As variable renewable wind and solar resources constitute a larger fraction of electricity supply, interest in flexible resources, including demand response, dispatchable generation, transmission interconnection, and storage technologies is growing. This paper evaluates the utility of storage assets given different electricity system configurations, market paradigms, and management schemes using a production cost model. When a large share of non-renewable generation is derived from inflexible sources, storage is imperative even at relatively low renewable penetrations. At high renewable penetrations, storage becomes increasingly important in flexible systems as well. In addition to renewable penetration, storage utilization rates are sensitive to the storage assets' market bidding structure and ownership paradigm, particularly in inflexible electricity systems. Storage assets consume during low-cost hours and generate during high-cost hours, regardless of bidding structure, but the price delta is largest for a centrally controlled storage asset bidding with a price arbitrage motive. Storage utility cannot be deduced from an individual metric, but rather depends on the interaction between bidding mechanism, renewable penetration, and system flexibility. (C) 2018 Elsevier Ltd. All rights reserved.