NASA and Boeing Look to Hybrid Jets for Possible Fuel Savings

Over the next half century, international air travel is expected to as much as triple. But with more flights and more flyers comes a rising environmental and consumer cost to flying.

So what’s being done to make air travel more efficient? In the short run, the answer is actually building larger aircraft. The Airbus 380, which is the largest passenger airliner in the world, has actually managed to bring down per passenger fuel use by 20 percent compared to a 747 simply by seating more flyers. The plane is also capable of running on a biofuel blend—which may or may not be impressive depending upon your opinions about biofuels.

In the longer term though, there numerous hybrid and electric airplane concepts that could provide possible alternatives to traditional internal combustion aircraft. Boeing recently presented a design called the SUGAR Volt to NASA as part of the N+3 initiative, whose goal it is to “overcome significant performance and environmental challenges or the benefit of the general public.”

The SUGAR Volt is in many ways similar to hybrid vehicle. Twin jet engines are used to power electric motors that in turn supplement those engines, yielding as much as a 70 percent increase in fuel economy. But the principle at play here isn’t regenerative braking.

The electric motors in the SUGAR Volt aren’t there to power the aircraft, but rather to run fans that mix cool air in with the hot air that is produced by the jet engines. Increasing the ratio of cool to hot air leads to greater efficiency because the hotter the air that passes through a turbine, the harder the engine has to work to propel the aircraft.

Right now, air travel is estimated to account for just about 2 percent of global emissions, but with the global push to decrease carbon levels in the coming decades, the aviation industry’s footprint shouldn’t be allowed to triple while others are being cut. Furthermore, flyers shouldn’t be held hostage to fluctuating fuel prices. For example, for every dollar increase in the price of a barrel of crude, American Airlines’ annual operating costs increase by $80 million—and those costs get passed on to consumers in the form of higher fares.


  • Old Man Crowder

    Air travel is only 2% of global emissions?? I had no idea it was so small.

    I read somewhere that during the few days that all aircraft were grounded following 9/11, scientists detected a ‘statistically significant’ increase in temperatures because there were no contrails to block incoming sunlight.

    All this just goes to show how every little thing we do can have major consequences on the planet.

  • ex-EV1 driver

    The weight savings of the strut braced wing shown in the picture probably helps reduce fuel consumption almost as much as the fancy propulsion cooling system.

  • DC

    It is not 2%, the actual accepted figure from IPCC is closer to 4%. If you consider the other activities related to air-travel, that number would probably increase substantially as well. Also, the writer must be incredibly opimtistic if he thinks the world will have enough liquid fuels 50 years from now to sustain a tripleing of current air-traffic volumes. In 50 years, most likey the only people flying will be the very wealthy or those on goverment or critical tasks.

  • DaveX

    The answer is turboprops, which can be significantly more efficient than jets and provide near jet speeds.

  • Shines

    Twin jet engines are used to power electric motors that in turn supplement those engines. So the weight of the electric motors is offset how?!? I could see “painting” the wingtops and upper fuselage with lightweight solar cells. Once above the clouds additional power might be significant. (just dreaming…

  • Anonymous

    often the trade-off of higher efficiency (such as turbo props) is speed. this could add significant travel time for long distance travel. it will be interesting to see if a viable solution can be developed for long flights

  • ms

    The writer is very optmimistic when referring the increase by 3 times of air transportatio,if he is not aware of the peak oil.

  • Anon

    @Old Man — it was a statistically significant increase by day, and a statistically significant decrease by night. The key thing is the lack of contrails meant more sunshine by day, and more radiative cooling by night, just as with really clear weather you get a bigger difference between high and low than you do with cloudy weather.

  • cliff

    Hi!

    The electric motors will enable the plane to not have a hydraulic system, for one thing. Hydraulic liquid, tanks, lines, valves, etc., etc. are heavy and maintenance intesive. An all-electric plane with no hydraulics will help improve efficiency…the -787 is most of the way there, already.
    Current planes use hydraulics for landing gear movement, braking, steering, and power for much of the flight controls, among other things.

    cliff
    MIA

  • Anonymous

    Oh, I’m impressed with the fact that the Airbus 380 is being used to reduce fuel cost. As a pilot student, I would love to fly an Airbus 380. So far I’ve only flown it utilizing my flight simulator download program – flightsimulatordownloadd.org Can’t wait to fly the actual plane.

  • Anonymous

    Oh, I’m impressed with the fact that the Airbus 380 is being used to reduce fuel cost. As a pilot student, I would love to fly an Airbus 380. So far I’ve only flown it utilizing my flight simulator download program – flightsimulatordownloadd.org Can’t wait to fly the actual plane.