Electric GA - what would it take?

[kimberlyanne546]

Were there no emissions from the energy used to manufacture the batteries, or when generating the electricity used to charge the batteries?

The second part of your question, yes, if you view the site it was from the steam (I think) PGE plant. They made a point of mentioning that the charging station was powered by emission free local energy.

 

[kimberlyanne546]

Geo Thermal powered

The charging station's electricity consumes no fossil fuels. It is supplied entirely by Sonoma County Geyser Geothermal station. This can charge 12 aircraft at the same time and deliver each 9600 watts.

 

[kimberlyanne546]

 

[Piloto]

In my picture posted above, it's easy to see the relative specific energy (energy density or power density) of various sources of power. What's less simple to understand is the relationship of powerplant efficiency to real world output.

Put another way, a gasoline engine at 33% efficiency will consume 3 times more energy than a battery/motor combination at 100% efficiency (silly example, I know)

So, while the differences are not as great as the chart shows, battery powered aircraft will remain quite limited.

Electrochemical energy and it's physical - theoretical limits are well known and understood. For practical, real world parity, electrochemical energy would have to improve beyond the limits of physics.

Consider powering an airliner by batteries, for example. The level of energy required is massive. And, no matter how fast you could drive the fan with an electric motor, you still don' have the heat, pressure and thrust of the core engine (all key factors in high speed flight) .

By looking at your chart hydrogen energy density by weight is by far much higher than any of the fuels. Hydrogen fuel cells appears to be the best choice for any weight sensitive vehicle. Current research has been able to store hydrogen atoms in a non gaseous state without the need of high pressure or refrigeration tanks. Hydrogen is available in water and its by product is just water. The ocean and the sun its all you need to get hydrogen by electrolysis. Although other methods may be more efficient. But the beauty of hydrogen is that is self recycle into water.

José

 

[MAKG1]

The problem with hydrogen is that the energy density per kg is pretty good. The energy density per liter SUCKS. It's just not a very dense material, and it's difficult to get enough kg on an aircraft safely to be feasible for anything but extremely short flights.

Hydrogen should be viewed as another type of battery. If you think of it as a fuel, you don't understand it. Yes, it's "in" water, in the same sense that AvGas is in carbon dioxide and water (plus a few miscellaneous additives like TEL). You can make it from sunlight in the same manner as you can make electricity from sunlight -- and that's the conventional way to make hydrogen. In principle, in very large quantites (given infinite infrastructure), but in practice, not anywhere near enough.

As a battery, the only advantage hydrogen offers is the speed of charging. Not a negligible advantage, but at present, you have to trade off almost all of your mission to pull it off.

 

[Piloto]

Geo Thermal powered

The charging station's electricity consumes no fossil fuels. It is supplied entirely by Sonoma County Geyser Geothermal station. This can charge 12 aircraft at the same time and deliver each 9600 watts.

Although 9600 watts appears to be impressive it is only 12HP=(9600/740). You need 150KW just to produce 200HP. That would imply a 480 volts motor running at 312 amps and a good size battery. You would be better off with a hydrogen powered rocket engine.

José

 

[MAKG1]

Although 9600 watts appears to be impressive it is only 12HP=(9600/740). You need 150KW just to produce 200HP. That would imply a 480 volts motor running at 312 amps and a good size battery. You would be better off with a hydrogen powered rocket engine.

José

OK, now I'm thoroughly convinced you don't understand hydrogen. No modern work burns hydrogen as in an internal combustion engine. Or a rocket engine, for that matter (which would give you an instant minimum 8:1 weight penalty due to the oxidizer). Hydrogen fuel cells are electrical generators and run electric motors.

There are quite a lot of internet investor scams about "miracle hydrogen technology" intended to defraud the gullible. I hope you haven't fallen into that.

And you seem to have discovered that charging is slow. Yes, it is. The charging station does not need to deliver the same power as the electric motor. It would be nice if it did, but it is not essential. It just means a few hours of flight per day, and the rest of the time charging.

 

[cujet]

200 miles in a glider? 400 Miles per gallon equiv? In a glider? Are you kidding me?

I've spent 9 hours aloft without any fuel what so ever in a DG 505 glider. Sorry, but that does not count. Powered gliders are very, very, very efficient. And so slow, typical local winds have you flying backwards.

