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Platystemon posted:How is the graphite heated? Resistance heating elements? Or is this only for solar thermal? Graphite typically has restive heating elements and thus takes an electrical input, and gas channels in it for thermal output. You circulate a gas and put it into a heat exchanger to make steam. You can use the steam for thermal processes (district heating, steam chillers, etc) or to run electrical generation. Of course, when you're going back from thermal to electrical, you're limited by thermodynamic efficiency of existing systems. And as you said, there are economies of scale for engines. Applications for thermal output are economical at smaller scale. There are already some companies that do this commercially for hot water and low grade heat. The higher the quality heat you want, (and if you want electricity back out) the bigger the system needs to get to make sense. bawfuls fucked around with this message at 05:21 on Feb 3, 2018 |
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Feb 3, 2018 05:15
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I think you need to consider different categories of energy storage. You'll have power storage and energy storage. Battery packs (if not lithium then something else, flow batteries maybe) are good for power storage, when you quickly need to maintain frequency, take out peaks in demand etc. They'll have sub-second response time and can dump a huge amount of power to help out a surprise supply shortage of Watts or Hertz. Then you have energy storage, which will be your pumped hydro, maybe compressed air or molten salt. It takes some time from when you push the button to when the stored energy hits the fan. It's more suitable for planned drops in power, for instance predicted changes in wind and solar. It has at best multi second response time, possibly minutes, which isn't a problem when it's planned. It cannot throw out a huge peak, but it can deliver steady amount of Joules for a longer time than the power storage units. If you can find one that can do both, nice. Pumped hydro and lithium batteries is the only thing that exists at present, isn't it? There's huge potential in this, it also enables profitability in many marginal sustainables, but it does depend on nation or continent level cooperation and there might be a lot of political hurdles on the path to something sustainable and good.
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Feb 3, 2018 18:49
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i just wanted to say that i love the smell of gasoline and fueling up my motorcycle is never a chore because it takes 30 seconds and costs 8 dollars
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Feb 3, 2018 19:11
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Things you think when you are: Rolling across asphalt because a Prius cut you off suddenly Or Enjoying a leisurely ride through rain and sleet.
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Feb 3, 2018 19:19
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An opinion: With one-pedal driving, brakes are rarely used and more rarely properly heat cycled. In salt happy Norway, this is murder on the brake discs. You can scrub the surface with a few hard stops, but the metal in the cooling channels gets rusted to hell and the disk swells and warps. Obvious solution: No cooling channels, single disk. More provocative solution: Back to drum brakes. Without big, regular heat cycles, the paint doesn't disappear and you can rust proof it much better than fossils. But you still have to be able to stop a heavy car quite quickly. Thoughts? Perhaps non-vented disk in the front and drum in the rear, like some mid-90s hatch? Ola fucked around with this message at 19:38 on Feb 3, 2018 |
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Feb 3, 2018 19:34
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Fly wheels are another option: https://en.wikipedia.org/wiki/Flywheel_energy_storage#Form_of_energy_storage Whats even cooler is that in the 50's there were very short range buses that ran off fly wheels: https://en.wikipedia.org/wiki/Gyrobus
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Feb 3, 2018 19:40
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What kind of effect on earth's rotation could a pile of thousand pound flywheels spinnning at a bajillion RPM have? I know the UPS flywheel systems use carbon fiber flywheels so when it explodes it turns to fluff instead of lawsuits, but i would imagine for large scale energy storage, weight matters and you could just bury it underground to contain the shrapnel.
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Feb 3, 2018 20:11
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I don't know which influence the flywheels would have if they all spun in the same direction, but if they spun in random directions, which wouldn't influence their purpose, their effect would probably be zero. But a bigger thing about flywheels is why would you bother? It's such a huge amount of steel that needs to be melted, shaped, shipped and craned into a set of titanic bearings suspended by a super strong structure inside a vast cavern. And many flywheel pitches mention chamber vacuum as a way to increase efficiency, but that works against the scenario. It's better to overpressurize an underground chamber than to underpressurize it, because then the weight of the ground above is working in your favor. (edit: this is kind of dumb when I think about it. 1 atm of vacuum vs say 5 atm of overpressure) If you're digging a spherical hole, storing air pressure seems like it does at least the same job at lower build cost and possibly better efficiency than a flywheel. An unexplored thing is high volume, low fall hydro, where you'd pump a huge amount of water up a small amount of height. That could be useful in a much bigger part of the world than hydro is today. Ola fucked around with this message at 20:31 on Feb 3, 2018 |
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Feb 3, 2018 20:28
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Ola posted:I don't know which influence the flywheels would have if they all spun in the same direction, but if they spun in random directions, which wouldn't influence their purpose, their effect would probably be zero. Because with magnetic bearings and a vacuum chamber, you could theoretically have a hundred years of 90+% efficient energy storage and recovery with no degradation and potential for being 95% recyclable at it's end of life. I remember reading that orientation of large flywheels relative to the rotation of the earth would affect bearing wear and that voyager using Jupiter as a gravity boost slowed it's orbit by a very tiny amount . I'm just wondering if enough flywheel capability to meet our energy storage needs could alter the rotation or path of the earth a measurable amount.
