How do current transformers work?
Current transformers consist of:


A primary, which has few if any turns. Often, it's just a straight piece of wire. The primary carries a large alternating current.
A ring of high permeability material around the primary, or with the primary turns on it.  This is the core.
A secondary wound onto the core. Usually wound like a toroidal transformer.
The secondary is connected to something with a low impedance, often an ammeter.


The current in the secondary is much smaller, and almost proportional to, the current in the primary.  Thus it is a good way of measuring a large current in the primary.  Additional benefits are the minimal electrical disturbance to the primary, and the fact they can be made of two semicircular cores and clipped onto a wire.

All in all, they are a good tool for measuring large currents, but I don't see any way of using them to generate large currents. If you want a >100A current, but at low-ish voltage, why not use one or more car batteries? One decent car battery should provide 100A at 11.5V or so, and you can add more in series for higher voltages, or parallel for longer run times.