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Sunday, Sep 20, 2026

Does wind power require backup from fossil fuels?

Sue Bin Park, Skeptical Science
no

Most power grids still combine fossil fuels with renewables, but some already run entirely on renewable energy and offer models others could follow.

The majority of 100% renewable grids rely primarily on hydropower, though certain nations have significantly incorporated wind in their portfolios. Costa Rica and Uruguay have achieved 99-100% renewable power with around 17% and 35% coming from wind, respectively.

Several U.S. municipalities meet electricity demands using diverse portfolios of renewables, including wind. Burlington, Vermont’s 2024 supply was 99.9% renewable, mainly via hydropower, biomass, and wind; Seattle, Washington was 95% renewables powered in 2024. In Kansas and South Dakota, wind alone comprises 60% of generation.

Energy storage is also rapidly expanding as a solution to intermittency, with the U.S. ranking second globally and achieving record growth in 2025. Such combinations of renewable resources, storage, and transmission continue to enable more reliable, renewable grids.

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