Spain saw wind power become its main source of electricity generation last month, underscoring the country’s progress in becoming one of Europe’s greenest nations.

Power network operator Red Electrica (REE) said Iberian wind farms generated 4,738 GWh of electricity in March to meet 21% of demand, 5% above the year-ago monthly rate, fueled by heavier winds than usual.

“As parks spun their blades, the country saved €250m by lowering its oil-import bill. It also saved 1.7m tonnes of CO2,” according to Spain’s Wind Industry Association AEE.

Altogether, clean energy met 42.2% of electricity demand though this was down from 48.5 percent against March 2010.

Hydropower accounted for 17.3%, solar energy for 2.6%, nuclear for 19% and coal-powered for 12.9%.

“This historic milestone reached by wind energy shows that this energy source, as well as being indigenous, clean and increasingly competitive, is also capable of supplying power to three million Spanish households,” AEE president Jose Donoso said in a statement.

The production was enough to cover Portugal’s monthly electricity consumption, AEE noted.

Spain is the world’s fourth-largest wind-power market.