Posted on 22 September 2026 by Sue Bin Park

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Does wind power require backup from fossil fuels?

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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Sources

Climate Council 11 countries leading the charge on renewable energy

Ministry of Foreign Affairs of Denmark Denmark #1 in share of renewables in net electricity generation for 2024 in the EU

IEA Lithuania

City of Burlington Electric Department Our Energy Portfolio

City of Seattle Power Supply and Delivery

Analysis of EIA data Share of electricity gen by wind, by state, 2025

U.S. Energy Information Administration Electricity Data Browser

U.S. Grid Energy Storage Factsheet University of Michigan

Princeton University Net-Zero America

NREL NREL Report Redefines Wind as a Grid Stabilizer, Not a Liability 

Columbia Law School Sabin Center for Climate Change Law Rebutting 33 False Claims About Solar, Wind, and Electric Vehicles

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