Next year, developers hope to start building offshore wind turbines in the U.S., which is already a leader in on-land wind generation. As turbines spin off the coast in a dozen other countries, particularly the UK, Denmark, the Netherlands and Germany, global offshore wind capacity has expanded nearly six-fold since 2006. Most of these installations are in shallow water though winds are stronger out further. If the U.S. is to have offshore turbines, many residents want them distant enough so they can’t be seen or heard.