dark energy and mass-energy conservation

[AmongTheRull]

If dark energy is a property of space-time, and more dark energy is created as space-time increases, and the additional dark energy accelerates the expansion of space-time, what is left of the notion of the conservation of energy or of mass-energy?

Does energy conservation become a purely local property? And if so, how much volume can included in the "location"?

[DaleSpam]

Hi AmongTheRull, welcome to PF!

Well, it is a non-trivial question and the answer is fairly involved. Here is the best link I know of at a reasonably non-technical level:
http://math.ucr.edu/home/baez/physics/Relativity/GR/energy_gr.html