The 2015 Green Speed Cup

Robert Adam writes to let the CAFE Foundation know that the 2015 Green Speed Cup is underway, just now finishing its second of three days of competition.  Think of a Green Flight Challenge with a need for green speed balanced against a need for economical use of energy.  Taking place out of Strausberg Airport in Germany, the event consists of three days of tasks which always bring the competitors back home ever day.

“Every task comes with a minimum energy consumption. It will be derived from the energy used by a reference airplane on 10% of the tasks length at MCP. Combustion and electric aircraft use different reference airplanes. Class definitions All aircraft capable of taking off under own power, are allowed in the following classes:

  • Electric – Class (but alas, no entrants this year)
    • Electrical driven aircraft
    • All aircraft with one to four seats
    • Up to 2700 kg ( MTOW 5950 lbs)
    • Maximum task distance of 400 km (216 NM) (actual tasks depend on competitors and their abilities)
  • Combustion – Class
    • Aircraft with combustion engines (piston or turbine)
    • All aircraft with one to four seats
    • Up to 2700 kg ( MTOW 5950 lbs)
Darmstadt Akaflieg D39b leads the pack so far.  Think of it as a cleaner version of Carat or RF-4

Darmstadt Akaflieg D39b leads the pack so far. Think of it as a cleaner version of Carat or RF-4

“Hybrid aircraft are allowed to choose their class. The energy consumption is the sum of the energy used by both, the electric and the combustion engine. The batteries can be recharged by the combustion engine or from the grid. The charging will be supervised and included in the overall energy consumption.”

The usual list of competitors includes a lot of Stemme products, that group being a founder and major supporter of the contest.  Robert tells us this year is unique.  “We have a quite interesting and completely different field compared to the last years. It looks like a race of the Taifun vs. Scheibe Falke ;). Also on board we have a 2 stroke Piccolo (placed third yesterday on a 240 nautical mile – 276 statute miles task), an RF5, D39 (Akafalieg Darmstadt Protoype) and of course, a Stemme S10 and S6.  Today an Aquila will join the field as the 12th competitor.”

Piccolo is ultralight sailplane based on a design by the late Swiss sailplane builder, Neukom

Piccolo is ultralight sailplane based on a design by the late Swiss sailplane builder, Albert Neukom, best known for his Elfe series

The Piccolo is a single-seat, tricycle-geared motorglider designed by Neukom and built in Switzerland.  It is motivated by a two-stroke engine, usually a Solo.  The Aquila is a relatively new Light Sport Aircraft (ULM in Europe) with a Rotax engine and longer than usual wings (33 feet).

Day One saw two outlandings, the first in this event.  “The 240Nm task was a little over the top for the Scheibe B-Falke with only 30 liters of fuel capacity. The team tried to extend their range by using thermals and actually did it suceesfully. However they had to land on an airfield some 10 minutes before the finish line. They even walked to a gas station as the field had no fuel and borrowed a leaking gas can to refuel for the last 15Nm. Our rules allow landings in between, as a Penalty the time counter will continue running until they arrive back at the finish line. Another C-Falke did a less spectacular refueling stop halfway in the race to ensure a safe landing.”

Three Valentin Taifuns are participating in this year's event - outnumbering Stemmes

Three Valentin Taifuns are participating in this year’s event – outnumbering Stemmes

We’ll look forward to the third day’s results and learning more about how the little two-stroke Piccolo has managed to maintain a solid third-place standing so far.  It reinforces the need to design clean, light airframes for best performance and economy.  Fuel use for the leaders is great so far and we’ll report tomorrow on the ultimate outcomes.  It’s too bad there are no electric aircraft in the event this year, but there are several, such as the D-39 and Piccolo that do well with the right batteries.


At 79 hours into the flight Flight Director Michi Anger let viewers on Solar Impulse’s web site know that the “U-turns” the airplane performed were to get the maximum amount of solar energy in the plane – “That’s why it looks as if we’re facing the wrong direction.”

“André got a good amount of rest during the last 12 hours, but we had some problems finding calm air. André had 300m of resting periods but could only sleep for 170m. The autopilot is designed to function only in calm air so we had to wake André up from the MCC. This is a rude awakening for him so it made it more difficult for him to go back into sleep.

Hovering over Hawaii in the early morning light.

Hovering over Hawaii in the early morning light.

“André passed 76h 45min of flight, breaking Steve Fossett’s 2006 record for the longest solo flight (in any kind of plane).

