How does the power output of a traditional windmill compare to a modern wind turbine?

Asked by: Ray Ellis, Durham

One working Dutch windmill (Veldkamps Meul’n in Bellingwolde) supposedly generates 18kW of usable mechanical power. If this was hooked up to an efficient generator, you might get up to 80 per cent of that – 14kW or so – in electricity. This windmill has a sail diameter of 20m, whereas modern wind turbines used for large-scale power generation are generally at least 40m across. These have a power output of about 500kW. If we assume that power generation rises with the square of the diameter, a scaled-down modern turbine would still generate 125kW. Which is nearly nine times more efficient.

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