Tilting with windmills: innovations in wind energy on Windmill Day
Today is Windmill Day, and what better moment to discuss the latest developments in generating wind energy? Using windmills to generate energy has a long history. Traditional windmills that mill grain or pump water have been important until well into the eighteenth century. Nowadays, we mainly use wind turbines to generate electricity. With all the technological developments happening, wind energy has become an economically viable source of power, and the windmills will only get better. So let’s have a look at these sources of clean, renewable energy and some of their latest innovations. Happy Windmill Day!
Vertical-axis wind turbines
You probably know the wind turbines with three propeller-like rotating blades high up on poles. These common types of wind turbines are called horizontal-axis wind turbines (HAWTs). However, these HAWTs take up a lot of space, as they need to be placed far apart not to steal each other’s wind. Researchers at Stanford University have developed a model for the arrangement of vertical-axis wind turbines (VAWTs), which take up much less space.
VAWTs are not a new concept. They generally have a cylindrical shape with the blades aligned parallel to, and rotating around, a pole on which the rotor is mounted. They tend to be much smaller than HAWTs, about 10 times shorter in height and output only 0.1 per cent as much power.
However, while a single VAWT is not nearly as energy-producing as an individual HAWT, if arranged closely together, an array of VAWTs can potentially generate up to 10 times more power per unit of land area than an array of widely-spaced HAWTs, according to the researchers.
Because of their smaller size, VAWTs could be used in cities and on islands, where it is harder or impossible to place a HAWT. VAWTs are also potentially less environmentally impactful than HAWTs.
The researchers are currently working on designing appropriate numerical and experimental studies, so no doubt we will hear more from this in the future.
Flying wind turbines
Is it a bird? Is it a plane? Actually, it is. The Dutch company Ampyx Power has developed a flying wind turbine, shaped like a glider.
A HAWT has to be high up, because it needs room, but also because the higher it stands, the more wind it catches. Most of the material in a common wind turbine is used to construct the pole, while most energy is generated by the tips of the blades. The idea of the glider wind turbine is that it takes out the pole and the founding, while still generating energy. According to the company, it is a cheap, sustainable, and efficient alternative to common wind turbines.
The idea comes from Dutch astronaut Wubbo Ockels, who came up with a construction of kites that at a certain angle exert tractive power on a rope. Because a glider is more aerodynamically efficient, the kite was replaced by one.
The glider is attached to the ground with a rope, which allows the device to fly without a motor as the tractive power of the cable and gravity cancel each other out. The rope is the key in the process. Attached to an inductor, the rope is pulled out of its steel box as the glider flies in a cross wind figure-8 pattern. If the rope has reached it maximum length, the glider dives down and the rope is pulled back into the box. Through the movement of the rope, the generator connected to the inductor generates energy.
In 2018, the company hopes to bring its model to the market: a gilder with a span of 30 metres that generates as much power as a HAWT.
Ampyx Power has launched a crowd funding campaign to finance the wind turbine.
Handheld wind turbine
While the above projects are great to generate large amounts of power, they won’t do you any good if you find yourself in the middle of nowhere with an empty phone battery. But fear not, because even there wind power has your back.
The Waterlily turbine by the Canadian start-up Seaformatics can be powered by wind and water, generating energy to charge any USB-compatible device. The turbine weighs 800 grams (1.8 pounds) and fits into a backpack.
A chart on the website states that with a wind speed of 36 kilometres per hour (22 miles per hour), your phone will be charged in about 2.5 hours.
Waterlily is currently available for preorder.
Photos: Ampyx Power / Waterlilyturbine.com