China has started construction of the world’s biggest hydroelectric dam, a project that’s set to be far larger than the Three Gorges Dam — already the world’s biggest single source of green power — and more expensive than the International Space Station.

The project on a river that runs through Tibet and India downstream could dwarf the Three Gorges Dam when completed.

The investment is set to benefit hydropower plant and grid equipment makers, but some analysts warn that market enthusiasm may wane soon.