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You can't buy a lithium-air battery (yet). You've probably never even heard of one. They were only invented 15 years ago, and for now, they're still just laboratory curiosities.

But with the latest lab breakthrough, the lithium-air battery (also known as the lithium-oxygen battery) is nosing up into the energy density region seen in gasoline. If you're thinking battery-powered car, maybe your sights are too low. How does battery-powered airplane sound?

The technical stuff

Batteries are composed of three layers: two electrodes (a negative one called an anode and a positive one called a cathode) separated by an electrolyte. The electrolyte allows cations (atoms or molecules with a positive electric charge, because they're missing an electron) to flow through from anode to cathode, but it won't allow the matching electrons to flow through. So to balance out the charges, the electrons have to take another path from anode to cathode, which is a wire, where they do work in the process. The whole thing works until the electrolyte runs out of ions, at which point the battery has to be recharged.

The lithium-air battery uses metallic lithium as the anode, and air-permeable carbon as the cathode. The electrolyte is a thin gel that allows lithium ions (Li+) from the anode to migrate over to the cathode, where they combine with oxygen from the air to form lithium oxide or lithium peroxide. Eventually one of two things happens: either all the lithium in the anode gets used up, or (more likely) the carbon in the cathode becomes full of lithium oxide and doesn't have room for any more. When the battery is recharged, the lithium oxide is dissociated and the lithium ions migrate back to the anode.

Since lithium is the lightest metal (in weight), any battery using lithium will be light. But since lithium-air batteries also have a light cathode, they are the lightest batteries known.

What's New

Now researchers at MIT have added carbon nanotubes to the cathode, with spectacular results. With a lot more surface area, the cathode can now hold a lot more lithium oxide, which means that the battery can run a lot longer before it needs recharging. The result is four times the energy density of the previous Li-air record holder: the old record of about 600 Watt-hours per kilogram has been upped to about 2500 Wh/kg, in the fully discharged state. This is getting close to the theoretical maximum is 3215 Wh/kg for a discharged lithium-air battery.

Specifying the charge state is important when you talk about the energy density of lithium-air batteries, because the battery actually gains weight as it discharges (since it's taking in oxygen from the air). In the fully-charged state, the battery weighs less: the MIT researchers have reported energy densities of over 10,000 Wh/kg when fully charged, which is essentially at the theoretical limit right now.

Power-to-weight and energy-to-weight ratios. Blue: previously reported best lithium-air battery with cobalt catalyst cathode (discharged). Red: new MIT battery with carbon nanotube cathode (discharged). Black:  new battery fully charged.

Doing a little unit conversion, in the discharged state 2500 Wh/kg = 9 Megajoules per kg, and in the charged state, 11000 Wh/kg = 40 MJ/kg. For comparison, gasoline is about 44 to 47 MJ/kg, and jet fuel is 43. So in the fully charged state, the Li-air battery is close to the fossil fuel level. (The lithium-ion battery in your cell phone is around 1 MJ/kg, the alkaline battery in your flashlight is 0.6 MJ/kg, and the lead-acid battery that starts your car is about 0.1 MJ/kg. So even in its discharged state, 9 MJ/kg is pretty huge.)

The implications

This has obvious implications for the transportation industry, where the weight (and cost, and availability) of batteries is the biggest obstacle to practical electric cars. Note that the power-to-weight ratio reported is between 1000 and 2000 W/kg, or between 0.6 and 1.2 hp per lb, which also compares favorably to a gasoline engine.

But when you consider a battery this energy dense, air travel also presents an interesting opportunity. Imagine an aircraft with a hybrid engine that uses both battery power from a Li-air battery, and energy from burning renewable biofuel. As the plane flies, the liquid fuel runs out and the plane gets lighter; but the battery takes on oxygen, and the plane gets heavier. So it would be possible to design a hybrid-powered aircraft that stays at the same weight throughout the entire flight, as weight lost and weight gained were exactly counterbalanced.

Currently, as a plane flies it loses weight, and to compensate the pilot must lose lift in an equal amount, which he or she does by pointing the nose just slightly more downward as the flight proceeds. This affects what's called the "angle of attack" of the wing and reduces lift (and also reduces drag). But while lift varies linearly with angle of attack, drag varies exponentially, which means that there is one and only one angle of attack at which the ratio of lift-to-drag is at it's highest. At this precise angle of attack, the plane is operating at its most efficient point, aerodynamically speaking.

Pilots today don't worry about this efficient point at all (except for a few long-distance record setters). That's because pilots know they can only fly at that ideal angle of attack for a short while before fuel burns off, lift must be reduced, and the angle of attack must be changed to something less ideal. But with a constant-weight airplane, it would be possible to fly the airplane at the ideal angle of attack for the entire flight, making the entire trip more energy efficient. All a pilot would have to do would be to know the weight of the aircraft when loaded, then look up the correct airspeed for weight and altitude on a chart, and fly at that airspeed.


Peer-reviewed abstract in Energy & Environmental Science
MIT press release
Supplemental data (pdf)

Originally posted to The Numerate Historian on Fri Aug 12, 2011 at 09:10 AM PDT.

Also republished by Kossack Air Force and Kosowatt.

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    by Keith Pickering on Fri Aug 12, 2011 at 09:10:19 AM PDT

    •  Diary was outstanding. (24+ / 0-)

      I read it out loud to the SO and did not understand one word of what I was saying.
      He's an Engineer for JCI and even he was a little confused in parts, but impressed as all H.

      I do not understand the following:
      How do planes stay up in the air.
      How do 38948349384938 ton ships not sink.
      How the earth does not float out of it's bobbles.

      And I never will.

      "Oh changed your hair color? It's just so dark. You like it? And with your skin tone?" My Mom ♥ 12.25.2007 ------- A true sportsman is a hunter lost in the woods and out of ammo. ~Robert Brault

      by Christin on Fri Aug 12, 2011 at 09:28:00 AM PDT

      [ Parent ]

      •  Don't forget: (2+ / 0-)
        Recommended by:
        SnyperKitty, Christin

        How do you run a jet engine off a battery?

        Linking to a news article is journalism in the same sense that putting a Big Mac on a paper plate is cooking.

        by Caj on Fri Aug 12, 2011 at 10:07:31 AM PDT

        [ Parent ]

        •  Use a propeller (16+ / 0-)

          Contrary to popular belief, not that much slower if designed right.


          by Keith Pickering on Fri Aug 12, 2011 at 10:13:50 AM PDT

          [ Parent ]

          •  props for large planes (5+ / 0-)

            The biggest problem with props for a large plane that flies at high altitude is that you wind up losing most of your thrust as the air gets significantly thinner.  That's not really a problem that you can easily deal with as the only real solution is to make the props much, much bigger, which causes other problems.

            If that problem can be solved though (by installing huge numbers of total props for example, or having a design where the prop blade extends in flight) you eliminate problems of not having enough oxygen to burn in your fuel, which can limit your altitude.  This allows you to fly basically as high as the previously discussed prop issue would allow without requiring any modifications, theoretically permitting you to go to altitudes where wind resistance is very minimal.

            It basically will boil down to how fast and how far you want to travel, you could travel very far, fairly slowly and very efficiently, or you could travel very fast, over very short distances, but the middle ranges would be difficult.

          •  Battery driven prop planes would be (8+ / 0-)

            less noisy, right? Perhaps ideal for regional air traffic.

            Use renewable electric power to charge the batteries and air travel would become carbon neutral.

            •  I wonder if wing and fuselage-mounted solar cells (5+ / 0-)

              could provide additional power in-flight, perhaps even enough to power flight controls and avionics in case of main battery or engine failure.


              by kovie on Fri Aug 12, 2011 at 11:32:58 AM PDT

              [ Parent ]

              •  Additional power, sure (1+ / 0-)
                Recommended by:

                but I'd hate to rely on solar 15,000 feet in the air...

                "Mediocrity cannot know excellence." -- Sherlock Holmes

                by La Gitane on Fri Aug 12, 2011 at 03:03:28 PM PDT

                [ Parent ]

                •  Why? After all, you're that much closer (1+ / 0-)
                  Recommended by:
                  La Gitane

                  to the sun.

                •  It would be used to backup and supplement (0+ / 0-)

                  a plane's primary source of electric power, which I assume will always come from engine-recharged batteries, to save money and provide insurance, so there would be no need to rely on it when under clouds or, of course, at night.

                  Also, why do you assume 15k feet, when most commercial planes fly at 30-35k, well above cloud cover, with less atmosphere and pollution which I assume would provide even more solar power to the cells?


                  by kovie on Fri Aug 12, 2011 at 06:57:32 PM PDT

                  [ Parent ]

              •  While that would be cool, (1+ / 0-)
                Recommended by:

                the amount of power solar cells provide is so low that it's doubtful it would offset the power consumed from drag due to their weight.

                Note how solar powered cars and planes are built exceptionally light, with huge cell area. For comparison, A 747 at cruise is putting out the equivalent power as ~1/4 the city of Boston.

                I think I've seen a Prius configuration that does what you describe, put some solar cells on the roof to power electronic accessories in the car etc.

                There have been proposals to have electric planes powered by a concentrated energy beam from the ground. That's much more  power density than just sunlight, and there are a whole host of other issues with that configuration.


                by Simplify on Fri Aug 12, 2011 at 05:02:59 PM PDT

                [ Parent ]

                •  They could be designed to be flush (0+ / 0-)

                  with the wing and fuselage surfaces and coated with smooth and transparent materials such that their contribution to drag would be minimal. And solar cell technology is evolving rapidly with cheaper, lighter and more efficient cells coming out all the time. This would of course never even begin to be able to provide a commercial plane's primary power, but as supplement and backup, it might someday make sense.


                  by kovie on Fri Aug 12, 2011 at 06:52:57 PM PDT

                  [ Parent ]

                  •  Weight... (0+ / 0-)

                    Airplanes are built to weigh as little as possible:  every extra pound of weight has a direct requirement for additional thrust during flight.  Solar cells are heavy, and would make maintenance a lot more "interesting".

