Maybe they are not yet big enough! Check out the following excerpt from this report by David Roberts (via Vox; link in original): “It is impressive as an engineering feat, but the significance of growing turbine size goes well beyond that. Bigger turbines harvest more energy, more steadily; the bigger they get, the less variable and more reliable they get, and the easier they are to integrate into the grid. Wind is already outcompeting other sources on wholesale energy markets. After a few more generations of growth, it won’t even be a contest anymore”