When an airplane lands in crosswinds (i.e. wind direction is not parallel to the runway) its nose is pointed at an angle to the runway. When it touches down, the plane needs to abruptly swivel so the nose is pointed down the runway, as now it is being directed by wheels rather than wind. In strong crosswinds, this operation looks really freaky. Here are crosswind landing videos.
Here we have a plane with landing gear much much further apart than any ordinary plane. I wonder whether this makes it harder to do that abrupt swivel? If so, the plane will have much greater restrictions on crosswind landings.
If the gasoline engine is supplying electricity to a hybrid, it doesn't need a very wide RPM range. It can run at optimum RPM at all times except briefly when starting up and shutting down.
For cars and cell phones, energy density matters a lot. For stationary home and industrial scale installations, it matters much less. Are lithium ion batteries still the best choice for such applications? (For the purpose of this question, I'm only considering batteries. I am aware that there are many other industrial scale electricity storage technologies proposed or in use.)
In principle, once you have the continuous communication anywhere in the world, you can program the transponders to start churning out black-box type telemetry whenever a dangerous anomalous condition is detected in the plane (e.g. stall, upset, fire.) So it is a somewhat separate issue, rather than a completely separate issue.
Such emergency uploads aren't going to eliminate the need for black boxes: the bandwidth won't be available to transmit everything, and sometimes the vital clue is something that happened 30 minutes before the crash. (And sometimes the interval between detecting 'something is wrong' and total destruction is a few seconds.)
The only infectious human disease we have ever eradicated is smallpox, which was eradicated way back in the 1970s. From an eradication point of view, measles and smallpox are very similar: they are viruses, they are highly infectious, they do not mutate super-fast, they infect only humans, it is obvious when someone has the disease, there is a very effective vaccine. From a technical point of view, eradicating measles is a very similar task to eradicating smallpox.
However, there is one significant difference: measles is a fairly worrying disease, whereas smallpox is absolutely terrifying. This means there hasn't been the social and political will to push an eradication program. If the will did exist, we could wrap it up in about 10 years (wild guess on my part), and then nobody would ever need a measles vaccination ever again. Don't like vaccinations? Push for eradication. Your kids will get the jab, but your grandkids, great-grandkids, etc. forever, will not.
The list of diseases considered eradicable (as of 2008) is quite short. For example, influenza is not - it readily jumps species (so eradication from humans would require vaccinating wild ducks, for example) and it mutates rapidly, so new vaccines are constantly needed.
The list: Smallpox (eradicated) Polio (on the verge of eradication, probably 5 to 10 years off) Dracunculiasis/Guinea worm (on the verge of eradication) Yaws (on the verge of eradication) Malaria (eradication still decades away) Hookworm Lymphatic filariasis Measles Mumps Rubella Lymphatic filariasis Cysticercosis
How many hardware engineers does it take to change a light bulb? None - we'll fix it in software.
How many software engineers does it take to change a light bulb? None - we'll document a workaround.
How many tech writers does it take to change a light bulb? None - the user can figure it out.
So in this case we have:
How many hardware engineers does it take to not crash an airplane with a faulty sensor? None - we'll detect and avoid it in software.
How many software engineers does it take to not crash an airplane with a faulty sensor? None - the pilots can be trained to disable the auto-trim mechanism.
How many trainers does it take to not crash an airplane with a faulty sensor? None - the pilots can figure it out.
How many pilots who have no idea why the plane is reacting as it is does it take to crash an airplane with a faulty sensor? None - the plane will do it for them.
"Garfield" - could be a person or a place, let's keep going "Garfield phones" - OK, Garfield is phoning someone. "Garfield phones beach" - maybe a public phone on the beach, or we'll get a useful continuation like "lifeguard" to which "beach" is an adjective. "Garfield phones beach mystery" - OK, I've lost the plot here. Abstract concepts don't usually accept phone calls. Maybe "lifeguard" will still come next to rescue some sense out of this. "Garfield phones beach mystery finally". Nope, no lifeguard, no rescue. Perhaps "Garfield phones beach, mystery finally solved..." Totally makes sense, but I have to assume a nonexistent comma. Maybe Garfield is a place with a beach, and the beach has a phones mystery. But then it should be "Garfield Beach phones mystery..." Maybe there is a Phones Beach? But then what is Garfield doing? Surely nobody named a place "Garfield Phones"?
