Ignoring T. H. Moray's ventures into solid state physics with emphasis on his pre-1912 results using a long-wire antenna, a ferrous metal powder "Coherer" and a good ground opens up several possibilities for extracting useable energy from the cosmos.
http://www.rexresearch.com/moray2/morayrer.htm "[p. 20] "I started my experiments with the taking of electricity from the ground, as I termed it, during the summer of 1909. By fall of 1910 I had sufficient power to operate a small electrical device, and I made a demonstration of my idea to two friends... This demonstration in the early stages consisted of operating a miniature arc light... It soon became evident that the energy was not static and that the static of the universe would be of no assistance to me in obtaining the power I was seeking... " "During the Christmas Holidays of 1911, I began to fully realize that the energy I was working with was not of a static nature, but of an oscillating nature. Further I realized that the energy was not coming out of the earth, but instead was coming to the earth from some outside source. These electrical oscillations in the form of waves were not simple oscillations, but were surgings --- like the waves of the sea --- coming to the earth continually, more in the daytime than at night, but always coming in vibrations from the reservoir of colossal energy out there in space. By this time I was able to obtain enough power to light the old 16-candlepower carbon lamp for about one half capacity, and I did not seem to make any further improvement until the spring of 1925." " Man-made radio waves (if Tesla wasn't around) would be hard put to exceed 50 millivolts per meter (2.2E-14 Joule per cubic meter) or 6.6E-6 watts per square meter at any given frequency most of which were from radio telegraphy transmitters that predated amplitude modulated (cat whisker detector-rectifier) voice broadcasting. Some "non-radio" possibilities: 1, Zero point energy (ZPE) extraction-resonance effects in the Coherer? 2, Thermoelectric (Seebeck-Peltier) thermal effects between the Aerial and the cooler-warmer earth Ground? 3, Surface Heterodyne (beat frequency) action between visible to far infrared photons striking the Aerial? 4, Radio Frequency energy coming out of the earth and radiating off the Aerial? 5, A reverse ground wave emergency network (GWEN) transmitter? < grin > Fred