                    Typical figure of merit:  a Boeing 747 has an L/D (lift-to-drag) ratio of about 20/1.  That means for every twenty pounds of weight, it needs one more pound of thrust to cruise.  Using the power from solar cells, they would not now be capable of making up that power (thrust) in flight, best case.  The practical cases are all much worse.

                    •  And emerging solar cell technology (0+ / 0-)

                      is still way too heavy? I thought that the newest cells are wafer-thin now and very light, and could almost be "painted" on a wing's surface. Not quite?


                      by kovie on Fri Aug 12, 2011 at 09:24:30 PM PDT

                      [ Parent ]

                      •  Could be... (0+ / 0-)

                        but the effect of merely painting airliners has a noticeable effect on their performance.  The regular paint to do it weighs several hundred pounds.  Airlines like to leave their aircraft unpainted for performance, but like the advertising and the anti-corrosion properties.

                        And for the solar cells, you still need to convert the power to whatever the plane wants to use and regulate it.  Not that it's impossible, but it's hard to keep it light and reliable and efficient.

                  •  Wind power! (0+ / 0-)

                    At that speed there must be lots of air rushing past so you could install wind turbines to charge the batteries that turn the propellers. Simples!

                    Recharging is the big drawback with any use in commercial transportation unless you had elaborate swap out facilities as they have tried using in Israel for electric cars. Short haul budget airlines in Europe rely on turn-around times of less than 30 minutes to keep costs low. They would not appreciate having to plug the thing is overnight after a single trip so how long do these take to recharge?

                    The separate jet/propeller engine concept is also dubious. What about drag from the engine that is not being used at the line. Modern high efficiency jet engines as used on the Airbus A320neo are big. very big. Boeing are going to have to design a replacement for the 737  or make radical changes to the airframe to fit them. Currently the wings are too low for the PW1100G PurePower from Pratt & Whitney and CFM International’s LEAP-X to fit.

                    Some sort of dual fuel turbo prop engine would be possible I suppose.

                    Fight poverty, oppression, hunger, ignorance, disease and aggression wherever they occur.

                    by Lib Dem FoP on Fri Aug 12, 2011 at 11:29:10 PM PDT

                    [ Parent ]

                    •  Thermodynamics Second Law Violation (0+ / 0-)
                      "...At that speed there must be lots of air rushing past so you could install wind turbines to charge the batteries that turn the propellers. Simples!"

                      This was snark, right?  You clearly know enough about aircraft design to know that just mounting wind turbines on an airplane to charge the batteries basically is a violation of the second law of thermodynamics.  That wind might be rushing past, but its produced by the props being driven by motors drawing energy from the batteries.  Why have the batteries?  Just use the wind turbines to power the motors for the props.  Now, that's efficiency.

                      "Refueling" still seems to be the major stumbling block for electrically powered vehicles.  Commercial operations like airlines, truck lines, railroads, bus lines, etc. would seem to be best situated to develop experience on perfecting the best methods for this.  Only after the alternatives have been tested will a really good system be available for the standard consumer.  Just plugging the vehicle in overnight or at work would seem to confine electric vehicles to solely a short-distance envelope, making them relatively unattractive economically.  Now, if somebody thought of developing a swappable power module, that might change the equation.


                      by PrahaPartizan on Sat Aug 13, 2011 at 08:26:02 AM PDT

                      [ Parent ]

            •  Solar powered Zepellins would be awesome (5+ / 0-)

              and safe.

              " Resistance is NOT futile, it gives me a warm fuzzy feeling." Wino

              by Wino on Fri Aug 12, 2011 at 11:53:05 AM PDT

              [ Parent ]

              •  Not quite (0+ / 0-)

                Even with helium for lift, a number of zeppelins were lost in the 30s due to other causes ( the Akron went down ina weather related incident, killing 73 or the 76 on board).

                •  No pre-war Zeppelins used helium (1+ / 0-)
                  Recommended by:

                  Helium was only available from the USA which denied exports of what was considered a strategic military material. That's why airships like the Hindenberg and the British R101 used hydrogen and were lost in fires whereas the US airship you quote was badly handled.

                  BTW, the Zeppelin Luftschifftechnik company sold three of its NT airships to Goodyear in June. These will be used for their tire publicity flights in the USA from 2014


                  by Lib Dem FoP on Fri Aug 12, 2011 at 11:55:19 PM PDT

                  [ Parent ]

                •  Radar Changes Everything (0+ / 0-)

                  Those dirigibles were lost because weather forecasting was pretty primitive in the 1930s.  With modern forecasting techniques, ground weather and traffic control radar, and vehicle mounted radar, dirigibles could be controlled to avoid major weather problems, just as we do with standard aircraft.  Modern electronics would seem to have changed the game conditions for using dirigibles.


                  by PrahaPartizan on Sat Aug 13, 2011 at 08:29:04 AM PDT

                  [ Parent ]

              •  It's been proposed (2+ / 0-)
                Recommended by:
                eyesoars, Wino

                for high-altitude unmanned airships. Charge up during the day and have just enough to fly through the night. Those are super-light systems, though, with very little payload weight allowable and low thrust requirements.


                by Simplify on Fri Aug 12, 2011 at 05:04:33 PM PDT

                [ Parent ]

            •  Also, diesel/electric trains (1+ / 0-)
              Recommended by:
              Bill White

              with far less diesel.


              by StrayCat on Fri Aug 12, 2011 at 01:06:39 PM PDT

              [ Parent ]

          •  And the fans in turbofans are enclosed propellors (5+ / 0-)

            So in theory this could replace the turbines that power them.


            by kovie on Fri Aug 12, 2011 at 11:31:03 AM PDT

            [ Parent ]

            •  Still need fuel to head up the air (1+ / 0-)
              Recommended by:

              It's super-heated and thus rapidly expanding air that generates the thrust from a jet engine, not the turbofans themselves.

              •  Not true (0+ / 0-)

                The fans provide most of the thrust. Or else what's their purpose?

                From the Wiki entry for turbofans:

                The turbofan is a type of airbreathing jet engine that is very typically employed for aircraft propulsion, that is based around a gas turbine engine.[1] Turbofans provide thrust using a combination of a ducted fan and a jet exhaust nozzle. Part of the airstream from the ducted fan passes through the core, providing oxygen to burn fuel to create power. However, the rest of the air flow bypasses the engine core and mixes with the faster stream from the core, significantly reducing exhaust noise. The substantially slower bypass airflow produces thrust more efficiently than the high-speed air from the core, and this reduces the specific fuel consumption.[2][3] In other words, for many jet applications (not all), turbofans were a step forward in fuel efficiency from turbojets.


                by kovie on Fri Aug 12, 2011 at 01:24:40 PM PDT

                [ Parent ]

                •  You can reduce the amount of fuel with more (1+ / 0-)
                  Recommended by:

                  bypass, but the fact remains that you need a source of heat (and, ideally, extra expanding gasses).  You can make heat from electricity, but that's a very inefficient way to go about it, especially given that jet engines are notably more efficient than gasoline ICEs (at least in peak operation).

                  IMHO, the ideal renewable jet aircraft for the foreseeable future is a hybrid high bypass hydrogen-electric turbofan.  The compressor and fan assemblies are the rotors of an AC synchronous motor and the turbine is removed.  Should actually make the engine cheaper and lower maintenance.

                  •  Heat is required to run a turbine, (1+ / 0-)
                    Recommended by:

                    but the electric motor proposed in this post replaces the turbine entirely as the power source.


                    by Simplify on Fri Aug 12, 2011 at 05:05:57 PM PDT

                    [ Parent ]

                    •  Thank you (0+ / 0-)

                      Exactly what I'm saying. Heat is an unavoidable incedental of turbines, but not what actually drives the fan or moves the plane. Air doesn't have to be hot to move a plane fast. Certainly conventional propellor-driven planes could be built with light, high-efficiency and capacity electric motors and batteries. I don't see why an enclosed "turbofan"-type engine couldn't be built as well using the same basic technology. The question is whether it could compete with standard turbine-powered turbofans for power, cost and range.


                      by kovie on Fri Aug 12, 2011 at 06:47:25 PM PDT

                      [ Parent ]

                      •  Wrong. (1+ / 0-)
                        Recommended by:

                        Jet engines are driven by expanding hot gasses.  That's what moves them forward.  That's how jet engines work, and why they're fundamentally different from prop planes.  A compressor concentrates atmospheric oxygen enough to get a strong, efficient, rapid burn of fuel.  The expanding hot gasses lose a little energy running a turbine that drives the compressor, and the rest causes the thrust out the back of the engine.  That's how a jet engine works.   No hot gasses = no jet engine.  All you have is a prop engine.

                        Jet engines allow for higher speeds than prop engines because prop engines are generally limited by the speed of sound on the blades, and since the blades have to move notably faster than the aircraft will move, the aircraft must be notably slower than the speed of sound.  The jet of hot gasses coming out the back of a jet engine, however, moves at several times the speed of sound.

                        •  It's my understanding (1+ / 0-)
                          Recommended by:

                          that the majority of forward thrust at normal cruising speeds from a turbofan comes from the outer blades pushing compressed air at very high speeds but no hotter than the momentary compression involved creates, and not the turbine, which of course heats the air to very high temperatures in the process of first compressing it to much higher pressures than the outer blades do, then burning it with jet fuel, but whose primary purpose at normal cruising speed is to spin the outer blades. The turbine certainly provides thrust, but not the main thrust, at least at normal cruising speeds, as opposed to during takeoff and/or landing.

