 70 mph aka 2x the speed of container ships.
| I mean there cargo space would be like 1/40 but with the
| difference in speed thats only 1/20 in the rate of moving
| cargo not to mention that you aren't bound by water which
| is the major issue with ports. They are just very
| congested and ships are stuck in ship lanes. The air is
| much more limitless in terms of shipping paths.
| lb1lf wrote:
| -It would help; the question is more whether it would be
| worth it in the grand scheme of things; seeing as the
| weight differential between air and hydrogen is
| approximately 1.15kg/cubic meter at sea level, ignoring
| any weight in the airship itself, you're going to have to
| displace on the order of 25,000 cubic meters of air to
| lift one 20/40ft container (the max gross weight is only
| a couple of tons larger in a 40ft than in a 20ft unit).
|
| This volume of hydrogen is a cube with 30m sides. For one
| container. Neglecting the weight of the ship itself.
|
| The big container ships can carry upwards of 20,000 20ft
| units - so you're going to need a lot of airships (which
| will require a lot of airspace) to make an appreciable
| dent in the cargo unloading time.
|
| (The main issue really being that container ships are
| absurdly large!)
| vineyardmike wrote:
| > This volume of hydrogen is a cube with 30m sides. For
| one container
|
| This is actually smaller than i was imagining.
| FabHK wrote:
| FWIW, the article contemplates cargo airships with a
| million m^3, which would carry around 40 containers. That
| would be a cube with 100m sides, and you'd need 500 of
| those to replace one big container ship.
|
| Seems not a realistic option to replace container ships,
| but might be realistic for specific use cases.
| xphos wrote:
| So like to move a shipping container weighing 40 tons
| requires what 32x32x32 cubic meter space to be supported
| that's pretty tiny considering the other advantages. They
| could travel fast and in basically all weather.
| Lightening is a worry but if you isolate your hydrogen
| well it shouldn't be a problem. Not to mention they would
| be much more fuel efficient. Heck you could probably slap
| solar on them and get net zero energy discharge for low
| container ship speeds. The only issue being is I don't
| know if they would alleviate unloading issues if there
| was high winds. I don't really know the method for
| securing an airship but if they just let down a big rope
| and tie themselves done you can do that anywhere.
| lb1lf wrote:
| -Also, much slower and lower cargo capacity.
|
| That being said, I can see them being used where roads are
| sparse, inland (so shipping is not an option) and far away
| from the nearest railroad.
|
| We definitely need more green-tinged options; I root for
| airships!
| elcritch wrote:
| Not necessarily slower than cargo ships, and possibly
| significantly faster. This paper claims that by using the
| jet streams a hydrogen blimp could circumnavigate the globe
| in about 14-16 days [1]. Google gives about 77 days to do
| the same on cargo ship. Of course there would be lots of
| details to consider on the exact route taken, but from
| first principles it seems plausible.
|
| 1: https://www.sciencedirect.com/science/article/pii/S25901
| 7451... 2: https://arimotravels.com/how-long-does-it-take-
| a-cargo-ship-...
| pharke wrote:
| They could conceivably be very cheap if the gas pockets
| were mass produced. Everything else on board for propulsion
| and housing the pilot would be on the scale of a small prop
| aircraft. As long as the cargo can be easily managed,
| perhaps in a shipping container, then these would be easy
| to deploy en masse. They can land in any suitable field
| that has a crew on hand to guide them in with ropes. You
| might not even need pilots since these would be perfect
| targets for automation.
|
| As for speed, you can optimize the shape of the aircraft
| and the position of the propeller for this. I've seen a
| number of videos that show surprisingly good performance
| for pointier fuselage with a pusher prop on the tail.
| scarby2 wrote:
| > Everything else on board for propulsion and housing the
| pilot would be on the scale of a small prop aircraft
|
| It's likely that any cargo airship would fly for
| days/weeks at a time and would require at least 4 crew-
| members and everything they would need for the length of
| the voyage. So less a small prop and more something akin
| to facilities available on a yacht/Large RV.
|
| > You might not even need pilots since these would be
| perfect targets for automation.
|
| This would perhaps be the best solution
| kemiller wrote:
| With a huge balloon and flexible solar panels + fuel cell
| (they've already got to carry H2) they could be nearly zero.
| dragontamer wrote:
| > Too slow for transportation, maybe. But leisure travel?
| Imagine a one week air safari over the Serengeti, Ngoro Ngoro
| crater, and Kruger Park. It could be awesome.
|
| Well, if we're talking about weird Sci-Fi ideas (that might be
| possible), lets just go all in on it.
|
| Rocket launches are extremely expensive, and most of it is in
| the lifting costs. Would it be cheaper to "lift" a rocket with
| hydrogen slowly?
|
| Yeah, we also need to get enough kinetic energy to enter orbit.
| But surely getting rid of a huge chunk of "Gravity" costs could
| lead to substantial rocket-fuel savings?
| vkou wrote:
| It's not expensive to go to space because you have to go up.
| Going up into space is 'easy'.
|
| It's expensive to _stay_ in space because you have to go
| sideways, really, really fast. 8 km /s fast, in fact.
