Solar powered planes

A plane took off today that will hopefully circle the globe on solar power. To give a sense of technological change, the Wright Brothers first flew in 1903, jet airplanes were in use by WWII, and we landed on the moon 66 years after the first flight. Not to pick on high speed rail (HSR) and other technological solutions to energy inefficient intercity travel, but there is a real possibility that solar powered air travel via planes or blimps will be viable and common before HSR is fully deployed in 25 or more years. Such advances will minimize potential energy savings from HSR and need to be taken into account when estimating future benefits.