fivethirtyeight.com did a good job on the poll analysis. Somewhat simplified, before the 2016 election they were saying: Clinton is clearly ahead in the polls, but the amount she is ahead by is about the same as the typical polling error (i.e. when after the election we compare average-of-polls to actual-votes-cast.) This means there are three roughly equally probable outcomes: 1/3 probability, the polls are close to being correct, and Clinton wins. 1/3 probability the polls are significantly out, underestimating Clinton's support, so Clinton wins big. 1/3 probability the polls are significantly out, underestimating Trump's support, so Trump wins narrowly. (Of course their analysis was more subtle - they didn't just identify three outcomes and arbitrarily say they were equally likely, it just so happened that these possibilities came out to be roughly 1/3 each.)
I haven't looked at the analyses that were giving something like 98% win to Clinton, but likely they made a bad assumption that poll errors were uncorrelated - that if Trump outperformed polls in one state, that made it no more or less likely that he'd outperform in other states.
Thanks for a well thought out response, as opposed to those who take me for an evil anti-net-neutrality shill. (As stated in another response, I am pro net neutrality.)
To see if I understand correctly, I shall try to summarize. The colocation benefits are small and possibly non-existent. Designing regulations to encourage colocation is likely to have adverse effects (on competition) that outweigh the benefits. So enforce net neutrality, and let colocation fall where it may.
Is this about right?
I like the trade you describe for Akemai. It is mutual benefit without either side trying to squeeze maximum money from the other. One problem I see is that in the simple case you describe, Akemai has no incentive to use power efficient hardware. There are a variety of ways minor tweaks to the agreement could deal with this, which for simplicity or because you are not privy to them, you have omitted.
OK, substitute 'efficient' for 'smart'. I agree that is a better word.
If regulations favours inefficient solutions over efficient ones, this is not great. It might well be a price we're willing to pay (e.g. companies spending lots of money on advertising to get market share in a fixed sized market is inefficient), but it at least suggests there might be a problem with the regulations which could be fixed.
My non-net-neutrality solution was not put forward as 'smart' (efficient), just as a way in which non-net-neutrality might cause the efficient solution to come about. (I.e. I care that colocation happens, not that the commercial arrangements that make it happen are organized in any particular way.) I concede that it is not the only way in which things might go without net neutrality.
The point remains: under the right circumstances, colocation is the efficient solution. Implementing the solution produces a surplus, which can be shared in some way between the participants. This is all true with or without net neutrality. What incentives are there to implement the efficient solution, and how does the surplus get divided, with or without net neutrality?
Consider that 1000 of my local ISP's customers want to watch a hot new Netflix show. My ISP is 1000 km from the nearest Netflix data center. The dumb solution is that 1000 customers sent requests to ISP who sends them 1000 km to Netflix who sends the show 1000 times over the backbone connection. The smart solution is that Netflix colocates a server in my ISP's small local data center which they send the popular shows to just once over the backbone, and this server sends it to the 1000 local customers.
For the smart solution to happen, there have to be incentives for Netflix and the ISP to do it. Without net neutrality, it could work: ISP gets to advertise that Netflix is 0 rated (or 0.5 rated or whatever) towards customer data caps, and benefits from being more attractive to customers and not paying for so much backbone data. Netflix benefits by not needing so much internet backbone. Customers benefit obviously, at least in the short term. (Customers may suffer in the long term through lack of competition.) Would-be Netflix competitors are very unhappy. Possibly money changes hands between ISP and Netflix to make this work, although I'm not sure in which direction.
With net neutrality, the ISP can't offer reduced rating on Netflix data. How do the incentives work in this case? The great reduction of data going over the backbone should provide savings, but who was paying this cost in the first place? Does the ISP want to pay Netflix to colocate a server, or to charge them for it?
I've long wondered why Boeing doesn't make a clean sheet replacement for the 737. For a plane sold in such vast numbers, the case for a clean redesign is much easier to make. My understanding is that currently they're looking to a 757 replacement/A321 competitor (https://en.wikipedia.org/wiki/Boeing_New_Midsize_Airplane) as their next clean design, with a 737 replacement possibly after that.
Back in my day, we waited 1997 and then worked excessive hours in a panic for three years. If it was good enough for us, it should be good enough for you.
