At the Wild Horse Wind Farm in eastern Washington state, dozens of giant wind turbines dominate the landscape near busy Interstate 90.
The 10,000-acre wind farm is one of three large wind facilities owned by Puget Sound Energy, which bills itself as the nation’s second largest utility generator of wind power. Combined, PSE’s three facilities can produce enough electricity to power about 230,000 homes.
Like any commercial structure, these and other wind turbines across the country are regularly checked for potential damage and repaired. Although inspections of the 221-foot-tall structures are usually conducted manually by inspectors dangling from ropes, there is increasing interest in a new method: drones.
Danny Ellis is CEO of SkySpecs, an Ann Arbor, Michigan-based company on the forefront of integrating drone use into commercial inspections. Ellis, who founded the company in 2012 with a team of fellow aerospace engineers from the University of Michigan, hopes to contract with wind farms like Wild Horse when the Federal Aviation Administration allows commercial drones to fly. The company has developed a working relationship with UpWind Solutions, one of the largest third-party inspectors of wind turbines in the U.S.
Ellis and others visited a Texas-based Upwind facility in January to do flight demos with their quadcopter drones and were also invited to witness a turbine inspection at a wind farm in Michigan. There, the group stood at the base of a turbine, watching workers stop the rotating blades, climb up the tower and then rappel down to inspect one.
Inspecting just one blade, Ellis said, took more than an hour, and getting a look at it required inspectors to work with the wind to stop the blade in the right position; they missed three times. An inspector told Ellis he usually spends more time untangling his ropes than he does on the actual maintenance inspection.
Using a drone equipped with cameras and scanners to visually inspect each turbine and blade, Ellis contends, would not only save time; it would also be safer.
“Not having a guy hanging from a rope from a large structure—it could be a bridge, it could be a building, almost anything that is inspected regularly—if you can get your eyes on it without putting a guy up there, you’re going to increase the safety significantly. It’s hard to put a price on that,” he said.
At Wild Horse Wind Farm, plant manager Dan Rottler said the primary cause of turbine damage is from lightning strikes. Impacts from ice or bird strikes can also cause problems.
Initial inspections are conducted from the ground using a high-resolution camera and a zoom lens of either 300 or 500 millimeters. If moving, turbine blades are brought to a halt so that pictures can be taken and analyzed.
If a turbine is thought to be damaged, a closer look is taken using rope access. That involves an inspector touching and tapping parts of the blade or turbine to physically feel for damage. Drones can’t do that. But it’s a trade-off between safety, cost and inspection quality, Rottler said.
In most cases, inspections are contract-based through a company like UpWind. Rottler said costs range between $250 and $1,000 per turbine, depending upon a company’s quote and the nature of the inspection. Ground inspections are fine in most cases, he said; he even conducts occasional spot checks with his own camera and a 500 mm lens.
Wild Horse’s 149 turbines have all been inspected in the past two years, and minor damage was found on only 12 of them. By the end of the year, Rottler said, half will be repaired.
One of the biggest problems with using drones for any inspection is not having them crash. Ellis said he’s heard of failed inspection attempts in Mexico and Texas, where wind gusts sent drones into the sides of turbines, or untrained inspectors lost control of them.
The “holy grail” of the industry, he said, is avoiding object collision, and that’s why SkySpecs has focused its efforts on developing an Immediate Obstacle Detection and Avoidance System. Though Ellis said the project is still in the patenting phase, the idea is to use a “suite of sensors and software” to allow a drone to detect and avoid obstacles including — moving ones — in all directions, even if a pilot on the ground isn’t capable of avoiding them on his own.
Ellis said doing so would allow practically anyone — including an inspector — to fly a drone with minimal training. “We learned that most of these guys, they don’t care about flying,” he said. “A lot of hobbyists … have a lot of fun doing it. The inspectors? They just want the data.”
SkySpecs has done a number of indoor tests with its obstacle avoidance technology. It even invited three children to its warehouse, asking them to try crashing a drone into a series of poles. All three failed.
Ellis said the technology can be used for many applications unrelated to commercial inspections, including aerial photography. It could help prevent accidents like one that happened in Australia in April, when a drone used to take video at a triathlon struck a participant in the head,causing her minor head injuries.
SkySpecs has a six-month, $150,000 Small Business and Innovative Research grant from the National Science Foundation, which will help it continue its work on both collision avoidance and a complete sense-and-avoid system for drones.
Currently, the technology allows SkySpecs’ drones to avoid stationary objects from up to 30 meters away, at test speeds of 20 mph, though Ellis said its design allows for speeds of up to 35 mph.
A business on hold
Greater than any technological hurdle, however, is the fact that commercial outdoor drone use is currently illegal. The FAA recently announced six official drone testing sites — in Texas, Alaska, North Dakota, New York, Nevada and Virginia — but is expected to miss a 2015 deadline to have many other regulations for commercial drone use in place.
Ellis hopes the FAA will open regulations that allow small unmanned aircraft — those weighing 55 pounds or less — to be tested. SkySpecs’ drones weigh only 10 pounds.
Any company hoping to test will need a Certificate of Authorization from the FAA. So far, COAs have been available only for government use or public entities like universities and law enforcement and not commercial groups. Some of SkySpecs’ competitors, Ellis said, are choosing to operate anyway, but some have been hit with cease-and-desist letters from the FAA.
Once a company obtains a COA, Ellis said, it will be able to legally test at the FAA’s sites. SkySpecs is hoping to test in either North Dakota or Texas, Ellis said, and it hopes to start outdoor testing by the end of the summer.
The eventual goal, Ellis said, is to test outdoors with a real wind turbine at a Texas-based UpWind site, but SkySpecs is still trying to figure out the details.
“We’re working to try to be as safe and legal as possible,” he said. “Whatever we need to do to prove to the FAA that we can go out and fly on wind farms, that’s what we’re working to do.”
Rottler said a PSE employee owns a quadcopter and has flown it at the site before, and a private company from Portland, Ore., also once used a drone to gather video at the Wild Horse site.
The company that inspects another of PSE’s wind facilities, Hopkins Ridge, is already in the process of incorporating drone use into its inspections, Rottler said.
“I think it will grow in popularity,” he said of turbine-inspecting drones. “It’s a tool. I’m not going to say it’s always the best way to do it, but there will be times where it’s an efficient way of doing things. It won’t replace some rope access and blade inspections from the ground, but there will be times where the drone inspections would be the best way to do it.”