“In a few hours SI2 will climb up to 28 000ft until “Energy-Neutral Evening”, the point at which there will not be enough solar power to charge batteries.

“Holding pattern: we’re slowing down the flight to ensure we cross the 2nd weather front at the optimal moment.

“The coming night will be the most difficult energy-wise. The batteries will be at the most depleted level we’ve ever seen: they could get down to 8% of charge.”  (Luckily and probably partly because of dedicated energy management on Andre’s part, Solar Impulse landed with considerably more energy still available.)

When Andre’ Borschberg landed at Kalaeloa Airport in the early morning of July 5, he had managed to climb the equivalent of five trips up Mt. Everest, and spent four days, 21 hours and 52 minutes at the controls of an airplane slower than most ultralight aircraft and bigger than a Boeing 747.

Through incredible weather planning the ground support team in Monaco was able to have him hold until opportune moments allowed Andre’ to slip into tailwinds that sometimes drove his ground speed to over 70 mph.  This ability to gauge clouds and winds across a 6,000 mile stretch of ocean was crucial to the success of the flight, and weather windows seemed to change for the good and bad mid-voyage.

Bertrand Piccard's vision realized through Andre' Borschberg's courage and piloting skills

Bertrand Piccard’s vision realized through Andre’ Borschberg’s courage and piloting skills

It will be interesting to see what the effects of repeated climbs to 28,000 and even 30,000 feet in an unpressurized cabin had on Andre’.  He made his first steps in five days after a careful leg massage by a team member and with help from Bertrand Piccard.  Considering the recent ordeal, he seemed to be cheerful and fully mobile.

One might grow complacent, thinking the biggest part of the around-the-world trip is done, but there are still two oceans to cross, days growing shorter, and as always, unpredictable weather to outthink and outfly.  The hazards are ever-present and the consequences of bad planning or execution just as severe.

While Andre’ has a well-deserved rest and Bertrand and the Solar Impulse team prepare for the next leg of the RTW, we consider the worldwide importance of what these adventurers and scientists have accomplished.  They’ve focused an otherwise fickle world on clean energy and potential solutions for what could become a climate crisis.  They have encouraged millions to sign petitions pledging support for practical solutions at the upcoming climate conference, COP21, to be held in Paris in December.

And they have made all of who share the sky and know its beauty quite proud to be at least vicarious passengers on their gigantic slow airplane.


Several sources report on Samsung’s announcement that they have developed a new technology that enables them to coat silicon battery cathodes with high crystal graphene, virtually doubling the capacity of lithium-ion batteries.

Of course, Samsung relates this immediately to their popular smartphones and tablets, but the significance of this is not lost on electric vehicle designers.  Doubling the range of EVs “without adding a single pound of weight” would be a true game changer.  But don’t get excited too quickly.

Silicon electrodes have been a major research effort for people like Dr. Yi Cui, who spoke at this year’s Electric Aircraft Symposium.  Issue surrounding their successful use have included silicon’s expansion when being charged and contraction when being discharged.  This errant flexibility causes eventual disintegration of the electrodes and shuts down the battery.  Attempts to use silicon nanowires still have led to embrittlement. reports Cho Jin-young from BusinessKorea explaining, “Currently, the development of high-capacity battery materials has been mostly done in the United States. In particular, the research is active on silicon as a substitute material capable of raising the capacity more than 10 times that of the graphite currently used as an existing cathode material. There is, however, still the technological problem of the shortening the battery life by repeated charging and discharging.”

SiC-free graphene growth on Si NPs. (a) A low-magnification TEM image of Gr–Si NP. (b) A higher-magnification TEM image for the same Gr–Si NP from the white box in a. (Insets) The line profiles from the two red boxes indicate that the interlayer spacing between graphene layers is ~3.4 Å, in good agreement with that of typical graphene layers based on van der Waals interaction. (c) A high-magnification TEM image visualizing the origins (red arrows) from which individual graphene layers grow. (d) A schematic illustration showing the sliding process of the graphene coating layers that can buffer the volume expansion of Si. Credit: Nature Communications 6, Article number: 7393 doi:10.1038/ncomms8393