| klyrs wrote:
| This is fun to think about. You only need that horizontal
| velocity to stay in orbit, right? But what about getting to
| the moon? Turns out it only goes about 1km/s. Still bloody
| fast, but it's a bit less scary. Daydreams of capturing
| that energy on descent to power a moonbase... but then the
| moon is quite a long way away, and you need to escape over
| 99% of the earth's gravity, opposed to the 10% needed to
| reach space. Phooey, lunch is never free.
| evan_ wrote:
| That would also let us do the rocket launch from the middle
| of the ocean rather than near inhabited areas.
| wantoncl wrote:
| I can't find it now, but there was previous discussion on HN,
| about the amount of atmospheric drag a balloon-launched
| rocket would save as not being worthwhile. Most of the
| orbital velocity is spent going horizontally, the vertical
| part is <20% of even the most aggressive orbital trajectory,
| and the drag is virtually nil past 150K feet. And the delta-v
| needed to reach orbit is some very high percent of the total
| fuel and thrust.
|
| Basically balloon launches would only benefit small sub-
| orbital sounding type rockets.
| dylan604 wrote:
| >Basically balloon launches would only benefit small sub-
| orbital sounding type rockets.
|
| So you're saying Jeff Bezos should look into this for Blue
| Origin since you essentially described his capabilities?
| ;-)
| Ajedi32 wrote:
| JP Aerospace has an interesting concept where the entire
| balloon would get slowly accelerated to orbital velocity
| using electric/chemical hybrid propulsion:
| http://www.jpaerospace.com/atohandout.pdf
|
| That could potentially be viable, as it'd save fuel over
| more traditional rockets by allowing for the use of high
| efficiency, low thrust engines which would otherwise be
| infeasible for an orbital rocket due to gravity losses.
|
| Not sure though, I haven't done the math. It might be that
| the losses due to drag exceed what a more traditional
| rocket would lose to gravity.
| londons_explore wrote:
| There is a big benefit... Rocket nozzles that are most
| efficient in a vacuum don't work at sea level (oscillations
| cause the whole thing to shake apart). Therefore launching
| from high up means you can skip the less efficient rockets
| and just have a single type of more efficient rocket
| engine.
| sfblah wrote:
| This is a very interesting point. Is there a
| counterargument to this?
| onethought wrote:
| Vacuum optimised rockets require a vacuum. Balloons
| require atmosphere... so there is a gap where the balloon
| can't go higher and the engine isn't in vacuum yet
| bin_bash wrote:
| somewhat unrelated but wouldn't this also defeat the
| purpose of a space elevator? It seems that also would only
| save on the vertical part. I realize I'm almost certainly
| wrong but I'm curious why.
| ajford wrote:
| The idea of a space elevator usually requires an orbital
| anchor point, in which case lifting yourself up the
| tether would pull you fully out of the gravitational
| well.
|
| I've not done the mechanics in a long time (not since
| college), but I believe the tether itself would be
| providing all horizontal propulsion. Essentially by
| riding the tether up, it starts pushing you faster and
| faster. Since the payload's mass would be small compared
| to the anchor, the drag on the anchor would be
| negligible.
|
| There's likely some need for thrust compensation on the
| anchor over time to counteract the delta V lost to the
| lifting of payloads, but that would all be part of
| station-keeping and would be there for tether drag as
| well.
| Retric wrote:
| The anchor is past geosynchronous orbit so it's applying
| a constant upwards force. The energy for horizontal
| motion comes from the rotation of the earth, much like
| how a rotating ice skater slows down when they spread
| their arms.
|
| Station keeping may be used to dampen oscillations, but
| managing climbing rates works just as well.
| ajford wrote:
| So the constant upwards force is providing enough tension
| to keep the cable in the realm of a rigid body
| approximation? I would have assumed the force applied to
| accelerate the payload would also deflect the tether and
| anchor backwards (in a miniscule amount) and would have
| built up over successive payloads.
|
| Not arguing, just curious. It's been at least a decade
| since I've messed with orbital mechanics.
| Retric wrote:
| It does defect the anchor from pure vertical, but like a
| ball on a pendulum the vertical force from the anchor
| translates into a horizontal force.
|
| EX: https://www.researchgate.net/publication/312934526/fi
| gure/do...
|
| Of course if you really dig into things it's more
| complicated, but the basic principle is very similar.
| [deleted]
| [deleted]
| jameshart wrote:
| Space elevators get you all the way out to geosync orbit
| (and beyond) - as you climb you accelerate as you move
| away from the surface of the earth, and so by the time
| you reach geosync height you are traveling at orbital
| velocity.
| MobiusHorizons wrote:
| To be effective, a space elevator would have to deliver
| the payload all the way out to geostationary orbit
| altitude. At that hight, the payload would already be in
| orbit without adding any additional horizontal velocity.
| But almost all of the height is higher than you can float
| a lighter than air craft (42164km vs ~40km for lighter
| than air craft).
| bialpio wrote:
| My guess would be: top of the space elevator needs to
| stay in orbit so it already needs to have appropriate
| "horizontal" part.
