I just spent 15 minutes reading part of the the WP article on nuclear power
and it was quite reassuring. Given todays rate of power consumption 150 billion years worth of deuterium. Although given a .1% increase per year that gets eaten up pretty quickly (about 19000 years, but then we would be using 150 million times the energy we do now, which seems unlikely to me, with a carrying capacity of twice todays levels thats still 75,000,000 times as much energy per person, we would incinerate ourselves).
I am no longer worried about running out of fuel.