As countries around the world race to decarbonize their power systems in an effort to mitigate climate change, the body of research analyzing paths to zero emissions electricity grids has substantially grown. Although many commercially available technologies are typically included in these studies, only a few of them have considered offshore wind and wave energy as contenders in future zero emissions grids. We model, for the first time, offshore wind and wave energy as independent technologies with the possibility of collocation in a power system capacity expansion model of the Western Interconnection with zero emissions by 2050 and a high geographical and temporal resolution. Our key contributions are to identify cost targets for offshore wind and wave energy to become cost effective, to observe a 17% of reduction in total installed capacity by 2050 when offshore wind and wave energy are fully deployed, and to show how total curtailment decreases as offshore wind increases its deployment.