| inglor_cz wrote:
| With the space elevator, you can get to _space_ easily,
| but getting to _orbit_ is much harder. Basically, you
| only achieve orbital speed once you have crawled to the
| geostationary orbit, e.g. 35,786 km above the Earth.
| Crawling that far from the Earth costs a lot of energy.
|
| If you crawl only to the LEO altitude (e.g. 300 km) on
| the space elevator, you will be in space, but not in
| orbit. If you let go of the elevator there, you will
| immediately start falling to a gruesome death.
| adolph wrote:
| It could become a thing.
|
| https://en.wikipedia.org/wiki/Space_diving
| jbotz wrote:
| Because a real space elevator would go all the way to
| geostationary orbit where the orbital speed is the same
| as the rotation of the planet. Remember that the further
| up you go, the slower the orbital velocity, i.e. the
| "horizontal part" shrinks until the "vertical part"
| becomes the whole thing.
|
| In fact, the way to build a space elevator is not to
| build a "tower to space", but to put an anchor rock into
| geostationary orbit and then hang a cable down to earth
| from it. You can then connect the cable to terra firma so
| that it doesn't sway, but in terms of the main forces
| involved it's hanging down, not standing up.
| fanf2 wrote:
| The tether needs to go past geosynchronous orbit to act
| as a counterbalance
| foxyv wrote:
| A space elevator not only raises payloads, but also
| accelerates them to geostationary orbital velocities
| (~3000 m/s). Luckily these velocities are much much lower
| than LEO orbits (7600 m/s).
|
| Ideally the energy to perform this acceleration comes
| from the rotation of the planet below, transmitted via
| the tether. The anchor station would have to be
| stabilized to prevent oscillation and rotation. However
| that technical challenge is minor compared to the tether
| material itself.
|
| Another advantage of a space elevator is that we can use
| electrical power from a base station instead of onboard
| power on the vehicle alone. Also the power can be much
| lower than a comparable rocket. To ascend on the
| rail/tether you can accelerate much slower. It doesn't
| need to lift fast or fall. It can just slowly accumulate
| altitude and velocity.
| thatguy0900 wrote:
| A space elavator would also lend alot of centrifugal
| force past the atmosphere due to the tethered rotation
| that you wouldn't get with a balloon, if it's high enough
| it will be able to escape just by virtue of that when
| released
| dylan604 wrote:
| What about doing the 2-stage system similar to Virgin
| Galactic? Use the "balloon" to lift the system to upper
| altitudes, and then fire off the rocket to do orbital
| insertion type stuff.
| jvanderbot wrote:
| I asked this question once and got laughed at. My
| embarrassment burned it into me: Going fast is the challenge
| with orbiting, not going up.
| IntrepidWorm wrote:
| Certainly no need to feel bad. Orbital mechanics are
| counterintuitive to us ground dwellers- even astronauts
| sometimes need a refresher course!
| frosted-flakes wrote:
| Well, if you could go high enough, you could be in a
| geosynchronous orbit without moving horizontally at all. I
| think that's how space elevators would work. But then to
| move to a lower orbit you would actually need to speed up.
| jvanderbot wrote:
| If you "fell" from geosync, wouldn't you speed up?
| Angular momentum needs to be conserved, right?
|
| Edit:my terrible wording created answers to a different
| question.
| [deleted]
| jameshart wrote:
| If you 'fall' from geosync orbit, you fall in a circle
| and wind up where you started. Orbiting _is_ falling.
| blacksmith_tb wrote:
| That's my understanding, geosync is the point at which
| you continually fall toward the Earth and miss, closer
| and you'd eventually hit, farther and you would move
| away.
| jameshart wrote:
| That's not really correct.
|
| Geosync is the altitude at which a circular orbit takes
| 24 hours - meaning it takes as long to complete one orbit
| as it takes the earth to complete one revolution.
|
| But there's an orbital velocity at EVERY altitude, and
| therefore there's an orbital period at every altitude
| too.
|
| If you are at a particular altitude and you are going at
| a different speed than the one needed for a circular
| orbit, you are either going too fast (in which case you
| are in an elliptical orbit and you will gradually
| increase altitude and lose speed until you reach the top
| of that ellipse) or you are going too slow to stay in a
| circular orbit (in which case you will follow an ellipse
| down to a lower altitude and gain speed).
|
| In that 'too slow' case, if it's _much_ too slow then the
| ellipse you follow will take you low enough to hit the
| surface or atmosphere of whatever you're orbiting (ie you
| will crash into it)
| frosted-flakes wrote:
| I think GP means that _if you are stationary relative to
| the ground_ (such as on a space elevator or a rocket
| going straight up), 35786 km up is the only height which
| is a stable orbit. If you let go of the elevator too
| early, you 'll fall to the ground; too high and you'll
| fly off into space.
| tialaramex wrote:
| I _think_ you knew this but it wasn 't obvious from how
| you wrote it. Your orbit is _not_ required to be a
| circle. The diagrams we draw for children are nice
| circles, but most things that we know are orbiting
| something do not travel in a circle, e.g. the Earth -- if
| the orbit was circular our seasons would be very
| different and the insight that the orbits can be non-
| circular ellipses was critical to the reasoning that
| eventually got us a heliocentric model of our solar
| system.
