The results of two quantitative scenarios balancing global energy supply with demand for the period 1980–2030 are reviewed briefly. The results suggest that during these 50 years there will be a persistent demand worldwide for liquid fuels, a continuing reliance on ever more expensive and “dirty” fossil fuels, and a limited penetration rate of nuclear generated electricity into the energy market. The paper therefore addresses a possible “second” grid driven by nuclear heat — a grid based not on electricity but on “clean” liquid fuels manufactured from gaseous and solid fossil fuels using nuclear power. Such a second grid would be an important complement to the electricity grid if the world is to progress towards a truly sustainable energy system after 2030.