                          I have it wrong, and it's the other way around--the outer blades provide the supplemental thrust, and not the turbine?


                          by kovie on Fri Aug 12, 2011 at 09:13:50 PM PDT

                          [ Parent ]

                          •  The external air thrust is subsonic. (0+ / 0-)

                            Only the jet exhaust is supersonic.  They recombine to produce a slower supersonic flow.

                            The speed of the aircraft is limited to the speed of the airflow from the source of thrust, but always significantly less.  So if you take out the jet propulsion aspect, you're going to have a slow aircraft.  That's just the way it is.


                            It sounds like you're confusing a turboprop with a turbofan.  A turboprop does not involve jet propulsion -- simply the use of a jet turbine to turn the prop.  A turbofan involves both prop ("fan") propulsion and jet propulsion, combining them at all times.  Turboprop aircraft are notably slower than turbofan aircraft.  You're proposing to turn a turbofan into a bizarre (and inefficient) prop engine.  Which is of course pointless.  If you want an electric prop aircraft, just make an electric prop aircraft.  What's the point of involving compressors?

                          •  Let's make this very simple (0+ / 0-)

                            At normal cruising speeds, what proportion of a commercial airliner's turbofan thrust is provided by the turbine exhaust, and what proportion by the fan blades (that are turned by the turbine)? And does the thrust provided by the fan blades in any significant way depend upon their blending with and being superheated by the much hotter turbine exhaust, or is the heat immaterial to their thrust?


                            by kovie on Fri Aug 12, 2011 at 10:15:01 PM PDT

                            [ Parent ]

                          •  I did some further online research into this today (0+ / 0-)

                            It seems that commercial jet aircraft use high-bypass turbofans in which up to 80% of the thrust is produced by the outer fan blades, not the turbine jet flow, at relatively low speed, pressure and heat. Given this, why couldn't the turbine be replaced with a high-efficiency and reliability electric motor, assuming that such a beast could be built cost-effectively and that the battery technology in terms of weight, capacity and cost-effectiveness also existed? You'd lose at least 20% thrust by removing the turbine, but that could be compensated for by a different blade design, a very efficient motor, or more and lighter engines.

                            Also, I think you either don't understand the difference between a propellor, which is better at lower speeds but unable to move a plane beyond 450mph for various reasons, and a ducted fan, which is better at higher speeds and able to move a plane well into supersonic speed, or else misunderstood that I was referring to the latter, not the former (although for short haul and lower-speed planes, an electric motor-powered prop plane could also make sense).

                            And are you still saying that even with a high-bypass turbofan engine, the hot exhaust gaes from the turbines are essential to total thrust, even though they don't mix with the much cooler fan exhaust until the very last stage? Because I don't see how the high heat of the turbine's gases have much to do with the thrust created by the fan blades? Care to explain?


                            by kovie on Sun Aug 14, 2011 at 12:08:15 AM PDT

                            [ Parent ]

                        •  The whole idea of a turbofan (0+ / 0-)

                          is to reduce the velocity of the jet to its most efficient value for the speed of the plane, taking account of the increasing weight of an increasingly large fan.

                          Another effect is the reduction in temperature of the exhaust stream (made up of both cold flow from the fan and hotter flow from the stream that goes through the combustors and turbine). Any temperature increase above that implied by the stagnation properties of the fan exhaust represents energy lost in the exhaust stream. If you could manage to get enough expansion in the turbine to get that stream down to basically ambient temperature that would represent the maximum efficiency for a turbine-driven fan.

                          If you are not driving the fan with a heat engine, you have much more efficiency and this would be the case with an electrically driven fan.

                          There is nothing magic about expanding "hot" gases, the thrust comes from expanding gases. The best case is for the temperature rise of the exhaust coming entirely from the adiabatic compression that occurs in the fan, since the expansion and acceleration of the fan stream would bring the temperature back down close to its initial value before it entered the fan.

                          Moderation in most things.

                          by billmosby on Fri Aug 12, 2011 at 10:39:14 PM PDT

                          [ Parent ]

                          •  Yes and no. (1+ / 0-)
                            Recommended by:

                            I was arguing that you still need the air heating, not that the heating must come from burning fuel.  :)  And yes, I have several times here proposed removing the turbine and electrically driving the compressor/fan.  This is hardly an original concept, however.

                            No, the heat from air compression isn't close the heat from burning fuel.  One can determine how much energy is being put into the airstream from the compression stage -- kinetic plus thermal -- by how much energy it takes to run the compressor. Clearly the energy output cannot be greater than the energy input.  Obviously, if the energy to run the compressor was equal to or greater than the energy from burning fuel -- and thus the heating from the compressor was equivalent -- regular jet engines would not work at all.  :)  It turns out that it's usually in the ballpark 10% of the energy of the fuel is used to run the compressor, capping off the maximum heating from compression at around 10%.  That's actually too high, though, because aircraft turbines are also used to run generators, oil pumps, fuel pumps, etc.  

                          •  No, you don't need heating. (0+ / 0-)

                            Hi bypass turbofans get almost all their thrust from the air that flows through the fan and around the rest of the engine, and that is not heated at all, other than by the fairly small compression achieved in the single fan stage generally used these days.

                            For much higher flight speeds, you do need an exhaust speed higher than a fan alone would give, so heating helps in that case. Unless of course the "fan" becomes a multistage compressor with the required pressure ratio. Up to now the m

                            This is all for air breathing engines, which derive thrust by increasing the momentum of the fluid they take in at one end and discharge at the other- the discharge speed has to be higher than the intake speed to develop positive thrust. For a rocket, the working fluid starts out at the speed of the vehicle so any rearward discharge speed will give positive thrust (barring flow field effects, that is, which may disrupt the discharge flow depending on geometry).

                            Moderation in most things.

                            by billmosby on Sat Aug 13, 2011 at 07:47:37 AM PDT

                            [ Parent ]

                          •  Oops, incomplete erasure, lol. (0+ / 0-)

                            delete "Up to now the m".

                            Moderation in most things.

                            by billmosby on Sat Aug 13, 2011 at 07:48:48 AM PDT

                            [ Parent ]

                          •  Argh (0+ / 0-)

                            Once again, if you remove the jet from a turbofan, you no longer have a turbofan.  You have a turboprop that has a compressor that's doing nothing but waste energy.  If you want a prop plane, just make an electric prop plane.  Please stop trying to pretend that you'd get something better than that by trying to convert a turbofan.

                            In a modern high-bypass turbofan (note that high bypass turbofan jets have lower max speeds than low-bypass), only about 25-30% of the thrust comes from the jet exhaust.  But without this aspect, the jet would be far slower.  The exhaust moves at several times the speed of sound, unlike the subsonic flow from the fan.  It's the difference between an aircraft that cruises at 350 mph and one that cruises at 550 mph.

                            So of course you can make an "engine" without heating.  But let's stop this silly notion of simply taking out the heating element from a turbofan and thinking it'll still perform like a jet.  All you're doing is making an electric prop aircraft that wastes energy running a pointless compressor.


                            Are the propulsion courses and books from the 60s I took in on the way to my degree in Aero engineering that out of date?

                            The hot exhaust from a modern turbofan does not move at several times the speed of sound. If it did, the other purpose of a turbofan, quietness, would be defeated. Hi bypass turbofans have 5 or 6 stage turbines to remove as much energy from the exhaust as possible and give it to the fan. The fan flow is not heated, although energy is added to it by the fan and that does of course raise its temperature accordingly. No combustion involved in that flow path, though. Some designs in the past have mixed the cold and hot flows (RR Conway comes to mind), though.

                            Moderation in most things.

                            by billmosby on Sat Aug 13, 2011 at 10:41:26 PM PDT

                            [ Parent ]

                          •  You're confusing the velocity of the exhaust as a (0+ / 0-)

                            whole -- which includes the recombined bypass air -- with the velocity of the jet exhaust from within the engine before it recombines, which is supersonic.  The combination of the two yields a high subsonic net velocity of a much larger volume of air.  To substitute some numbers, you'll get something like 75% of bypass air at 450mph mixed with 25% of jet air at 1300mph to yield 660mph net exhaust velocity.

                            Once again, I'll reiterate: there's no point to a compressor if you're not going to be burning fuel past it. You're just wasting energy.  If a compressor alone could create jet aircraft speeds, "compressor-powered aircraft" would have preceded jet aircraft.  The point of the compressor is to make the air denser to allow for faster, more efficient combustion.

                      •  Won't work. (0+ / 0-)

                        The 'gas generator' section of a modern turbofan produces a huge amount of power in very little volume.

                        There's no technology for anything comparable using electricity, and battery or solar technology to deliver that kind of power would have prohibitive weight. Worse, to deliver that power efficiently from a battery to an electric heater would require extremely high-power, high efficiency electric power conversion well beyond our present abilities.

                        It would be much, much, much easier just to melt (or burn!) the batteries.  Even if one was trying to solve this problem. This is the kind of problem that probably doesn't have a solution: the batteries are going to have to generate heat comparable to or greater than that generated by the engines. Maybe you can make use of that, but they're going to have a lot of volume, and it will be difficult at best to use that heat effectively.

                        •  There's no challenge in the power/weight ratio... (0+ / 0-)

                          for electric motors, ala driving the compressor.  The Tesla Roadster (not a light car) is driven from 0-60 in 3.7 seconds by a motor the size of a watermelon.  The problem is, however, as you note, heating.  Even if you could deliver the heat sufficiently, such as microwave bombardment, it's going to be a grossly inefficient process.  You don't have the free exhaust gasses helping you out, and electricity loses its main advantage versus combustion (a lack of Carnot losses = much higher efficiency).  And this is in an operation where weight is critical and where the "energy storage mass to vehicle and payload mass" ratio is way higher than in a car (which is a big disadvantage to batteries)

                          As for batteries, let's see.  Advanced commercial li-ions yield a few kW per kg.  The cruising energy of a fully loaded 747 is 45MW.  After accounting for losses, let's say 60MW is needed, and that the cells used are 3kW/kg.  You'd need 20 tonnes of batteries.  Actually, that's not unrealistic, given that an international flight carries more than that in fuel.  Of course, the energy density becomes critical.