|
| Geostationary communications satellites do have a
| basically circular orbit, as you said, but many other
| birds do not.
|
| Russia has a bunch of stuff in orbits that "linger" very
| high over Russian territory for much of their orbital
| period then shoot right around close to the back side of
| the planet quickly and linger again, these are called
| Molniya orbits.
|
| The US has a bunch of secret (presumably spy) satellites
| that fly less obvious orbits like this too, for
| presumably similar reasons.
| kempbellt wrote:
| Theoretical geosync means zero velocity in any direction
| relative to ground. Zero up, down, forward, back, left,
| or right. You're stuck above a single point of
| dirt/water, over the equator, at a fixed altitude.
|
| The only way to "fall" (lower your altitude) from here
| would be via some sort of acceleration force _towards_
| ground (like a burn). So yes, your speed would have to
| increase.
| jvanderbot wrote:
| Well fine. I meant that orbital speed (the "along track
| part") would increase if you lowered the altitude of a
| geosync object with rockets, string, or any other force,
| I think.
| mLuby wrote:
| Nobody should have laughed--your misconception was one 99%
| of the population shares!
|
| Nature is enough of a gatekeeper to space, she doesn't need
| mortal deputies.
| jvanderbot wrote:
| The learning journey has been more good than bad. My
| favorite was that orbit seems far away, until you look
| out from an aircraft and realize you're 30% of the way
| there. Usually, from where you live, the next major town
| is further than LEO.
| rejectedandsad wrote:
| This is a brilliant turn of phrase and I'm definitely
| going to steal it
| solarkraft wrote:
| Nope. I don't have numbers but according to Elon Musk (who we
| probably at least agree on has a grasp of the basic
| principles) "space is easy, orbit is hard".
| toomanybeersies wrote:
| You're describing rockoons [1], which were used for launching
| (non-orbital) sounding rockets back in the 1950s.
|
| I think they fell out of use as high altitude jet aircraft
| became more common and economical as a launch platform.
|
| [1] https://en.wikipedia.org/wiki/Rockoon
| josephcsible wrote:
| > Rocket launches are extremely expensive, and most of it is
| in the lifting costs. Would it be cheaper to "lift" a rocket
| with hydrogen slowly?
|
| No: https://what-if.xkcd.com/58/
| aww_dang wrote:
| https://en.wikipedia.org/wiki/Rockoon
|
| https://en.wikipedia.org/wiki/Northrop_Grumman_Pegasus
|
| https://en.wikipedia.org/wiki/Scaled_Composites_Stratolaunc
| h
| josephcsible wrote:
| It's not impossible, sure. It's just usually not worth
| it.
| R0b0t1 wrote:
| The idea is that this gets you above the densest atmosphere
| and that could save you fuel. I used to think this, but if
| you run the numbers it doesn't work out.
| soperj wrote:
| >Getting to space[1] is easy. It's not, like, something you
| could do in your car, but it's not a huge challenge. You
| could get a person to space with a small sounding rocket
| the size of a telephone pole. The X-15 aircraft reached
| space[2] just by going fast and then steering up.[3]
|
| Loved that line. Puts the Branson/Bezos thing into
| perspective.
| toomanybeersies wrote:
| These days there are even amateur rocket clubs that have
| managed (unmanned) suborbital space launches [1].
|
| [1] http://www.uscrpl.com/traveler-iv
| radeck wrote:
| You would save around 5% fuel and multiply costs by 10.
| People have tried and tested, much better to just make the
| rocket reusable.
| RobertoG wrote:
| Never mind how crazy is your idea, there is always somebody
| that it's already trying it:
|
| https://www.zero2infinity.space/bloostar/
|
| Of course, you still have to accelerate to orbit, but you
| don't have to deal with the atmosphere.
| soperj wrote:
| From linked xkcd what if: Gravity in low Earth orbit is
| almost as strong as gravity on the surface. The Space Station
| hasn't escaped Earth's gravity at all; it's experiencing
| about 90% the pull that we feel on the surface.
| parineum wrote:
| Parent isn't talking about gravity, he's talking about
| alleviating the rocket equation by not having to lift your
| fuel with fuel.
| [deleted]
| dghlsakjg wrote:
| Yes, but...
|
| The majority of energy expended in getting to orbit is
| spent in getting to orbital velocity (going sideways),
| rather than getting to orbital altitude (going up).
| Balloons only help in going up, and only to where the
| density of the atmosphere is so low that the balloon is
| no longer lifting, they are still far short of the
| altitude necessary for orbit. Balloons top out at around
| 20-30 miles while LEO is ~100 miles.
|
| So launching using a balloon only really gives you a very
| small fuel savings
| jandrese wrote:
| That's the issue though. The hard part about achieving
| orbit isn't the height, it's the speed. In both a ground
| launch and a balloon launch you are starting at 0.
|
| This article does a better job explaining it than just
| about anything else on the web: https://what-
| if.xkcd.com/58/
|
| So complex schemes to lift the rocket to the edge of
| space don't end up buying you very much.
| postalrat wrote:
| Imagine an open deck on an airship. Or at least being able to
| open your window.
