The expected outcome of utility integrated resource planning (IRP) is the optimum combination of power generation resources that will produce the most cost-effective and reliable generation for the rate-payer. That process is relatively simple for a nuclear and fossil fuel-based system. However, the difficult process of integrating renewable generation has made asset optimization and operational flexibility paramount.
Reaching that goal is often further complicated by external influences. For example, states/nations with Renewable Portfolio Standards often require a set quantity renewable generation to be produced each year.
Others have market-driven rules or have enacted legislation that require placing renewable generation first place in the dispatch queue, thereby pushing conventional assets further down the list, often from baseload to cycling operation. The unpredictability of renewable assets that operate only when the wind blows and the sun shines require more frequent cycling, start/stops, and ramping of assets that accelerates equipment wear-and-tear. Planners have a difficult job optimizing grid efficiency with so many moving parts.