How to replicate lightning?/What is lightning?

Or maybe it has to do with the low pressure and cold air beneath the clouds. So maybe if you fill the top half of a cup with steam and the bottom with cold water, then a powerful magnet below the whole thing, charge would flow from the steam, through the cold water and into the magnet where it could be stored.

you need to be creating and using electricity to keep the steam as steam
so you need to make more electricity than your using to create the environment.
the steam would likely need to be super heated to maintain its separation from the other liquid.

steam boilers are nothing new
sticking a piece of copper through it to conduct and receive electricity would seem pointless to me unless you had a megga structure boiler the size of a big hydroelectric damn
which would use more electricity than it would produce probably.

using solar energey is vastly superior