Way back in the dim recesses of my head I remember a guy who yanked the heater blower from his truck, duct taped it on his Harley and cherry picked his way to a record.
The rule should be re-written to state "mechanically or exhaust gas driven by the engine"
If you still want to cherry pick you can run a tiny smog blower, can't you?
For the serious record attempts, I think all blower power should come from the engine. No stored energy. To make it easier on the inspectors, the electric blower would have to be powered by a power source separate from the engine electical. So on a typical blown car that has a battery to start the engine and an alternator to make power, require another alternator that is clearly not connected to the battery.
We have a constant struggle to stay with our roots and only allow "traditional" engines, yet stay cutting edge and encourage the boundless minds out there that have a better idea to set a record.
Oh, and if you are looking to get a different feel of a long topic, read everything, then read it again skipping JackD's posts. Jack is truly knowledgeable, but your head tends to spin less when you read it the second time.