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Feb 3, 2018 22:14
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The Earth has a rotational kinetic energy of about 2.1x1038 J. The best figure I can find for the human race's current annual energy consumption is 5.7 × 1020 J. So the spinning planet has around 370 quadrillion times as much energy in it as we use in a year. Put another way, if we could somehow extract every single joule of our energy requirements directly from the planet's rotation by using giant flywheels in the proper orientation, and we did that every year from today until the infinite future, the Earth would not run out of spinning energy until after every star in the universe has burned out and cooled to a few degrees above absolute zero. If we start today, then by the sun becomes a red giant and engulfs the Earth's orbit, we will have used up 0.000002% of the Earth's rotational energy, corresponding to a 1.8-millisecond increase in the length of the day. I think we're okay.
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Feb 3, 2018 22:34
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Powershift posted:Because with magnetic bearings and a vacuum chamber, you could theoretically have a hundred years of 90+% efficient energy storage and recovery with no degradation and potential for being 95% recyclable at it's end of life. But air pressure is better than flywheel in every way. Use the same airtight chamber and a vacuum pump. But then you just need a some sort of wind pipe to a surface generator, not the bearings or the hundreds of tons of flywheel, a flywheel bearing, a flywheel bearing carrying structure or gears and axles to couple the flywheel to the generator in an air tight manner. And if it's truly air tight, the air pressure will maintain its energy longer than a gravity affected flywheel will.
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Feb 3, 2018 22:46
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Ola posted:But air pressure is better than flywheel in every way. Use the same airtight chamber and a vacuum pump. But then you just need a some sort of wind pipe to a surface generator, not the bearings or the hundreds of tons of flywheel, a flywheel bearing, a flywheel bearing carrying structure or gears and axles to couple the flywheel to the generator in an air tight manner. And if it's truly air tight, the air pressure will maintain its energy longer than a gravity affected flywheel will. Unless you can perfectly insulate the pressure vessel against heat transfer, you lose a whole lot of energy that way. Compressing air creates a lot of heat.
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Feb 3, 2018 23:03
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Platystemon posted:Unless you can perfectly insulate the pressure vessel against heat transfer, you lose a whole lot of energy that way. Alright, hear me out. We make a gigantic thermos...
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Feb 3, 2018 23:06
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Platystemon posted:Unless you can perfectly insulate the pressure vessel against heat transfer, you lose a whole lot of energy that way. That is a very fair point. But you can fetch that heat and use it, just like you can with the electric motors used in both scenarios.
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Feb 3, 2018 23:11
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Ola posted:Pumped hydro and lithium batteries is the only thing that exists at present, isn't it? And like I said, there are thermal systems in use as well. Molten salt for concentrated solar thermal, and graphite is in use for low-grade heat. edit: trying to store gigawatt-hours of energy in pressure vessels or massive flywheels is a losing proposition. Both methods have the potential for catastrophic release of energy if systems were to fail, aka dangerous as hell. If your hot thermal storage system fails it's containment, it just cools off over time instead of blowing poo poo up. bawfuls fucked around with this message at 23:19 on Feb 3, 2018 |
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Feb 3, 2018 23:15
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Trash Trick posted:Yep. That's true, but they'll still need to actually test the system, eventually. The metrics on disengagements once they do will be VERY intriguing. That’s if you actually believe the data they’re getting is of value. It all has to be extensively categorized by hand, and no one I’ve spoken to of late thinks Tesla has any sort of lead or advantage here.