                          •  I think we're on the same page... (0+ / 0-)

                            The gas generator section of a modern turbofan generates and transforms a huge amount of power in very little volume and weight.  100,000 horsepower electric motors weigh a lot.  Getting three or four of them onto an airframe would be "interesting".

                            As someone said below, we can make electric airliners, but we'll have to give up a lot of speed if we want to do this.

                          •  I did a little searching... (0+ / 0-)

                            I looked up about gyrotrons as a potential source of microwave air heating.  The ones in use currently are obviously designed for ground applications, and not at all weight optimized.  The ones I saw were about 2-3kW/kg.  I don't know that specifically gyrotrons are the best power/weight ratio; I just know that they're the most powerful.  I'd imagine that one could probably manage an order of magnitude better between system selection and part weight reduction -- 20-30kW/kg.  So about 2 tonnes to handle the air heating for the engine.

                            As for the compressor, a thought occurred to me.  If you're doing microwave heating, what do you need a compressor for?  Well, I mean, the higher the air pressure, the higher the thrust from the engine if you heat all the air inside of it, and the easier it'll be to heat.  BUT, you have no need to cycle air out to replace oxygen at a given rate.  So instead perhaps you can have a loop, using a standard expansion nozzle to maintain directionality, with inlet and outlet shutters.  The shutters are initially largely closed.  Laminar flow draws in more air as the flow rate increases.  The force keeping the air cycling depends on the difference in temperature before and after the expansion nozzle -- hence, how much air enters and exits the system combined with continued heating -- so careful shutter control could manage that.  I don't know, I'd have to run a CFD to see if it'd actually work, but anything that could eliminate compressors and still allow a start from a stop would be awesome   ;)

                            But really, anyway, the whole discussion is moot for now.  You'd need 1-2 orders of magnitude or more increase in battery energy density to even consider something like an electric jet engine.  

                        •  Most of that power is required (0+ / 0-)

                          to drive the compressor that feeds the turbine. Only about 1/3 or less of the energy ends up driving the air that provides the thrust. If you don't have a turbine driving things you only need about 1/3 of the power for a given thrust.

                          Moderation in most things.

                          by billmosby on Fri Aug 12, 2011 at 10:43:08 PM PDT

                          [ Parent ]

                          •  I should qualify this, (0+ / 0-)

                            it's really more for a turbojet. For a high bypass turbofan, much less of the total air flows through the hot part of the engine, so is not subject to the higher compression ratio and therefore most of the energy input into the fan goes into producing thrust in contrast to the case of a turbojet where all the air is subjected to a higher compression ratio.

                            Moderation in most things.

                            by billmosby on Sat Aug 13, 2011 at 08:13:50 AM PDT

                            [ Parent ]

                          •  But... (0+ / 0-)

                            (and this applies to Rei's comment above too)

                            The compression determines the efficiency of the Brayton cycle.  You see this as a figure-of-merit in modern turbines, new ones are about 40-1 (quite high).  This compares directly to a gasoline or diesel engine's compression ratio, and limits the potential thermodynamic efficiency (they are all ultimately (open-cycle) Carnot cycle engines).

                            There are compressorless jet engine designs (pulsejets, ramjets, PDWE's, Coanda effect jets, ...) but they are not usually very efficient, or have very limited operating ranges.

                          •  ... then again... (0+ / 0-)

                            If you're doing it all electrically, then you don't want the heat at all.  You only care about the fan section, and then you want the power.

                            Dunno then if you want to actually use a cowled fan or not -- uncowled engines don't work so well at high speeds, but cowls pay a large efficiency price for the extra exhaust velocity.

                      •  Oh, and... (0+ / 0-)

                        you're wrong. Heat is precisely what drives the turbines.

                        Any kind of heat source in the engine will work, but it needs to generate a lot of heat, and quickly transfer that heat to the air flowing through. It's difficult in turbines ("keeping a match lit in a tornado"), but is soluble.

                        But it is the heat that drives the cycle: they are classical heat engines, limited by the Carnot cycle and its laws, even if they actually use the Brayton cycle (where a car engine would in comparison use the Otto cycle).

                        •  We're talking about heat in two different ways (0+ / 0-)

                          here. One is the heat that is the inevitable and unavoidable by-product of gas turbine technology, regardless of what the turbine is used for. This heat in and of itself provides absolutely no useful "power" or thrust. It just comes with the technology (e.g. gas turbine generators, although I suppose that the surplus heat could be used to power steam turbines that could then produce supplemental electricity via secondary generators). The other is the heat that escapes as expanding exhaust gases, that DO provide thrust.

                          But I'm not talking about either kind of power here, i.e. heat power, but rather the power that is transferred mechanically, NOT thermally, to drive the outer blades, that then produce additional thrust. Are you saying that this thrust is secondary, and far less than the thrust directly produced by the turbines through hot expanding exhaust gases, or that it's primary, but is only of use if heated up when combined with the hot turbine exhaust gases before exiting the engine?


                          by kovie on Fri Aug 12, 2011 at 09:23:00 PM PDT

                          [ Parent ]

                    •  No. (0+ / 0-)

                      Please read what I wrote: "the turbine is removed".  The turbine in a traditional jet engine is what turns the compressor and fan; in a hybrid electric/fuel engine, electricity runs the compressor and fan.  Heat, however, is required for the jet propulsion.  Jet propulsion is driven by expanding gasses.  No expanding gasses = no jet thrust.  All you've got is a strangely shaped prop engine.

                  •  You're missing the point (1+ / 0-)
                    Recommended by:

                    Heat is an unavoidable by-product of all propulsion systems, but it's not necessary in and of itself to propel a plane.

                    For example, one can produce a propellor-driven plane whose propellors are powered by battery-powered electric motors with absolutely no fuel-burning engine involved. A turbofan is simply a special kind of propellor, with many more blades with their tips "cut off", and the propellor encased in a cowling. That turbofans are powered by fuel-burning turbines whose exhaust gases contribute part of the engine's propulsion is irrelevant to the fan itself.

                    Another example is turbine-powered helicopters, whose turbines power the rotors but generally don't actually move the helicopter forward up provide lift.

                    Maybe I'm missing something here, and of course there's the question of whether an electric motor exists or could be built using existing or foreseeable technology that would be powered by these batteries, that could drive an enclosed fan, and whether these batters would be light, powerful and have enough capacity to power a plane long enough to be worthwhile.

                    But in theory, one could replace a turbine with such a motor, and move a plane at high subsonic speeds, and perhaps someday even at supersonic speeds.


                    by kovie on Fri Aug 12, 2011 at 06:43:00 PM PDT

                    [ Parent ]

                    •  No. (0+ / 0-)

                      A turbofan is not simply a glorified prop engine.  A turbofan is a "high bypass jet engine".  They combine a jet engine with a prop engine, to be optimized for operations at high subsonic speeds, versus medium to low speeds for prop engines and low to mid supersonic speeds for turbojets.  If you take the "jet" part out, you have a turboprop, which is a very different kind of engine, and not capable of achieving the same sort of speeds.

                      And yes, a compressor can be the rotor of an AC synchronous motor.  That's not the problem.  The problem is that if you remove the stream of hot exhaust gasses, it's no longer a turbofan; it's a poorly-optimized turboprop.  If you want a turboprop, convert a turboprop, not a turbofan.

                      To achieve supersonic speeds on purely electricity would be an extremely difficult feat.  It's hard to envision without the use of significantly supersonic-speed prop blades.

                    •  You need to transform the power. (0+ / 0-)

                      And turbines have the highest power/weight ratio of any class of engines. They directly transform the heat to thrust, generating/using/transforming huge amounts of power.

                      It's awkward to talk about jet engines in terms of horsepower, but the amount of power a modern airliner (single!) turbofan generates is on the order of 100,000. Electric motors are not going to replace turbofans any time soon, and almost certainly never. They just don't have the power density (power/weight or power/volume).

                      •  Weeellll..... (0+ / 0-)

                        The Tesla Roadster's motor is nearly 4kW/kg, but AC traction motors can get over a dozen kW/kg.  100,000 hp is 75k kW.  So you're talking ~6 tonnes.  A conventional 100,000 jet engine weighs about 40 tonnes.  Soooo....

          •  Not really a good substitute for jet engines (1+ / 0-)
            Recommended by:

            Unfortunately, battery-powered propellers are unlikely to be an effective substitute for jet engines. That's because the thrust produced by jet turbine engines is to a large extent a product of the forceful, directed expulsion of the combustion gases in the engine. This effect is most relevant when the engine is running at its most efficient - when running at high altitude and high speed. Think of it as somewhere between a propeller engine and a rocket engine. Jet turbines can run propeller engines - that's what a turbo-prop is - but their performance is not in the same league as a jet engine.

            Large, swept back propellers can greatly increase the top speed of prop planes, but not to the speed of a jet engine, and certainly not to supersonic speeds. Unless we are willing to accept exchanging slower air speeds (and longer flight times) for quieter, non-polluting battery-powered flight, I think jet engines will be around for a long time.

