RealClearScience links to an article about the potential for space travel that doesn't consume propellant. What is inferred, but not made explicit, is that the space travel described all occurs within our solar system.
It involves using the pressure of sunlight against sails or the magnetic or electrical equivalent of sails. My guess is that the power derived from sunlight drops with the square of the distance from the sun.
Out past Pluto there won't be much push on your "sails," the space equivalent of being "becalmed." Thus true interstellar travel using solar 'winds' isn't likely to be practical, solar powered interplanetary travel may be possible.
