  This is a design study into the capabilities of the Australian Square
Kilometre Array Pathfinder in performing a full-sky low redshift neutral
hydrogen survey, termed WALLABY, and the potential cosmological constraints one
can attain from measurement of the galaxy power spectrum. We find that the full
sky survey will likely attain 0.6 million redshifts which, when combined with
expected Planck CMB data, will constrain the Dark Energy equation of state to
20%, representing a coming of age for radio observations in creating
cosmological constraints.
