Earth has a number of very high power semi directional transmitters operating. By this I mean the assorted 50 hertz and 60 hertz AC power systems. These are coherent in areas because there are separated adjacent systems that act to isolate them. These are long in wavelength at about 3000 miles and will penetrate the ionosphere via capacitance. If we had a long wave receiver in orbit past the earth, it could listen on an incrementally varying wavelength from 25 hertz to ~~300 hertz for any similarly radiating civilisation. This radiation would be reduced by square law spreading, but a phase locked loop receiver that gradually scanned this frequency space should be able to detect such radiation out to 100-500 light years. The PLL listens for a long integrating interval, and then steps to the next frequency. The antenna can be tuned to cover the 25 Hz to 300 Hz spectrum by use of mechanically adjustable loading coils. Such an antenna could be a simple long wire that is gravitationally solar stabilised so it would sweep annually. A similar one could be earth centered to enable sweeps at it's far from earth orbit much faster than annually? This is a project that Elon Musk could easily perform and it might get us a Nobel? if we found anything? It would sit there and sieve data in hope of success?