The capital of Greenland, Nuuk, has been running on pure green power from the Buksefjord hydroelectric power plant south of the city for years.
But this week, the city’s nearly 18 000 residents had to make do with gray energy—150 000 litres of diesel a day—as severe weather caused one of the three phases on the transmission line from the hydroelectric power plant to unravel and short circuit, so several attempts at restarting the power plant failed.
When it was at its worst, the whole country had a communications breakdown because their telecommunications company’s backup batteries ran out of power.
The start-up of the emergency power plant in the city was also challenging due to, among other things, lack of telecommunications, as everything from electric heating to supermarket refrigerators and servers was plugged in and ready to receive electricity again.
But on Friday, the technicians from the energy company Nukissiorfiit finally started the necessary repairs, while the citizens were urged to minimise all unnecessary power consumption, says Nukissiorfiit’s chief executive, director of energy, and engineer Kaspar Mondrup.
He had feared that it would take them days or weeks, but a temporary repair was managed in a day.
“This means that Nuuk is no longer in a crisis situation, as the city is supplied from the emergency power plant in Nordhavn, and that citizens and companies can once again use electricity as before,” reads a briefing to the Government of Greenland.
It has been a hectic week in which the country’s entire emergency response system had to be activated, it turns out, as Ingeniøren asked the director of energy to retell the course of the events from the beginning, when the connection to the plant first went out in the middle of a hurricane.
“We experience this on rare occasions when we have accumulated ice and a strong storm. There can be leakage from one power line to another. When the hydroelectric power plant was new, it happened often. But then some different separators were installed in the areas that were particularly sensitive, so they were kept apart,” Kaspar Mondrup says.
To fully understand the context, it is important to know that Greenland does not have a grid like Denmark. Each city runs on “island operation” (supplies itself, ed.), mainly from diesel power plants, while six cities, including Nuuk, are supplied via hydropower.
The supply comes from the Buksefjord hydroelectric power plant, which was completed in 1993 and has an output of 45 MW with three turbines.
The electricity is sent 56 kilometres north to Nuuk via three high-voltage power lines, one for each phase, including via one of the longest spans of an electrical overhead power line in the world—5376 meters long—over the Ameralik Fjord.
The power lines are routed all the way through a dramatic and rugged landscape with deep fjords and high mountains, and are inspected on foot by Nukissiorfiit’s technicians twice a year.
“Typically, the power lines swing uniformly back and forth during a storm, and nothing happens. But in special weather situations—and we have had extreme thawing, a hurricane and everything you could think of—there can be leakage between power lines. And then the hydroelectric power plant shuts down automatically,” the director of energy says.
It was the latter, which was assumed to have happened on Monday evening at 11 p.m. local time, when the power supply from Buksefjord hydroelectric power plant stopped and the capital lost power.
Nukissiorfiit’s procedure is always to try to restart the hydroelectric power plant rather than start up the emergency diesel power plant.
But that takes time—a city's electricity supply cannot just be connected in one fell swoop. First, the load must be disconnected—the city must be disconnected in sectors. When the hydroelectric power plant is online again, the city will have to be gradually reconnected to normalise operations.
“It takes a couple of hours to reconnect the city. When we just finished reconnecting it after the first outage on Monday night, another one came. Then we had to start all over again and disconnect the load, start up the hydroelectric power plant again, and reconnect the city. So even if it sounds simple, it takes quite a long time. And it happened three times in a row during Monday evening and night,” the director says.
Something serious was going on. But the extreme weather was still raging, so it was impossible to send a helicopter out into the field to find out what was the problem.
“At one point we had to realise that we simply could not reconnect the hydroelectric power plant anymore. Everything pointed to a definite short circuit. We could measure it on our lines, and it looked like we either had a knocked down tower or a damaged power line. That was our immediate assessment. But we could not fly out and check what it looked like due to the weather at that time,” Kaspar Mondrup says.
By then, the city had been without power for hours, and Nukissiorfiit realised that it was time to get the diesel backup going. Without supply from outside, the Arctic capital is completely blacked out in the middle of winter.
“It’s dark. Various critical functions such as healthcare services, retirement homes, the police, and the fire department do have emergency generators. But at some point, for example, our telecommunications operator’s backup to the data centre that operates all data communication in Greenland ran out of power. And on Tuesday, we lost both telephone communications throughout the country and all internet throughout Greenland,” he says.
Low air pressure meant plus degrees during those days. And that was lucky. The citizens either use oil furnaces, which require electricity. Or they use district heating, which runs on electricity.
District heating can switch from electric boilers to the original oil-fired boilers, which are preserved as part of the security of supply strategy if there is no electricity from the hydroelectric power plant. But it needs electricity to start up. And there had been none for 17 hours straight.
