How to straighten hair, without heat?

Ok, so I`ve done what I asked, and that was have most of the dead ends of my layers off - blended into the length of my hair, and not much off the actual length. And it looks fantastic, not to mention a lot healthier (and less frizzy!).

However, when my stylist straigthend mine (as I have naturally wavey/curly hair) she used a pair of straighteners which had cermaic and not metal (which apparently is slightly better on the hair).

I`m trying to avoid heat styling on my hair, for a while, until my hair becomes really healthier.

Can anyone tell me a good way to straighten hair, without having to result to heat products?

Thanks!