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Feb 3, 2018 23:41
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bawfuls posted:
I agree with you here, but there's a fallacy of scale lurking between your lines. 1 GWh in 1 balloon is dangerous but 1Wh in 1 ballon in 1000 clusters of 1000 clusters of 1000 balloons is no problem because the total energy doesn't release at once if there is a problem in 1 balloon Wikipedia says Norway produced 135.3 TWh of hydro power in 2007. If we in 2006 talked here about storing 135.3 TWh of hydro power in potential kinetic energy above people's heads, wouldn't you say that was a dangerous thing? What if the dam breaks and all that water floods people? Is it much more dangerous than your theoretical molten salt scenario? Turns out, in real life there are many dams, it is much more benign and much more distributed than the simple energy numbers say. A more important thing in energy harvesting is to avoid phase changes as best as you can. Molten salt is not good in that case.
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Feb 3, 2018 23:59
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Ola posted:I agree with you here, but there's a fallacy of scale lurking between your lines. 1 GWh in 1 balloon is dangerous but 1Wh in 1 ballon in 1000 clusters of 1000 clusters of 1000 balloons is no problem because the total energy doesn't release at once if there is a problem in 1 balloon You can't just do 1000 distributed 1Whr flywheel or pressure storage systems because the efficiency when you try to convert back to electricity at that tiny scale is absolute garbage. They have to be a minimum size to make the electrical generation on the back end worthwhile. I don't know what you mean about avoiding phase change, because the latent heat of phase change is an excellent storage mechanism. This is why people have been trying to make it work for awhile. There are other challenges with it however. And molten salt systems generally don't rely on phase change. bawfuls fucked around with this message at 00:25 on Feb 4, 2018 |
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Feb 4, 2018 00:21
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bawfuls posted:If you want distributed storage, then batteries are already winning that fight. Plus they can switch from storing energy to releasing it in a fraction of a second - way faster than activating the generator function of a flywheel/pressure/thermal system: http://www.independent.co.uk/news/w...e-a8130986.html
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Feb 4, 2018 02:21
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This deck is a bit old but is a really good overview of grid scale storage technologies and needs. https://www.arpa-e.energy.gov/sites/default/files/documents/files/GridScaleEnergyStorage_Johnson.pdf 
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Feb 4, 2018 02:42
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To be clear, I think there's a place for both distributed and centralized storage ideally. They have different purposes, strengths, and weaknesses. Some technologies are better for one or the other. It is large utility scale storage that we currently lack. edit: that big circle that says "Need Storage At Cost" is where thermal fits best, and it's where we currently lack a technologically mature solution.
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Feb 4, 2018 02:44
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bawfuls posted:I don't know what you mean about avoiding phase change, because the latent heat of phase change is an excellent storage mechanism. This is why people have been trying to make it work for awhile. There are other challenges with it however. And molten salt systems generally don't rely on phase change. Wrong word used by me, I didn't mean phase change but type of energy, i.e. from electricity to heat to another thing to etc. Heat is quick to store by powering a resistor, but to extract it you might need to convert water to steam, then use steam pressure to drive a turbine. The more energy transfers, the bigger losses.
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Feb 4, 2018 10:43
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 brand new sixty thousand dollar car (incl. options and fees)
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Feb 4, 2018 19:22
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Ola posted:Wrong word used by me, I didn't mean phase change but type of energy, i.e. from electricity to heat to another thing to etc. Heat is quick to store by powering a resistor, but to extract it you might need to convert water to steam, then use steam pressure to drive a turbine. The more energy transfers, the bigger losses. bawfuls fucked around with this message at 20:52 on Feb 4, 2018 |
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Feb 4, 2018 20:30
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bawfuls posted:Yes this is true. The fundamental problem is you can't just store "raw electricity" per se.  https://en.wikipedia.org/wiki/Superconducting_magnetic_energy_storage
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Feb 4, 2018 20:45
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atomicthumbs posted:
I read a story awhile back about the history of the plant Tesla owns now which was once called NUMMI. It was a joint venture between GM and Toyota and the idea was Toyota would teach GM to make cars that didn't suck and GM would help Toyota sell cars in the US. One of the biggest lessons in all of it is in a Toyota plant any worker could stop the line if there was a problem with a car and they would fix it and then study how to prevent the problem in the future. In a GM plant you could basically stop the line only if a person was about to die and even then you thought about how much you liked the guy before you did it, so cars that were completely hosed up just kept rolling down the assembly line being assembled even though they were undrivable trainwrecks that would have to be disassembled again to fix them and then they put them in a lot to unfuck up later. Apparently the lesson that Tesla learned from all that was to do it the GM way but just go ahead and ship them to consumers.
