Moreno

Let say we have a ferroelectric capacitor which is capable to store 1 joule of energy. Then we remove charged plates and remain only fully polarized ferroelectric. Are there some ferroelectrics which are capable to retain its polarization for a long period of time? If yes, then are they capable to store energy just in polarization (without plates or free electrons)? Could there be some significant potential energy change when ferroelectric polarizes? If yes, how much? Will it release some energy (for example in the form of heat) when it depolarizes for some reason? If a capacitor with plates is capable to store 1 joule of energy then how much energy the same polarized ferroelectric would be able to store without plates? Is there some way to polarize a ferroelectric without free charge accumulation, but just by passing current next to it somehow?

Also MHD could be used on the power plants or for generation in remote areas where is no wires. Portable generation.

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They hope to bring down battery costs with reduced Cobalt/reduced cost chemistry in pouch cells.

I have doubts they will bring them down much. All kind of Li-ion are quite expensive. Even contra, some manufacturers are planning switch to solid-state Li-ion or monolith-crystal cathode (like Elon Musk) in the future, what doesn't look cheap at all.

2 hours ago, swansont said:

Yes, that’s the point - you don’t maximize the electric capacity for a hybrid. But you framed this as plug-in technology. BEVs are plug-in technology 

Sorry if I'm wrong but the term "plug-in" is commonly reserved for hybrids only. In contrast to all-electric BEVs. I used it accordingly to tradition. Currently the longest electric range among plug-in hybrids on the wide market is 85 km. But I suggested in the future it may increase to 200 km. In this case plug-in hybrids may be able to run 95% of total time on electricity. And still will relieve the drivers from range anxiety and necessity to charge them fast. 

1 hour ago, swansont said:

The Volt is a hybrid, so it’s not optimized for longer range electri-only. But there are cars that are

https://en.wikipedia.org/wiki/List_of_modern_production_plug-in_electric_vehicles

Still Chevy Volt does have the longest claimed range on this list among PHEVs. The rest (with longer electric range) are BEVs or fully electric. BEV stands for Battery Electric Vehicle. Typically they have no hybrid capability. I don't expect that majority of customers will choose all-electric in the nearest decades.

Possibly plug-in technology is not exactly there yet. Chevy Volt is capable to run just 85 km on electricity at best. I'm looking at the plug-in's with 200 km electric-only range. Definitely they will need to release some much cheaper and energy dense batteries than Li-ion to make them affordable. Possibly zinc-air or sodium-sulfur?

7 hours ago, Ken Fabian said:

This would not be the case if battery powered vehicles did not work satisfactorily now - and they will almost certainly work even better and be cheaper in 10 years time, let alone 50.

 

Cheaper in 10 years - unlikely. They will struggle to do it in 50. Plug-in's consume 5-10% of what regular non-hybrids do. I think it could be sufficient emission cut measure in the nearest 100 years even if they will run on fossil fuels. But there suppose to be enough ethanol or bio-methane to power them all.

10 hours ago, Ken Fabian said:

1) What do the proposed MHD devices use as fuel/energy? The Wikipedia description fails to say where the energy required is coming from; they must be powered with something. 2) I admit I don't really understand how these are expected to work as automobile "engines".

3) In any case I think it is not ICE vehicles that it must prove significantly better than; MHD will struggle to compete with battery electric - which, for all the well known limitations, appears well capable of delivering enough range for most practical purposes, with fast charge stations becoming common enough and fast enough that long trips are not being found to be problematic. Everyday commuter use charging is mostly a matter of plugging in when garaged, saving time, not adding to it - and added up, most ICE vehicle users spend more time refueling than EV users spend waiting at charge stations.

 300 - 500 km range is common (not far short of range with many ICE cars) and over 600 km (390 miles) is already commercially available; any significant improvements in battery energy density (and I think we will see improvements) will extend that.

I think the range "problem" for EV's, like the related battery energy density issue, is getting overstated. 

It does seem likely that most Tesla EV's will manage more than 500,000 miles/800,000km with reduced but still useful range without battery replacement - longer than we could expect an ICE drive train to last. Tesla is claiming improved batteries are being developed - not greater range if I understand it, but longer life, up to 1,000,000 miles/1,600,000 km.

Any competing technology has a high - and continually rising - bar to get over.

1) I think MHD's can be flexi-fuel. They can work on hydrogen, methane, perhaps LPG or even gasoline or ethanol. 

2) You take it too literally. It could work as a generator and charge a battery. Then run an electric motor. A system could be similar to what is used in Chevy Volt. But MHD could be even more compact than ICE generator and have higher efficiency for the absence of moving parts, liquid cooling and lubricating systems.

3) I think a reasonable person has to look at plug-in's together with EV's in the nearest 50 years. What is the price and weight of a Li-ion battery that allows to drive Tesla for 500 km? Perhaps not all people want or can afford it? Plug-in's on other hand give a small range anxiety and allow to ride on electricity 90-95% of time. 

I have a question to a specialists in MHD generation. There exist some claims that degree of interaction between flowing molecules (gases) and ions on one hand and flowing molecules (gases) and electrons on other hand is vastly different. Therefore movement of ions in a gas flow will occur much faster than movement of free electrons. If this is correct then why we need to use a strong magnets to separate ions and electrons in MHD generator? If speed of the ions and electrons movement in the same gas flow is vastly different then doesn't charge separation suppose to occur by itself just due to a gas flow? Shouldn't majority of electrons concentrate at the beginning of the duct while many more ions at the end? Then only thing we need to generate current is to put an electrode at the beginning of the duct and another one at the end and let electrons flow from the inside of the duct through the external load to the end of the duct and recombine with ions there? And no need for a magnets.

