Assuming that you are talking about an AC supply there is absolutely no way you can get anything like a good estimate of KWH from just a current transducer. You would need to use an estimated voltage, which might not be too difficult, and an estimated power factor, which will probably be impossible to guess at reliably. You can, however, buy multi function energy meters at quite reasonable prices these days and avoid all of the guesswork. I would go for one with a Modbus port but this would cost me around £250.00 (Merlin Gerin PM710) but if you only need KWH's then a cheaper model with a simple pulse output would suffice. You would also get a display of all of the normal electrical parameters plus information on maximum demands, THD and other information which might be useful.
Andybr