Mana Pool can be combined with a Minecart to create a Minecart with a Mana Pool, this can be used to transport Mana using a rail system. The Minecart with a Mana Pool can only be used to transfer Mana, you can not throw objects into it to absorb Mana nor can it have Mana sent to it via Mana Spreaders.
To transfer Mana in and out of the Minecart with a Mana Pool you will need to use a Mana Pump. This pump can be used to pump Mana either Into a Minecart with a Mana Pool or out depending on the direction of the pump. The blue end of the Mana Pump will always pull Mana from a source, this can be switched around with the Wand of the Forest. The transfer rate is incredibly fast and happens instantly even when a Minecart is going fast.