HVDC cables are typically built in pairs - the positive one and the negative one.
They are normally operated together, with equal current going through both.
But it's also possible to operate just one, with the return current going through the earth. Personally, I think that's a very bad plan, because putting 2000 Amps through the earth will probably have lots of unknown ecosystem effects. Things like bacteria that navigate or hunt via electric fields will be killed over an area many thousands of kilometers. Also, the chemistry that happens in rocks and underground rivers is altered by electrical current flowing.
But maybe that ship has already sailed - nearly every country has some project that puts big electrical currents through the earth, so maybe we have already destroyed everything that cares, and therefore doing more of the same wouldn't be so bad.
HVDC cables are typically built in pairs - the positive one and the negative one.
They are normally operated together, with equal current going through both.
But it's also possible to operate just one, with the return current going through the earth. Personally, I think that's a very bad plan, because putting 2000 Amps through the earth will probably have lots of unknown ecosystem effects. Things like bacteria that navigate or hunt via electric fields will be killed over an area many thousands of kilometers. Also, the chemistry that happens in rocks and underground rivers is altered by electrical current flowing.
But maybe that ship has already sailed - nearly every country has some project that puts big electrical currents through the earth, so maybe we have already destroyed everything that cares, and therefore doing more of the same wouldn't be so bad.