I would like to begin by saying I have no formal knowledge of electro-magneto statics. (included a bunch of extra useless theories here, then removed them as they do not pertain to the material :o)
I propose an electrostatic generator consisting of n-stacked conductive and insulated rotating disks propelled by a pressurized insulating fluid (or visa-versa; fluid propelled by disks). Think van de graff meets tesla turbine utilizing the flow electrification phenomena. The fluid will become charged (lacking its electrons) and each alternating disk will build a high electrostatic potential from excess electrons on the outer circumference. Flow electrification is proportional to the contact time and contact speed, as is the stacked disk design of the tesla turbine-- I believe this will lead to exponential efficiencies if the excess power is then fed back into the generator.
As of now I am unsure how the magnetic field of the spinning disks will manifest and it may be some time before I can conduct these experiments myself. I am also curious of what the effects of resonating a current within the fluid would be.
The key points of efficiency will be: minimizing vibrational losses, disk material/spacing, and fluid choice. The most documented fluid for flow electrification are hydrocarbons but the principle applies with something as common as air.
There is much R&D still needed on this but I thought I would attempt to bring it to the attention of someone more familiar with hands on experience rather than book knowledge. I can provide more detailed descriptions as well as some thesis and white papers regarding the principles of the generator if this peaks anyones interest.
Appreciate your time,
~Fictional~