SiC-free graphene growth on Si NPs. (a) A low-magnification TEM image of Gr–Si NP. (b) A higher-magnification TEM image for the same Gr–Si NP from the white box in a. (Insets) The line profiles from the two red boxes indicate that the interlayer spacing between graphene layers is ~3.4 Å, in good agreement with that of typical graphene layers based on van der Waals interaction. (c) A high-magnification TEM image visualizing the origins (red arrows) from which individual graphene layers grow. (d) A schematic illustration showing the sliding process of the graphene coating layers that can buffer the volume expansion of Si. Credit: Nature Communications 6, Article number: 7393 doi:10.1038/ncomms8393

Potential energy densities of 1,000 Watt-hours per kilogram are a great lure for further research, opening possibilities of batteries with five times the energy density of currently-available lithium-ion competitors. reports, “To circumvent that problem, the researches grew carbide-free graphene (to keep it from forming they developed a chemical vapor deposition process which included using a mild oxidant) on its surface creating a protective and restrictive coating. In addition to preventing expansion, the graphene also helped prevent the silicon from breaking down over time (which occurs due to constant expanding and contracting).”

Not quite the double promised in the headlines, the test battery had an initial energy density 1.8 times that of conventional batteries, and held steady at 1.5 times after repeated use.  Two things stand in the way of commercializing this breakthrough.  Graphene is not easily made in large quantities – yet.  And the laboratory techniques Samsung researchers used so brilliantly to coat silicon with graphene will need to be scaled up significantly to allow factory-level production.

We see loads of laboratory breakthroughs, but until someone comes up with ways to make these breakthroughs affordable and mass-producible, they are unfortunately still in the hoped-for near future.  Let’s hope Samsung and others are intent on that since the first out of that gate could garner enormous profits.

Samsung and its academic partners published their findings in Nature Communications.  The abstract provides a little more insight into the work and ends with some hope that this research will reach the market.

“Silicon is receiving discernable attention as an active material for next generation lithium-ion battery anodes because of its unparalleled gravimetric capacity. However, the large volume change of silicon over charge–discharge cycles weakens its competitiveness in the volumetric energy density and cycle life. Here we report direct graphene growth over silicon nanoparticles without silicon carbide formation. The graphene layers anchored onto the silicon surface accommodate the volume expansion of silicon via a sliding process between adjacent graphene layers. When paired with a commercial lithium cobalt oxide cathode, the silicon carbide-free graphene coating allows the full cell to reach volumetric energy densities of 972 and 700 Wh l−1 at first and 200th cycle, respectively, 1.8 and 1.5 times higher than those of current commercial lithium-ion batteries. This observation suggests that two-dimensional layered structure of graphene and its silicon carbide-free integration with silicon can serve as a prototype in advancing silicon anodes to commercially viable technology.”


Brazil and Paraguay join the few nations which have sent an electric aircraft into flight with the introduction of the Sora-e, an attractive two-seat light sport aircraft.  The 8 meter (26.25 feet) wingspan plane incorporates a Slovenian motor, Korean batteries and an American propeller, giving it a truly international flavor.  The two countries share a joint venture firm, Itaipu Binacional, building and developing the airplane and its future variants.

Pesquisa FAPESP (Investigation Sao Paolo Research Foundation), an online magazine dealing with various sciences, announced the first flight of a new, two-seat, electric-powered airplane.  The Sora-e’s initial flight will lead to a testing program that will eventually have the plane up for 90 minutes and reaching a cruising speed of 190 kilometers per hour (118 mph).

Designed by ACS-Aviation of Sao Paolo and built by ACS and Paraguay’s Itaipu Binacional, Sora-e is an all-carbon-fiber machine with seemingly excellent visibility.

The video shows the first test flight taking place at Hernandarias, Paraguay on June 23 and ACS aviation engineer and pilot Alexandre Zaramella trying out the cockpit before takeoff.

He and another engineer remove the motor cowling so Brazilian Itaipu director-general Jorge Samek can view the two-motor power system.  He says, in a central soundbite, “We started with cars, with utility vehicles, with trucks and now we’re working with planes and buses to show that, yes, it is possible to use substitutes to fossil fuels to avoid carbon emissions that cause greenhouse effects.”

Fittingly, the airplane could be charged by Paraguay’s Itaipu Dam on the Parana River which divides the two countries, making it a clean energy success all around.  Itaipu Dam is the world’s second biggest hydro-electric dam by maximum capacity and is run by Itaipu Binacional.