|
| Propellers far away from passengers to minimize any noise.
| DelightOne wrote:
| That and a Starlink not bound to a location - would be awesome.
| Would it be possible to live on such a ship?
| [deleted]
| findthewords wrote:
| A clear example how money in the military-industrial complex (or
| DARPA) directs innovation paths. The military does not approve of
| hydrogen blimps, and so neither can the civilian sector use them.
| jeffreyrogers wrote:
| None of the other countries are doing it either, so it isn't
| just DARPA. I think it just doesn't have an obvious use case.
|
| Everyone says cargo, but what is it better at at than rail,
| truck, ship, or air (cargo jet)? If you want cheap you go with
| rail or ship. If you want fast you go with jet and then truck
| for the last mile. Airship would be cheaper than air, but
| noticeably slower, so it basically has to compete with truck on
| price. Can it do that? Maybe, I have no idea.
| epistasis wrote:
| This is really interesting... I am suspicious of fossil fuel
| based hydrogen, but as electrolyzed hydrogen gets cheaper, this
| could be very useful for some applications.
| ajuc wrote:
| Interesting. I did some back of the envelope calculations.
|
| A 100% efficient electrolyser requires 39 kWh of electricity to
| produce 1 kg of hydrogen. Best practical ones need about 50 kWh
| [1].
|
| Hinderburg had about 18 metric tons of hydrogen [2], filling it
| would require about 1 GWh of energy. The good thing is - it
| could be used as a way to balance the electric network because
| we don't particularly care when we fill it as long as it's
| done. So we can do it when there's overproduction only. The
| energy would be quite cheap - in some cases you can get paid
| for using energy when electrical network needs balancing. Same
| thing is done with other energy-intensive industrial processes
| like smelting.
|
| In Germany (not particularly sunny but a lot of solar panels so
| effects of scale are there) the low bounds for price of 1 MWh
| of solar energy in 2018 was about 37 euro [3], let's round that
| up to 50 - filling Hindenburg would require about 50 000 euro
| of renewable energy.
|
| Additionally it would require about 9 * 18 ~= 162 tons of water
| and some additives to make it conductive. Maybe sea water could
| be used as is?
|
| [1] http://www.renewableenergyfocus.com/view/3157/hydrogen-
| produ... [2] https://www.history.com/news/the-hindenburg-
| disaster-9-surpr... [3]
| https://en.wikipedia.org/wiki/Cost_of_electricity_by_source#...
| epistasis wrote:
| Current cost of electrolyzed hydrogen is EUR2.5-EUR5.5/kg,
| and the EU hopes to get that to less than half by 2030:
|
| https://about.bnef.com/blog/liebreich-separating-hype-
| from-h...
|
| $100k for a filling, with many many re-uses, could maybe be
| feasible today, and $20k should definitely be.
|
| One note about hydrogen production, as I understand it, is
| that electrolyzers are enough of a capital expense that you
| want to be running them at fairly high capacity factors.
| Cheaper energy helps, but cheaper electrolyzers would
| probably help more.
| fire wrote:
| There are some really interesting chemical methods of creating
| hydrogen gas using like, aluminum and sodium ( or potassium? )
| in water that might be able to allow for on demand gas
| generation with otherwise solid/condensed fuel sources;
|
| it's "simple" enough of a concept that creators[1] are doing it
| to power their own systems, though I imagine scaling it up
| carries its own set of difficulties ( e.g., using aluminum
| nanoparticles for greater surface area to more rapidly generate
| gas, but keeping it cool enough to avoid problematic side
| effects, or like, you know, exploding in general )
|
| Edit: it looks like MIT is actually actively working[2] on this
| type of clean hydrogen production from the viewpoint of
| creating a scalable system!
|
| 1: https://youtu.be/LKfbZvpoQ0g?t=5m23s
|
| 2: https://energy.mit.edu/news/using-aluminum-and-water-to-
| make...
| Baeocystin wrote:
| Hydrogen gas leaks through _everything_ , and embrittles most
| metals. It is not an easy substance to work with. Combine that
| with having one of the widest ignition ranges of any flammable
| material, and I'll just stay on the dubious side of it ever
| getting used as a large-scale lifting gas again.
| jeffreyrogers wrote:
| It doesn't embrittle aluminum at normal temperatures and
| stainless steel is significantly less affected. I agree it is
| hard to work with, but think the reason it isn't used in this
| sort of application is more due to economics than inherent
| properties of hydrogen.
| trenning wrote:
| I've found it interesting that power plant generators are sealed
| and cooled with hydrogen gas. A hundred tons of steel and copper
| generating thousands of volts of electricity is cooled with
| hydrogen.
|
| Sounds like a recipe for an explosion movie style, yet there
| aren't any.
| jeffbee wrote:
| There aren't any because hydrogen cooled turbomachinery is
| complex and high-touch. There are systems that circulate the
| gas out of the generator and into separators that remove the
| inevitable air contaminants and dryers to remove the water.
| They aren't really seal-and-forget systems like a helium-filled
| hard disk drive might be.
| renewiltord wrote:
| An entertaining read
| https://twitter.com/RealhumanSchwab/status/14219494217810616...
