Four or five years ago, when superhydrophobic coatings were first creating excitement among electric cooperatives and other power utilities, People's Electric Cooperative in Ada, Oklahoma, was one of the first to take a closer look.
The co-op experimented with an early superhydrophobic conductor coating brought to them by a vendor, says John Hudson, the co-op's senior vice president for operations and engineering.
"There were some folks that were coming to us looking for ways to apply (their product) to power lines," Hudson recalls. "We worked with them on several different variations to see if there was a way to actually economically apply it to the electrical lines."
Superhydrophobic coatings, developed from advances in nanotechnology, aggressively repel moisture, thus shedding ice and contaminants. The nascent technology became of interest to co-ops when researchers at the U.S. Department of Energy's Oak Ridge National Laboratory demonstrated a newly conceived example.
If effective, durable, and economical, these compounds promise to significantly reduce maintenance and repair costs for electric utilities. A 2012 federal study estimated that outages caused by weather cost the United States up to $33 billion annually. More recent research has found that the number of severe weather events has been increasing this decade.
Superhydrophobic coatings could "save cooperatives millions on failures of equipment, not to mention millions from avoidance of damage to equipment as well as reduced expenses on preventative measures," says Tom Lovas, NRECA technical liaison and consultant.
In essence, the coatings work by creating large contact angles between drops of water and the coated surface, lessening the adhesion and causing water to roll off more easily. As the droplets slide off, they can carry other contaminants, such as dirt and salt, with them.
Superhydrophobics had been used in other industries for a while, but they drew serious attention from the power industry about five years ago. The possibility the coatings could "shed freezing rain like a duck's feathers shed water," as an article at the time put it, sparked hope that they could help co-ops with multiple challenges: not only ice damage, but corrosion and current leakage on insulators from ice and water streaking.
But when it comes to applying new products to transmission or distribution systems, co-op veterans know that hope, excitement, and potential all mean nothing without another essential ingredient: rigorous testing.
Mixed Testing Performance
In the case of superhydrophobics, the initial rush of enthusiasm has been followed by years of testing, in particular by the Electric Power Research Institute (EPRI). More tests lie ahead, but results are coming in, and the potential that supporters saw in superhydrophobics has been at least partly validated.
“It’s very exciting, the results that we’re seeing,” says Erika Willis, the EPRI senior project manager supervising the tests of superhydrophobic coatings for both insulators and conductors.
A measure of caution is still in order, though. The handful of products EPRI found promising came from a larger pool, most of which did not make it past laboratory tests to field testing. With salespeople touting different superhydrophobic products, EPRI’s results illustrate the need for any co-op to do their homework.
When People’s Electric considered an early coating, for example, staff worked with the vendor to see if a system could efficiently apply the coating to lines in the field, but nothing proved satisfactory, Hudson says.
The co-op also applied the coating to a section of test line to measure results and found that durability was an issue.
“We had some applied to lines, and by a year, the benefit had been lost,” Hudson says. “We had some spot checks, and over time, with the wind, the rains, the sun, it lost some of its properties.”
Lovas says ensuring long-term effectiveness was one of the reasons NRECA has supported the additional testing by EPRI.
“The big issues are how to coat conductors, how durable it is, and what impact it has on the system operations,” he says.
Other concerns include cost, application techniques, any potential environmental issues from field application, and how it could affect common maintenance procedures. As with any new product, some questions will only be answered as utilities gain experience with superhydrophobics in real-world settings over time.
Some Positive Results
Lovas points to EPRI’s tests as the most thorough examination so far of superhydrophobic coatings for insulators and conductors. The initial laboratory work includes 16 assessments—mechanical, electrical, and environmental—looking for “fatal flaws,” Willis says, and also making “sure there is a product enhancement.”
Three products for both conductors and ceramic insulators advanced to Tier-2 testing, she explains, which involves field testing at three locations. The products that made the grade for insulators came from Pioneer, Ritec International, and Nanofilm. The three for conductor were from Pioneer, Ritec International, and NEI.
The insulator field tests have been conducted at a Con Edison Mill Yard in New York and Southern Company sites in Georgia and Alabama. Willis notes that conditions at the three sites vary significantly. The Alabama site is near a rock quarry, exposing the insulators to extreme levels of rock salt and other mineral contamination, while the other two sites feature more normal levels of contaminants.
EPRI has been tracking performance through onsite inspections and monitoring devices, including cameras. The results indicate the superhydrophobic coatings at the quarry site didn’t provide superior performance in shedding contaminants, Willis says—the speed at which the contaminant settled on the insulators “didn’t give the coating time to clear the rock salt.”
But results at the other sites were positive.
“We’re learning that outside the extremes of contamination, it’s really helping,” she says. At the Southern Company site in Atkinson, Georgia, she adds, “it’s performing great. It really helped that site.”
EPRI is bringing the insulators back into the lab to study how well the coatings have held up.
“From our on-sight inspections, we’re not seeing any noticeable cracking or peeling of the coatings,” Willis says.
'Fast-Moving Market'
EPRI's conductor tests are taking place at an American Transmission Co. site in Wisconsin, a mountainous New York Power Authority location, and on transmission lines in North Dakota operated by Great River Energy, the G&T based in Maple Grove, Minnesota.
The weather has refused to cooperate at a couple of the sites, and EPRI is planning to continue the testing for at least another ice-and-snow season.
"Last year, we really didn't get any icing," Willis says. "We're hoping to get some good ice this year to be able to monitor through the winter."
But early results from the Great River Energy site were positive, she adds, indicating an improvement in shedding performance.
NEI, Ritec International, and Pioneer already have superhydrophobic products on the market for utilities. Pioneer has both conductor and insulator coatings, which can be applied to existing systems or to new equipment, says Stuart Helgason, director of business development at Pioneer Technology Solutions.
"Prior to installation for insulators is the most efficient way to do it," he says.
The cost of the coatings has been a concern, but Helgason believes superhydrophobics can be more than competitive.
"From a cost standpoint, I've done some research on this," he says. "It's more cost-effective than doing RTV (room temperature vulcanization), especially if you're going to do it on site."
He sees the market exploding as manufacturers adopt the coatings and utilities become comfortable with using the products to coat existing conductor, insulators, and other equipment that could benefit from the protection.
Although the utility industry has been relatively slow to adopt superhydrophobics, Willis notes that the coatings have taken off in several other industries.
"It's amazing to me the amount of new hydrophobics that are coming to the market," she says. "You see it all over: hiking boots that have hydrophobic coatings. It's just a very fast-moving market right now."
In fact, she says, EPRI is commencing a second round of tests with 55 products, which expand the category in new directions.
"We're tending to call them more 'surface modifications' rather than just hydrophobics. One, for example, you actually take a laser and etch the surface to provide the contact surface angle [that sheds water and ice]. They're actually starting to use this on the wings of planes."
The continued research and growth is a reason Lovas says superhydrophobics could eventually prove transformative for electric cooperatives. Hudson also remains enthusiastic about their potential.
"It's just one of those technologies where it's kind of a dream deal if it could become an integral part of operations," he says. "If you had a proven product, I think it would probably become standard for replacement and build-outs."