Example: Let's try a battery powered 182 in Alaska. Let me know how well it works out. After that failure, Let's try flying that battery powered 182 home to Florida. I clearly understand it's an absurd example. My point is that deep down, we all know why it won't work. Electrochemical batteries are, and will forever remain, incapable of powering practical aircraft.

 

[Piloto]

The problem with hydrogen is that the energy density per kg is pretty good. The energy density per liter SUCKS. It's just not a very dense material, and it's difficult to get enough kg on an aircraft safely to be feasible for anything but extremely short flights.

Hydrogen should be viewed as another type of battery. If you think of it as a fuel, you don't understand it. Yes, it's "in" water, in the same sense that AvGas is in carbon dioxide and water (plus a few miscellaneous additives like TEL). You can make it from sunlight in the same manner as you can make electricity from sunlight -- and that's the conventional way to make hydrogen. In principle, in very large quantites (given infinite infrastructure), but in practice, not anywhere near enough.

As a battery, the only advantage hydrogen offers is the speed of charging. Not a negligible advantage, but at present, you have to trade off almost all of your mission to pull it off.

You are right about current application of hydrogen. But I would not be surprised if an atomic sieve is developed that could separate hydrogen from oxygen in an efficient manner. This way water can be used as a fuel. After all oxygen generators use sieves to separate oxygen from nitrogen. Can you imagine the ramifications of this. Gas engines and nuclear power plants would be obsolete.

José

 

[Piloto]

OK, now I'm thoroughly convinced you don't understand hydrogen. No modern work burns hydrogen as in an internal combustion engine. Or a rocket engine, for that matter (which would give you an instant minimum 8:1 weight penalty due to the oxidizer). Hydrogen fuel cells are electrical generators and run electric motors.

There are quite a lot of internet investor scams about "miracle hydrogen technology" intended to defraud the gullible. I hope you haven't fallen into that.

And you seem to have discovered that charging is slow. Yes, it is. The charging station does not need to deliver the same power as the electric motor. It would be nice if it did, but it is not essential. It just means a few hours of flight per day, and the rest of the time charging.

From Wikipedia
Internal combustion vehicle

Main articles: Hydrogen internal combustion engine vehicle and List of hydrogen internal combustion engine vehicles
Hydrogen internal combustion engine cars are different from hydrogen fuel cell cars. The hydrogen internal combustion car is a slightly modified version of the traditional gasoline internal combustion engine car. These hydrogen engines burn fuel in the same manner that gasoline engines do.

Francois Isaac de Rivaz designed in 1807 the first hydrogen-fueled internal combustion engine.[34] Paul Dieges patented in 1970 a modification to internal combustion engines which allowed a gasoline-powered engine to run on hydrogen US 3844262.

Mazda has developed Wankel engines burning hydrogen. The advantage of using ICE (internal combustion engine) like Wankel and piston engines is the cost of retooling for production is much lower. Existing-technology ICE can still be applied for solving those problems where fuel cells are not a viable solution insofar, for example in cold-weather applications.

HICE forklift trucks have been demonstrated[35] based on converted diesel internal combustion engines with direct injection.[31]

José

 

[docmirror]

http://www.sonexaircraft.com/research/e-flight.html

Sonex has been experimenting with battery for a while. They publish some specs on their modified Sonex with battery and a motor, but afaik, they have no flight data to back up the numbers, only calcs.

I have to laugh a little when I hear non-engineers write stuff like: 'but when they have batteries that develop.....' and then some amazing efficiency improvement on the order of 300% or better. The physics of chemical energy storage and exchange between anodes and cathodes is well understood and finite. We have tried all kinds of esoteric materials in an effort to improve the physics, but it just ain't happening. Heck, it's possible that if you use some kind of Thorium, or Polonium and one of the various hydroxides you might double your density. But - at what cost? Are you ready to carry a battery that is ~ twice the mass density of lead? And if so, what would the cost of the battery be?

Sonex has some good engineers, we'll see what they come up with. I'm sure it's possible to put a battery and motor in a plane, it's just not useful except to say we did it.

 

[Mafoo]

I'm sure it's possible to put a battery and motor in a plane, it's just not useful except to say we did it.

Not only is it possible, it's been done.

http://yuneeccouk.site.securepod.com/Aircraft.html


I don't think anyone is saying battery power will surpass the energy in fuel. But it doesn't have to. It just has to make economic sense.

If someone can take a passenger in an electric aircraft someday, and go 1,000nm @ 80knots, with 5 stops along the way, and the trip costs them $50 in fuel and maintenance, I think there will be a market for it.

