Even as they work at the cutting edge of energy production, engineers are finding themselves battling an age-old foe: the inexorable force of corrosion.
Beyond death and taxes, there are few certainties in life. For engineers, corrosion is a close-run third. Throughout humanity’s history of metalworking, the destructive creep of corrosion has trailed like a spectre.
And as engineers seek new ways to adapt our infrastructure to the world’s demands for a future of cleaner, greener and more efficient energy sources, corrosion continues to eat away at their progress.
Genuinely sustainable energy
“Traditionally, the energy sector has been at the heart of corrosion engineering,” wrote Mike Yongjun Tan, Professor of Applied Electrochemistry and Corrosion Technologies at Deakin University, considering the topic in a paper he presented to the Corrosion and Prevention 2023 conference in Perth.
“Corrosion, hydrogen embrittlement and various types of materials degradation are expected to pose major challenges to the safety, durability and sustainability of essential infrastructure required for the production, delivery, storage and utilisation of renewable energy.”
From Tan’s perspective, corrosion resistance is needed to make renewable energy generation from such sources as wind, solar, hydrogen, geothermal, ocean and bioenergy genuinely sustainable – particularly at large scale.
“The biggest need in Australia in terms of corrosion [protection] is for renewable energy infrastructure,” Tan said.
Offshore windfarms, for instance, consist of enormous metal turbines that must maintain operation in highly corrosive marine environments. The wind from which they source their power also stresses and strains the windfarm’s steel components, making them more susceptible to corrosion.
These structures are currently designed to operate for two or three decades. Tan wants them to last four times as long.
“If, every 25 years, you have to knock down this huge structure that’s fairly hard to recycle, that’s not sustainable,” he said. “If we want this infrastructure – solar farms, wind farms – to last, I think we should target 100 years. Then that becomes a truly sustainable energy system.”
For offshore wind turbines – as with a lot of infrastructure susceptible to corrosive damage – the problems can start out quite small.
“In many cases the problem is what we call localised corrosion,” Tan said. “Only one per cent of the surface gets corroded, and the problem with that corrosion is that when it starts, it develops very quickly.”
That small area of corrosion might not even be visible, but if it occurs at a stress concentration point, the effects can be devastating. Early response is crucial, Tan said.
“That’s why, at the moment, we’re working to develop monitoring technologies. How to detect it, how to protect it – I think from my point of view, this is the biggest challenge for this field of corrosion science and engineering at the moment.”
Pairing that more precise data collection with advanced data analysis methods, and even artificial intelligence, will allow engineers to better target anti-corrosion tools such as cathodic protection or proactive maintenance.
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Keeping carbon secure
A better understanding of corrosion will help make renewable energy production more sustainable, but it is also important for carbon abatement strategies.
Professor Srdjan Nesic, Director of Ohio University’s Institute for Corrosion and Multiphase Flow Technology and an affiliated scholar at Western Australia’s Curtin Corrosion Centre, told create that transporting and sequestering carbon dioxide as part of carbon capture and storage approaches presents new challenges for corrosion engineers.
“Transportation is something we have to do in order to put away the carbon dioxide and not emit it into the atmosphere,” he said.
“And the challenges of transporting it from wherever it’s produced – in power plants and industrial facilities – to the injection sites in the ground through pipelines … is a huge challenge. You have to compress it and pump it in a very condensed form, so it becomes like a liquid, or something called a super-critical substance.”
High-pressure carbon dioxide is an entirely new question for corrosion experts. They understand what happens to steel in marine environments, industrial settings, and standard atmospheric conditions, but the conditions inside a pipe transporting carbon over great distances are novel.
“The challenges change as our technology changes and as our needs change,” Nesic said. “Fortunately, we can port some of the knowledge across from other fields, but there’s a lot of new things that we never encountered before that we are now having to resolve.”
Impurities such as oxygen, nitrogen oxides and sulfur oxides, which might have leached into the gas during production, complicate things further.
“Those cause really unusual types of attack on your pipelines – some catastrophic, some less, and we don’t understand them,” Nesic said. “We have to do it urgently because they’re already designing and building these pipelines for CO2 and putting them in place.”
High-pressure research
As well as the unusual impurities, the intense pressure that the gas is under adds a new wrinkle. Nesic compares the challenge to conducting experiments deep beneath the ocean’s surface.
“It’s hard to work and do experiments at a hundred bars, which is a very high pressure where everything’s dangerous and difficult and complicated,” he said. “Even the simplest of manoeuvres are extremely difficult at that pressure.”
The perfect solution is the least practical: building pipelines that extend for hundreds of kilometres out of stainless steel would cost far more than anyone would consider feasible.
That means Nesic, like Tan, is trying to better detect and predict the likely points of failure in a pipeline network.
“We have simulations of what goes on, and that’s what we’re constantly trying to improve on,” he said. “We can predict or signal ahead of time that [something] is going to be an issue and where it’s going to be an issue.”
Instrumentation is also getting more effective at detecting changes in performance, locating cracks, or monitoring the thickness of pipeline walls.
“Both of those, going hand in hand, are improving our ability to do something,” Nesic said. “But both of those are proactive strategies, so they cost money. And often governments or public institutions or even companies don’t want to pay that until they get a problem.
“It’s like not wanting to be vaccinated. You don’t want it until you get the disease and then you regret it. No-one wants to worry about and spend money on corrosion prevention and prediction until there’s an imminent catastrophe.”
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