Think dirigible. Most energy goes to lifting the plane from the ground, so if you have a lighter than air aircraft, you do not need that much energy. A dirigible may not move as fast as a plane, but it can be made a much larger and comfortable than a plane. Consequently, a trans-Atlantic flight may become a trans-Atlantic cruise with all its splendor, but faster. I would not mind spending a day or two on a dirigible flight to Europe if I spend that time in an ocean liner like cabin instead of being sandwiched in the stowage-class of an airliner.
A dirigible would also offer substantial savings of airport costs - as it could dock virtually anywhere.
As to safety, it does not have to be a flaming Nazi gasbag (the Hindenburg, that is, not Rush Limbaugh) - it could be filled with helium.
Wojtek