Fusion energy is very efficient and clean,but it's very hard to achieve it.That's why I think that instead of wasting energy on starting the fusion reaction we could use nuclear fission to start the fusion reaction. It's a simple concept:just let more neutrons in the fission reaction. This will raise the temperature (hopefully) to the one required to achieve fusion. This is a theoretical,untested concept. I would like to hear what you think about this subject!