Twin Emrax motors and Catto propeller grace nose of Sora-e

Twin Emrax motors and Catto propeller grace nose of Sora-e

According to Pesquisa FAPESP, “The Sora-e has two electric engines, 35 kW each. They are the Enrax model supplied by Enstroj of Slovenia. The power comes from six polymer lithium ion battery packs for a total of 400 volts. The batteries were assembled by ACS itself using cells made by Kokam of South Korea. The airplane uses a fixed pitch propeller made of wood and carbon. It was developed by ACS and Craig Catto of California. Catto is one of the most acclaimed makers of propellers for experimental airplanes in the world. With this configuration, the ACS electric airplane climbs at the rate of 1,500 feet per minute and reaches a maximum speed of 340 km/h (210 mph) with a range of 1 hour and 30 minutes, traveling at 190 km/h (118 mph).”

“We started with cars, with utility vehicles, with trucks and now we’re working with planes and buses to show that, yes, it is possible to use substitutes to fossil fuels to avoid carbon emissions that cause greenhouse effects,” the Brazilian Itaipu director-general Jorge Samek said after Sora-e’s inaugural flight.

“’Today, to move the fleet of automobiles in Brazil, we burn energy equivalent to what 9.3 Itaipus hydroelectric dams generate in a year. If the fleet were electric, 1.5 Itaipus would meet the demand,’ says engineer Celso Novais, the Brazilian coordinator of the Itaipu Binacional Electric Vehicle Project.”

Gull-wing doors add distinctive touch to Sora-e

Gull-wing doors add distinctive touch to Sora-e

The combined team has been working with 100 FIAT electric Palio Weekend cars assembled from parts in Brazil and 32 Renault Twizy compact urban vehicles.  They are also working on a hybrid bus, which like the cars will get part of its energy from Itaipu hydro power.

Zaramella thinks the main challenge for the new stage of the ACS electric airplane project is to increase the aircraft’s range. Although ACS is not involved in battery development, “We believe that in 2018 we will have batteries capable of keeping flights aloft for four and five hours at a cruising speed of 250 km/h in a two-seater electric airplane,” he says.

The team can provide longer flight ranges by making the airplane lighter. The lighter the airplane, the less energy it requires to keep it aloft. The company is focusing on this issue, Zaramella says. The already structure is made of a carbon fiber-based composite, with 100 kilograms (220 pounds) comprising battery weight and 27 kilograms (59.4 pounds) the motor.  That leaves 523 kilograms (1,150.6 pounds) for the rest of the airplane, including landing gear, instruments and all other structural and non-structural elements.

Next, ACS/Itaipu will use their findings from test flights to develop and sportplane and a motorglider based on the Sora-e.  Readers can follow their progress on their Facebook page, seemingly their communications medium of choice.  It includes additional short videos.


Solar Impulse Passes Midway Islands

With the sun soon to rise in the Pacific, Solar Impulse 2 continues scooting at over 60 mph toward Honolulu as the third night comes to an end.  Significantly, Andre’ Borschberg and the 747-size plane have made it past the Midway Islands, once a stop-over for Pan-Am Boeing 314 “China Clippers.”  Even with their 3,500-mile range, those luxurious planes needed a fueling stop mid-way between Hawaii and China or Guam.

Boeing 314 "China Clipper" had 3,500-mile range, total luxury for passengers - but still had to make stopovers for refueling

Boeing 314 “China Clipper” had 3,500-mile range, total luxury for passengers – but still had to make stopovers for refueling

The islands were important enough as a way station in the vast Pacific that one of the largest and most decisive battles of World War II took place near them.   In a battle terrible destructive to both sides, U. S. forces sank four Japanese carriers, essentially casting the fate of the remaining battles.

Midway National Memorial commemorates WWII battle.  Albatross next there, but are endangered by worldwide plastic pollution in oceans

Midway National Memorial commemorates WWII battle. Albatross next there, but are endangered by worldwide plastic pollution in oceans

The still-important role of the islands as emergency landing sites was reinforced in 2014 with the safe arrival of a Boeing 777 following “an odor” and failure of radar and other electronic systems.

The idea of a “point of no return” has been crucial in flight planning with fossil-fuel powered airplanes.  The midway point of a trans-ocean flight is a psychological and physical reality, with options quickly fading as the aircraft passes that imaginary point in the sky.  With a craft like the Solar Impulse, even marginally better batteries would negate the whole idea of crossing an imaginary line where turning back was impossible.  Flight planning for this leg of the journey has to take into account the short nights and long days in the Northern Pacific.  Trying this journey in the darker days of fall or winter would leave the current system wanting.  Near-future improvements in batteries will allow flight of solar-powered aircraft through the longest nights.