I actually had a 100% genuine post-Y2K bug that I needed to fix. I was one of the main people in charge of source control (which was SCCS) in our company at the time. On 2nd Jan my on-call cell phone rang (while I was watching Sleepy Hollow in a movie theatre - oops!) A few rather keen developers were working, despite it being a holiday, and were getting weird stuff happening in SCCS. It turned out that the server they were using had SCCS via someone just copying over the binaries, rather than correctly installing them, so when it got its Y2K-compliant OS upgrade, those binaries were not replaced, and were not Y2K-compliant. I was able to diagnose the problem, patch the dozen or so source code commits which they'd made with the bad binaries, and call in a sysop to install the correct binaries. (I didn't have root on that server.)
Ditto. I felt smugly superior to be using little-endian DD-MM-YYYY which was so much better (consistent) than the USA's middle-endian MM-DD-YYYY format. Then starting in 1988, my MSc thesis was on an experiment with many Japanese collaborators (they had the money, we had the supernova) and I saw them use YYYY-MM-DD and I was an instant convert. We're already big-endian in our decimal notation, so dates should be too. And in YYYY-MM-DD, chronological order and 'alphabetic' order are the same.
Yes, saves the airline a little bit of money to not have the passenger on board. A number I came across was that for a typical jet airliner each extra 100kg of payload increases fuel burn by about 3kg/hour. I think this number was in the context of long haul flights. Short haul and turboprop aircraft would have somewhat different numbers. I think I saw this number 5 to 10 years ago, so more recent higher efficiency engines likely have a smaller number.
This clearly has consequences for airlines deciding how much fuel to load. They have to take extra fuel beyond what they expect to burn to get to the destination, to allow for contingencies (and because they legally have to.) It is something like an insurance policy: loading an extra 10 tonnes of fuel for a 10 hour flight will cost you 3 tonnes of extra fuel burned, whether you use that reserve or not. Usually you won't, but sometimes it will save your bacon and avoid having to divert to an unexpected airport, and then having to perhaps get hotel rooms for all the passengers and rebook them to their expected destination, plus annoying passengers and having them perhaps never fly with you again. Usually airlines will load the legal minimum (from memory, something like fuel to fly to destination plus fuel to fly from there to the further of the two alternate landing airports plus 30 minutes) but if in-air delays seem likely (e.g. bad weather) they'll load more.
I had the impression there was some sort of feedback mechanism in how much bitcoin you get for mining a block. TFA doesn't talk about this. This would mean that if your mining costs are substantially higher than others, you'll be unprofitable no matter what the bitcoin price is doing.
Perhaps it is just a supply/demand thing? The more miners there are, the lower the chance you get to mine the block, so the lower the expected return you get in bitcoins. Then for a fixed bitcoin reward, the number of miners will bring the expected return in equilibrium with bitcoin value.
Could someone with knowledge please talk about feedback mechanisms?
I think nothing. They need a liquid electrolyte around the Na electrode, and it can't be aqueous because that would react violently with the Na. So they have an organic electrolyte into which the Na can dissolve, and then it passes through a membrane into aqueous solution where the rest of the reactions happen.
From my (not a chemist) reading of the paper: If you have a battery which is consuming sodium to produce electricity, you want the electrolyte around the cathode to be acidic, and the reaction will be producing OH-, neutralizing acids. Continuously dissolving CO2 into this water produces a source of acidity, so the CO2 not only makes the battery works better, but it simultaneously sequesters the CO2 as NaHCO3.
I think this really is the core of the proposal - make the battery work better and sequester CO2 at the same time.
Your suggestion of throwing Na into water wastes lots of energy - it has the same H2 production as the Na+CO2 scheme, but doesn't produce any electricity.
Yes, you need to use electricity (more than you get out) to create metallic Na, so this is a battery rather than energy source, and TFA deceptively omits this. I don't know how efficient this battery would be.
From my skimming of the paper, they'd be getting replacement sodium from sea water, not from the sodium bicarbonate which they produce. That would be sequestered somewhere.
Reading a bit more (I am not a chemist): "Because the potential of cathodic reaction is closely influenced by the pH of aqueous solution, the dissolution of CO2 renders a favorable electrochemical reaction environmentby acidifying the aqueous solution."