            I've always thought that the aviation industry was one industry that would be most hurt by either CO2 emission or the forthcoming slow death of extracted petroleum-based fuels. Fortunately, there is hope to be found for the future of air flight, and it is in algal-generated biofuels, not battery-powered flight. These are completely carbon neutral fuels because they are generated using only atmospheric CO2 as a carbon source. I have read that the U.S. military is already testing production and use of several types of algal biofuels in their planes and vehicles (they don't want to be at risk of operational unreadiness if access to oil is cut off in the future).

            I do foresee some niche aspects of aviation where such lightweight batteries would be very useful - basically all the areas where propeller-powered flight is still used today.

            •  Not quite (0+ / 0-)

              A Boeing 737 (turbofan) flies at Mach .78, which is the same speed as those large, multibladed, swept-blade propellers are capable of (Mach .8, according to NASA). So no, you don't have to accept a reduction in speed from current airliners. You only have to accept propellers.


              by Keith Pickering on Sat Aug 13, 2011 at 12:42:39 AM PDT

              [ Parent ]

      •   a flock of seagulls (9+ / 0-)

        with little leashes attached guide the plane.  

      •  would you expect 38948349384938 tons (0+ / 0-)

        of lumber to sink?

        the atmosphere weighs a lot more than 38948349384938 tons (about 5000000000000000 tons), actually, and it doesn't sink into the ocean. do you ever wonder why not?


        by UntimelyRippd on Fri Aug 12, 2011 at 01:46:04 PM PDT

        [ Parent ]

        •  It's all about volume and density... (0+ / 0-)

          "Double, double, toile and trouble; Fire burne, and Cauldron bubble... By the pricking of my Thumbes, Something wicked this way comes": Republicans Willkommen auf das Vierte Reich! Sie Angelegenheit nicht mehr.

          by Bluefin on Fri Aug 12, 2011 at 06:47:35 PM PDT

          [ Parent ]

  •  Yep. Just as I thought (83+ / 0-)

    From research at MIT - government-subsidized research.

    NOT private company research.

    Who (the private companies, I mean), incidentally, will jump on this tech qwhen it's perfecterd. Free ridership.


    Because the ROI on this type of development is terrible. So many dead ends as a NECESSARY process of a tech breakthrough. Only a subsidized, not-for-profit entity can invest in the many dead-ends it takes to create game-changing tech.

    And therein lies the fundamental flaw of docrtinaire "free market" ideology.

  •  I'll have to re-read this (20+ / 0-)

    diary several times because I am science/engineering/math challenged.  What I can comment on is the fact that MIT just keeps rolling out new energy saving prototypes one after the other recently.  

    Maybe the Car Talk Guys can make this clear to dummies like me!

    Thank you.

    Vi er alle norske " My faith in the Constitution is whole; it is complete; it is total." Barbara Jordan, 1974

    by gchaucer2 on Fri Aug 12, 2011 at 09:19:52 AM PDT

  •  I'd only worry about one thing... (4+ / 0-)
    Recommended by:
    Christin, GreyHawk, craiger, Noor B

    ...having a concentrated mass of lithium could be a problem, like with Sony lithium batteries that go boom!

    Lt's see how soon they can have a prototype powering a vehicle.


    by JeffW on Fri Aug 12, 2011 at 09:21:06 AM PDT

  •  Should factor in engine efficiency... (32+ / 0-)

    Electric motors are very efficient, jet engines and especially car engines aren't.

    So assuming 33% efficiency on gas engines vs. 90% efficiency on electrics, you've nearly got parity. (9MJ*.9 vs 43MJ*.33)

    Great article. T&R'd.

    Happy little moron, Lucky little man.
    -Spike Milligan

    by polecat on Fri Aug 12, 2011 at 09:38:02 AM PDT

    •  Great point (19+ / 0-)

      A battery doesn't have to replace the 70% of the gasoline energy that gets wasted as heat, just the part doing actual work.

      In fact, 2500Wh/kg is plenty.  The battery in the Chevy Volt can drive the car 40 miles and is only 80Wh/kg, needing 200kg to get to 16000Wh.  

      At 2500Wh/kg the battery would only weigh 6.4kg.  Or, the same 200kg battery could drive the car 1250 miles!

      They now have the energy density that, if they can hold it for mass production, to replace all gasoline usage, everywhere.  Then maybe we do get a solar economy...

      •  However, unless the charging electricity is from (1+ / 0-)
        Recommended by:

        a renewable, non-carbon generation, the efficiency of the transformation from fossil fuel to battery-powered turbine would be at best a wash with burning it directly in a gas turbine since the power generation plant operates at similar efficiencies.

    •  Not sure about these cells (3+ / 0-)
      Recommended by:
      polecat, MsGrin, raincrow

      but generally you can't fully discharge a lithium battery without doing permanent damage to the battery.  We might need to factor that into the equation too.

      •  Can't discharge lead-acid batteries 100% either (14+ / 0-)

        Deep cycle lead acid (LA) batteries are only designed for up to 80% discharge. Beyond that the voltage drops to a point where the remaining energy is not very useful anyway. Think of your flashlight when the batteries get low: you can see that the bulb is lit, but the amount of light that it puts out is not useful.

        I live off the grid, and power my whole house with a set of LA batteries (6VDC heavy duty deep-cycle units originally made for powering golf carts), and have designed thousands of off-grid power systems. The general rule is to not discharge the batteries more than 50% on a regular basis in order for them to give you a reasonable life span.

        For off-grid homes in temperate climates, I generally design the battery bank based on 6-times the daily load, which gives 3 full days of energy storage to a 50% depth of discharge (DOD). In reality, there is never a day when the energy sources (solar PV, wind, or micro-hydro power) produce zero, and there is also the fact that electrical loads running when the energy sources are producing are powered directly from the produced energy, not from the battery. So the battery will normally go more than three days to a 50% DOD, or at the end of the three days (maybe a storm that blocks most of the solar production), the battery will be above a 50% DOD.

        In fact from my experience, battery systems designed this way generally only see a 10-25% DOD per cycle, with 50% only a few times per year, and 80% only in emergencies. The batteries last a long time that way

        Using Norm in Chicago's figures above your comment, if the battery can power the car for 1250 miles to a 100% DOD, then it can go 625 miles to a 50% DOD, or even 250 miles to 20% DOD. That's pretty damn good. Of course, as others have said, we don't have enough
        info yet on cycle life compared to DOD to pop the champagne cork yet.

    •  then we go back to NASA for that super (3+ / 0-)
      Recommended by:
      StrayCat, ozsea1, Calamity Jean

      efficient propeller that they were working on. They came close to achieving jet speeds with it, but had some minor problems (harmonics? material science?)  and instead of funding it properly, they simply cancelled the program.

      With sufficient battery power, that prop might make a perfect marriage.


      by agnostic on Fri Aug 12, 2011 at 11:45:38 AM PDT

      [ Parent ]

    •  Ooo... (1+ / 0-)
      Recommended by:

      That makes my math way down below better.

      Remember 9MJ/kg is when discharged.  When charged the are about 40MJ/kg.  So, if available energy is 33% of 43MJ/kg is about which means a 10 gallon gas tank only has 360MJ of useful energy.  So, fully charged the batteries start at 9kg and will be at 40kg when discharged.  A 30kg difference is only about 70 lbs.  Basically, near discharge is like driving around with a child in the car for a small car with a "10 gallon" battery.  A large car with a "20 gallon" battery would be like driving with an extra adult when discharged.   Oops. did not add the 90% efficiency factor for the battery side.  So, add 3 kg.

    •  Whatever happened to research on... (0+ / 0-) temperature superconductors? I always thought that tech coupled with the new battery tech would blow the doors wide open regarding new propulsion systems.

      That way, in terms of aircraft, it offers options for where you place the "propulsion" and where where you place the power system, instead of having to co-locate them. This would open up all kinds of opportunities in terms of aircraft design.

      This night wounds time..

      by Alumbrados on Fri Aug 12, 2011 at 04:44:14 PM PDT

      [ Parent ]

  •  It all looks very wonderful (3+ / 0-)
    Recommended by:
    The Nose, mikeconwell, Calamity Jean

    and I'm waiting for the practical implications to hit the market...

    ¡Boycott Arizona!

    by litho on Fri Aug 12, 2011 at 09:51:37 AM PDT

  •  Great diary. That thing about the (0+ / 0-)

    battery getting heavier as it discharges though makes for a scary scenario were it to be used in an airplane. As the battery starts petering out, the plane gets progressively heavier. Yikes!


    by doc2 on Fri Aug 12, 2011 at 09:57:35 AM PDT

    •  The last section of the diary addresses this (2+ / 0-)
      Recommended by:
      mikeconwell, offgrid

      Good stuff about aerodynamics that I hadn't known before, too.

      I don't know if a hybrid fuel/electric airplane is realistic -- it means essentially doubling the number of engines on the plane, which of course adds weight -- but if my pessimism is off-base, then so much the better!


      by Nowhere Man on Fri Aug 12, 2011 at 10:09:39 AM PDT

      [ Parent ]

      •  Not additional engines (3+ / 0-)
        Recommended by:
        Nowhere Man, MsGrin, Odysseus

        We're not talking putting in additional engines of any sort, it would be more like how the Chevy Volt works, you have electric drive for the power train (i.e. the engine) and use a generator to generate additional electric power.  At least that is what I see as the most likely method.  Installing additional engines would simply be far too difficult and power intensive I would think.  

        The only other possible way to do this would be to have on something like a 4 engine heavy plane (think 747, etc) would be to have the inboard engines be powered by Jet A and the outboard turbines be powered by electricity, that way you have some redundancy and balance.  I don't think this is as likely as people get very nervous if they think any part of the plane is a "redundancy" that could fail.