|
| Very related. I won't spoil it for you but it's entertaining.
|
| Edit: Responders, please! You're spoiling the fun! If
| https://twitter.com/RealhumanSchwab/status/14219496075426160...
| doesn't give it away I don't know what will.
| jandrese wrote:
| That thread went down the insane conspiracy rabbit hole in a
| hurry.
| stickfigure wrote:
| Disappointing. The first 2/3 of the thread was pretty good,
| nice narrative with pictures. The twitter format sucks
| though.
| itsyaboi wrote:
| https://threader.app/thread/1421949421781061633
| paxswill wrote:
| Echoing a sibling comment, that thread goes down the conspiracy
| rabbit hole _very_ quickly. A few inaccuracies I noticed before
| giving up:
|
| * "Remember, only 13 deaths out of the 36 passengers on the
| airship died." This skips the crew deaths (who also died at
| about the same rate).
|
| * There were a bunch of photographers present at Lakehurst as
| it was the first crossing of 1937. The audio recording was not
| scripted, the original disc records a pressure wave which is
| followed by Morrison exclaiming that the Hindenburg is on fire.
|
| * "Mary Jane" can be a real person's name.
|
| * "Hugo Eckener, former head of the Zeppelin Company, Charles
| Rosendahl, commander of the Naval Air Station at Lakehurst, Max
| Pruss, captain of the Hindenburg and most of the surviving crew
| believed the airship had been sabotaged.". Eckener stated that
| it could be sabotage when he was first told the Hindenburg had
| gone down. He later backed the static spark theory.
| foota wrote:
| Out of curiosity, would it be feasible to produce enough helium
| for commercial use through fusion (either power generating or
| not)?
| ckastner wrote:
| Hydrogen is probably not as unsafe as the general population
| might think it is, but it find it bizarre just how much the
| article downplays the flammability issue. For example:
|
| > _Fun fact: pure hydrogen doesn't burn. It needs an oxidizer--
| like the oxygen in air._
|
| Airships literally float in that oxidizier!
| TinyBig wrote:
| "Floating in oxidizer" doesn't matter - airships are under such
| low pressure that leaks are too slow to maintain a flame front.
| I researched this quite a bit for the Army back in the day,
| even worked with a vendor who fired 50 caliber tracer rounds
| through an airship to try to get it to catch on fire, and it
| did not.
| MichaelZuo wrote:
| There are rumours that because of this fact, that the
| Hindenburg disaster was not from natural causes.
| solarkraft wrote:
| Okay, what's the alternative scenario and how do we ensure
| that doesn't happen?
| ElijahLynn wrote:
| Do you mean that it was sabotaged?
| aww_dang wrote:
| https://en.wikipedia.org/wiki/Pomeroy_bullet
|
| The British anti-zeppelin forces researched this problem and
| were unable to come up with a method of reliably igniting the
| hydrogen gas.
| Retric wrote:
| Crashing aircraft into them was quite reliable, it just
| wasn't cheap.
| JulianMorrison wrote:
| But they only burn easily at the interface. The trick would be
| to control fire there - keep them from mixing, keep the flame,
| if one were to start, from enlarging the hole.
| minikites wrote:
| Good point. I remember a science demonstration where lighting
| a balloon filled with a mixture of hydrogen and oxygen caused
| a much more violent eruption compared to a balloon of pure
| hydrogen.
| GauntletWizard wrote:
| Not only control where the fire is, but do so with materials
| light enough for an airship. It's a hard problem.
| JulianMorrison wrote:
| Not necessarily. Remember, you only need to control the
| interface. A bag, not a wall.
| R0b0t1 wrote:
| The burning plume escapes upward. It's probably safer than
| aviation fuel.
| varjag wrote:
| Right, seen that in Hindenburg footage.
| R0b0t1 wrote:
| The Hindenburg was covered in aluminum paint.
| varjag wrote:
| Aluminium must be really exotic material in airspace
| applications?
|
| Also:
|
| _The truth is that the dope used on the Hindenburg was
| specifically chosen for its low flammability, and the
| composition of the dope had almost nothing in common with
| the formula used to make rocket fuel._
|
| https://www.airships.net/hindenburg-paint/
| [deleted]
| kurthr wrote:
| Even that wouldn't be such a big issue, if the flammability
| limit of hydrogen is from 4% to 74% in air (~20x). For
| comparison gasoline vapor is 1.4% to 7.6% (~5x)
|
| In an open space that's not so bad since the flammable material
| literally floats away (while gasoline vapor settles), but it's
| still an issue in any contained area.
| contravariant wrote:
| Yeah it kind of defeats the point when your definition of
| 'doesn't burn' covers every single substance.
| dragontamer wrote:
| Except Li-ion batteries, which burn with their own oxidizer.
| hobs wrote:
| Well there's plenty of monoprops that supply their own
| oxidizer, and oh boy are they absolutely dangerous as hell.
| https://en.wikipedia.org/wiki/Monopropellant
| yellow_lead wrote:
| And rocket fuel? Technically
| dragontamer wrote:
| Rocket fuel is more of a "pre-mixed with oxidizier" sorta
| thing.