"Thus, notably, this combined cathodicreaction not only utilizes CO2 to generate H2 but also possesses highly efficient reaction kinetics,possibly overcoming the key issue of sluggish discharge rates for common metal-air batteries."
Figure 4 shows this is a rechargeable battery! "On repeating the discharge-charge process, the cathode potential profile(Ecathode) presents discharging and charging plateau, clearly proving that this system is rechargeable."
"To confirm the reversibility of hybrid Na-CO2cell, the anodic charge profile (electrolysis profile) was observed. Because Na is one of the most abundant elements on earth, Na metal anode could be easily recycled through a charging process in Na-ion-containing aqueous solution, such as seawater. Figure 4A shows an oxidation rotating disk electrode profile for examining whether CO2 was reproduced during the charging process. Generally, the charging process is regarded as the opposite reaction of the discharging reaction. In this work, however, the generated H2 gas from the discharging process is naturally removed on the surface of electrode, and thus the oxidation reaction proceeds as the oxygen evolution reaction (OER) from the water oxidation (Equation 6). 2H2O -> O2(g) + 4H+ + 4e- Eo= 1.229 V"
As this equation does not involve Na, I'm still unclear on how they are regenerating their Na.
The paper can be downloaded (no paywall) from here. Equation 5 "Net equation" is 2Na + 2H+ -> 2Na+ + H2, E0 = 2.71V.
So yes, it works by consuming sodium metal. I am underwhelmed.
How much energy could we get from the metallic sodium if we didn't turn CO2 into NaHCO3 as a side reaction? What is our efficiency at making metallic Na? If these cells are sufficiently cheap, reliable, high power output, and efficient there might be potential for using this for grid scale energy storage in the form of metallic Na. Doing so would have an advantage of energy storage being limited only by your ability to store sodium, so it could work on seasonal timescales. Of course, then you'd have seasonal H2 production which would carry its own storage issues.
Slashdot Mirror
When an airplane lands in crosswinds (i.e. wind direction is not parallel to the runway) its nose is pointed at an angle to the runway. When it touches down, the plane needs to abruptly swivel so the nose is pointed down the runway, as now it is being directed by wheels rather than wind. In strong crosswinds, this operation looks really freaky. Here are crosswind landing videos.
Here we have a plane with landing gear much much further apart than any ordinary plane. I wonder whether this makes it harder to do that abrupt swivel? If so, the plane will have much greater restrictions on crosswind landings.
When the engine is driving a generator, you can optimise the engine and generator to operate at whatever torque and RPM works best.
If the gasoline engine is supplying electricity to a hybrid, it doesn't need a very wide RPM range. It can run at optimum RPM at all times except briefly when starting up and shutting down.
For cars and cell phones, energy density matters a lot. For stationary home and industrial scale installations, it matters much less. Are lithium ion batteries still the best choice for such applications? (For the purpose of this question, I'm only considering batteries. I am aware that there are many other industrial scale electricity storage technologies proposed or in use.)
In principle, once you have the continuous communication anywhere in the world, you can program the transponders to start churning out black-box type telemetry whenever a dangerous anomalous condition is detected in the plane (e.g. stall, upset, fire.) So it is a somewhat separate issue, rather than a completely separate issue.
Such emergency uploads aren't going to eliminate the need for black boxes: the bandwidth won't be available to transmit everything, and sometimes the vital clue is something that happened 30 minutes before the crash. (And sometimes the interval between detecting 'something is wrong' and total destruction is a few seconds.)
The only infectious human disease we have ever eradicated is smallpox, which was eradicated way back in the 1970s. From an eradication point of view, measles and smallpox are very similar: they are viruses, they are highly infectious, they do not mutate super-fast, they infect only humans, it is obvious when someone has the disease, there is a very effective vaccine. From a technical point of view, eradicating measles is a very similar task to eradicating smallpox.
However, there is one significant difference: measles is a fairly worrying disease, whereas smallpox is absolutely terrifying. This means there hasn't been the social and political will to push an eradication program. If the will did exist, we could wrap it up in about 10 years (wild guess on my part), and then nobody would ever need a measles vaccination ever again. Don't like vaccinations? Push for eradication. Your kids will get the jab, but your grandkids, great-grandkids, etc. forever, will not.
The list of diseases considered eradicable (as of 2008) is quite short. For example, influenza is not - it readily jumps species (so eradication from humans would require vaccinating wild ducks, for example) and it mutates rapidly, so new vaccines are constantly needed.