        •  That makes some sense (0+ / 0-)

          although maintaining a constant weight requires  the battery to be draining while the generator is running, and both driving the turbines... somehow it feels to me as if it's simpler (and therefore better) just to drive a turbine with the fuel. But I'm way out of my league here.


          by Nowhere Man on Fri Aug 12, 2011 at 10:35:59 AM PDT

          [ Parent ]

        •  NASA's propellor research created (7+ / 0-)

          a ten blade prop that was quieter, far more efficient than high bypass jet engines. They stopped research eventually.

          here's the last thing I could find on it. NASA propeller research


          by agnostic on Fri Aug 12, 2011 at 11:55:52 AM PDT

          [ Parent ]

    •  Ballast (1+ / 0-)
      Recommended by:
      Keith Pickering

      the diarist mentions using biofuel powered engines in conjunction with the battery, but a tank of water could also drain as the battery discharges to maintain a constant weight.


      by Subterranean on Fri Aug 12, 2011 at 10:37:30 AM PDT

      [ Parent ]

    •  It has its lowest weight and most power at takeoff (6+ / 0-)

      The lower weight makes takeoff easier and could actually increase the payload of an aircraft.

      Today's aircraft are overpowered just to overcome the fuel load and power demand of takeoff.  The new aircraft could be optimized and made even more efficient.

      With electrics it would also be more realistic to have multiple engines that can be turned off in flight.  Much less scary than killing a petro-fueled engine and praying it starts back up again.

  •  Lithium's got a low atomic number... (11+ / 0-)

    ...but how much is there out there, where is it, and what's the energy cost to acquire/refine it into battery-grade lithium?

    There's a pretty substantial gulf, production-wise, between an ounce or two in everyone's cellphone or maybe a pound in everyone's laptop, versus 75-200 pounds in every car and a few tons in every airplane.

    •  Excellent article linked here (4+ / 0-)

      Ordinarily, I consider the Daily Mail suitable for lining cat boxes or bird cages, but this is still worth a read.

      It is better to light one candle than to curse the darkness - Eleanor Roosevelt

      by Fish in Illinois on Fri Aug 12, 2011 at 10:32:52 AM PDT

      [ Parent ]

      •  Didn't realize that extraction was damaging (1+ / 0-)
        Recommended by:

        Thanks for the article. I didn't realize that extraction came at a heavy environmental cost. Looks like Bolivia won't go all in and allow extraction all at once.

        •  Li doesn't have to be mined. (2+ / 0-)
          Recommended by:
          Egalitare, Simplify

 South Korea plans to extract lithium from seawater

          Ugo Bardi: Extracting Minerals from Seawater: An Energy Analysis

          The results
          show that for most ions dissolved in seawater, the energy involved in extraction is very large in
          comparison to the present world production. Therefore, using metals from seawater to offset ore
          depletion does not appear to be feasible, with lithium being a possible exception.

          Combine this with something like the output of a desalination plant and you might get a much better cost of extraction.

          The Oil Drum of course has some great writing on the subject.

          There seems to be a consensus that Li extraction from seawater is 4-5x as expensive as mining, but that may not be the biggest issue to adoption.

          -7.75 -4.67

          "Freedom's just another word for nothing left to lose."

          There are no Christians in foxholes.

          by Odysseus on Fri Aug 12, 2011 at 02:17:05 PM PDT

          [ Parent ]

        •  It's not. (1+ / 0-)
          Recommended by:

          What a stupid hype article.  Flatly asserting that it's destructive doesn't make it so.  Lithium mining from brine is one of the least destructive types of mining you can possibly do.  You're in an area almost completely devoid of life, pumping up saltwater from below a salt crust, spreading it into baths on the top, and letting it dry in the sun.  Since salars like those in Bolivia flood annually, if you took down the mining facility, all traces that it was ever there would be gone in a few years.  Yeah, you're causing "water usage", but the water being evaporated is saltwater.

          The "huge piles of discarded salt" they describe in Chile are the very salt that came from the flat itself.  The only reason they're still in piles instead of flat is because the Atacama is, unlike salars in Bolivia, not subjected to annual floods which would wash them back in (they'll wash back in eventually).  The "lack of animal life" is because the area near the evaporation ponds, like most salars, never supported significant animal life (the only significant animal life in the Atacama is in Salar de Tara).  The "carcinogenic lithium and magnesium" are the elements that they're extracting from the salar because they're already there, as is the chlorine (everyone knows the formula of table salt, right?  Sodium chloride).  If people are short on drinking water in the region, it has nothing to do with brine being used up.  The Atacama has no outlets anyway.  Oh, and lithium is not the primary extraction product currently at any of these mines -- usually it's potassium salts and common table salt that are the biggest income earner.

          Oh, and I suggest that anyone who wants to see this "devastated" salar in Chile do a google image search for "Salar de Atacama".  Oh so devastated.  :P  Here, let's play a game: find the salt evaporation ponds using satellite images.  And if you guess the area near Calama, nope, that's a copper mine (same with Mina Escondida and several other places; if you see contour changes, it's not a lithium mine).  If the desert has been so devastated, this should be easy, right?

    •  A soon to be Lithium cartel? It's a problem OLEC (0+ / 0-)

      Not a lot of lithium in the world, and even less in the U.S.

      A better battery changes the world, but it not if it's made from materials in short supply.

    •  Lithium is not a commonly... (3+ / 0-)
      Recommended by:
      StrayCat, ozsea1, malharden

      ...found element but it's not considered rare.   The two major deposits are in Bolivia and Afghanistan.

      Never argue with idiots - they will drag you down to their level and beat you with experience. {-8.25 / -5.64}

      by carver on Fri Aug 12, 2011 at 12:23:29 PM PDT

      [ Parent ]

  •  I want one! (4+ / 0-)

    I am, however, still awaiting those methanol fuel cells they told me I'd have for my laptop and my phone a few years ago.


    by Fish in Illinois on Fri Aug 12, 2011 at 10:22:18 AM PDT

  •  Very nice diary - thanks (2+ / 0-)
    Recommended by:
    ColoTim, ozsea1

    I had heard that most of the lithium in the world is now controlled by China.  I'm curious as to how that will affect supply/demand of these types of batteries.  Does the US have sufficient quantities of lithium?

  •  Science is starting to piss me off (5+ / 0-)
    Recommended by:
    MsGrin, mikolo, raincrow, debaseTheBase, ozsea1

    I'm getting crazy mood swings.

    Yesterday I'm feelin' all "WE'RE ALL GONNA DIE!" with the stories about sun storms and electric grids going down for years and zombie apocalypse and talk about progressive survivalist camps

    and today I'm feelin' all' "PROBLEM SOLVED!" with this kind of story, which invariably has a comment in in that bursts the bubble and says, "But we're still 100 years from practical commercial application."

    I guess I should hold out on energy farms harnessing the power of moth farts before I get too impressed, or pay attention.

    Seriously though, thanks for the diary. T&R


    by SnyperKitty on Fri Aug 12, 2011 at 10:30:28 AM PDT

  •  Electric aircraft would need propellers, right? (1+ / 0-)
    Recommended by:
    Calamity Jean

    I can visualize batteries powering a propeller powered aircraft but not a jet.


    •  Yes (2+ / 0-)
      Recommended by:
      Clypheous, malharden

      Speed wise it's not an issue, unless you plan on going supersonic.  They just have to figure out how to make them less noisy.

      •  Well... (3+ / 0-)
        Recommended by:
        Dr Colossus, craiger, malharden

        It's not as much as matter of making the plane fly supersonic as it is the prop.  When the edges of the prop hit the speed of sound, you start having big problems.  That's why giant windmill power generators have to have governors to stop them getting that fast, it tears them apart.  I would argue your prop flying to pieces in flight would be bad.

    •  You're correct (1+ / 0-)
      Recommended by:

      Because there wouldn't be compression in the same way electric power thrust would most likely be from a large prop, probably one designed to extend during flight.

    •  How about ducted fan jets (7+ / 0-)

      If you mean jet in the sense of a turbojet engine that gains thrust only from the burning of fossil fuel, then there would exist no battery powered turbojets.  

      However, I have several model radio controlled (RC) aircraft with propellers powered by brushless DC motors using lithium batteries. Although I do not have them, there are also model RC aircraft with ducted fans. (We differentiate ourselves from other RC aircraft owners who use gas by calling them "slimers" because of the gas oil mix they use in their engines.)

      However, jet propulsion is defined as motion produced by passing a jet of fluid (e.g. air or water) in the opposite direction to the direction of motion. By conservation of momentum, the moving body is propelled in the opposite direction to the jet. The squid and octopus use jet propulsion for locomotion.

      A class of jet propulsion involves turbofans which provide thrust using a combination of a ducted fan and a jet exhaust nozzle. All currently manufactured commercial jet aircraft use turbofans i.e., ducted fans powered by burning fossil fuel.

      Thus, electric aircraft would need propellers or ducted fans.

      •  Actually those don't compare... (0+ / 0-)

        ...because the burnt fuel greatly expands the flow and adds mass to the flow, since it is the momentum change that propels the aircraft. Now, maybe if the electricity was used to create a plasma arc to expand the air, we could get something like an 'electric' jet. However, ducted fans in and of themselves don't tend to be as good as propellers when comparing the two. The duct just tends to add weight and drag.

        This night wounds time..

        by Alumbrados on Fri Aug 12, 2011 at 04:48:04 PM PDT

        [ Parent ]

  •  You are pretty damn cool (2+ / 0-)
    Recommended by:
    raincrow, CupofTea

    to explain this.  I guess I need more visuals to really grok what you're explaining, but I am someone has figured this out and that you've shared it with us.

    'Give away to the rich and punish the poor for the extravagance.....crazy' --LaFeminista

    by MsGrin on Fri Aug 12, 2011 at 10:35:46 AM PDT

  •  A truly cogent diary (2+ / 0-)
    Recommended by:
    raincrow, ozsea1

    Very high thoughts per square inch, so to speak. Thanks!

