Has this been suggested before?
Probably definitely
Then what's this?
I just wanted to put down my own vision of electricity and see what you guys thought
OK, SO
Electricity would be a late game alternative to rotational power, but it would also provide some sweet additional properties which would make it extremely useful for base longevity.
Electricity would require your dwarfs to get Neondynium, a rare earth metal which need to be aquired by sifting gravels for the metal shards. Neondynium shards can then be smelted into Neondynium blocks, AKA, magnets.
Once you have access to magnets, you can manufacture a new device, the electric motor, which requires you to use a magnet, some metal and some non-economic stone or wood. The electric motor takes a rotation input (from, for example, a wind mill) and makes electricity from it. Electricity can be transfered by power poles (provided the power poles have LoS to the target electric consumer/producer). Electric energy can then be used to power some new devices useful for late game longevity:
Lamps
Lamps produce some heat and light, which can be beneficial for avoiding cave adaption, and for cultivating above ground plant underground, in order to diversify your food supply. Lamps also give a happy thought to dwarves.
Searchlight
The searchlight would be a real kicker. The searchlight is a siege weapon which can be orientated at enemies to shine a powerful light towards enemies. Enemies within the light will be temporarily blinded if they have eyes. Creatures within the light will get worse hit roles when attacking creatures outside the light, due to them being unable to see them clearly, while creatures outside the light will get much better hit roles when attacking creatures within the light, due to them being able to see them clearly.
Electric motors
Electric motors can work in reverse, where they will produce rotary power instead of consume it, which can be useful for some applications
Electric furnaces
As an alternative to using magma furnaces, electric furnaces could be used instead, which as per the name, use electricity not magma to operate. They also would not need a dwarf to operate them. This allows players to have wood independent furnaces without relying on the location of magma. They will take a lot of power to operate however.
Automated workbenches
Automated workbenches would not need a craftsdwarf to man them in order to operate. However, automated workbench products will never be masterpeices. They can only produce one product, and will produce it continuously. Any change of the workbench's orders will require a dwarf to come to the work bench to change it's orders manually. Automated workbenches will drop their crafted contents straight into the world, unless the dropping area already has an item there. If a minecart is next to the workbench, it will be loaded into the minecart. Automated workbenches will pick up items needed for production from adjacent tiles.
Electric lever
The electric lever can be turned on or off like a normal lever, but it would not need a dwarf to do it manually. The electric lever will turn on or off automatically at the players discretion, with a random delay of a few seconds.
I'd also like to present a handful of new ways to make rotary power:
Steam Turbine
The steam turbine is placed over an empty space, and will vent any steam from said space into it, and will output water to adjacent tiles. The steam turbine would then output rotational power to connected axles. It would produce a lot of energy, useful for running electrical devices. The steam turbine would basically act as a renewable source of energy underground, using magma to superheat water into steam, then using said steam to make power, then repeat.
Hamster wheel/treadmill
The treadmill would require a dwarf to operate it, and would produce some rotational power. Would work as a simple, but weak, way to make renewable energy
Livestock crank
The crank would require an animal to be asigned to it, or even many, and would have said livestock continuously walk in a circle around the crank in order to power it. Would make a different amount of energy based on the animal operating it.