The list:
Smallpox (eradicated)
Polio (on the verge of eradication, probably 5 to 10 years off)
Dracunculiasis/Guinea worm (on the verge of eradication)
Yaws (on the verge of eradication)
Malaria (eradication still decades away)
Hookworm
Lymphatic filariasis
Measles
Mumps
Rubella
Lymphatic filariasis
Cysticercosis
How many hardware engineers does it take to change a light bulb?
None - we'll fix it in software.
How many software engineers does it take to change a light bulb?
None - we'll document a workaround.
How many tech writers does it take to change a light bulb?
None - the user can figure it out.
So in this case we have:
How many hardware engineers does it take to not crash an airplane with a faulty sensor?
None - we'll detect and avoid it in software.
How many software engineers does it take to not crash an airplane with a faulty sensor?
None - the pilots can be trained to disable the auto-trim mechanism.
How many trainers does it take to not crash an airplane with a faulty sensor?
None - the pilots can figure it out.
How many pilots who have no idea why the plane is reacting as it is does it take to crash an airplane with a faulty sensor?
None - the plane will do it for them.
(No, this isn't meant to be funny.)
"Garfield" - could be a person or a place, let's keep going
"Garfield phones" - OK, Garfield is phoning someone.
"Garfield phones beach" - maybe a public phone on the beach, or we'll get a useful continuation like "lifeguard" to which "beach" is an adjective.
"Garfield phones beach mystery" - OK, I've lost the plot here. Abstract concepts don't usually accept phone calls. Maybe "lifeguard" will still come next to rescue some sense out of this.
"Garfield phones beach mystery finally". Nope, no lifeguard, no rescue.
Perhaps "Garfield phones beach, mystery finally solved..." Totally makes sense, but I have to assume a nonexistent comma.
Maybe Garfield is a place with a beach, and the beach has a phones mystery. But then it should be "Garfield Beach phones mystery..."
Maybe there is a Phones Beach? But then what is Garfield doing? Surely nobody named a place "Garfield Phones"?
fivethirtyeight.com did a good job on the poll analysis. Somewhat simplified, before the 2016 election they were saying: Clinton is clearly ahead in the polls, but the amount she is ahead by is about the same as the typical polling error (i.e. when after the election we compare average-of-polls to actual-votes-cast.) This means there are three roughly equally probable outcomes: 1/3 probability, the polls are close to being correct, and Clinton wins. 1/3 probability the polls are significantly out, underestimating Clinton's support, so Clinton wins big. 1/3 probability the polls are significantly out, underestimating Trump's support, so Trump wins narrowly. (Of course their analysis was more subtle - they didn't just identify three outcomes and arbitrarily say they were equally likely, it just so happened that these possibilities came out to be roughly 1/3 each.)
I haven't looked at the analyses that were giving something like 98% win to Clinton, but likely they made a bad assumption that poll errors were uncorrelated - that if Trump outperformed polls in one state, that made it no more or less likely that he'd outperform in other states.
Thanks for a well thought out response, as opposed to those who take me for an evil anti-net-neutrality shill. (As stated in another response, I am pro net neutrality.)
To see if I understand correctly, I shall try to summarize. The colocation benefits are small and possibly non-existent. Designing regulations to encourage colocation is likely to have adverse effects (on competition) that outweigh the benefits. So enforce net neutrality, and let colocation fall where it may.
Is this about right?
I like the trade you describe for Akemai. It is mutual benefit without either side trying to squeeze maximum money from the other. One problem I see is that in the simple case you describe, Akemai has no incentive to use power efficient hardware. There are a variety of ways minor tweaks to the agreement could deal with this, which for simplicity or because you are not privy to them, you have omitted.
OK, substitute 'efficient' for 'smart'. I agree that is a better word.
If regulations favours inefficient solutions over efficient ones, this is not great. It might well be a price we're willing to pay (e.g. companies spending lots of money on advertising to get market share in a fixed sized market is inefficient), but it at least suggests there might be a problem with the regulations which could be fixed.
My non-net-neutrality solution was not put forward as 'smart' (efficient), just as a way in which non-net-neutrality might cause the efficient solution to come about. (I.e. I care that colocation happens, not that the commercial arrangements that make it happen are organized in any particular way.) I concede that it is not the only way in which things might go without net neutrality.
