is it taking so long? it is hard, it is really hard, very complex, but it's worth it and we just have to do it for the future. fusion energy is carbon—free, but it is not going to be ready in time to get us out of the climate crisis. that shouldn't stop this research, say supporters. the enormous promise fusion holds means we have got to keep working on it. justin rowlatt, bbc news, oxfordshire. we can now speak to saskia mordijck, who's an assistant professor in the department of physics at william & mary research university. sazski has been working with labs throughout the world to solve the complicated problem of refueling fusion reactions. in terms of what we have been hearing today, we are talking about assured space of time, a small amount of energy that has