What is talked about in the beginning of the passage?

Although European countries have been spending more money on wind generating electrical facilities than we have been here in the U.S., there are combinations of factors which make the outlook quite promising for domestic wind farms. Many of the projects which have been attempted in Europe have not been commercially successful because they have been centered around massive projects—some as tall as twenty-story buildings with propellers a hundred meters across—that they have developed structural and other technical problems. Here in America, by contrast, we typically rely on smaller propeller units distributed across large land area, such as the five thousand acre installation near Palm Springs. Although these small installations are technically less efficient, in practical terms they have turned out to be much more reliable. The other factor which has helped to make the domestic wind power projects more successful has been the introduction of computers to regulate the interactions between the propellers and the electrical generators.Because of the reduced cost of computerized controllers and the greater efficiency they bring, the cost of wind generated power has dropped from 30 cents per kilowatt hour to 7-9 cents—less than the cost of conventional coal or oil burning power plants.