Seemingly odd behavior of Solar Impulse turning its back to the sun is to speed battery recovery with favorable angle for solar cells

Seemingly odd behavior of Solar Impulse turning its back to the sun is to speed battery recovery with favorable angle for solar cells

We continue to applaud the brave and resourceful pilot and the superb intelligence behind this voyage.  God speed!


A Second Night on Solar Impulse

Pixar’s current film, Inside Out, depicts the emotions of an 11-year-old girl having her life disrupted by family circumstances.  Different voice actors depict Joy, Fear, Anger, Disgust, and Sadness, emotions struggling for control within Headquarters (get it?).  Imagine your editor’s surprise to find that Solar Impulse’s Headquarters reports on its audience’s emotional state as part of the graphics which inform us about the flight’s progress – now in its second night over the North Pacific.

Anger, fear, trust disgust and sadness from Pixar's Inside Out.  Solar Impulse shares three other emotions

Anger, disgust, trust, fear and sadness from Pixar’s Inside Out. Solar Impulse shares three other emotions of the viewing audience

Luckily, Andre’ Borschberg is a man of a well-disciplined character, with training in Yoga and self-hypnosis to help him benefit from the 20-minute rest periods that take the place of a normal night’s sleep.  But depending on events in the flight, those of us checking in (or glued to our screens) make our feelings known on Twitter, and our tweets give some algorithm at Solar Impulse the input to display eight different emotions on screen.  Along with those acted out in the Pixar film, we share Anticipation, Surprise, and Trust on this special display widget.

At this checkpoint, Disgust is non-existent, showing zero percent on the chart, with Fear at eight percent and Joy at twenty percent.  Overall, positive feelings outrank negative, and the audience, as it is kept well informed by the frequent updates and generally positive tone of the spokespeople at Solar Impulse, stays upbeat.

There might be a lesson here for those who attempt to communicate with the public.  Maintaining open lines of communication, even during times of great stress, helps people deal with current reality and probably instills higher levels of trust than would otherwise be possible.

Andre's Borschberg maintains good attitude, both in flight and in person

Andre’s Borschberg maintains good attitude, both in flight and in person

In the meantime, Andre’ and Solar Impulse 2 wait out a decreasing cold front before progressing once more toward Honolulu.  All systems seem to be functioning well and we remain trusting and hopeful.


Three major automobile and motorcycle races are adapting electric or hybrid power, and seeing winners in all categories.   The three take place in the month of June every year, making the month a showtime for innovation and a demonstration of incredible driving skills.

Isle of Man

Perhaps the most dangerous of all events, the Isle of Man Tourist Trophy motorcycle race covers 37 miles on public roads running through countryside and villages.  Over 200 riders have been killed on the course since the first race in 1910.  This doesn’t discourage over 100 riders from qualifying every year and hitting top speeds near 200 mph.  The winning gasoline-powered superbike this year averaged 128.749 during its six laps around the island.

By comparison the winning electric bikes in the TT Zero race do only one lap around the course, limited by the current state of battery development.  This year’s winner, John McGuinness riding a Honda/Mugen electric, averaged 119.279 mph, edging into superbike territory.  A few more years, and doubtless electric and gasoline superbikes will be competing for the whole six laps.  A mere minute and 10 seconds separated the first-place and sixth-place finishers in the TT Zero event.

John McGuinness shows winning form on Honda/Mugen electric TT Zero bike

John McGuinness shows winning form on Honda/Mugen electric TT Zero bike

 Le Mans

Le Mans has been dominated by Audi with its superb Diesel/electric hybrid LMP1 (Le Mans Prototype 1) racers for the last several years.  Porsche surprised them by achieving a one-two finish this year – also with hybrid racers, followed by Toyota with its own hybrids.  This is not your grandfather’s Prius, though.  LMP1 means Le Mans Prototype 1, the all-out extreme race car for this event.  Porsche used a 2.0-liter V-4, while Audi had a 4.0-liter Diesel engine in its machines.  Results showed a hybrid sweep.

