Wow, there are so many questions here that affect the scenario.

What size (quantity) of wash are you running in the keg? and what is the ABV?

Are you running a pot still, plate still, reflux, etc? Makes a difference on how many times you are boiling off and condensing the liquids.

Would have to make some wild assumptions on burner efficiencies and assume that the electric is 100%.

Also, what is your cost per KWH, including taxes?

Generally speaking, the cost of electricity is fairly close to the cost of propane. Both of these are about 3X the cost of natural gas. However, I have been considering converting my boiler to electric because of the convenience and ease of control.

Thanks for the responses.
I'm going to attempt to factor in the other components. But I do believe that they both are pretty close to being the same cost.
Lets use this scenario 12 gallon wash with an ABV of 14% using a 15.5 keg on propane, distilling in pot still mode with a Brewhaus PSII column.
Oh and the KWH in my area is 8.697 although that changes monthly.
Its getting pretty cold outside in the garage and I've thought about switching my keg to electric and moving the operation indoors. If i do this i'll get a second keg to convert.
But before I go to the trouble I wanted to compare time/expenses.