In 2015, Denmark generated 42% of its electricity with wind turbines, breaking its own record set the year before. While the country isn’t the biggest producer of wind power in the world, it does enjoy the largest proportion of turbine-generated power, which is arguably a more important measure.
Denmark is serious about wind power, aiming to produce 50% of its electricity by 2020, which seems a pretty easy target given these figures. Production in the past five years has almost doubled, from 22% in 2010 to 42.1% in 2015, according to figures from Denmark’s Energinet. Due to import and export of electricity (see below), the figure for actual power-in-the-wall-socket electricity is different: 39% of power used in Danish homes and businesses came from wind turbines.
Once a country gets to these levels of wind power, some surprising things happen. For instance, on September 2 last year, the Denmark ran for a whole day without any of its regular power stations being in operation—the country’s electricity came from wind, solar, cogeneration, and imported electricity.
On less windy days, Denmark imports energy from neighboring countries—hydroelectric from Norway, solar from Germany, and from Swedish power-stations. But much of the time it produces so much wind energy that it sells power back to those countries. Last year, western Denmark (where the majority of wind power is farmed) produced more power than it could consume for 1,460 hours, or 60 days, or 16% of the time. This trading of power back and forth between countries is a big part of Northern Europe’s push to green power. Sweden even imports trash to burn and generate power.
Denmark’s excess of green power has one little downside: negative prices. One percent of the time, the combined output of wind, solar and old-fashioned power stations is just too much, and the producers have to pay to get rid of it. To combat this, producers switch off their turbines some of the time, but it’s a small disincentive, if any.
"I usually say that just because a farmer has problems selling his milk three days a year," says Energinet’s energy strategy adviser Carsten Vittrup, "it does not mean that he will close down his farm, or that it is bad business the other 362 days of the year."