In article ,
Christopher Tidy wrote:

About 20 years ago I worked with a physicist, he thought this might
work. So as his tech I proceeded to build a Van de Graaff with oil as
the medium to move the charge, We used a sump pump to pump the oil.
It didn't work on the first try, and there was no attempt to alter
it to make it work. I don't know if he figured out a flaw in the idea,
or, if we decided we needed to go back to money making work. I was
disappointed, it was just dropped with no further thought.
We did use a high voltage power supply as you suggest above.
Mikek

Hi Mike,

That's interesting to hear that someone has already tried it. I'd be keen to
hear a little more about the details of the design and materials, if you can
recall them. There might be a fundamental problem, but it might just be a
minor design issue which could be resolved.

My suspicion is that oil isn't a good enough insulator, especially in
practice with a pinch of dirt and water in it.

Joe Gwinn