To obtain nuclear fusion you need to have frozen hydrogen pellets, hit them with a laser powerful enough to make the hydrogen nuclei combine, and release neutrons into the vicinity. The big problem is the laser.
The National Ignition Facility (NIF) at the Lawrence Livermore National lab already has lasers powerful enough to do that, but researchers are already aiming towards petawatt (a thousand trillion watts – 1015) and exawatt (1018 watts) powers.
Such a researcher is Todd Ditmire, from the University of Texas, who has invented a laser device that can produce petawatt power through a process of chirping, that takes a short light pulse (150 femtoseconds) and stretches it out in time, amplifies it to higher energy and then recompresses it to about 100 femtoseconds in time, obtaining 190 joules of energy. Though it is not much, it is in a very tiny bundle and that gives it the power.
Ditmire says his near-petawatt laser outruns NIF’s laser, and he even has plans for making it more powerful by using some special laser glass which can amplify the power to 100 kJ, about 500 times more. Building an exawatt laser would take up to 10 years to achieve, with proper governmental and private funding, he says.
Producing nuclear fusion would clear the way towards a much easier production of energy, and would simplify the entrance of electric cars onto the market, making the transition from a coal and petrol powered world to a cleaner, electrified one.