Looking for an alternative to Ginseng?

I'm a full time teacher and work for about 9/10 hours a day. I need lots of energy during term time, and have been taking Ginseng for two months which has done the job nicely. I'm conscious that I shouldn't be taking Ginseng as a permanent supplement. Could anyone suggest any other supplements for boosting energy levels? I take a multi-vitamin and echinecha daily as well.