The point remains: under the right circumstances, colocation is the efficient solution. Implementing the solution produces a surplus, which can be shared in some way between the participants. This is all true with or without net neutrality. What incentives are there to implement the efficient solution, and how does the surplus get divided, with or without net neutrality?
I'm in favour of net neutrality. Your vitriol is misdirected. I just want to know how incentives work in various systems.
I have a general net neutrality question.
Consider that 1000 of my local ISP's customers want to watch a hot new Netflix show. My ISP is 1000 km from the nearest Netflix data center. The dumb solution is that 1000 customers sent requests to ISP who sends them 1000 km to Netflix who sends the show 1000 times over the backbone connection. The smart solution is that Netflix colocates a server in my ISP's small local data center which they send the popular shows to just once over the backbone, and this server sends it to the 1000 local customers.
For the smart solution to happen, there have to be incentives for Netflix and the ISP to do it. Without net neutrality, it could work: ISP gets to advertise that Netflix is 0 rated (or 0.5 rated or whatever) towards customer data caps, and benefits from being more attractive to customers and not paying for so much backbone data. Netflix benefits by not needing so much internet backbone. Customers benefit obviously, at least in the short term. (Customers may suffer in the long term through lack of competition.) Would-be Netflix competitors are very unhappy. Possibly money changes hands between ISP and Netflix to make this work, although I'm not sure in which direction.
With net neutrality, the ISP can't offer reduced rating on Netflix data. How do the incentives work in this case? The great reduction of data going over the backbone should provide savings, but who was paying this cost in the first place? Does the ISP want to pay Netflix to colocate a server, or to charge them for it?
I've long wondered why Boeing doesn't make a clean sheet replacement for the 737. For a plane sold in such vast numbers, the case for a clean redesign is much easier to make. My understanding is that currently they're looking to a 757 replacement/A321 competitor (https://en.wikipedia.org/wiki/Boeing_New_Midsize_Airplane) as their next clean design, with a 737 replacement possibly after that.
Back in my day, we waited 1997 and then worked excessive hours in a panic for three years. If it was good enough for us, it should be good enough for you.
I actually had a 100% genuine post-Y2K bug that I needed to fix. I was one of the main people in charge of source control (which was SCCS) in our company at the time. On 2nd Jan my on-call cell phone rang (while I was watching Sleepy Hollow in a movie theatre - oops!) A few rather keen developers were working, despite it being a holiday, and were getting weird stuff happening in SCCS. It turned out that the server they were using had SCCS via someone just copying over the binaries, rather than correctly installing them, so when it got its Y2K-compliant OS upgrade, those binaries were not replaced, and were not Y2K-compliant. I was able to diagnose the problem, patch the dozen or so source code commits which they'd made with the bad binaries, and call in a sysop to install the correct binaries. (I didn't have root on that server.)
Ditto. I felt smugly superior to be using little-endian DD-MM-YYYY which was so much better (consistent) than the USA's middle-endian MM-DD-YYYY format. Then starting in 1988, my MSc thesis was on an experiment with many Japanese collaborators (they had the money, we had the supernova) and I saw them use YYYY-MM-DD and I was an instant convert. We're already big-endian in our decimal notation, so dates should be too. And in YYYY-MM-DD, chronological order and 'alphabetic' order are the same.
Yes, saves the airline a little bit of money to not have the passenger on board. A number I came across was that for a typical jet airliner each extra 100kg of payload increases fuel burn by about 3kg/hour. I think this number was in the context of long haul flights. Short haul and turboprop aircraft would have somewhat different numbers. I think I saw this number 5 to 10 years ago, so more recent higher efficiency engines likely have a smaller number.
This clearly has consequences for airlines deciding how much fuel to load. They have to take extra fuel beyond what they expect to burn to get to the destination, to allow for contingencies (and because they legally have to.) It is something like an insurance policy: loading an extra 10 tonnes of fuel for a 10 hour flight will cost you 3 tonnes of extra fuel burned, whether you use that reserve or not. Usually you won't, but sometimes it will save your bacon and avoid having to divert to an unexpected airport, and then having to perhaps get hotel rooms for all the passengers and rebook them to their expected destination, plus annoying passengers and having them perhaps never fly with you again. Usually airlines will load the legal minimum (from memory, something like fuel to fly to destination plus fuel to fly from there to the further of the two alternate landing airports plus 30 minutes) but if in-air delays seem likely (e.g. bad weather) they'll load more.
