Semis burn 5x more fuel yet cause 80x more damage.
Is that taking into account traffic volume, as a typical loaded tractor trailer is going to cause several thousand times the damage as a typical sedan.
Electrolysis has nothing to do with thermodynamics
By that, you actually mean everything has to do with thermodynamics. You're adding energy to disassociate a molecule. Thermodynamics dictates that you cannot recover that same amount of energy by letting the constituent elements recombine. Tyr07's uncertain belief coincides with one of the fundamental principles at play in any real world system.
Fuel cell efficiency varies greatly, it goes up to 85% for current marketed high temperature hydrogen fuel cells.
No it doesn't. The only way you could hope to achieve anywhere near that is through some combined cycle process that scavenges waste heat from the fuel cell. You might find some experimental units pushing 70%, but anything commercially available is going to be under 60%.
Total cycle efficiency is going to be under 25%.
That is complete nonsense, you must be bad in math.
Assuming realistic values for electrolysis and fuel cells, you're already well under 40%. Depending on your compression ratio, you're only likely to recover 50-60% of the energy spent compressing the hydrogen for storage, so that's either higher losses, or higher capital costs for storage volume. Tack on a couple percent for leakage, and 25% is very reasonable.
The energy required to compress and cool the hydrogen into a liquid in the first place, as opposed to just larger, less insulated, high pressure gas tanks, would more than offset any gains made by using the boiloff to cool your data center.
conversion ratio wise I believe it takes more power to produce the hydrogen than it returns so there is a loss
Yes. Electrolysis does not violate the laws of thermodynamics. What I assume you were getting at, electrolysis usually runs around 50-60% efficiency and fuel cells range from 30-70% depending on the chemistry, and in practice since you have to store it, you also have to factor in compression losses, hydrogen leakage, and burners to bring your decompressed gas back up to the operating temperature of your fuel cell. Total cycle efficiency is going to be under 25%.
You can expect about 900kWh yearly per 1kW of typical solar panel installed in Denmark. Therefore it takes an installed capacity of 240GW of solar panels to cover Denmark.
That makes the assumption that your daily average production and consumption is anywhere close to your yearly average, or that you have an absolutely massive energy storage system capable of storing hundreds of petajoules to last the winter months.
Because it would be meaningless to "compensate" for the time difference between clocks moving and accelerating differently. Time literally moves at different rates in different reference frames. The clocks are correct; the problem is that the concept of similtaneity is fundamentally flawed.
I'll admit, I don't understand why the arbitrary reference time we use currently is any less valuable now that we have surface clocks whose real time is measurably changing due to relativistic effects.
So someone who straps a couple homemade AP motors to the side of an ultralight qualifies as well? (One could argue doing such a thing would preclude them classification as an ultralight...)
They're daring, sure, but they're not pioneering new territory, as we did this over 50 years ago; they're just making it cheaper. Even when they do get there and make it cheaper, there's no way to expand upon its capabilities without a complete from-scratch redesign. They're not enabling anything further. Unless they directly expand science, industry, or medicine, or indirectly provide the tools for others to do so, they're not benefiting society, just themselves personally. Being a hero implies acting for the benefit of someone other than one's self.
The guys (and woman) who died in Challenger were heroes. The casualties from this crash were like the people who died building the Empire State Building.
- you know you are an actual asshole, right? What, the difference between people that are flying space ships for private business and for NASA or whatever agency is that in private business they are billionaires? Nope. The owner of the company is, the people flying the fucking rockets are heroes even before they blow up.
The NASA astronauts were working to expand our breadth of knowledge. Orbital Sciences, SpaceX, Bigelow Aerospace, Blue Origin, while ultimately working for profit, are building technologies that enable the expansion of expand science and civilization. Virgin Galactic and XCOR Aerospace exist to provide entertainment. Their designs cannot be scaled to actually reach orbit. Their designs cannot be scaled to provide practical transportation. It's for entertainment, and while entertainment is important, it's just a distraction to fill down time.
That's right. People risk their lives to do adventures like this because it's worth it.
