Windmills pay. On a breezy Saturday at the end of March, Aeolian Parks scattered across the hill-top ridges and off-shore sandbanks of Spain produced 40.8pc of the country's electricity needs - 9,862 megawatts to be precise.

The much-derided turbines produced enough wattage to power the great cities of Madrid, Barcelona, Seville, Valencia, Toledo, Cordoba, Granada, Santander, Bilbao, and Zaragoza combined. The workday record on a Tuesday, March 5, was 28pc.

Years of nurture by the Spanish government have paid off. Spain is a global superpower in the wind race, with 15,000 MW of capacity. The region of Navarra is 70pc green, shielded against gas-shocks, Russian politics and soaring oil prices.

Today's wind turbines are a far cry from the archaic mini-mills that scar the landscape for little return, and provoke such fury in the English shires. They are vast. Each mast can power a neighbourhood.

Here in the wet misty mountains of Asturias, the German power group E.On is erecting a battery of mills that tower 410ft into the sky. They are higher than the dome of St Paul's Cathedral or the US Congress on Capitol Hill. The rotors alone dwarf the wingspan of an Airbus A380 super jumbo.

"We are beyond the boutique phase," said Frank Mastiaux, the head of E.On's green operations. "When this began in the 1970s it was a niche play, a nice tax break for German dentists and doctors. Now it is turning into an industrial business. Productivity has grown by 150 times in 25 years."

Every mill costs €2.6m (£2m) to buy and erect, yet the Danish manufacturer Vestas is sold out until 2010.

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