1. Hulkenberg/Tandy/BamberGER Porsche 919 Hybrid 395 laps LMP1
2. Webber/Hartley/Bernhard GER Porsche 919 Hybrid 394 laps LMP1
3. Lotterer/Fassler/Treluyer GER Audi Sport Team Joest R18 e-tron 393 laps LMP1
4. Duval/di Grassi/Jarvis GER Audi Sport Team Joest R18 e-tron 392 laps LMP1
5. Jani/Lieb/Dumas GER Porsche 919 Hybrid 391 laps LMP1
6. Wurz/Conway/Sarrazin JPN Toyota Gazoo TS040 Hybrid 387 laps LMP1
7. Albuquerque/Bonanomi/Rast GER Audi Sport Team Joest R18 e-tron 387 laps LMP1
8. Davidson/Buemi/Nakajima JPN Toyota Gazoo TS040 Hybrid 386 laps LMP1

Hybrid mechanisms varied.  Porsche had a kinetic energy recovery system (KERS) taking energy from braking to recharge a lithium battery pack, and recovered energy from exhaust gases and the second turbocharger.

Porsche's 919 surprised Audi team this year at Le Mans

Porsche’s 919 surprised Audi team this year at Le Mans

Racecar Engineering reports on Porsche’s layout, which has two turbines in the exhaust system. “…the first is part of a conventional turbo-charger layout in that it is linked to a compressor but the second turbine, which is sat alongside the first is only linked to an electric motor (GU-H), and not to a compressor or the other turbine. This layout allows the Porsche to recover energy at all times the engine is running, the only LMP1 design currently able to do this, all others are only able to recover energy under braking. Energy from both the MGU-K and the GU-H is stored in a battery provided exclusively to Porsche by A123.”

 Audi includes a flywheel in its hybrid system, like other such units pulling its energy from braking.  Toyota used a V-8 engine and a supercapacitor energy storage system with otherwise fairly conventional KERS type energy recovery – again, mostly from braking.

Because of this, Dr. Seeley cautions, such energy recovery systems don’t necessarily work well with airplanes, although Pipistrel regains an extra trip around the field from about an hour’s worth of touch-and-goes in its Alpha Electro – it takes a special propeller and a steep descent to regenerate energy.

Pikes Peak International Hill Climb

Pikes Peak was won this year by a pure electric racer for the first time.  The Drive e0 car didn’t quite make its goal time of under nine minutes, but it did use its six motors to good advantage.  Rhys Millen took the six-YASA-motor vehicle up the Peak in style, driving the first electric competitor to win the event outright.  The motors put out a total of 1,020 kilowatts (1,367 horsepower) and a fairly staggering 2,160 Newton-meters (1,593 foot-pounds) of torque.

Second place fell to Tobuhiro “Monster” Tajima, a legend on the mountain, with his Tajima Rimac E-Runner Concept_One, propelled by four Rimac motors with an output of 1,100 kilowatts (1,475 horsepower) and 1,500 Newton-meters (1,106 foot-pounds) of torque – enough to kick the 1,500 kilogram (3,300 pound) car from 0 to 62 mph in 2.2 seconds.  He was a mere 25 seconds behind Millen.

Both cars had battery packs just big enough to last the fewer than 10 minutes necessary to top the hill – a purposely designed consideration for such missions.

What makes these events of interest is the competition-driven development and necessarily flawless execution.  Light weight, high power and torque contribute to winning these events, factors we want in our future electric airplanes.  Competition does improve the breed.


Solar Impulse Pulls a Fast One

Confusion surrounded the takeoff of Solar Impulse 2 from Nagoya, Japan in Sunday’s early hours, with some news reports showing that the airplane had departed, but the project’s web site silent.  That was cleared up over nine hours into the flight, with revelations that Andre’ Borschberg and the control center in Monaco had spent hours resolving issues with the aircraft’s systems and determining that the flight would continue.  They did this without the press of the press adding to the tension.

Mrs. Borschberg holds an oddly appropriate flag with Japan's rising sun sending her husband toward the dawn

Mrs. Borschberg holds an appropriate flag with Japan’s rising sun sending her husband toward the dawn.  Photo: Solar Impulse | Revilard

The team made crucial decisions regarding safety and system reliability and made the big choice to continue on the five day, five night voyage.  Weather conditions over the 8,340 kilometer (5,170 mile) course remain promising and motors, batteries and all systems seem to be operating flawlessly.  With sunrise within four hours of this writing, batteries should be able to sustain flight until Borschberg and the giant airplane meet the sun well out over the Pacific.

