The energy-momentum of plane-fronted gravitational waves in the   teleparallel equivalent of GR
  We show that in the framework of the teleparallel equivalent of general relativity the gravitational energy-momentum of plane-fronted gravitational waves contained in an arbitrary three-dimensional volume V may be easily obtained and is non-negative in the frame of static observers. 
J. W. Maluf and S. C. Ulhoa