    Well? Shall we go? At least that man is gone.

    by whenwego on Fri Aug 12, 2011 at 10:42:52 AM PDT

    •  There is a really high... (0+ / 0-)

      ...engine power to weight in choppers I don't know if you could get enough power out of an electric motor to get a chopper off the ground.


      by carver on Fri Aug 12, 2011 at 12:30:29 PM PDT

      [ Parent ]

  •  We need to try many research directions, (2+ / 0-)
    Recommended by:
    raincrow, ozsea1

    even if most of them end up being dead ends.  Who knows when or if this technology will be commercialized.  Sometimes these things end up being used in specialized applications.  But if these type of batteries end up being suitable for cars, that will be a big help.

    There are a lot of high risk high reward research possibilities that private companies will seldom do, especially in these days of Wall Street judging companies by the next quarter.  Government must do these things, if we want to have a better future.

    Now if we can just get lucky and find a good fusion power solution...


    by Thutmose V on Fri Aug 12, 2011 at 11:02:18 AM PDT

  •  All modern jetliners are powered by turbofans (5+ / 0-)
    Recommended by:
    NYFM, craiger, StrayCat, ozsea1, kurt

    A turbofan is a composite engine, consisting of an inner turbine (or turbojet) that burns jet fuel, with some of the released energy directed rearward as exhaust gas, providing some of the engine's forward propulsion, and most of the released energy directed towards turning the outer enclosed fan blades, which provide most of the engine's forward propulsion. It's a very efficient design.

    I wonder if an electric motor powered by these cells could replace the inner turbine. It would lose the propulsion provided by the turbine, but perhaps its lightness and efficiency could more than make up for that? And is it possible to design an electric motor this powerful, efficient and reliable?


    by kovie on Fri Aug 12, 2011 at 11:29:10 AM PDT

  •  This is awesome technology, and (1+ / 0-)
    Recommended by:

    thanks for posting it. I feel a little more optimistic about the future. Anything to end our reliance on fossil fuels!

  •  Before people get too excited... (4+ / 0-)
    Recommended by:
    NYFM, PerpetualMind, StrayCat, Simplify

    Consider some of the other issues. First one off the top of my head: recharge rate.

    Consider your average car. No, consider the extreme example, something like a NASCAR racer. In less than 15 seconds, without anything other than gravity, you can get 40 or 50 miles worth of fuel in the tank (and that's with engines that have stupidly low fuel economy). In a normal car, say 200 miles worth of go-juice. In well under a minute.

    How long does it take to recharge these batteries?

    It might not be a problem for your average car that is used for a daily commute and sits around most of the time so it can be plugged in, but for aircraft which are refueling while they load and unload passengers and crew?

    There's lots of technologies that sound completely awesome but don't work for some things.

    •  also nothing abut the production process (1+ / 0-)
      Recommended by:

      for example, producing the Prius is apparently a very polluting process.  
      What's needed to make a carbon nanotube?

    •  Good point, but ... (4+ / 0-)
      Recommended by:
      vets74, StrayCat, Odysseus, kurt

      most people don't run their vehicles 24/7: they sleep at night, when their cars can be recharged. Since as a general rule a battery's recharge rate is about the same as its discharge rate, all you need is a battery big enough to drive you all day, and it should be able to recharge at night.


      by Keith Pickering on Fri Aug 12, 2011 at 11:57:13 AM PDT

      [ Parent ]

      •  And much more efficient than gas/diesel engines. (1+ / 0-)
        Recommended by:

        The import cost at POE for enough oil to run a car for a year is $1,200.

        Import fully processed uranium fuel and you're looking at $50.

        The at-the-pump and at-the-wall-plug rations should be closer than they are. But it's still way ahead for the electricity.


        by vets74 on Fri Aug 12, 2011 at 12:22:24 PM PDT

        [ Parent ]

    •  Recharge time may not be important (1+ / 0-)
      Recommended by:

      The plane's batteries could be replaced while the plane sat at the gate. Then the discharged batteries could be recharged over a longer period of time.

      Depending on the recharge rate, you might end up with 1 or 2 or 3 charging for every one in the air.

    •  Also can cars recharge off normal plugs? (0+ / 0-)

      Or would they have to find some specialized outlet somewhere?

    •  For airplane (2+ / 0-)
      Recommended by:
      Odysseus, NYFM

      You would probably swap discharged batteries for charged batteries at the airport.  The discharged batteries would be charged to be swapped with the next plane that needs them.  It could likely be designed to be faster than refueling.

      You could do the same thing with cars but it is a lot more of a hassle for an individual driver than for the ground crew at an airport.


      by Quanta on Fri Aug 12, 2011 at 12:48:43 PM PDT

      [ Parent ]

      •  Swappable batteries add weight (1+ / 0-)
        Recommended by:

        Note how laptops with non-removable batteries are lighter.

        Liquid battery technology is encouraging in this regard, but I doubt it has the same low energy density that these batteries do.


        by Simplify on Fri Aug 12, 2011 at 05:11:00 PM PDT

        [ Parent ]

  •  Lots of research; nothing yet to buy (3+ / 0-)
    Recommended by:
    vets74, debaseTheBase, kurt

    And this is the frustrating part. You can go to a website like Cleantechnica and read about 10 such breakthroughs a week in the field of renewable energy or green tech and while promising and fascinating, they're nowhere near commercialization. With global warming reaching a tipping point and many other ecological issues becoming critical, we need these miracle technologies to be deployable on a wide scale now, but they are still just in the R&D phase.

    Research into Li-O batteries has been ongoing for a decade and a half and as others have stated, there are still so many issues to deal with it'll likely be another 15-years before even a flawed product is available to the public. And this is what happens when science funding is constrained. Many of these technologies would be closer to deployment phase if the R&D projects they spring from were better funded. It's amazing how the only quantum leaps in deployable technology seem to come in the defense sector, where the government literally pours an endless amount of money, obscene amounts of money, into all manner of research. I wish NIH, NASA, DoE, NOAA and the myriad grant programs that exist to fund university research got some of that loot instead of Northrop or General Dynamics.

    •  Lithium Makes Hydrogen Look Simple (1+ / 0-)
      Recommended by:

      I must imagine safety concerns with lithium metal in any sort of battery must be paramount.  One simply does not want lithium metal coming into contact with water in any of its myriad forms, solid, liquid or gas.  We all need to remember our high school chemistry classes where the teacher drops a pellet of lithium into a beaker of water, only to watch it react violently and burn incredibly brightly.  Using lithium-air batteries in ground transportation would be much easier than trying to adequately harden the battery pack in a flying vehicle.


      by PrahaPartizan on Fri Aug 12, 2011 at 12:08:13 PM PDT

      [ Parent ]

    •  Got a garage ??? (1+ / 0-)
      Recommended by:

      This stuff is going to get broken open by a small operation. Something tiny with a couple of sharp engineers.

      Apple II.

      Btw: the Israelis have the right economic model for supporting these small shops. They get all the advantages.

      Big enterprises are socialized mostly.


      by vets74 on Fri Aug 12, 2011 at 12:26:10 PM PDT

      [ Parent ]

  •  Biofuels fare worse than gasoline (0+ / 0-)

    Ethanol is 30MJ/kg.   At a minimum ethanol mandates in fuel should be replaced by plug-in hybrid mandate using these batteries.

    Also, a little math to show the weight gain in the car case is no big deal.

    10 gallons = 40 liters
    At 0.70kg/liter it weighs 28kg.

    So, we start with a 28kg new lithium air at 40MJ/kg is 1120MJ.  So, at 9MJ/kg discharged it would weigh 124kg.  Basically, about 100kg of added weight. or 220lb.  So, for each "10 gallons" of fuel tank on the battery powered vehicle the performance difference between charged and discharged is like driving around with a linebacker.

    Considering larger vehicles with 20 gallon tanks, it would be like driving your SUV around with 5 passengers instead of 3.

  •  Fantastic! (3+ / 0-)
    Recommended by:
    wblynch, ozsea1, CupofTea

    I hope that the lead-acid batteries powering my house last long enough to switch to lithium technology, and this particular technology looks very promising.

    You explained it very well. I suspect that many people who are not particularly science-oriented would come away with a good understanding of your subject.

    Great diary. Keep up the good work.

    •  Exactly my thought (1+ / 0-)
      Recommended by:

      Batteries like this, that can charge all day in sunlight and then power your house at night, can solve an awful lot of problems and greatly reduce our monthly electricity bills.

      •  V2G (3+ / 0-)
        Recommended by:
        CupofTea, Keith Pickering, wblynch

        There are people working on the concept of "Vehicle-to-Grid", or "V2G". The idea is that your electric car is a mobile energy storage unit. Millions of them plugged into the grid all over the country can act as a distributed energy storage mechanism, absorbing peaks in renewable energy production, and releasing energy back to the grid to make up for temporary short falls. With a proper "smart meter" you could receive reduced energy cost by donating energy when it is needed.

        Combined with a solar electric system on each house, the whole country can be tied together, not just as "consumers" but also as "producers".

        I think that the only way we can do this is if the electric grid were nationalized. But that is just too much socialism given our current political climate.

  •  The real difficulty with electric cars... (1+ / 0-)
    Recommended by:

    Electric infrastructure.

    A 10 gallon tank of gas has 1600MJ of energy divided by about 40% efficiency relative to battery and electric motor.  So, 360MJ of battery would be needed which is 100KWh.

    So, a typical US household with a 240V 100A input has a maximum power of 24KW, it would take 4.1 hours to charge a vehicle if all household power could be delivered to the vehicle, assuming the batteries could accept charge at that rate.

    It is not insurmountable, but the battery problem is starting to look like it will be solved well before the infrastructure problem.

