Portable energy sources.

All the same, using Kg as his unit is still valid as the concern is how much material is needed to store a certain amount of energy. I don't know how you define "mass", but I'd consider the question of "how much stuff" to be adequately answered by mass.

It's just using "watts" as opposed to "watt-hours" or something to describe its capacity. I seriously doubt you can just wipe away the whole idea of a hydrogen economy because you still can't escape the fact that resources like chromium or polymers are still dependent on mining/drilling output.

I also can't help but wonder, though. Assuming you have a battery that can store massive charge... where is all that electricity going to come from? Think about re-charging something that will need to drive 200 hp(~150 kW) worth of motors for distances of ~250 miles. So probably a good... 2300 kW-hours per charge? That's a huge amount. You apply that over every car on the road, and the electrical infrastructure and output we have currently is hardly going to support that.
 
 
Yes. While not specifically for cars and other things that use such large amounts of energy, that is basically my question.

Edit: there are basically two ways to accomplish something from an engineering perspective: be very smart and use as little energy as possible (this approach requires many decades), or use the brute force method, which requires lots of energy. Portable energy is the hard part in this.

Edit2: Yes, nuclear radiation sources could make a great energy source. But it also has lots of problems: for starters, they're not disposable or refuelable, or at least not in a way accessible to the general public.
 
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there are basically two ways to accomplish something from an engineering perspective: be very smart and use as little energy as possible (this approach requires many decades)
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Trying to cut back on power on something like an automobile without much of a sacrifice will probably entail things like lighter weight materials, better aerodynamics, better power distribution, and for that matter, public acceptance. While it is true that a 50 kW electric motor can probably get me ~300 lb-ft of torque, that means acceleration is probably pretty darn good, but what about speed? I don't think you can convince people to keep it under 50 mph on the highway.

I just don't think you can manage anything trying this approach. A hydrogen economy still poses the same problem since you're basically going to acquire hydrogen from water, and for all the electrical energy that went into doing that ... you'll only get around 60-70% of that in the actual vehicle.

or use the brute force method, which requires lots of energy. Portable energy is the hard part in this.
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This is also I think the more likely outcome.

If I give you $30,000 to go buy a car, are you going to buy a hybrid or some turbocharged pocket rocket or a big SUV? Most people wouldn't buy the hybrid unless they were strongly principled about environmental issues. And that's not something you can escape -- auto manufacturers dug their own grave on that one. Even with more hybrids coming out, people are still going into Chrysler dealerships with the first question of "'zat ting gotta Hemi?"
 
my car is 50hp (about 37KW) and goes up to more than 140kph, though it's 3.5 meters long and 760Kg. (so, I lack the flux capacitor but I can reach 88mph :))

50KW is certainly enough to power a mid-sized car. You're thinking of 200hp, if that's the average american car, they are well overpowered, 200hp is for sports car IMHO

also, car's rated power is max power, you don't have to sustain it all the time.
 
50KW is certainly enough to power a mid-sized car. You're thinking of 200hp, if that's the average american car, they are well overpowered, 200hp is for sports car IMHO

also, car's rated power is max power, you don't have to sustain it all the time.
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Well, yeah, that's kind of the reason why the average American mid-size sedan is a 200 hp V6. They don't really make that kind of power until you push it to 6000 rpm or something, and that's usually also measured at the flywheel. In the typical usage range down below 2800 rpm, it's probably not going to deliver more 80 bhp to the drive wheels. A lot of massively powered sports cars make enough power at the engine that they actually are delivering 200+bhp to the wheels.

While the Japanese can make a mid-size sedan that weighs under 3200 lbs (a little under double the mass of your car), American manufacturers make theirs generally a few hundred pounds heavier and well beyond. It's sometimes scary when I see things like a 2-seater with a dry weight of 4700 pounds. Then again, people will generally feel more secure in something that is heavier and has more raw power. You'll find people out here who say they don't really feel completely safe in their vehicle until it puts out at least 500 hp.

Well, people tend to feel the power more because of torque than horsepower and that's kind of why the electric motor can be really great as it delivers its peak power and torque at very low rpm (e.g. 1200-1500 rpm). But if you try to push it to higher speeds, it does drain power and fall off in its output, which is something that is less of a problem for an ICE.
 
There are all kinds of nifty, new electric motors since the last five years or so.

A generic electric motor is bad with very low RPM, and you would want AC for the best result. Essentially, you want multiple, fast rotating electromagnetic fields at all times, synced to one another. Normal electric motors have problems with that when standing still or rotating slowly. Then it's basically just shorted and the energy transformed into warmth directly. And DC motors aren't very efficient for their weight.

