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Human Powered Flight

 The Gossamer Albatross in 1980 at NASA : Image Link
Ultra energy efficient aircraft powered by people & more recently batteries + solar panels exist, yet super efficient commercial passenger aircraft do not exist, except perhaps the Boeing 787 if you want to call that one energy efficient. 

The First Human Power Plane
Gerhart Cycleplane 
Human powered airplanes have been around since 1923 (Gerhart-Image above) in various one off niche formats, notably in recently history by student teams from MIT who won a series of Kremer cash prizes that are available for groups that exceed specific performance targets like average speed, flight duration, range, etc. The first Kremer prize was awarded to the team behind The Gossamer Albatross 2 for example, which flew using only 0.35 hp (260 watts) at a slow 11mph (18km/h), covering 2172 meters in a figure 8 pattern. Again this plane claimed the second Kremer prize when Bryan Allen flew it from England to France in 2 hours 49minutes, having traveled 22mi (35km)

The low power levels of human powered aircraft meant that lithium ion powered electric aircraft were possible. Today the world has been circumnavigated in a solar battery electric airplane carrying two pilots as in the case of Solar Impulse 2. With a record flight of 118hr covering 4,819 mi from Nagoya Japan to Kalaeloa Hawaii in stage 8 of the 17 stage circumnavigation.

Solar Impulse 2 : Image Link

Electric Passenger Aircraft ? 

The big question from the Iron Man movie, when "Tony Stark" asks "Elon Musk" about electric commercial aircraft; when will battery electric solar generator enhanced commercial aircraft become a reality that moves ~100 people + luggage  3000 + miles at speeds of at least 400mph? I suspect within 40 years. Battery energy density will need to improve by a factor of 30 to achieve power density parity with gasoline, assuming that at least 6 major innovations in battery technology occur that rough double energy density each time!

Gasoline Hard to Compete Against 

Today Lithium Sulfur batteries are 2.5x better than the best lithium ion in terms of energy density, finding bespoke use cases in aerospace defense UAV applications. Commercial lithium ion batteries typically store about 200wh/kg in the best quality cells, while high quality lithium sulfur batteries store 500wh/kg! Gasoline is 12,000wh/kg by comparison, a very high bar for battery technology innovations.

5x Lower Costs Needed

The national renewable energy laboratory claims that rechargeable battery technology needs to become 500% more affordable in order for electric cars to compete directly against gasoline powered cars in the mainstream automobile markets of the world. Tesla is going to be manufacturing Panasonic tech lithium ion 18650' cells by the billions at it Gigafactory, which is currently under construction. Analysts estimate that when the Gigafactor reaches peak production capacity, the battery packs it produces will be 70% less costly @ $38/kWh, sometime around 2018.

Balancing Metrics

Cost & performance (cycle life, energy density, calendar life, charge/discharge rates, safety) are always a balancing act or a box of compromises depending on which chemistry (at least 12  exist for lithium ion), as was noted by battery industry expert Isidor Buchmann, who has studied rechargeable battery technology for more than 30 years as the founder and CEO of Cadex Electronics inc. I have more than 3 years of professional experience with rechargeable battery technology, having invested thousands of hour in research reading to keep up with Green Car Congress's publishing ^^ We have a long way to go and many innovations are yet to come that will enable practical battery electric passenger aircraft to exist.

Smartphones & Electric Vehicles 

Today the batteries are unsafe (Galaxy Note 7 fires), too expensive (Tesla Model S), and cannot be recharged fast enough (many dozens of minutes, sometimes hours). The real push is the lack of electrical outlets where people park their cars for 20+ hours every day, especially in overpopulated countries like China and India. Similarly multifamily dwellers all over the world lack electrical outlets where their cars are parked.

Nissan Leaf Experience

While the Nissan Leaf gives people an affordable EV option (since 2011) under $35K , I leased one for 24 months and came away with this feeling that the single charge range ~90mi was not exactly competitive against my gasoline powered Prius which can be refueled with 10gal of gas in under 10 minutes, able to travel over 400mi on that 10 gallons. It took hours to recharge the 2013 Leaf S by comparison.

The 13 Leaf S was a blast to drive, especially with hard acceleration off the line, the instant torque giving it sporty acceleration that almost always put a smile on my face. The longest single day drive Meg and I did in the Leaf was 138mi; we stopped to charge for 2 hours on Level 2 public charging stations two different times + we used the 115v convenience charger when we were parked for hours at the destination before heading home and still had about 15mi of remaining range when we made it home. This made the trip take almost 4 hours longer than our normal gas powered Prius trip to and from her parents old home. The Leaf is great for in city driving, and ok for driving between bordering cities even at highway speeds. The vast majority of people drive less than 50mi per day, meaning the Leafs' 90mi range can cover that distance, but that is when the battery is brand new. Sadly, rechargeable batteries lose their capacity while their performance degrades over time.

Electric Vehicles Considered

I watch the electric motorcycle scene with some enthusiasm, similarly following electric bicycle technology. I am interested in electric vehicles because the electric motor is quiet, produce torque instantly, and is very efficient! I started to become interested in electric vehicles because of hybrid vehicles, later an electric scooter peaked my interest, I even found a way to use the electric scooter ($400) to avoid paying more than $800 of university parking fees :), by parking roughly 1mi away from campus, then using the 12mph electric scooter to cover the final leg. I brought the charger in my bag and would top up the battery (sealed cyclone PBA) from power outlets that Students would normally plug their laptop adapters into. I got into some interesting discussions by showing the scooter to people who stopped to ask about it.

Later I got a lithium iron phosphate powered Prodeco Phantom X with a 500w hub motor, it was stollen, although they did not get the charger or key set for the battery power lock :) At 62lb, that folding electric 8sp hybrid bike was remarkable, but hard to lift in and out of a car. I have seen more recent electric bikes that weigh less than 40lbs. Electric aircraft exist that use around 100lbs of lithium ion with an electric motor, but they are slow, have limited range, and can only carry a few people; Mostly trainer type aircraft, which is great for pilot practice, since they are quite and lack a tail pipe :) and gliders that have to be launched using other alternatively powered systems.

Clean Air Technology

The more electric vehicles are used in a given area to replace cars with tailpipes, the cleaner the air becomes in that area because electric are cleaner. Electromotive technology is going to make the future less toxic because of the emissions reductions that hybrid, plug-in hybrid, and pure electric cars produce where their are operated.

Many Global Issues

Addressing the issue of finite foreign oil, we can also consider the ecological and economic benefits of electric vehicles. Most developed countries are net oil importers, meaning that countries like America have to export billions of cash to import oil every day! This drains the economy of net oil importing countries while creating piles of cash in oil exporting countries. National security is also an issues surrounding foreign oil because of the countries that produce oil vs the countries that consume oil. Climate change is also affected by carbon emissions that come from burning oil products, namely gasoline, kerosene, diesel and jet fuel, but also coal, propane, natural gas and butane. There is actually a lot to consider when you stop to think about electric vehicle technology :)

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