  •  Charging time? (0+ / 0-)

    This is also a significant impediment, although it's driven by lack of infrastructure as well as by battery capabilities.   But even if I have a 50kw outlet to charge my truck, the battery has to be able to take it quickly enough to compete with "filler up" at the gas pump, preferably without getting the battery overheated.

    The underlying lesson here is that this stuff is moving forward.  Sonner or later it will work, and sufficient R&D can make that "sooner."  Maybe not exactly this, but it's a safe bet now that sufficient battery capability is on the way, at least for transportation.

  •  I heard talk of lithium-air several years ago (0+ / 0-)

    in the portable medical device industry.  I am amazed by the energy density of the lithium batteries I use for my drill and bicycle headlight.  Batteries have come a long ways from lead-acid, through nickle varieties, and now lithium batteries are amazing!  Looking forward to seeing these in commercial applications.  It would be amazing if electric cars became affordable to the masses.

  •  This is exciting! I don't think people get it. (2+ / 0-)
    Recommended by:
    ozsea1, CupofTea

    I saw a couple of pundits from the Left offer advice to President Obama to not visit "yet another battery factory".

    While he certainly should be doing more, I think many people do not get the importance of this work and the implications.


    by sebastianguy99 on Fri Aug 12, 2011 at 01:14:46 PM PDT

  •  So With The Energy Saved (0+ / 0-)

    You could power incandesent light bulbs! That would make Michelle Bachmann happy.

    Help! The GOP is NUTS (& the Dems need some!)

    by Tuba Les on Fri Aug 12, 2011 at 01:33:09 PM PDT

  •  Where am I wrong? (0+ / 0-)

    still got to burn oil or coal (or nuke) to charge this & any other battery, no? And isn't a lot of energy lost in electrical transport, so aren't electric cars still a bad choice if they are dependent on fossil-fuel derived electric generation - or, in fact, worse given loss in transport?

    Please tell me I'm wrong - I'm sure I am...

    •  In a few places ... (0+ / 0-)

      You still need an electric grid to charge the battery, but (a) an increasing fraction of the grid will be powered by non-fossil sources like wind, hydro, geothermal, and LFTR; (b) you can recharge the car at night, when electricity rates are low; and (c), electricity transmission is remarkably efficient, in the 98% range for most purposes.


      by Keith Pickering on Fri Aug 12, 2011 at 02:38:14 PM PDT

      [ Parent ]

      •  what are the percentages? (0+ / 0-)

        of non-fossil sources now? How soon till they are a significant portion? Do you have a reference for that 98% efficiency figure? I always heard electric generation is, by the very nature of the infrastructure kinda "leaky" - more like 70% efficient at best (?), regardless of usage - but it sounds like you know this stuff pretty well. Anyway, you're still burning fossil fuels in the vast majority of cases to charge the battery, which is a fact that must not be swept under the rug by those who might think electric = green, cause it doesn't, it just shifts it away from the tailpipe to the smokestack.

  •  OMG!!! This is SO timely! You won't believe (1+ / 0-)
    Recommended by:

    the conversation that I had just last week with my tea-party millionaire cousin (YES, he owns his own corporate jet and has TWO pilots pm call.)

    I asked a general question to my family about batteries and whether they or another technology will be on the rise in the new future.  I thought it was an innocuous question!

    To my surprise, my far right cousin (we'll call him Dan) responded that "It was all political."  I said "What?  What is all political?"  He said "All of it.  Batteries are a dead issue and only sub-cultures like mine are interested and it's going to be oil for the next hundred years."

    I almost laughed in his face (becuase I thought about the developments of the PAST hundred years and how although he is wealthy, he probably made his money on things STAYING THE SAME and that's all he knows despite all his money.)

    Thanks for flagging this!

  •  Your diary never says why lithium-air batteries (0+ / 0-)

    aren't being used today (I understand that the carbon nanotubes are a recent innovation).  What is the projected production date for them? What are the obstacles to their production and use?


    by Wisdumb on Fri Aug 12, 2011 at 01:59:16 PM PDT

  •  Hole in battery, little bit of water, "BANG" (0+ / 0-)

    Huge explosion as all the energy can be released quickly (the definition of an explosion).

    To make a bomb:
    1. Charge battery
    2. Drill hole in battery
    3. Drop in full sink or toilet

    •  Hole in gas tank, a little bit of fire, "BANG" (1+ / 0-)
      Recommended by:

      Gasoline already has 5 times the energy density of TNT, and you use it every day. Why aren't you up in arms about that?


      by Keith Pickering on Fri Aug 12, 2011 at 02:41:41 PM PDT

      [ Parent ]

  •  overall energy usage (0+ / 0-)

    About the idea that a plane that has constant weight uses less energy, I don't think this is true. Yes, you can maintain an optimized efficiency point at fixed weight, but the problem is you still have to carry the weight, and therefore lift, and therefore drag all the way through the flight. That takes more energy overall than a gas-fueled airplane that both gets lighter as it goes along and gets the slight benefit of extra thrust from fuel mass ejected out the back (like recoil on a gun).

    Also, a plane that has to land with all that mass will have a heavier structure. Modern airliners can't land fully loaded. (If an airliner has to land too soon after takeoff on a fully loaded flight, they have to dump fuel to get the weight down to where the structure can handle the landing forces safely.) That heavier structure requires even more fuel to take it the intended distance, which is even more weight... You get the idea.

    Electric planes could happen in the foreseeable future for slower, short-haul flights. It'll take something more revolutionary for medium- and long-haul flights.


    by Simplify on Fri Aug 12, 2011 at 04:53:40 PM PDT

  •  Super Nerf Toys? 8-s nt (0+ / 0-)

    " 'You Rock?!?' (But been through less gravel.) My mystique suggests battle. And, what have You?" -Common

    by malharden on Fri Aug 12, 2011 at 05:41:43 PM PDT

  •  Even a year ago I thought that electric planes (0+ / 0-)

    would not be possible for another half century or so.

    Now EADS(Airbus) already has a concept out, called the Voltair, and plans to start production by 2030, at the latest.  

    VoltAir's two next-generation lithium-air batteries would power two highly efficient superconducting electric motors, which would in turn drive two co-axial, counter-rotating shrouded propellers at the rear of the aircraft. The motors would have a relatively easy go of it, as advanced carbon fiber composite airframe design, aerodynamics and low weight would make the airliner as easy to push through the air as possible. As is the case with most proposed and existing electric aircraft, it would also be very quiet.

    The batteries would be housed in the lower front section of the VoltAir, where they could be removed and installed just like baggage, at the airport. Recharging would take place when the batteries were out of the aircraft, so planes would simply land, swap out their depleted batteries for charged ones, and take off again. Not only would this arrangement make turnaround times similar to those of conventional refueling, but it would also reduce the weight and technical complexity of the aircraft.

    One of the reasons that the sky isn't full of VoltAirs already is the fact that electric motors still don't offer enough power density for large aircraft. With advances currently being made in the field of high-temperature superconducting (HTS) materials, however, EADS sees a potential solution on its way.

    The speed at which science is currently innovating and developing is downright breathtaking.... solar and wind-powered air travel would be soooo awesome.


    by Lawrence on Fri Aug 12, 2011 at 06:53:54 PM PDT

  •  great diary (0+ / 0-)

    thank you.
    all articles on new energy systems are good for all of us to follow.

  •  Heavy fossil fuel can also be used (0+ / 0-)

    to simply get airplane off the ground and up to cruising altitude, at which point the batteries can take over.

    Already the heaviest of USAF planes take-off with near empty tanks and refuel immediately once airborne. Same idea.

    Form follows function -- Louis Sullivan

    by Spud1 on Fri Aug 12, 2011 at 07:42:58 PM PDT

  •  I'm worried. (0+ / 0-)

    If all that lithium dioxide gets into the water supply, we might not have Teabaggers anymore.  They might wake up one day, feel refreshed, and suddenly go, "I voted for WHAT?"  

    Or Charlie Sheen.  Charlie Sheen in particular I would miss, because he's got all that Tiger Blood.

  •  yeah, more MIT bullshit. (0+ / 0-)

    don't know what's going on there , but they keep coming out with PR release of the weak designed to set up an IPO for the folks in charge of the research, or just to get more research dollars.

    They did give us A123 which desgined a battery with high discharge rates, but lesser capacity.

    So this is another fund raising PR release.  Let me know when any of this sh*t makes it into production, because for at least the last few years none of it has. ESPECIALLY if it has anything to do with nanotubes.

    big badda boom : GRB 080913

    by squarewheel on Fri Aug 12, 2011 at 09:54:04 PM PDT

  •  You have misrepresented the energy density. (0+ / 0-)

    The energy density of gasoline is on the order of 4*107 J/Kg. These batteries have a maximal energy density of, at best,  4*104 J/Kg (10KWh/Kg), so they only have about 1/1000th the energy density of gasoline.

    Your diary title is misleading and wildly inaccurate. Please modify it accordingly: this is supposed to be a reality based community, not one where misleading propaganda (no matter how noble its cause) thrives.

    Energy Densities of various materials.


    by xynz on Fri Aug 12, 2011 at 11:00:15 PM PDT

    •  My bad....never mind. You're right. (0+ / 0-)


      10KWh = 10000W*3600sec = 3.6*107


      by xynz on Fri Aug 12, 2011 at 11:06:26 PM PDT

      [ Parent ]

    •  Check your math (0+ / 0-)

      10 Kilowatt hours x 3600 = 36,000 kilowatt seconds.

      36000 kilowatt seconds x 1000 = 36,000,000 watt-seconds = 36,000,000 Joules = 3.6 x 10^7 Joules per kg, comparable to gasoline.


      by Keith Pickering on Sat Aug 13, 2011 at 12:50:39 AM PDT

      [ Parent ]

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