All in all, the authorities had to step up to the plate. Crisis response was activated in all sectors. Among others, the police, fire authorities, Joint Arctic Command, and the energy company all sat down together and coordinated the efforts from the police station and the military headquarters.
“We started connecting the diesel power plant. But because the city had no electricity for a long time, the need for energy in the city was extreme. And that’s why the diesel power plant had difficulties with reconnecting the city. The load that the power plant encountered when we started the engines was quite extreme,” Kaspar Mondrup says.
It was therefore difficult to start up the power plant, which consists of five engines. When they are overloaded, they knock each other out and shut down.
“It was amplified by the fact that our telecommunications were not working due to the power outage. So we could not automatically connect the city in the sectors we wanted. We had to do it manually. Our people simply had to drive out to the various substations to connect them. It took a really long time,” the director of energy says.
Then the weather improved and suddenly it became possible to get in touch with the hydroelectric power plant.
Fortunately, there were no broken power lines. And no knocked down towers either. So the diesel backup solution was dropped and the efforts were again directed at getting the hydropower energy back.
“We got it up and running and everyone was happy. And then another storm came and knocked it out again. And that’s why it was starting to take days. We constantly believed that this time it would work. But that did not happen because of the weather and the situation,” he says.
An attempt by the Joint Arctic Command to inspect the power lines on Wednesday went wrong due to the weather.
“So we needed this diesel backup to work. And it also succeeded within six hours. Then we got the whole city up and running on diesel,” he says.
Both the hydroelectric power plant and the emergency power plant are set to be upgraded around 2025. But right now, the diesel power plant is reasonably large enough for the city’s growing population if everyone only uses electricity for the essentials. It is only particularly busy around dinnertime.
In the meantime, the fault was found on the power lines to the hydroelectric power plant when a helicopter from the Joint Arctic Command could finally depart on Thursday with Nukissiorfiit on board.
One of the three phases on the transmission line unravelled about 30 kilometres from the hydroelectric power plant, fortunately over land.
“It happened due to accumulated ice and a hurricane. This is something that happens with such power lines. We normally visually check the power lines several times a year, more often than they do in Norway, for example, which also uses hydropower. There is no one to blame,” says Kaspar Mondrup.
“The power lines swung back and forth and one or more of these power line strands have given out, and then the power line unravelled. This caused the distance to the other power lines to be shorter, so a spark could more easily be formed when the power lines swing during a storm. In the beginning, a fairly strong wind was needed for the hydroelectric power plant to shut down. But in the end, it didn’t take much, so it got worse as the days passed and the storm continued,” it reads.
Why can you not disconnect one phase and use the other two?
“This is because three phases—one in each power line—are required to transmit the electricity from the power plant to the city,” the director of energy says.
On Friday morning, the energy company believed that it could take days or weeks on emergency power spending 150 000 litters of diesel a day to repair the unravelled power line.
But yesterday, Nukissiorfiit and Air Greenland, who were responsible for getting the technicians to the location, succeeded in temporarily repairing the power line, so the hydroelectric power plant came online once again.
“Today the weather has again allowed a helicopter to be sent to the damaged power line and a team of Nukissiorfiit’s technicians has put in great efforts and managed to temporarily rectify the fault on the transmission line. This means that we can now reconnect the hydroelectric power plant and return to normal and stable operation,” said Kasper Mondrup on Friday night.
The final evaluation of the week’s dramatic events has not yet been made. But the director of energy is ready to draw some conclusions already.
“We have become better at starting our diesel operation and we have practiced our backup procedures. Now we know exactly what to do. This is the first time we have had such a long outage,” he says.
However, until the hydroelectric power plant and the emergency facility are expanded in four years’ time, Nuuk’s residents will have to live with the fact that the events of last week can happen again.
“All other times it had been possible to get the hydroelectric power plant up and running within a few hours. But we could have a situation in which a power line unravels again, and then we will have to carry out the procedure we did this time. Explain to the citizens that it takes some time to get back into operation and appeal them to use only the power that is really needed,” he says.
“We have connected our city in such a way that all critical functions get power first—grocery stores, police, military, fire department, retirement homes, and so on,” Kaspar Mondrup says.
According to the Greenlandic newspaper Sermitsiaq, Nuuk’s energy supply was reviewed in 2018, and the review stated that “if we are to maintain the historical level of security of supply, a new electricity backup must be established in Nuuk as soon as possible”.
DKK 90 million has been set aside for two new generators at the emergency diesel power plant. Its current output is 32.8 MW.
“I had expected that the emergency supply would work much faster when the power plant in Buksefjord fails. We found that it doesn't work like that. That’s not how it should be, and we must do something about it,” said the Minister for Agriculture, Self-Sufficiency, Energy and Environment Kalistat Lund for Sermitsiaq.
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