Is Tai-Chi really self defense?

I'm looking for new styles to incorporate into my martial arts training. A lot of kung fu schools in my area all list forms of Tai-Chi as internal energy and styles. I always thought it was meditation and relaxation. Yet I see "some" videos online that talk about combat movements. how do I learn which styles are more along fighting terms than the latter? I'm not looking to fight or anything, but I'd like to think that I'm at least some defensive/offensive measurements.