But there are very interesting new designs, like brushless motors, that have a very high torque right from the start, and can be designed do operate best at very low RPM (~300), or very high RPM, up to about 90,000, or to operate over a wide range. They have a microcontroller to time individual pulses over all the coils, to simulate multiple rotating fields, in small slices. And you can easily build them hollow and thin, if you want.

That's great for cars! You just put one in the rim of each wheel. They will work as generators and brakes as well, although you still want some regular brakes for emergencies.

And you can put lots of batteries in the former engine compartment that way.

Edit: and a 50 KW brushless motor has WAY more torque than even an 150 KW combustion engine at low RPM.
 
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Cant get much speed on the autobahn in a car like that.

BTW did youguys see the new idea for nuclear energy? It suggests giving countries modular reactors that cannot be opened, simply delivered and taken away when they are used up or something. Reprocess the fuel and move on. Some of the ideas have merit btw. (It is a bush proposal kind of, look on www.washingtonpost.com)
 
Sxotty said:
Cant get much speed on the autobahn in a car like that.
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Why? 120 km/h is only about 1000 RPM. That's really no problem at all, and a perfect fit for brushless motors. Your tires will burst much earlier than the motor will give up. Although wind resistance will start to win if you go fast enough.

You can easily design such a motor for a range of, say, 0..12000 RPM and still have it perform close to optimal throughout that. That's 0..1440 km/h...

BTW did youguys see the new idea for nuclear energy? It suggests giving countries modular reactors that cannot be opened, simply delivered and taken away when they are used up or something. Reprocess the fuel and move on. Some of the ideas have merit btw. (It is a bush proposal kind of, look on www.washingtonpost.com)
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Yes, and if you use fast decay isotopes, a heat pump and something like a stirling engine, you can even make them tiny. But they will be very expensive, considering the amount of energy you can get out of them. Mostly because of the very expensive reprocessing. And don't forget the mess of safety rules you're getting in!

I'm not even sure if they would make much sense for large power plants. Although they could be nice for things like heating your house.
 
DiGuru said:
Why? 120 km/h is only about 1000 RPM. That's really no problem at all, and a perfect fit for brushless motors. Your tires will burst much earlier than the motor will give up. Although wind resistance will start to win if you go fast enough.

You can easily design such a motor for a range of, say, 0..12000 RPM and still have it perform close to optimal throughout that. That's 0..1440 km/h...


Yes, and if you use fast decay isotopes, a heat pump and something like a stirling engine, you can even make them tiny. But they will be very expensive, considering the amount of energy you can get out of them. Mostly because of the very expensive reprocessing. And don't forget the mess of safety rules you're getting in!

I'm not even sure if they would make much sense for large power plants. Although they could be nice for things like heating your house.
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I was alluding to wind resistance in the first part.

And the second was tangentially related, I was just throwing it out there since people interested in energy were perusing the thread. It is discussing making electricity from nuclear power more safely and so forth, not really related sorry :p
 
Btw, I asked a bunch of more or less random people how they would feel about an electric car. None of them liked it, they all said they wanted a nice sound and fast acceleration. They were totally not convinced. Or, in other words: they really have no idea whatsoever, and see electric cars as tiny and very slow. Golf carts and such.

Electric cars probably suffer more from an image problem than anything else.

And consider this: a century ago, all races were won by electric cars! Everyone wanted one at that time! The first real cars were electric ones, with steam coming a close second.
 
Sxotty said:
I was alluding to wind resistance in the first part.
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Yes, that's where the high horsepower engines will be better. But then again, it's fairly easy to regulate the amount of power with a brushless motor, as opposed to a regular electric one where you have to change the voltage, so you could use a heavier one. You would lose some comfort though, as your wheels get heavier.

And the second was tangentially related, I was just throwing it out there since people interested in energy were perusing the thread. It is discussing making electricity from nuclear power more safely and so forth, not really related sorry :p
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No problem, discuss those things here at your leisure. ;)
 
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Btw, if you put the motors in the wheels, that's where the power is applied, directly. No intermediate losses at all. And you can get rid of the differential(s), the gearbox, and the coupling. Essentially, you increase the efficiency by about half. So, together with the very high torque, I think 4 12.5 kW motors would probably outperform a 150 kW combustion engine.
 
DiGuru said:
Btw, I asked a bunch of more or less random people how they would feel about an electric car. None of them liked it, they all said they wanted a nice sound and fast acceleration.
Click to expand...

