poor secret, not getting much enthusiasm are you?
i think for an oil power plant it should have the tower bit like a generals oil derrick, with some smoke stacks, and a glowing core or something
but look at pictures on the net to see what most oil power plants look like, then make a cooler version of it for your team
and whay not have it like generals, so instead of countries, have them all be their own, so have America, Europe, China, Russia, maybe others like Africa, Middle East, Australia, Canada, etc
but start off small, and work your way up, so start with the countries already in YR, which would be Russia, and America/Europe, whatever you decide allies will be
and you can have it that some teams have some of the same stuff, so that it isn't to much work, like Europe, America, Canada and Australia all having allied power plants, while China and Russia both have nuclear and tesla
but if you don't want to do that i can understand, I'm just throwing out ideas here, feel free to take them or leave them....