REFLEX: Renewable Energy Flexibility Model

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REFLEX is a production simulation model designed to identify system integration and operational flexibility needs under high renewables penetration. REFLEX, which E3 developed in 2011, captures real-world constraints on operational flexibility to evaluate investments in flexible resources such as combustion turbines, reciprocating engines, energy storage, and demand response. REFLEX can also assess the impact of changes in operating procedures such as improved forecasting, changes in natural gas scheduling, participation in regional markets, and renewable curtailment. REFLEX can be tailored to any production simulation application.

  • In a groundbreaking study conducted on behalf of California’s five largest utilities, we used REFLEX to evaluate the operational challenges, costs, and potential solutions for achieving a 50 percent renewable portfolio standard (RPS) in California by 2030. The study detailed the steps necessary to achieve integration of high levels of renewable energy while maintaining the reliable operation of the California power system.
  • In assessing the need for power system flexibility at high levels of renewable energy for the Western Electric Coordinating Council and the Western Interstate Energy Board, REFLEX demonstrated that it is technically feasible to operate the western grid with renewables providing 40 percent of energy needs, and that enhanced coordination among neighboring utilities would significantly reduce the cost and operational challenges.
  • We used REFLEX to evaluate the cost and benefits of large-scale, long-duration energy storage projects in California and the Western Interconnection. Long-duration storage has the potential to absorb significant quantities of excess energy supply during peak solar production, and it would alleviate renewable integration challenges and reduce the cost of achieving California’s 50 percent RPS targets.


In a model of operational needs for meeting California’s 50 percent renewables portfolio standard, REFLEX showed that overgeneration is a significant challenge at 50 percent penetration (left). REFLEX also showed that storage would greatly ease the problem (right).

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