So in future we'll see electric cars with really expensive sound systems dedicated to making them sound and vibrate like 'proper' cars. :devilish:
 
Btw, if you put the motors in the wheels, that's where the power is applied, directly. No intermediate losses at all. And you can get rid of the differential(s), the gearbox, and the coupling. Essentially, you increase the efficiency by about half. So, together with the very high torque, I think 4 12.5 kW motors would probably outperform a 150 kW combustion engine.
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Yeah, that's pretty much where GM is taking their research work with fuel-cell electric, having an AC motor at each wheel (their layout is apparently total of 90kW, though that's including all the ancillary electronics and interior junk). I'm fairly sure everybody sees that as the ideal layout.

Well, even assuming that 50 kW is enough, it still raises that question that relates back to the original point of the thread about how you're going to store and generate all that energy. Say at an average speed of 30 mph (i.e., mostly city stop-and-go, smatterings of highway driving), you want to go 270 miles on a single charge (or fillup of hydrogen or whatever)... so... 450 kW-hours stored in a battery/tank (maybe more like 500 if you want to include everything else that eats up power). The average household in the US probably doesn't use up that much in 2 weeks. For an apartment, that's probably a month's worth. And yet, in a car, you'll plow through that in the first few hours of a road trip. Maybe 1 week's worth of commuting to and from work. Which amounts to a pretty insane increase in electrical demands.
 
Mariner said:
So in future we'll see electric cars with really expensive sound systems dedicated to making them sound and vibrate like 'proper' cars. :devilish:
Click to expand...


Actually that is true, GM tunes the exhaust on their cars extensively so it sounds "nice".

Further Toyota made an electric concept sports car, and a big complaint was from pedestrians who were used to the noise, and almost got ran over by stepping out in front of the silent car approaching at high speeds.
 
ShootMyMonkey said:
Yeah, that's pretty much where GM is taking their research work with fuel-cell electric, having an AC motor at each wheel (their layout is apparently total of 90kW, though that's including all the ancillary electronics and interior junk). I'm fairly sure everybody sees that as the ideal layout.
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Large gears turn slow, and the same goes for large corporations. There are MUCH better electric motors by now than just the regular AC ones.

But then again, from perception to concept car takes many years. They have some catching up to do with the current state of the art.

Well, even assuming that 50 kW is enough, it still raises that question that relates back to the original point of the thread about how you're going to store and generate all that energy. Say at an average speed of 30 mph (i.e., mostly city stop-and-go, smatterings of highway driving), you want to go 270 miles on a single charge (or fillup of hydrogen or whatever)... so... 450 kW-hours stored in a battery/tank (maybe more like 500 if you want to include everything else that eats up power). The average household in the US probably doesn't use up that much in 2 weeks. For an apartment, that's probably a month's worth. And yet, in a car, you'll plow through that in the first few hours of a road trip. Maybe 1 week's worth of commuting to and from work. Which amounts to a pretty insane increase in electrical demands.
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Yes. Does that tell us something about the demands for power, or the sheer idiocy of the current designs? Probably both.

Consider this: model helicopters. I'm sure you'll agree, that a helicopter is about the worst transportation possible, energy wise. Five years ago, those things were pretty large and bulky, and you needed a very beefy combustion engine to get it into the air for a few minutes at a time.

But nowadays, you can buy electric helicopters in all sizes, from really tiny to huge, that have to carry the heavy and inefficient batteries as well, but are still running loops around the ones with combustion engines long after those have landed because they ran dry. Just because of the incredible efficiency of those lightweight, but extremely powerful brushless motors.
 
Some personal titbit: I've been in quite some factories and such by now. And there's a whole lot of ridicoulously powerful machines in those. And I really get a kick out of that. I think very large and heavy, but stupendously elegant moving robots are incredible. Especially when handling very large things as if they weight nothing. And huge turbines are totally meshmerizing, especially when you can see the blades. The sheer power!

But the very best is standing next to a really huge electric motor when it powers up.

:D
 
ShootMyMonkey said:
Well, even assuming that 50 kW is enough, it still raises that question that relates back to the original point of the thread about how you're going to store and generate all that energy. Say at an average speed of 30 mph (i.e., mostly city stop-and-go, smatterings of highway driving), you want to go 270 miles on a single charge (or fillup of hydrogen or whatever)... so... 450 kW-hours stored in a battery/tank (maybe more like 500 if you want to include everything else that eats up power). The average household in the US probably doesn't use up that much in 2 weeks. For an apartment, that's probably a month's worth. And yet, in a car, you'll plow through that in the first few hours of a road trip. Maybe 1 week's worth of commuting to and from work. Which amounts to a pretty insane increase in electrical demands.
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Please tell me you didn't just take the distance, divide it by speed and multiply by the motor's maximum power rating... please :oops:
;)
 
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