Yes, its far less convenient then a gasoline powered aircraft, but convenience is not the entire equation

 

[DrMack]

Small liquid-thorium reactors. It could be done =/

http://en.wikipedia.org/wiki/Aircraft_Reactor_Experiment

 

[docmirror]

http://en.wikipedia.org/wiki/Aircraft_Reactor_Experiment

Not a battery. Nuclear power conversion is not possible at the electron level. It needs to perform a materials transformation(during fission) at the nucleus of the atom to work.

Now, I have worked with planes for a long time, and nuclear power for even longer, but the idea of strapping a Uranium Fluoride slurry reactor to a 172 and running a small turbine just isn't in the cards.

This reactor/engine combo was one of the ideas for the XB-70 long range supercruising bomber. There were grand plans afoot to have an unrefueled range of weeks, and not hours or days using a nuclear heat source. As I recall from vague memories, the scale of the plane was going to have to be almost double the size of the B-52 to support the reactor, and various safety shielding just to get off the ground, nevermind a payload........

Ah,,,, the 50s. What a time.

 

[docmirror]

Not only is it possible, it's been done.

http://yuneeccouk.site.securepod.com/Aircraft.html


I don't think anyone is saying battery power will surpass the energy in fuel. But it doesn't have to. It just has to make economic sense.

If someone can take a passenger in an electric aircraft someday, and go 1,000nm @ 80knots, with 5 stops along the way, and the trip costs them $50 in fuel and maintenance, I think there will be a market for it.

Yes, its far less convenient then a gasoline powered aircraft, but convenience is not the entire equation

Ok, let's use the specs as advertised. You could go get a burger, then head home(1.5 hour total flight, @ 60MPH) and charge it up for 3-4 hours. Sure, it can be done, and someone has done it. With the best possible battery around, they can now do today, what we could do with an engine in 1920.

If we're getting 80% conversion efficiency(very generous) in a plane that spends most of it's time soaring, and you want to go 1000NM, it's going to take just under 20 hours aloft, and about 13 recharges for 38 total hours charging.

Let's face it, this is a burger run mission, and there's nothing wrong with that. I encourage private funding of all kinds of new stuff. But, don't make it into something it can never be, even with the most liberal numbers you can make up(Volt thinking).

 

[Mafoo]

Let's face it, this is a burger run mission, and there's nothing wrong with that. I encourage private funding of all kinds of new stuff. But, don't make it into something it can never be, even with the most liberal numbers you can make up(Volt thinking).

Well, I am not one for the government doing anything if it has the word research in it, but that's for the spin zone....


And as for the aircraft in 1920. That aircraft at the time was state of the art. Today it's a joke. I see the same with electric power in the future.

And even though it's in its infancy, people are looking at capacitive batteries. The advantage of them are they never ware out, and they can be charged instantly.

Two characteristics that apply very well to the application of travel.

 

[docmirror]

And even though it's in its infancy, people are looking at capacitive batteries. The advantage of them are they never ware out, and they can be charged instantly.

Where do you get this stuff? You think a capacitive device doesn't wear out?

And whats the discharge cycle?

Like I said, a complete rewrite of the physics of electrical conductor storage.

 

[Mafoo]

Where do you get this stuff? You think a capacitive device doesn't wear out?

And whats the discharge cycle?

Like I said, a complete rewrite of the physics of electrical conductor storage.

Where do I get this stuff? MIT

http://peswiki.com/index.php/Directory:MIT_Nanotube_Super_Capacitor

Yes, they wear out. but there life cycle will be recorded in many decades, and not just years.

 

[docmirror]

Where do I get this stuff? MIT

http://peswiki.com/index.php/Directory:MIT_Nanotube_Super_Capacitor

Yes, they wear out. but there life cycle will be recorded in many decades, and not just years.

Looks good. They are fast approaching about HALF the energy density of a Lithium Ion battery! This is what I thought you were talking about. I'm familiar with it, as it's been around since the late 80s. I used to build the LPCVD reactors for the nanotube growth system.

http://lees.mit.edu/lees/posters/RU13_Oct05.pdf (table 1)

They might present a compelling case where there is a highly cyclical load on a vehicle that could be used in place of friction braking, but for hauling a plane in the air,,,, no - sorry. Unless you could come up with a ballistic case, where the discharge was on the way up, and a recharge was on the way down. Sounds scary.

 

[denverpilot]

I believe in layman's terms, that was called a smackdown.