This is spaceflight in definition only. It's nowhere near orbit. It's not even useful as a suborbital transportation system. If you want to perform tests in rarefied atmosphere or vacuum, sounding rockets are vastly cheaper and offer better performance. This exists for tourism, for people who want a few minutes of weightlessness all at once, rather than a several arches in a "vomit comet" a dozen seconds at a time, and for people who want to claim they technically went to space, even though most people expect that means you actually stayed there for more than a few seconds.
The real cost of any (liquid fueled) launch is in the vehicle, rather than the fuel. Thus, the ultimate goal of cheap spaceflight is to recover and reuse that launch vehicle. Whether you achieve that with an extremely elaborate multi-mode gas turbine engine on an SSTO spaceplane, or a traditional staged rocket whose boosters abort and return for a powered landing back at the launch facility, you get the same end result. The question simply becomes which one is cheaper to design and maintain.
The same goes for my thermostat. And my lights. And my stove. And my freezer. If you're not taking security seriously, I'm not taking your fscking product seriously.
The entire industrial control world is completely indifferent to security. Things like HMI applications may implement user-level restrictions, but ultimately the hardware they interface with is usually just open access over OPC or HTML. This works in general when you're on an isolated industrial network, of course these networks are typically not completely isolated, allowing remote access for maintenance and support. Even when completely isolated, you still have the issue of operators connecting infected hardware to the network, as seen with stuxnet.
The problem with IoT is that the same embedded and controls engineers are just applying the same methodology to this as industrial applications, and assuming someone upstream will handle the security issue. Security is a double edged sword. While it's necessary at some level, it's going to add considerable overhead and latency, and is all but unusable if you intend to do real time control. The isolated, open network is the only sensible approach. Now IoT parts could completely embrace the industrial methodology, and while the typical controls engineer might think nothing of running ethernet or RS-485 drops throughout their home with a central secured gateway for access, the typical consumer user is enamored will all things wireless. On the other hand IoT parts are not doing any form of real time control over their remote interfaces, so there's no reason for them to be externally behaving like industrial hardware, and programmers stuck in that mindset should not be left in charge of building those interfaces.
I can't tell if this was supposed to be a joke or not. No one uses backscatter X-ray scanners any longer. It's all millimeter wave these days, and if you're concerned about irradiation from those, you better not go outside. As for groping, well I've not personally been groped by TSA, but then perhaps I'm not so well endowed that I look like I'm carrying a weapon, or otherwise pique the officers' curiosity...
Most cars come with analog readouts for speedometers, temperature and gas tanks.
You may be surprised to find out that many of those are now actually digital. The gauges look all old-timey and appear analog but the actual signal being communicated is a digital signal and thus so are the gauges technically speaking.
The video was about hooking analog gauges into the analog outputs available on an Intel dev board. By that logic, they would be digital outputs just the same.
We won't own houses either, banks will own them and make sure that no-one can pay for them.
The amusing thing, often times these distributors don't even own their own warehouses. They have them built and outfitted to their specs, then sell them to and lease them back from an investment firm.
No one who's qualified should ever compete in these, because they're not for people who are qualified. They're for engineering students to get some hands on practical experience, and maybe come up with some novel ideas along the way.
I admit, I did not read that far down. The first few paragraphs mention the GSK program to develop one, but was only speaking in generalities about vaccines.
There is no vaccine. The article is merely expecting that vaccines will be ready for testing several months, and is questioning how the testing of those vaccines should take place when available.
In the long run, however, I wonder if the arrival of convenient fusion will mark the start of issues with waste heat.
No. Current solar absorption (accounting for albedo) is on the order of 50PW. By comparison, current peak world wide energy production is a paltry few TW. We're several orders of magnitude away from the point where our civilization's thermal output becomes a concern.
Slashdot Mirror
Semis burn 5x more fuel yet cause 80x more damage.
Is that taking into account traffic volume, as a typical loaded tractor trailer is going to cause several thousand times the damage as a typical sedan.
You would need a nuclear reactor to provide enough power to land on the Moon using an arcjet.