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Feb 4, 2018 20:46
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bawfuls posted:Yes this is true. The fundamental problem is you can't just store "raw electricity" per se (well, electric field potential but yeah). Just not very much of it.
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Feb 4, 2018 21:08
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Three Olives posted:I read a story awhile back about the history of the plant Tesla owns now which was once called NUMMI. It was a joint venture between GM and Toyota and the idea was Toyota would teach GM to make cars that didn't suck and GM would help Toyota sell cars in the US. One of the biggest lessons in all of it is in a Toyota plant any worker could stop the line if there was a problem with a car and they would fix it and then study how to prevent the problem in the future. In a GM plant you could basically stop the line only if a person was about to die and even then you thought about how much you liked the guy before you did it, so cars that were completely hosed up just kept rolling down the assembly line being assembled even though they were undrivable trainwrecks that would have to be disassembled again to fix them and then they put them in a lot to unfuck up later. The story of that plant was one of my favorite case studies in uni. Kaizen, baby.
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Feb 4, 2018 22:09
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He later updated that thread with a picture of the stops adjusted out to their limits at each side. He still suspects it may be a bent panel but it looks ok with the adjustments to me. Concerning for sure: https://lh3.googleusercontent.com/9...QSGWu0=s1125-no
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Feb 5, 2018 02:17
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Ola posted:An opinion: Drums can be worse about salt build up internally that causes them to fail. They also occasionally have to be activated in reverse to insure they are properly adjusted. I guess you could go completely inboard sealed as an option. Ultimately, it should be nothing for car manufactures to update the the brake controls to apply a bit of regular brake every so often
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Feb 5, 2018 07:23
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HFX posted:Drums can be worse about salt build up internally that causes them to fail. They also occasionally have to be activated in reverse to insure they are properly adjusted. I guess you could go completely inboard sealed as an option. Ultimately, it should be nothing for car manufactures to update the the brake controls to apply a bit of regular brake every so often Yeah, particularly with one pedal driving and temp/rain sensors as input, some computer wizardry should be able to figure out when to apply mechanical brakes instead of regen. Inboard sealed is interesting. You save a bunch of unsprung weight. They're harder to cool and to replace brake pads on, but that's not a big deal if you use them very rarely.
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Feb 5, 2018 10:46
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I'm not sure whether to be overjoyed or horrified about the prospect of a "lifetime" braking system. 
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Feb 5, 2018 13:35
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Bjørn Nyland is very enthusiastic about the e-pedal mode on the new Leaf. https://www.youtube.com/watch?v=4aUZAE2Cl24 (Nose overhang trigger warning)
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Feb 6, 2018 12:51
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I think hill start assist is standard car dreck nowadays.
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Feb 6, 2018 21:54
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Elephanthead posted:I think hill start assist is standard car dreck nowadays. But not hill stop assist. I first tried hill start and parallel park assist in a VW Tiguan in 2007, so yeah definitely not new, but I had to touch the brake pedal there.
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Feb 6, 2018 22:28
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Am I missing something or is the e-pedal that Nissan keeps bragging about basically the aggressive regen of Teslas and the i3 with hill assist? They keep making such a big deal about it it feels like I have to be missing something revolutionary about, I know an i3 will come to a complete stop with one pedal because I do it daily.
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Feb 6, 2018 22:33
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The Tesla Roadster is now the world’s fastest production car. https://www.youtube.com/watch?v=wbSwFU6tY1c&t=2032s
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Feb 6, 2018 22:34
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Three Olives posted:They keep making such a big deal about it it feels like I have to be missing something revolutionary about, I know an i3 will come to a complete stop with one pedal because I do it daily.
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Feb 6, 2018 22:40
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Three Olives posted:Am I missing something or is the e-pedal that Nissan keeps bragging about basically the aggressive regen of Teslas and the i3 with hill assist? I guess it's just the sensation of it and that it mixes in friction brakes seamlessly.
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Feb 6, 2018 22:44
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Three Olives posted:Am I missing something or is the e-pedal that Nissan keeps bragging about basically the aggressive regen of Teslas and the i3 with hill assist? Yes.
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Feb 6, 2018 22:45
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