Sorry Mafoo... think the doc has your number, on that particular topic.

 

[bflynn]

I have to laugh a little when I hear non-engineers write stuff like: 'but when they have batteries that develop.....' and then some amazing efficiency improvement on the order of 300% or better.

You have to remember that the average layman has two reference points - lead acid batteries leading to lithium batteries. So in the recent past, we have had a massive jump in battery capabilities and continued refinement of the lithium family. For those not well versed in the technology, it appears we're on the verge of a break through.

It's the same way with people pushing solar or wind - they don't realize what the actual output capabilities are. We didn't choose oil, gas and coal over solar and wind because we wanted to polute, we did it because oil, gas and coal delivered power that solar and wind do not.

 

[douglas393]

This is one of the more interesting threads I have read. I think we all agree that it would be nice to have a reasonable alternative to flying than using our dinosaur eating devices, but I think the reality of the chances of that occurring in the near future or far future is unlikely. Forgetting about all of the physics, engineering, and scientific issues, I think we have to look at the issue from a more practical view point.

Presently, the average age of a plane used in GA is about 25 years old(I am sure someone will tell me my number is off), and the vast majority of planes sold today or being designed today(over 98% I would say though again I am sure someone has a more accurate number) are using basically the same technology for turning the propeller as they did when Orville and Wilbur flew, that being the internal combustion engine(I know our powerplant is loads different but they both run on convered a volatile liquid into power by small controlled explosions).

So even if Space Aliens or some super genius solved all the technical and scientific issues of the problems with electrical flown planes, we still have the present GA fleet and its slow overturn to contend with. From what I have read in this thread, the solutions to the issues of electrical power are still a major issue, so even with the small number of planes presently using electrical power, I do not see a change occuring anytime soon.

What I would like to see, and I tnink is much more likely, is a change in the engines we use when we overhaul to more modern(read fuel efficient) engines, or even diesel replacements for our engines.

Doug

 

[Anthony]

Presently, the average age of a plane used in GA is about 25 years old(I am sure someone will tell me my number is off

I think the average age is over 30 years old, but I am not exactly sure either, but I get your point. The golden age of GA manufacturing was in the 1970's.

What I would like to see, and I tnink is much more likely, is a change in the engines we use when we overhaul to more modern(read fuel efficient) engines, or even diesel replacements for our engines.

Especially with the current environment for GA aircraft values, I don't see ANY type of replacement as an economically viable solution due to installation, and certification costs. The replacements would be just too expensive for owners to justify. Current existing replacement engines that burn 100LL, are pushing $30K installed, and that is for the exact same thing that's in there now. Many of our planes aren't worth much more than that at this point.

 

[Mafoo]

I believe in layman's terms, that was called a smackdown.

Sorry Mafoo... think the doc has your number, on that particular topic.

I think he knows a lot more about it then me, and I aslo don't think anything in my lifetime will be created that's of any reasonable utility.

But I always take pause, when an expert says something along the lines of "we have tried everything, and it's just not going to happen".

New technologies emerge, better manufacturing happens. One day we will get there, and when we do (might be 150 years), one thing I an certain of, is it will be with a solution none of us today imagined.

 

[jhausch]

docmirror,

Any thoughts on the "molten aluminum" battery recently out of MIT? I could not find any info on power density, but the "molten" part seems like it would help with (whatever is the right term for) "conversion/production/supply rate"

 

[Anthony]

My question is still, why do we want/need and electric alternative? Is this just an academic exercise?

 

[Mafoo]

My question is still, why do we want/need and electric alternative? Is this just an academic exercise?

We need a cheaper alternative. Right now, the prevailing thought is the best way to make transportation (including flying) cheaper, is through the use of electricity.

I agree that the form of population of the future will be an electric motor. How that energy is stored on the vehicle however, I have no clue. Could be chemical, could be hydrogen, and it could be something we haven't even invented/discovered yet.

 

[Anthony]

We need a cheaper alternative. Right now, the prevailing thought is the best way to make transportation (including flying) cheaper, is through the use of electricity.

I agree that the form of population of the future will be an electric motor. How that energy is stored on the vehicle however, I have no clue. Could be chemical, could be hydrogen, and it could be something we haven't even invented/discovered yet.

As I said before, the cost to install anything different than the existing engine in the GA fleet will be cost prohibitive, and I don't see most GA pilots buying a new electric plane that costs $350 - $500K.