28 minutes ago, swansont said:

Einzel lens

https://en.wikipedia.org/wiki/Einzel_lens

Thanks. So, which law governs relation between unidirectional speed of electrons and the density of a beam? Why beams could become denser if electrons fly faster?

What dependency exist between electron beam density and speed of electrons in this beam? What methods could allow to increase beam density quite a much without increasing the speed of electrons?

37 minutes ago, zapatos said:

So why not make the men more like the women?

In order to erase differences completely we would need to endow men with the ability to get pregnant from the females. Not to say this is completely impossible. This is what sea horses and similar species are doing for millions of years. But it would be tremendously difficult task for genetic engineering. Without that there always will be some principal evolutionary differences related to the same sex competition and therefore anything else. But this is not what I propose. 

39 minutes ago, Raider5678 said:

But regardless of that, biologically modifying someone isn't likely to change this.

 

But men are much taller and stronger than females on average and therefore a female often have no chances to stand male aggression one on one in a closed environment. I think that humans in general rather physically weak and too vulnerable but with females situation gets critical. 

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Why not accept the differences and equality?

Equality can be only formal if there are significant biological differences...

It seems majority of people on this forum support designer babies.

I don't claim I do support it myself, but would be glad to know opinion of other people: if designer babies will ever become a commonplace, should humanity try to erase any difference between males and females and any sexual inequality by means of genetic engineering and modification? Should females become as tall, physically strong, having brains of the same size as males? Should they have the same ability to aggressive self-defense and military jobs? Or even humanity may go so far some day and endow females with ability to impregnate the males, making equality complete in this way? Or perhaps we need to give even some allowance to females by making them stronger and taller than males taking in account what they experience? Please take a note this is just an assumption and you may regard it just as a joke. 

A tree falls down on a road and obstructs the way. A robot faces a choice to avoid collision: to turn left and roll over a dog, to turn right and roll over a helpless child. A robot takes choice N2 for making no priorities between dogs and humans. For it they are just a moving objects which radiate infrared. Good luck with robot drivers justification.

I cannot imagine self-driving cars for the reason of a lot of unpredictable circumstances on the roads. For example: icy and slippery roads, construction works, a pedestrian or an animal running on the red light, dangerous behaviors of other drivers or intoxicated pedestrians, traffic lights out or working improperly or replaced by a human traffic controller, some criminal situations etc, etc. For example, what if a self-driving car will face a choice: "to hit a dog at full speed and continue driving or start to slow down abruptly to avoid collision with dog on a highway, but create a very dangerous situation to humans it this way"? Any reasonable human driver would choose variant N1, but who knows about a robot? Very likely it will not be able even make a difference between a dogs and a humans technically and hence their life priorities. For a robot they all would be just a "moving pieces of meat". For now I simply cannot imaging self-driving legalization.

9 hours ago, John Cuthber said:

It hardly matters.
There isn't enough room in the tank for the methane- that's why the pressure gets so high.
If you put solvent in the tank there is less room for the methane.

Hard to say. There are claims that methane in adsorbent pressurized to 400 bars is capable to achieve 500 v/v density. Certainly it wouldn't be possible without adsorbent. You would be hardly able to compress methane to 500 v/v. http://onlinelibrary.wiley.com/doi/10.1002/ente.201600172/abstract

Possibly a solvent can play role similar to an adsorbent.

How well does methane dissolve under high pressures in different substances? For example, what methane solubility may we expect in paraffines under 600-700 bar pressures?

4 hours ago, John Cuthber said:

Extrapolating from that it looks like you need more than 20 KBar

Are you sure in it?!

3 hours ago, John Cuthber said:

However if for some reason that doesn't work (or is not fitted) then yes, the tank will burst- probably violently.

So, how strong tank do you need if 700 bar tank will rupture?! 

2 minutes ago, StringJunky said:

It seems LNG only combusts when it constitutes 5-15% of an air/gas mix.

You don't need to get a combustion process initially to get a cylinder rupture. Even cylinder with pure liquid Oxygen or Nitrogen can get rupture if cylinder walls cannot hold increased pressure any more. 

So, if we will fill a cylinder designed to withstand 700 bar pressure (similar to those in Toyota Mirae) with LNG and will left it unattended and with no further refrigeration, will it explode with time?

3 hours ago, swansont said:

You need to provide the specifics of the container. I picked an easy value, but all it is is P1V1 = P2V2 and we know what P2 and V2 are: 1 atmosphere  and 22.4 L at 0 ºC and then correct for the temperature (going from 273K to 293K is only ~ 7.3% change) 

Where did you take it from? When LNG reaches room temperature, I think it's closer to -167 C to +25 C change. Where did you take 0 C from? I think container could have around 50 L volume. Let say initially it was completely filled with LNG. How much pressure will grow, when its content will reach +25 C? What pressure the cylinder walls will experience?

3 hours ago, swansont said:

At STP, an ideal gas occupies 22.4 liters per mole. If we start with a volume of 0.224 liters (you'd need to do the calculation to get the exact number), you could apply PV= nRT. At room temperature, the gas will exert 100 atmospheres in that volume. That should approximate what would happen for a non-ideal gas.

Maybe you may make calculation for methane in particular? For example, if we fill some cylinder with LNG and will wait when temperature of LNG will become equal to room temperature. How much pressure on cylinder walls it will exert now?

How much LNG pressure suppose to increase when it will reach room temperature?