We assess the implications on long-run average energy production costs and emissions of CO 2 and some criteria pollutants from coupling wind, solar and natural gas generation sources. We utilize five-minute meteorological data from a US location that has been estimated to have both high-quality wind and solar resources, to simulate production of a coupled generation system that produces a constant amount of electric energy. The natural gas turbine is utilized to provide fill-in energy for the

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... upled wind/solar system, and is compared to a base case where the gas turbine produces a constant power output. We assess the impacts on variability of coupled wind and solar over multiple time scales, and compare this variability with regional demand in a nearby load center, and find that coupling wind and solar does decrease variability of output. The cost analysis found that wind energy with gas back-up has a lower levelized cost of energy than using gas energy alone, resulting in production savings. Adding solar energy to the coupled system increases levelized cost of energy production; this cost is not made up by any reductions in emissions costs.