The battle to replace fossil fuels with low-carbon power is bumping up against a new practical reality.

As people crowd into cities, the world's need for concentrated power sources is growing just as low-carbon green power is heading in the opposite direction. While the world needs high-density energy — the amount of power used or produced in a given space — low-carbon power sources such as solar, wind and hydro sprawl out over the distant hinterland.

Energy economist Christina Hoicka says the world needs "a new geography of energy" to satisfy soaring power requirements in densely populated urban clusters.

Just as that problem looms, there are growing hints that a long-promised energy solution, nuclear fusion — the low-carbon, high-density, power of the sun — may arrive in time to solve the geographic challenge.

In some ways, the tantalizing prospect of safe and unlimited fusion energy adds to the confusion as the world struggles to move away from high-carbon fossil fuels. Long-term planning would be much easier if we knew how soon the technology would arrive.

Canadian experts say a burst of new technology and new private sector investment mean the commercialization of fusion could be ten or 15 years away. Other estimates have been even more optimistic.

To read more, click here.