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North Sea Link: Why the New UK-Norway Power Cable Is a Big Deal

Norway, the land of the Vikings, is essentially a giant battery.

Norway. Photo: Vesna Vujicic-Lugassy

Although it does not sound like it, Cambois is a place in England. A former coal mining village on the coast of Northumberland, it is the place where the new 450-mile (720-km) undersea power cable, stretching across the North Sea, makes landfall.

The other end of the cable is in Kvilldal, Norway. Not coincidentally, it’s where a large complex of hydroelectric power plants is located. Its reservoir holds enough water to power the hydro turbines, at full power, for months.

It might not be as a fashionable topic as electric cars, but the number of undersea power cables connecting European countries with each other is increasing. And these cables have some role to play in keeping the electrical grid reliable while ditching fossil fuels.

The whole concept of the “dispatchability of hydropower” is simple. When other, intermittent sources of electricity (think wind power or solar power) are pushing a lot of power into the grid, hydropower plants can “make room” for them by reducing their own power. During that time, the turbines of a hydropower plant can operate at a very low power (for simplicity, you can assume that they are simply stopped); and the water level in the reservoir increases. And when the solar and wind power output falters, the hydro turbines can compensate for that by operating at a high power (with more water flowing through them than entering the reservoir — so, the water level in the reservoir decreases).

It is basically a form of energy storage. And a way of building an all-renewables electricity grid relatively easily — without using batteries, and without burning biomass.

As hydropower is dispatchable, it can smoothen out the intermittency of solar and wind. You get the average production of hydropower + the average production of solar power + the average production of wind power; but you get all of it constantly and reliably.

Still, it only works if you have a lot of hydropower.

Photo: Marcus Ramberg

An additional limitation is the amount of energy the hydropower plants’ reservoirs can hold. It makes sense to talk about the amount of energy — and not just the amount of water — because the height at which the reservoir is located also matters. Just as an example, you can get more energy from a reservoir of the same size if you can drop the water coming from it from the height of, say, 1000 m as opposed to 50 m (that would be about 3,300 ft and 165 ft respectively).

And if you’re looking for places where you can build a large artificial lake high in the mountains, and yet still located right next to the sea (which is, well, at sea level), then there are few better places than Norway.

So, it should not come as a surprise that multiple European countries are trying to plug into that large battery called Norway. To store their renewable energy there and get it back when needed — or simply to get a steady one-way stream of clean electricity flowing from Norway toward them.

It’s getting crowded in the North Sea (and Skagerrak and the English Channel too).

Denmark — specifically, Jutland — has an undersea DC cable connecting it to Norway. And, given its relatively small population and the high throughput of the cable, is heavily dependent on it, more so than the other countries mentioned here. The Netherlands? Connected to Norway with the NorNed cable more than a decade ago. Germany? Just recently connected to Norway with the NordLink cable.

But let’s take a look at the UK specifically.

There used to be one interconnector* (in the form of a group of submarine DC cables) linking the UK and France. Now, in a short period of time, that number jumped from one to three. In addition to the old IFA interconnector (in operation since the 1980s), we got IFA2 (operational) and ElecLink (not commissioned yet). Which means there should be about 4 GW of power that the UK can get from France alone. Then there’s the BritNed cable to the Netherlands; and the NemoLink cable to Belgium.

And there is a project called Viking Link which is supposed to connect the UK to Denmark directly (the project’s website says construction has already started).

But there was no power cable linking the UK with Norway directly — until the North Sea Link was completed this year. It hasn’t been commissioned yet — it’s undergoing testing — but it has at least once operated at its full capacity of about 1.4 GW as part of this testing.

Giulio Verne, the ship which was used to lay the North Sea Link cable. Photo: Prysmian Group.

If you look at the interconnectors linking the UK with France — which are bidirectional, just like the North Sea Link is— it is quite apparent that the power is still usually flowing in the direction of the UK; not the opposite way. And it wouldn’t be a bad thing if the new cable to Norway operated the same way. The whole idea of using the cable to send clean electricity to Norway and then transfer it back when needed sounds good. But the UK is still burning a lot of natural gas to generate electricity; importantly, natural gas power plants are still in the mix even when wind power generation is high. So the most effective way of using this cable to bring down the UK’s CO2 emissions would be to use it as a one-way street: to drain clean electricity from Norway all the time.

And if the UK ever gets a temporary surplus of renewable electricity, reversing the direction of electricity flow in the cable would give British wind/solar farms an option to unload an extra 2.8 GW before their output needs to be stored elsewhere, or curtailed.

(Why 2.8 GW? Because in this scenario, we assume that the UK getting a steady 1.4 GW imported from Norway is the normal — baseline — state. We can then make room for an extra 1.4 GW of domestic electricity production by simply reducing imports from Norway to zero; and on top of that, we can accommodate an additional 1.4 GW by sending it to Norway.)

But is it going to happen? Norway is expanding its own generating capacity, but it does not mean it’s ready to accept 1.4 GW of additional constant drain.

So, it seems more plausible that the cable will be used, at least initially, as advertised: to transfer electricity in both directions. To store British wind and solar electricity behind Norway’s dams. And to transform wind and solar power into reliable, weather-independent, always-on energy sources.

Norway. Photo: Martin NH

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*The naming can be a bit confusing: what is called a synchronous grid in Europe is called an interconnection in the United States. And an interconnector, in European terminology, is a link, like a cable, between two different synchronous grids (a link between two different interconnections).

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