Technology

The technology behind the turbines

 By Peter Ward

Wind is one of the most important components of renewable energy as we attempt to move away from emissions-heavy power resources. But it’s easy to take for granted the technology behind the turbines, and how it’s advancing at a rapid rate…

Wind turbines aren’t really anything new. Ever since windmills were used to pump water and grind grain, humans have been harnessing wind power for energy. These days wind turbines look a little different to the quaint windmills that used to be around. But despite the appearance change, the technology hasn’t changed a great deal, until now.

First turbines

The first turbines that were built specifically to generate electricity were in Scotland, Denmark and the U.S. in the late 19th century. However, these were mainly used to give power to rural areas where regular power systems can’t reach. It’s only in the last 20 years that wind turbines have been used to generate electricity and send it into existing power grids.
The technology of wind turbines operates on fairly simple set of principles. The turbines usually have two or three blades, like propellers on an airplane. When the wind blows, these blades move around a rotor. The rotor is connected to the main shaft, and that spins a generator to create electricity.
Of course, wind turbines are in fact much more complicated than this. The gear box, which connects the low-speed shaft with the high-speed shaft, is where a lot of innovation is happening. This part of the turbine increases the rotational speeds from around 30-60 rotations per minute to about 1,000-1,800 rotations per minute. That sounds like great efficiency but gear boxes are currently costly and heavy, and it’s one of the areas where engineers are trying to improve. Direct-drive generators have been posed as a potential solution to this problem, as they operate at a lower generation speed and remove the need for a gear box completely.

Rotor shaft and brake assembly (Paul Anderson, Wikimedia)

Turbines are always found on tall towers, for the simple reason that more wind is found higher off the ground. The blades are also an area where technology has made significant advances. Wind turbine blades work best when they face the wind. To ensure that they are in the right position most of the time, turbines are equipped with anemometers, devices that sense the direction of the wind and the wind speed, and then tell the turbines how much they must move to be facing the wind and gathering the optimal amount of energy.

Size and capacity

One of the major ways wind turbine technology has improved in recent years has been a simple increase in size and capacity. Before 1999 the average capacity factor, which is used to measure power plant productivity, of wind turbines in the U.S., was around 22 percent. By 2000 it was 30 percent and today it is around 33 percent, according to the Office of Energy Efficiency and Renewable Energy.
The technology improvements associated with wind turbines in the U.S. have also increased in value over time. Wind turbine technology exports grew from $16 million in 2007, to $488 million in 2014, again according to the U.S. government.
Research in 2017 suggested technology in turbines would improve enough to see prices drop significantly up to 2030 and beyond. Researchers from the Lawrence Berkeley National Laboratory conducted a survey of energy experts, asking them to predict the future of wind energy costs.

Functional schematic of the structure of a wind turbine (Jalonsom, Wikimedia)

Maturing tech
The results found that energy experts are boisterous about the future of wind energy, perhaps in part because the technology is not yet mature. When an energy technology is immature, it is prone to enjoying steep drops in prices when it does develop further.
“That was the question we were trying to get at with this expert survey,” LBL Senior Scientist Ryan Wiser was quoted in a Forbes article. “Is this a mature technology where only somewhat modest incremental improvements are plausible? Or instead do there remain significant opportunities for cost reduction?”
“Onshore wind technology is fairly mature,” Wiser concluded, but the survey suggests that “further advancements are on the horizon—and not only in reduced up-front costs. Experts anticipate a wide range of advancements that will increase project performance, extend project design lives, and lower operational expenses. Offshore wind has even greater opportunities for cost reduction, though there are larger uncertainties in the degree of that reduction.”

READ MORE: Neutralising wind turbine noise by Benjamin Plackett

about the author
Peter Ward
Business and technology reporter based in New York. MA in Business Journalism at Columbia University Journalism School 2013. Five years experience reporting in the U.S., the U.K., and the Middle East.