|
| Although I am enjoying the side discussion about
| monopropellants.
| gpm wrote:
| Most modern rockets are liquid and mix the fuel and
| oxidizer only at the point of combustion, burning H2/O2,
| Kerosene/O2 or more recently CH4/O2.
|
| Mono-propellant, and solid (not hybrid) rocket fuel fits
| the description though
| crazydoggers wrote:
| > _Mono-propellant, and solid (not hybrid) rocket fuel
| fits the description though_
|
| Decomposition doesn't count as "burning" which means
| combustion. Fusion and fission release energy as well,
| but I don't think anyone calls fusion "burning" hydrogen.
| gpm wrote:
| Generally I don't think this type of language debate is
| useful, we aren't debating what is happening, just what
| to call it, and that's pretty boring. If you want to call
| it not burning, ok, be my guest. Hopefully my answer is
| still an interesting point about the kinds of violent
| chemical reactions that exist and could make a substance
| dangerous to work with in an environment without
| (outside, in the case of solid rocket fuel) oxidizing
| agents.
|
| I'll make an exception and reply about the language in
| this case because I there's a broader point I want to
| make:
|
| English isn't a language defined based of "X happens if
| chemical reactions Y happens behind the scenes", because
| we didn't even know about chemical reaction Y when
| English was invented. Moreover if you tried to define it
| as oxidation you'd fail, rust isn't burning, meanwhile
| (non-oxidizing) chemical burns, sunburns, etc all exist
| because they were just analogous enough to the concept of
| fire. If people knew about some chemical that decomposes
| into plasma in the 1600s, they definitely called it
| burning even if there was no oxidation.
|
| Meanwhile people definitely refer to fusion as "burning",
| e.g. see this stackexchange question with lots of links
| to wikipedia and the like which refer to different kinds
| of fusion as burning [1] or ctrl-f burning in this
| wikipedia article [2] (which is linked from [1]).
|
| [1] https://astronomy.stackexchange.com/questions/43907/h
| ydrogen...
|
| [2] https://en.wikipedia.org/wiki/Stellar_nucleosynthesis
| crazydoggers wrote:
| I don't really take this as a language debate though. It
| clearly is about the fact that people don't understand
| what an oxidizer is at a chemical level.
|
| Someone who says the following isn't just using language
| inaccurately, it actually shows a fundamental
| misunderstanding of combustion:
|
| > _pure hydrogen doesn't burn. It needs an oxidizer--like
| the oxygen in air._
|
| That statement, no matter how you take it, leaves an
| assumption that other gases might burn like hydrogen
| without oxygen, which is again a fundamental
| misunderstanding of chemistry.
|
| In addition calling something "self oxidizing" doesn't
| make sense. There are always mixtures of fuel and
| oxidizers... whether those are gas and fuel, solid and
| fuel, mixed in gunpowder form, mixed as gasoline and air
| in a carburetor, etc. So if I supply you a balloon with
| the proper stoichiometric ratio of gasoline and air, is
| that "self-oxidizing"? If so then everything is self
| oxidizing.
|
| And while I would agree that people do refer to hydrogen
| as "burning" I actually thing this is a again a prime
| example of people not understanding the underlying
| physics. Most people don't understand how fusion works,
| so calling it "burning" is a lazy way to conceptualize
| what the sun is doing. Leading to yet another source of
| scientific illiteracy.
|
| Words are tools. They should be used wisely.
| gpm wrote:
| Self oxidizing mixtures exist. Gun powder is probably the
| classic example.
|
| Monopropellants, that aren't mixtures, exist and "burn" too,
| high concentration H2O2 for instance.
| toomanybeersies wrote:
| T-Stoff/High-Test Peroxide doesn't actually burn, but
| rather decomposes into water and oxygen.
| rbanffy wrote:
| They can still burn in the presence of an oxidiser. They
| don't need it, but that won't stop them from burning, or
| blowing up, or doing whatever they want to do, as
| monopropellants are really (no pun intended) impulsive.
| crazydoggers wrote:
| Gunpowder still requires an oxidizer, it just happens to be
| mixed in. The potassium nitrate is the oxidizer, KN03,
| whereas the sulphur and charcoal are the fuels that burn.
|
| Pretty much any combustion requires a molecule with oxygen
| to accept the electrons: exceptions exist with halogens
| like chlorine... but these are still called "oxidizers"
|
| So saying hydrogen doesn't burn without an oxidizer still
| makes little sense. Hydrogen will combust with either
| oxygen or chlorine for example, both oxidizers. Without
| those then nothing happens because nothing can combust
| without an oxidizer... You may just not realize the
| oxidizer is mixed with the fuel.
| jandrewrogers wrote:
| Technically speaking, sulfur is an oxidizer in gunpowder,
| not fuel. Sulfur is even in the same elemental group as
| oxygen.
|
| Sulfur is commonly used as an oxidizer for metal fuels.
| In the case of gunpowder, that would be the potassium in
| potassium nitrate.
| Retric wrote:
| Mixtures aren't single substances. Monopropellants don't
| burn, their just one of many exothermic reactions.
| gpm wrote:
| > Monopropellants don't burn, their just one of mangy
| exothermic reactions.