Electrolysis has nothing to do with thermodynamics
By that, you actually mean everything has to do with thermodynamics. You're adding energy to disassociate a molecule. Thermodynamics dictates that you cannot recover that same amount of energy by letting the constituent elements recombine. Tyr07's uncertain belief coincides with one of the fundamental principles at play in any real world system.
Fuel cell efficiency varies greatly, it goes up to 85% for current marketed high temperature hydrogen fuel cells.
No it doesn't. The only way you could hope to achieve anywhere near that is through some combined cycle process that scavenges waste heat from the fuel cell. You might find some experimental units pushing 70%, but anything commercially available is going to be under 60%.
Total cycle efficiency is going to be under 25%. That is complete nonsense, you must be bad in math.
Assuming realistic values for electrolysis and fuel cells, you're already well under 40%. Depending on your compression ratio, you're only likely to recover 50-60% of the energy spent compressing the hydrogen for storage, so that's either higher losses, or higher capital costs for storage volume. Tack on a couple percent for leakage, and 25% is very reasonable.
The energy required to compress and cool the hydrogen into a liquid in the first place, as opposed to just larger, less insulated, high pressure gas tanks, would more than offset any gains made by using the boiloff to cool your data center.
conversion ratio wise I believe it takes more power to produce the hydrogen than it returns so there is a loss
Yes. Electrolysis does not violate the laws of thermodynamics. What I assume you were getting at, electrolysis usually runs around 50-60% efficiency and fuel cells range from 30-70% depending on the chemistry, and in practice since you have to store it, you also have to factor in compression losses, hydrogen leakage, and burners to bring your decompressed gas back up to the operating temperature of your fuel cell. Total cycle efficiency is going to be under 25%.
You can expect about 900kWh yearly per 1kW of typical solar panel installed in Denmark. Therefore it takes an installed capacity of 240GW of solar panels to cover Denmark.
That makes the assumption that your daily average production and consumption is anywhere close to your yearly average, or that you have an absolutely massive energy storage system capable of storing hundreds of petajoules to last the winter months.
Because it would be meaningless to "compensate" for the time difference between clocks moving and accelerating differently. Time literally moves at different rates in different reference frames. The clocks are correct; the problem is that the concept of similtaneity is fundamentally flawed.
I'll admit, I don't understand why the arbitrary reference time we use currently is any less valuable now that we have surface clocks whose real time is measurably changing due to relativistic effects.
Why can't we compute what the relativistic slew rate between two different locations will be and compensate?
So someone who straps a couple homemade AP motors to the side of an ultralight qualifies as well? (One could argue doing such a thing would preclude them classification as an ultralight...)
They're daring, sure, but they're not pioneering new territory, as we did this over 50 years ago; they're just making it cheaper. Even when they do get there and make it cheaper, there's no way to expand upon its capabilities without a complete from-scratch redesign. They're not enabling anything further. Unless they directly expand science, industry, or medicine, or indirectly provide the tools for others to do so, they're not benefiting society, just themselves personally. Being a hero implies acting for the benefit of someone other than one's self.
To be fair, we already reached that specific frontier over 50 years ago.
The guys (and woman) who died in Challenger were heroes. The casualties from this crash were like the people who died building the Empire State Building.
- you know you are an actual asshole, right? What, the difference between people that are flying space ships for private business and for NASA or whatever agency is that in private business they are billionaires? Nope. The owner of the company is, the people flying the fucking rockets are heroes even before they blow up.
The NASA astronauts were working to expand our breadth of knowledge. Orbital Sciences, SpaceX, Bigelow Aerospace, Blue Origin, while ultimately working for profit, are building technologies that enable the expansion of expand science and civilization. Virgin Galactic and XCOR Aerospace exist to provide entertainment. Their designs cannot be scaled to actually reach orbit. Their designs cannot be scaled to provide practical transportation. It's for entertainment, and while entertainment is important, it's just a distraction to fill down time.
That's right. People risk their lives to do adventures like this because it's worth it.