Joe the Cartoon Shark follows the flight on Solar Impulse's excellent on-line tracking

Joe the Cartoon Shark follows the flight on Solar Impulse’s excellent on-line tracking

We’ll continue with best wishes for the safety of the epic flight.  With a current ground speed of 10 knots (11.5 mph), the airplane could probably use a providential tailwind to expedite the passage.


Cambridge Crude Reborn in Simplified Battery

We first saw the appellation, “24M” four years ago in our report on research done at MIT to produce an ionic liquid called “Cambridge Crude,” usable in flow batteries.   Dr. Yet-Ming Chiang headed up that work in collaboration with Professors Angela Belcher and Paula Hammond at MIT and Glenn Amatucci at Rutgers, among others.  They formed a commercial spinoff and seemingly went underground for the next four years.

Dr. Chiang and his associates had previously gone commercial with A123, which went through the trial of bankruptcy and being acquired by overseas investors.  It’s now solvent and looking to double output.  24M is a spin-off of A123.

We found that Professor Chiang had resurfaced when friend and blog reader Marshall Houston sent an article from Quartz about Chiang’s work with Dr. W. Craig Carter to expand on the foundational energy storage technology of 24M – based on the thick black electrolyte they’d created and a resulting semisolid electrode.

Their semi-solid lithium-ion cell benefits from streamlined manufacturing processes which might reduce costs 50 percent.  24M claims advantages in time and cost for their process, taking one-fifth the time required to make a conventional battery. “Because semisolid lithium-ion doesn’t require binding, drying, solvent recovery or calendaring, it removes entire steps in the manufacturing process.”

Because the battery has a simpler structure than conventional “jelly-roll” cells, plants can be smaller and less complex with fewer manufacturing steps.  According to 24M, their facilities require about one-tenth the investment of a conventional plant and occupy much less real estate.

Throop Wilder, 24M’s CEO, explains, “Together, our inventions achieve what lithium-ion has yet to do—meet the ultra-low cost targets of the grid and transportation industries. By 2020 our battery costs will be less than $100 a kilowatt-hour (kWh). We’re emerging at the right time with the right technology.”  The cost per kWh competes with Elon Musk’s Tesla Gigafactory’s goals for a far smaller investment than the $5 billion projected for that project.

One factor gave Sony an edge in bringing the original lithium-ion battery to market, their predominance in cassette tapes (remember those?).  Once CDs and DVDs took over that market, Sony had a manufacturing base with no particular use anywhere else.  But – winding a battery-sized width of material off one of their tape machines and layering it with other materials into concentric circles on a spool gave the lithium-ion battery its distinctive “jelly-roll” internal structure.  It was a brilliant transition into a new market, but Dr. Chiang is not all that impressed with the legacy.

Simplified internal structure of 24M battery leads to quicker, less expensive battery

Simplified internal structure of 24M battery leads to quicker, less expensive battery

“The lithium-ion battery is a brilliant, enabling technology, but its economics are flawed. It’s prohibitively expensive; it’s cumbersome and inefficient to make; and today’s version is approaching the limits of its cost reductions. 24M has fixed the flaws. We’ve made the world’s favorite battery better, fundamentally changing its cost curve by designing a more elegant and simpler cell and then making the batteries the right way – the way they should have been made from day one.”

Dr. Chiang and his team had gone down a rat-hole of their own, following development of their flow battery to its logical end and finding that the material volume required to run an EV, for instance, would be impractical.  They realized they needed to start down an entirely new path, and like Sony with their tape-winding machine, found they had a semi-solid goo with promising properties.

Talking their fellow workers into starting down this new path was hard enough, but they also had to convince investors who’d poured millions into the flow battery concept that they needed to help fund the new direction.  Chiang and Wilder must do a great PowerPoint presentation, because they’re now in a third funding loop, tracking purposely toward their new goal.

The team has removed large amounts of materials that do not store energy – 35 percent according to Dr. Chiang.   They created a manual assembly line where they could make automobile-battery-sized cells in six minutes, probably at least because of the internal simplicity of the new battery structure.

Quartz explains the changes made to improve the new battery and its manufacture.  “He started out by whacking out whole parts of the filler. His researchers developed a way to make the electrodes without the glue-like binder. Lithium-ion cells typically contain 14 separate material layers; Chiang simplified them, allowing him to reduce the layers to just five. He reduced the filler to 8% of the battery cell. Finally, he overturned the foundations of lithium-ion manufacturing by figuring out how to dispense entirely with the drying process; instead, he would inject the wet electrolyte into the cell from the start.