|
| Gave a fairly full reply to this over here
|
| https://news.ycombinator.com/item?id=28121336
| Retric wrote:
| No offense intended, but the fact language evolves isn't
| an excuse to be imprecise. As arch discharge lighting
| became popular the idea of burning began to separate from
| the creation of plasma because nothing was being used up.
| We still say electrical components "burned out" because
| of this idea of fire as something that consumes.
|
| Anyway, as long as you understand that's not what is
| meant by the term burning I don't really think there is
| anything worth arguing about here. And hey in 100 years
| your definition might win.
| gpm wrote:
| I guess I got into this argument, so to be clear, I am
| not conceding this (nor do I particularly want to
| continue this part of the argument, so I won't and ask
| the others do not take a lack of reply as you conceding
| the opposite)
|
| > that's not what is meant by the term burning
|
| Monopropellants may not agree with your use of the term
| burning, but I deny that they do not agree with the
| majority of english speakers use of the word burning, or
| the definition of the word burning that you will find in
| common dictionaries [1].
|
| [1] For example merriam-webster defines "burning" as
| "being on fire", "fire" as "the phenomenon of combustion
| manifested in light, flame, and heat" and "combustion" as
| "a usually rapid chemical process (such as oxidation)
| that produces heat and usually light".
| Retric wrote:
| Fair enough, I will not try and persuade you. I am sure
| you can find people using the term burning in association
| with monopropellants.
|
| For anyone reading this I will say Wikipedia and at no
| point is combustion or burning used do describe them.
| "Monopropellants[1] are propellants consisting of
| chemicals that release energy through exothermic chemical
| decomposition"
| https://en.wikipedia.org/wiki/Monopropellant
| dragosmocrii wrote:
| Although there's a slight difference in meaning, I prefer the
| term zeppelin to blimp.
|
| fyi: the difference is in the frame construction. A zeppelin has
| a rigid frame that keeps it's shape if the gas is lost, whereas a
| blimp has a semi-rigid frame that will deflate if the gas isn't
| present.
| newbie789 wrote:
| This article is interesting. "Hydrogen doesn't explode without
| being mixed with air first then ignited" is a kind of funny
| statement. I read that as "hydrogen doesn't explode outside of
| when it does"
|
| I'd ask "was this written by a hydrogen sales team?" but it'd be
| mind boggling if it weren't. The blaming of special interest
| groups right off the bat, and the blaming the lower-performing
| helium as the cause for a crash (that iirc, involved a leak so
| I'm not sure how that 8% difference could've saved everyone) are
| naked examples of sales speech.
|
| "Maybe you'll blow up! Who cares? You get 8% more lift and stick
| it to the uh, Bureau Of Mines"
| iso1210 wrote:
| Fossil fuel companies getting PR to spin everything they can into
| trying to improve hydrogen's image.
| jeffreyrogers wrote:
| Hard to imagine a solution to climate change that doesn't
| involve the fossil fuel companies given their enormous
| political importance.
| toiletaccount wrote:
| What's wrong with hydrogen? You can produce it with renewables,
| it basically works with existing IC technology and the exhaust
| is just water. The only hangup is the energy/volume ratio,
| which is an area of ongoing research.
| throw37388 wrote:
| Hydrogen burns and produces greenhouse gas!
| jbotz wrote:
| Although water vapor is technically a "greenhouse gas", it
| is not responsible for forcing any global warming. That's
| because at the temperatures we're interested in water is a
| liquid, not a gas, and what small amount of water remains
| gaseous is entirely determined by the air's temperature. So
| water vapor can't force any warming, it can only amplify
| other forcings.
| detaro wrote:
| uh, no?
| iso1210 wrote:
| Well technically yes
| throw37388 wrote:
| Yes
|
| >> Water vapor is known to be Earth's most abundant
| greenhouse gas
|
| https://www.nasa.gov/topics/earth/features/vapor_warming.
| htm...
| toiletaccount wrote:
| Run it through a condenser, feed it into a holding tank
| and dispose of the water at each filling station?
| jbotz wrote:
| No need, the atmosphere is a sufficient condenser. Unless
| you heat the atmosphere with a lot more energy than the
| little bit you get from combusting the hydrogen in
| question... but then you'll have bigger problems as your
| oceans begin to evaporate.
| detaro wrote:
| Large-scale hydrogen production is commonly based on fossil
| fuels right now, and that's what many fossil fuel companies
| push when they talk hydrogen. End-to-end efficiency is also
| not that great. That doesn't necessarily disqualify hydrogen,
| but it's not as obvious as often presented.
| toiletaccount wrote:
| It seems like a good hydrogen chain could look like: solar
| panels floating in the ocean split the water and store it,
| a tanker picks it up and takes it to port. Burn hydrogen at
| a power plant for the grid, condense the vapor and use it
| for drinking or farming.
|
| It seems like a great fit for...a lot of use cases. (if we
| can get over some of the storage hurdles)
| namibj wrote:
| Even then it's comparatively trivial to capture the carbon
| dioxide from steam reforming, as opposed to gasoline in a
| car.
| binbag wrote:
| Is this a reprint from April 1st?
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