Inside the world’s first digital twin of a hydroelectric power station

Technology provider Akselos is creating a structural digital twin of energy utility ESB’s aging Turlough Hill hydroelectric power station in County Wicklow, Ireland. The project, a world first, hopes to extend the operational life of the colossal asset and help it find new modes of operation. Heidi Vella finds out more.

Image: Joe King/wikimedia  

Originally designed in the 1960s, with engineering work completed in the 1970s, the Turlough Hill hydroelectric power station in Ireland is reaching the end of its design life.


However, the plant, which is the only pumped storage station in Ireland, is still a key asset for its owner and operator ESB and helps stabilise the local grid at times of peak demand.


Keen to explore ways to potentially extend the power station’s life, in October last year ESB brought in software provider Akselos to create a digital view of the asset.


Using its predictive and digital design technology, Akselos has created a detailed digital twin of the Turlough plant and is working on building a Digital Guardian of the asset which Akselos says can extend its useful life by up to twenty years

/ The challenge for ESB is how to continue to operate and on what basis? That's what the digital twin can help answer. /

What’s the problem? 

Located approximately 60km south of Dublin in the Wicklow Mountains, the Turlough Hill hydroelectric power station generates 292MW during peak demand periods by releasing water from its upper reservoir and allowing it to flow through its four turbines into a lower reservoir.


During periods of lower demand the water is pumped back to the upper reservoir ready to be used again.

/ The challenge for ESB is how to continue to operate and on what basis? That's what the digital twin can help answer. /

The energy storage that Turlough provides is increasingly important in the changing energy ecosystem, which is moving towards more flexibility to incorporate renewables. But due to its age and size, ESB does not know how much structural life the hydro plant has left and whether its operations can be made more responsive in the future.


As part of the Free Electrons Accelerator Programme - an initiative to connect startups with energy utilities to support and foster innovation - ESB was introduced to Akselos to help find some answers.


“The challenge for ESB is how to continue to operate and on what basis? That's what the digital twin can help answer,” says Andrew Young, Akselos' VP of projects and delivery.

/ Young estimates the CAPEX invested for Akselos' digital twin technology by a utility can be recouped within a three year period. /

Building the digital twin

To build the digital twin, engineers at Akselos needed to collect all available data on the gigantic asset which could then be used to create a 3D rendered structural digital model.


This task was made harder, however, by the lack of available digital information. Akselos’ engineers had to work with paper records only, which put the project behind by two months. In total, it took five months to complete.


To build the model, it was key to establish the geometries, interactions and stresses in the plant system to create an intuitive heat map. The map can show when and what tensions are running through the power station and direct maintenance inspections to specific areas of concern, rather than just doing a random walk through.

/ Young estimates the CAPEX invested for Akselos' digital twin technology by a utility can be recouped within a three year period. /

The digital twin is essentially a tool with which ESB can simulate many parameters around the day to day operation of the plant and visually pan through the entire structure and see how it reacts.


“Our technology allows maintenance engineers to really pinpoint, using rules of science and engineering, where the issues will likely occur and we can also establish what the operational life is in terms of fatigue assessment. It also supports predictive maintenance,” says Young.


An inspection can cost around €3-5m, through a combination of lost production and penalties for down time, so the technology can potentially save companies money.


Young estimates the CAPEX invested for Akselos' digital twin technology by a utility can be recouped within a three year period, just on the basis of improved inspection. Furthermore, he says it can provide a 20-50% life extension.

Using its predictive and digital design technology, Akselos has created a detailed digital twin of the Turlough plant. Image: Akselos

/ A GE report notes that structural integrity provides a 90% predictive capability. /

The technology: why is it different? 

Predictive maintenance is not new. Bigger companies such as ABB and GE also offer this technology; so what makes Akselos’ offering different?


According to Young, existing predictive maintenance modelling and applications typically use asset management tools to achieve around 30% predictive. However, Akselos add a scientifically based structural integrity component.


“We can simulate future events because of the nature of our physics-based twin, whereas what other companies are doing is assessing the probability of a known and identified defect reoccurring,” explains Young.

/ A GE report notes that structural integrity provides a 90% predictive capability. /

Essentially, Akselos’ software assesses and identifies the risk of any type of failure based on the structural assessment; a fault doesn’t have to already be pre-identified.


