Technology

Energy kites

 By Eniday Staff

In the summer of 2019, an Alphabet-owned company called Makani Technologies demonstrated a key aspect of its unique wind energy technology for the first time.
A white glider with a 26-meter wingspan and eight rotors spinning like propellers hung vertically from a tall, bright yellow buoy floating in the North Atlantic Ocean. As engineers in a nearby ship watched, the glider slowly ascended, playing out cable connecting it to the buoy as it went…

After reaching an altitude of about 300 meters, the glider—actually more of a kite given its tether—began to execute lazy circles. As it went, crosswinds spun the rotors, generating 600 watts of electricity—about the amount used by 300 modern homes—and sent it down the tether to the buoy.
The test followed more than 10 years of effort, during which engineers at the California-based company built successively larger “energy kites”, generating increasing amounts of electricity. The company had finally enjoyed success testing a commercial scale kite in the conditions under which production models will operate.
“This test demonstrated successful flight of Makani’s energy kite from a floating platform anchored in deep water”, explained Neal Rickner, Makani’s chief operating officer, in an email. “This is important because it moved our system a big step closer to a commercial product that could bring renewable wind power to billions of people around the globe”.
Is this the beginning of a revolution in wind power?

The first flight of the Makani's kite off the North Sea

Unexploited wind energy

Most of the world’s wind energy resources are over ocean too deep for conventional wind turbines to anchor. That’s the opportunity sought by the engineers at Makani Power with their turbines on wings.
“The low mass of Makani’s energy kite means it can be easily installed offshore on a floating platform, accessing wind resources that are otherwise stranded”, explained Rickner.
Each kite performs a complex dance with its buoy and the wind to safely and reliably generate electricity. The buoy rises and falls with ocean swells. It rotates with the wind so the kit can reach the best orientation to generate electricity. And the kite flies itself with the help of onboard flight control software, control surfaces and sensors that include a GPS navigation unit.
Rickner said the team was happy with the results of the testing. “Our two flights proved that our models for kite and buoy interaction were accurate”, he said. “It also demonstrated robust crosswind flight”.
Makani is the realization of a dream 13 years in the making.

Kitesurfing for power

“Makati was originally founded by a group of kiteboarders who understood how much power could be harvested by kites—they felt it—and tried to find a way to harvest that power to do good”, Fort Felker, Makani’s CEO, says in a recent video about the project released by ARPA-E, one of the company’s early funders.
Makani, whose name is derived from the Hawaiian word for wind, was conceived by champion windsurfer Don Montague, who also helped start the sport of kiteboarding. In kiteboarding, a kite, rather than a sail, pulls a board and its rider over the waves.
Montague brought in engineers and fellow kiteboarders Saul Griffith and Corwin Hardham to start Makani in 2006 with funding from Google and ARPA-E, an agency of the U.S. Department of Energy. The company became an independently operating subsidiary of Alphabet, Google‘s parent company, in early 2019.
A key innovation behind Makani’s kites is their lightweight construction—a mere 90% of the weight of conventional offshore turbines generating the same power.
“Makani’s kite operates on the same aerodynamic principles as a conventional wind turbine but is able to replace tons of steel with lightweight electronics and smart software”, says Rickner. The lower weight makes the kites cheaper to manufacture and easier to transport and lets them anchor far out to sea, well beyond the range of conventional turbines.
The kites can also anchor to fixed platforms on land, giving them even more places they can be used.

kites-using-wind-energy
Makani's kite will cost significantly less than existing technologies, making it a very competitive alternative within the wind power (makanipower.com)

Next steps

After the successful test flights off the Norwegian coast, the Makani team went home to California to analyze the data they had collected to help them further improve the system. Then they headed to the company’s test site in Hawaii for more testing. The goal, says Rickner: longer duration flights with less hands-on interaction.
Working with Royal Dutch Shell, Makani planned to return to Norway the following summer for more testing, this time in a longer-duration pilot project to prove out the system’s market viability.
“Taking on the climate crisis with kites is a bold idea”, Rickner says, “but we believe we’ve solved the technical miracles necessary to make energy kites a reality. What remains is to roll up our sleeves and work together with industry and community partners to get our kites out into the world where they can be part of the solution”.

READ MORE: The World’s first floating wind farm by Amanda Saint

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Eniday Staff