WAIMEA — Two miles east of West Hawaii Concrete, Kate Stirr walked out in the deep brush Tuesday afternoon to get a better look at the hover kite. The tail was just above the ground as its rotors were idling, constrained by cables and connected by a tether.
Suddenly the ground crew powered up the rotors, which began spinning quickly.
It was the first day of constrained hover testing by Makani — a project of X, a division of Alphabet, Inc. — after almost four years of preparation on the company’s nearly 650-acre site 5 miles outside Waimea town center.
Last week, Makani staff started with the hover kite on the ground, turning the motors on and off. They then made sure all the communication systems were working and placed it on the perch. The constrained ground testing for the hover kite will continue for several more weeks before crosswind testing will begin for the ultimate prototype: an 85-foot M600 power-generating kite.
“The crosswind kite — our power-generating kite — will fly loops in the sky and generate power,” Stirr, Makani’s flight testing program manager, said Tuesday with excitement in her voice.
If all goes as planned, later this year the M600 will be their first power-generating kite to fly on Hawaii Island as part of their research project.
In between testing, staff review hover kite video and audio data, as well as sensor data, for ideas to make any possible tweaks or modifications. The prototype has already been tested in California for hundreds of hours.
Makani’s overall mission is to create kites that efficiently harness energy from the wind. They’ve been designing, building and testing energy kites for more than a decade.
The Alameda, California-based research and development company signed a grant of easement with Parker Ranch in 2014. Since then they have built a tent and kite site on 3.52 of the 650 acres.
Between June 2014 and May 2016, Makani staff assessed the winds there using a wind monitoring system called a lidar — meaning light radar.
“It helped us understand the wind at our specific location to determine how to best work with varying wind conditions,” Neal “Rudy” Rickner said, Makani’s head of operations.
In June, the project progressed when parts to build a new 15-foot base station and an 85-foot M600 energy kite arrived from Alameda headquarters. The kite and ground station together are approximately 10 percent of the mass of a conventional wind turbine of a similar power rating.
“At the test site, the tether will ultimately extend approximately 1,400 feet — allowing the kite to make a full circle every 10 to 25 seconds,” Stirr said. “The operational area of the kite in flight was defined by the kite’s tether length.”
The kite’s wing will be tethered to an unmanned base station to harness energy from the wind. Positioned downwind, it will climb to an altitude dictated by a flight controller, with the motor initially consuming a small amount of energy to produce thrust in the rotors, Stirr explained.
The kite will then transition into crosswind, flying autonomously in loops to generate maximum power, also decided by the flight controller. As the kite loops, the wind will spin the rotors, driving onboard generators to produce electricity that will transfer down the tether and into the grid.
When the kite isn’t flying, it’s kept near the ground station. Its lightweight design — made mostly from carbon fiber and a bit of aluminum and titanium — makes the energy kite easy to transport and install. Two containers house power inverters for the research project.
“Working at Makani, we’re trying to do something that nobody else has done,” Jimmy Haley, Makani’s strategy and operations manager, said on site Tuesday. “I love blazing new territory.”
Makani is also working on a lighting and marking system.
“One of our objectives is to have the FAA come out and do flights so they can observe and validate that the marking scheme — lights on the wing tips that produce a flashing pattern — so it can be visible enough but not distracting for pilots,” Stirr said. “We’ve been working with them since 2010.”
In addition, Makani staff have undergone training with Hawaii Wildlife Center on how to respond if birds or other animals are injured in their area prior to operating the kite.
Where it all began
Don Montague, one of Makani’s founders, moved to Maui in 1982 to “chase the wind,” as he described it. He fell in love with the island and raised two kids there.
“Montague was an early pioneer of kiteboarding, developing software that enabled rapid kite design. He met Saul Griffith through this community of early kite surfers, and Corwin Hardham was also active in the development of wind sports since he grew up racing on windsurfing gear he designed himself,” Stirr said.
In 2006, the three founders spent time kiting together off of Maui, which helped distill their conviction that kites could be used to generate power. This led them to test soft kites on Maui in 2008 and return in 2013 to explore potential locations for a future test site.
Moving forward
Makani aims to be part of a long-term solution to eliminate the need for carbon in energy production.
“Right now we’re set up on our own little micro-grid just for testing. That system allows us to test without being connected to the grid, but a goal of ours is to be grid-connected so we can prove out the validity of our system being tied to a commercial-scale grid,” Stirr said.
She said this will most likely happen in the next month. To better understand how it works, Rickner explained, “Power generated onboard the kite comes down the tether in DC — direct current. Once it gets to those inverter boxes it’s switched over to AC — alternating current — and eventually will feed into the grid.”
The kite’s rated power-generating capacity is 600 kW — enough to power 300 homes instantly.
Sometime later this year, Makani staff hope to share their knowledge with children. So far, they’ve had initial meetings with several schools in the region. In addition, they’ve met with community groups regularly to share updates.
“We’ve had a ton of support with our test site set up from local partners, and we look forward to engaging with more folks from the community as we continue flight testing,” Stirr said.
Info: Email the team at makani@x.team