Preliminary analysis of the possibility of making use of part of the   energy flow of zero-point radiation
  The energy flow of zero-point radiation is very great, but difficult to put to use. However, the observations made by Sparnaay in 1958 and by Lamoureux in 1997 reveal the possibility of making use of a very small fraction of that immense amount. This possibility is big enough for such a minute fraction to have significant importance, but such a possibility requires miniaturisation to a degree which may be unattainable. It is worth trying to achieve it, since it would open the way to interstellar travel. 
R. Alvargonzalez and L. S. Soto