Combining intermittent renewable generation with energy storage in the electricity grid has become a preferred route to maintaining stability and reliability while decarbonizing. The effects of combining three uncorrelated intermittent resources with energy storage are not well understood. This study reports on a data-driven model and control strategy that optimizes relative installed capacities of wind, solar, and in-stream tidal generation with energy storage for smoothing and shaping to follow electrical load perturbations. The model is applied to a case study in Nova Scotia, Canada which has strong wind and tidal resources, and moderate solar resources. For load-perturbation control on hour shaping timescales the total system capital costs are approximately 20% greater than the costs of the renewable generation without energy storage and output shaping. Shaping timescales of days and weeks favour greater installed wind, solar, and tidal generating capacity and the use of curtailment for economic optimization, with less installed energy storage capacity. Hour-timescale shaping uses the energy storage to mitigate power variability in intermittent generation, which benefits short-term electricity generation dispatch and reliability. Day-timescales shaping uses the energy storage to supply the load's variable energy needs using for day-ahead or future electricity generation scheduling.