I had the impression there was some sort of feedback mechanism in how much bitcoin you get for mining a block. TFA doesn't talk about this. This would mean that if your mining costs are substantially higher than others, you'll be unprofitable no matter what the bitcoin price is doing.
Perhaps it is just a supply/demand thing? The more miners there are, the lower the chance you get to mine the block, so the lower the expected return you get in bitcoins. Then for a fixed bitcoin reward, the number of miners will bring the expected return in equilibrium with bitcoin value.
Could someone with knowledge please talk about feedback mechanisms?
I think nature would rather strip oxygen out of the water rather than the chlorine, so you'd end up with oxygen and dilute hydrochloric acid.
I think nature would rather strip oxygen out of the water rather than the chlorine, so you'd end up with oxygen and hydrochloric acid.
I think nothing. They need a liquid electrolyte around the Na electrode, and it can't be aqueous because that would react violently with the Na. So they have an organic electrolyte into which the Na can dissolve, and then it passes through a membrane into aqueous solution where the rest of the reactions happen.
From my (not a chemist) reading of the paper:
If you have a battery which is consuming sodium to produce electricity, you want the electrolyte around the cathode to be acidic, and the reaction will be producing OH-, neutralizing acids. Continuously dissolving CO2 into this water produces a source of acidity, so the CO2 not only makes the battery works better, but it simultaneously sequesters the CO2 as NaHCO3.
I think this really is the core of the proposal - make the battery work better and sequester CO2 at the same time.
Your suggestion of throwing Na into water wastes lots of energy - it has the same H2 production as the Na+CO2 scheme, but doesn't produce any electricity.
Yes, you need to use electricity (more than you get out) to create metallic Na, so this is a battery rather than energy source, and TFA deceptively omits this. I don't know how efficient this battery would be.
From my skimming of the paper, they'd be getting replacement sodium from sea water, not from the sodium bicarbonate which they produce. That would be sequestered somewhere.
Reading a bit more (I am not a chemist):
"Because the potential of cathodic reaction is closely influenced by the pH of aqueous solution, the dissolution of CO2 renders a favorable electrochemical reaction environmentby acidifying the aqueous solution."
"Thus, notably, this combined cathodicreaction not only utilizes CO2 to generate H2 but also possesses highly efficient reaction kinetics,possibly overcoming the key issue of sluggish discharge rates for common metal-air batteries."
Figure 4 shows this is a rechargeable battery!
"On repeating the discharge-charge process, the cathode potential profile(Ecathode) presents discharging and charging plateau, clearly proving that this system is rechargeable."
"To confirm the reversibility of hybrid Na-CO2cell, the anodic charge profile (electrolysis profile) was observed. Because Na is one of the most abundant elements on earth, Na metal anode could be easily recycled through a charging process in Na-ion-containing aqueous solution, such as seawater. Figure 4A shows an oxidation rotating disk electrode profile for examining whether CO2 was reproduced during the charging process. Generally, the charging process is regarded as the opposite reaction of the discharging reaction. In this work, however, the generated H2 gas from the discharging process is naturally removed on the surface of electrode, and thus the oxidation reaction proceeds as the oxygen evolution reaction (OER) from the water oxidation (Equation 6).
2H2O -> O2(g) + 4H+ + 4e- Eo= 1.229 V"
As this equation does not involve Na, I'm still unclear on how they are regenerating their Na.
Help! Is there a chemist in the house?
The paper can be downloaded (no paywall) from here. Equation 5 "Net equation" is
2Na + 2H+ -> 2Na+ + H2, E0 = 2.71V.
So yes, it works by consuming sodium metal. I am underwhelmed.
How much energy could we get from the metallic sodium if we didn't turn CO2 into NaHCO3 as a side reaction? What is our efficiency at making metallic Na? If these cells are sufficiently cheap, reliable, high power output, and efficient there might be potential for using this for grid scale energy storage in the form of metallic Na. Doing so would have an advantage of energy storage being limited only by your ability to store sodium, so it could work on seasonal timescales. Of course, then you'd have seasonal H2 production which would carry its own storage issues.