The cost of the electricity generated from onshore wind is assessed through a method based on an estimation of the geographical distribution of the technical potential and a cost structure for the estimation of the local unit cost. Generation-cost curves are then employed to portray the evolution of the specific generating cost with the increase of the generated energy, until the limit of the technical potential is reached. The study also relates the energy cost to the land occupancy, the installed power and the capacity factor, and includes an assessment of the interplay between land usage and the cost of wind electricity. An analysis is presented to determine the uncertainty in the costs of the several model parameters. The method is applied to Spain, and allows to establish that, for an electricity-generation level of 300 TW h/y (roughly equal to the overall demand in Spain in 2008), the specific marginal cost is around 8.5 c(sic)/kW h. (C) 2010 Elsevier Ltd. All rights reserved.