24M's performance is highlighted in this chart

24M’s performance is highlighted in this chart

“These were defining improvements. But, while he was at it, Chiang made some tweaks to the science of the battery, too. Most significantly, he made the electrodes four times thicker—500 microns, or half a millimeter, in diameter—which added a lot to the cells’ energy density.”

All this and getting a proper slurry that took less drying time makes it possible to “spit out” the new batteries in a production-like manner. If the group can turn up productivity and lower cell cost to $100 per kWh, competitive with gasoline-powered vehicles, the batteries could be a huge success.  Interviews and corporate materials don’t highlight battery performance, but rather cost.  If these new, simplified and cheaper batteries can perform well, Dr. Chiang, Wilder and team may have a winner, and a model of where future batteries may aspire.


Supercapacitors? It’s a Wrap

Recent entries in alerted your editor to a novel combination of batteries and supercapacitors to gain power and energy – usually mutually exclusive in energy storage devices.  The Paper Battery Company (an intriguing name) makes an extremely thin supercapacitor that can be literally wrapped around a battery or structure to make a hybrid energy storage device that allows the best features of both.

Paper-thin supercapacitor can be wrapped around almost any shape

Paper-thin supercapacitor can be wrapped around almost any shape

Their PowerWrapper™ Supercapacitor is a half-millimeter thick (or as Paper Battery insists –thin) 4.5 Volt device that can be flexed to fit over or around “your device, folds, bends or cut outs.”  This conformability still allows hundreds of thousands of charge/discharge cycles, supercapacitor longevity being one of their big selling points.

Others, according to the firm’s web site include:

  • Voltage up- and down-conversions as either continuous streams or pulses at high power from any battery chemistry to maximize its extractable energy.
  • …Electronics integration of advanced high energy battery chemistries without conventional large, noise-inducing converters.
  • … High power and voltage delivery with a high energy, low voltage battery, making advanced high-energy battery chemistries more compatible with electronics.
  • … Asynchronous power pulse demands [can] be met easily using a cheaper or smaller battery, enabling better user experience for high power modes with longer battery run time.
  • Replace[ment of] board-space-consuming buck or boost converters.

A demonstration of PowerWrapper’s abilities involves its mounting on an appropriate paper airplane.

Because Paper Battery doesn’t give up much hard data other than two voltage levels, 2.7 and 4.5, for their products, it’s hard to judge just where the varying levels of power and energy fall among the company’s products – which fall between pure batteries and pure supercapacitors.

Paper Battery Company's PowerWrap and Power Responder represent upper and lower ends of chart.  Determining mix of conventional lithium batteries and Paper Battery components could enhance battery performance

Paper Battery Company’s PowerWrap and Power Responder represent upper and lower ends of chart. Determining mix of conventional lithium batteries and Paper Battery components could enhance battery performance

They tout their benefits in the following: “The higher power and energy densities (by weight and by volume), of both PowerWrapper(tm) and PowerResponder(tm), yield superior supercapacitor performance, and thereby greater gains in power, runtime and cycle life over supplementing batteries with traditional cylindrical supercapacitors. Designers now can use smaller batteries without losing performance or keep the same size battery and get increased performance. These PBC supercapacitor benefits can be extended beyond lower-installed battery cost, and into lower warranty, service, and replacement costs.

PowerResponders are hybrid supercapacitors that Paper Battery claims can store 150 Joules per cubic centimeter, about five to six times that of conventional supercapacitors.  That converts to about 0.0416 Watt-hours per cc, or 41.6 Watt-hours per liter – still not exactly outstanding volumetric efficiency compared to lithium batteries.

The firm claims either of the Paper Battery products will reduce the size of the installed power pack, batteries can be installed closer to the motor, eliminating long wire runs. Either unit can be recharged in under three minutes, another advantage of all capacitors.  The company promotes their products with the idea of lowering stress on batteries, increasing performance and overall service life.  For those wanting to test these premises, Paper Battery has a Fast Charge Developers Kit for $400 that includes a fast charger board, a user manual, technical support for optimizing the charging protocols and two 350F(arad) PowerResponder cells. Product developers can integrate the conformable PowerResponder™ supercapacitor over existing structural components, as in the headband of wireless headphones.

Paper Battery shows potential applications for electric scooters and small vehicles at this time.  Their energy density level seems comparable to lead-acid batteries at this stage.  Whether later developments bring even greater energy and power densities remains to be seen.