This is spaceflight in definition only. It's nowhere near orbit. It's not even useful as a suborbital transportation system. If you want to perform tests in rarefied atmosphere or vacuum, sounding rockets are vastly cheaper and offer better performance. This exists for tourism, for people who want a few minutes of weightlessness all at once, rather than a several arches in a "vomit comet" a dozen seconds at a time, and for people who want to claim they technically went to space, even though most people expect that means you actually stayed there for more than a few seconds.
This isn't worth it.
Considering no one has ever done that, are you saying the last half century of spaceflight has just been amateur hour?
The real cost of any (liquid fueled) launch is in the vehicle, rather than the fuel. Thus, the ultimate goal of cheap spaceflight is to recover and reuse that launch vehicle. Whether you achieve that with an extremely elaborate multi-mode gas turbine engine on an SSTO spaceplane, or a traditional staged rocket whose boosters abort and return for a powered landing back at the launch facility, you get the same end result. The question simply becomes which one is cheaper to design and maintain.
At $4,653/kg to LEO it would cost rought 400K to push an average human to LEO
Don't forget your life support and re-entry systems.
The same goes for my thermostat. And my lights. And my stove. And my freezer. If you're not taking security seriously, I'm not taking your fscking product seriously.
The entire industrial control world is completely indifferent to security. Things like HMI applications may implement user-level restrictions, but ultimately the hardware they interface with is usually just open access over OPC or HTML. This works in general when you're on an isolated industrial network, of course these networks are typically not completely isolated, allowing remote access for maintenance and support. Even when completely isolated, you still have the issue of operators connecting infected hardware to the network, as seen with stuxnet.
The problem with IoT is that the same embedded and controls engineers are just applying the same methodology to this as industrial applications, and assuming someone upstream will handle the security issue. Security is a double edged sword. While it's necessary at some level, it's going to add considerable overhead and latency, and is all but unusable if you intend to do real time control. The isolated, open network is the only sensible approach. Now IoT parts could completely embrace the industrial methodology, and while the typical controls engineer might think nothing of running ethernet or RS-485 drops throughout their home with a central secured gateway for access, the typical consumer user is enamored will all things wireless. On the other hand IoT parts are not doing any form of real time control over their remote interfaces, so there's no reason for them to be externally behaving like industrial hardware, and programmers stuck in that mindset should not be left in charge of building those interfaces.
I can't tell if this was supposed to be a joke or not. No one uses backscatter X-ray scanners any longer. It's all millimeter wave these days, and if you're concerned about irradiation from those, you better not go outside. As for groping, well I've not personally been groped by TSA, but then perhaps I'm not so well endowed that I look like I'm carrying a weapon, or otherwise pique the officers' curiosity...
Most cars come with analog readouts for speedometers, temperature and gas tanks.
You may be surprised to find out that many of those are now actually digital. The gauges look all old-timey and appear analog but the actual signal being communicated is a digital signal and thus so are the gauges technically speaking.
The video was about hooking analog gauges into the analog outputs available on an Intel dev board. By that logic, they would be digital outputs just the same.
If you need rate of change, why not actually display rate of change?
We won't own houses either, banks will own them and make sure that no-one can pay for them.
The amusing thing, often times these distributors don't even own their own warehouses. They have them built and outfitted to their specs, then sell them to and lease them back from an investment firm.
No one who's qualified should ever compete in these, because they're not for people who are qualified. They're for engineering students to get some hands on practical experience, and maybe come up with some novel ideas along the way.
I admit, I did not read that far down. The first few paragraphs mention the GSK program to develop one, but was only speaking in generalities about vaccines.
There is no vaccine. The article is merely expecting that vaccines will be ready for testing several months, and is questioning how the testing of those vaccines should take place when available.
No. The article is about how to do testing of a hypothetical vaccine that has not yet been developed.
In the long run, however, I wonder if the arrival of convenient fusion will mark the start of issues with waste heat.
No. Current solar absorption (accounting for albedo) is on the order of 50PW. By comparison, current peak world wide energy production is a paltry few TW. We're several orders of magnitude away from the point where our civilization's thermal output becomes a concern.