There is no way to self donate.

You can store your **own troops** in your clan castle if you have multiple accounts and donate to yourself ***from your other account***(s).

By the way, one good reason to join a clan is that clans with higher experience (Experience level 6 and up) can donate stronger troops - and so can you.  For example if you are in my clan and I give you my L5 giant, it becomes an L6 giant for you. Using this clan perk my TH9 account can give my TH7 account max Giants (L7) and max Dragons (L5).

The [Clan Perks](http://forum.supercell.net/showthread.php/567168-Full-information-on-Clan-Levels-and-Perks) are described in SuperCell's documentation and even in the game.