“A GE report notes that structural integrity provides a 90% predictive capability, so we believe it is actually complementary to what companies like GE are doing, but gives a higher level of understanding of the asset,” he adds.


In fact, Young says the company is currently in the assessment phase of several projects with OEMs, which he can’t name, on integrating Akselos’ technology within their offering.


“These companies are starting to offer digital twins with every piece of kit they sell, and in the future, if they deliver a twelve-megawatt wind farm, it will have Akselos’ software inside, running as part of their predictive capability offering,” says Young.

The digital map can show when and what tensions are running through the power station and direct maintenance inspections to specific areas of concern. Image: Akselos

/ Legacy assets still have to be managed for some years despite the energy transition, and they're looking for cost effective ways to do this. /

The next phase of the Turlough project 

Now the digital twin of the Turlough Hill hydroelectric power station is built, the next stage of the project would be to create a Digital Guardian, says Young. To do this, engineers will connect specially placed sensors to get a real time picture of what is happening in the hydro plant. This is expected to be planned for the next maintenance window.


Through the models, ESB will look to assess different modes of operation that might better work alongside renewables, such as storing electricity at different times of the day.


“An additional model of operation could be pumping in the daytime to store power when it’s needed, in addition to at night, as renewable energy sources are changing the dynamics of energy supply and pricing,” explains Young.


This means rather than having one cycle a day, the plant might have two or more. However, Turlough wasn’t designed to operate in this way, therefore ESB needs to understand what the impact might be on the structure. These factors, added to aging asset management risks, could increase inspection frequencies and costs or even require a significant CAPEX project.

/ Legacy assets still have to be managed for some years despite the energy transition, and they're looking for cost effective ways to do this. /

Using Akselos’ technology, Young says there is no reason why the life of the asset could not be extended another 20 years.


“I don't think ESB came on board just to do a pilot, I think the company is really interested in this technology and how they can apply it to different assets,” says Young.


Adopting the innovation is largely about adapting to the changing energy ecosystem sooner rather than later, and becoming more efficient and more cost effective in the process.


“Legacy assets still have to be managed for some years despite the energy transition, and they're looking for cost effective ways to do this,” says Young.


“The utility industry is one of the first to encounter huge disruption and ESB is adapting to it extremely well by applying innovation to find new business models, this is what we're hoping to do.”

Playing catch-up in the US

“In Europe, offshore wind has been there for a number of years, but I think in the United States we're a little bit behind that,” said Karustis.


Should it be successful, Halo’s approach could lead to a surge in US onshore wind, which has historically lagged behind other regions in terms of wind installation and production. Since 2016, according to the International Energy Agency, the US has installed just 22.6GW of new onshore wind capacity, compared to 30.7GW in the EU, and 50.3GW in China, struggles that Karustis hopes to address.


Last December, the Chinese Government approved a number of new offshore wind projects, totalling 13GW of production and costing around $13.3bn, as the country continues to invest in utility-scale power. Karustis hopes projects like Halo’s distributed turbine can contribute to a more balanced wind sector in the US, with both large- and small-scale operations expanding renewable power.


“The large-scale wind turbines wouldn't be phased out, it's kind of an ‘all of the above’ thing,” he said. “The large wind farms play a very important role for us in reducing the carbon footprint globally, and hopefully the micro wind market is going to augment that by producing energy where energy is being used. It's a good two-pronged approach.”


This two-pronged approach also includes other renewable power sources, including solar and utility-scale wind; Halo is not trying to replace all clean energy with its turbines, but offer another option for people eager to engage in renewable power, who may have been historically sidelined due to the high costs of building utility-scale facilities or the unsuitable geographical characteristics of the places they live.


“When you look at that market we're very excited because just as megawatt-scale wind is a large market, I think distributed wind can be as big of a market or bigger over time,” said Karustis.


“When you have incentives and improvements in the technology, the costs go down, so you can be more competitive and compete, and that's certainly the case with megawatt-scale wind,” he continued. “Just 15/20 years ago, it wasn't competitive with natural gas [and] coal, but it is now. So those government policies have helped and they've driven the technology improvements, so it's all bundled together.”

TECHNOLOGY

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