In these times of Brexit (don’t worry, read on, I won’t get into politics), marked by a mixture of mourning, incomprehension, anger and, I guess if we follow the logic of democracy, celebrations for some, I would like to talk about a subject that particularly lies at heart to me because it is … intrinsically European.

To put it simply, interconnectors are big cables allowing two separate electricity networks to exchange electricity production across their border. While you won’t see them as you go about in your everyday life, they are one of the most tangible elements of what unites countries together, more than the Erasmus programs, the passport-free holidays and the toll-free trade rights, which are usually what comes to most people’s mind when talking about Europe (don’t get me wrong, you do find interconnectors elsewhere, but I’ll focus on European examples for now).

Nowadays, most electricity networks in European countries are liberalised, so that the basic laws of supply and demand apply. However, unlike other markets, this balancing has to be done instantaneously, otherwise the lights go out pretty quickly. And as a grid operator, you certainly don’t want that happening during the screening of the Champions League final penalty shoot-outs, unless you like to put your life at stake.

This need for redundancy is why electric networks were built out on a larger scale in the first place, so that a power plant failure at one point could be replaced by power plants operating somewhere else. The higher the amount of connections between the points of a grid, the stabler it is. This makes electric grids the largest physically connected machines on Earth, as a power plant’s behaviour in Scotland for example will depend on another one in Cornwall (I mean, come on, the island I’m referring to remains at least physically big, relatively speaking…).

While in mainland Europe transmission operators agreed to build out a synchronous grid which facilitated cross-border power exchanges, areas which were physically more isolated such as Britain, Ireland, Scandinavia and the Baltics had to develop their own transmission system.

So traditionally, the main purpose of such grid network developments was avoiding getting knocked out by frustrated hooligans. However, in the 60s, France and the UK decided to put their false rivalry aside as they saw the opportunity for a market emerging, despite the moat separating them. Indeed, as each country has different energy policies and therefore production dynamics (mainly nuclear for France and coal/gas for the UK at that time), but also different consumption patterns (good ol’ 2h lunch break for the Froggies whereas kettles get boiling in unison at football half-times on ze Rosbif side), the market balance is reached at difference prices on either side of the Channel at different times of the day. By exchanging power from one market to another, interconnectors thereby allow to sell off electricity higher on one side while buying it cheaper on the other side. Easy way to make money while helping the neighbour in need!

And so after a first interconnector of 0.16GW was operational for 20 years, it was replaced by a second cross-Channel interconnector of 2GW in 1986, which is still operational nowadays. As a reference, the average evening consumption in the UK is around 40GW, so that at any point, 5% of the consumption can be supplied from abroad.

The clear benefits shown by the cross-Channel interconnector encouraged a series of others to be built and planned, as can be seen below.

These undersea cables are quite an engineering feat in itself. Many of you might have heard of AC and DC current (if this only sounds like a rock-band to you, maybe check out the Tesla vs. Edison Epic Rap Battle of the Century for enlightment), but don’t really know which is used when. Put very, very crudely, AC is considered easier to produce and transmit, while DC is better to use in household applications.

When it comes to electricity networks, transmissions losses are indeed a big topic. A certain percentage of electricity gets lost as heat (Joule effect) during transportation, and the longer the distance the higher the loss. Until recently, AC was the preferred way of transporting electricity over long distances. However, clever bits of engineering have allowed over the last couple of decades to develop HVDC (High Voltage DC), which turns out to be more efficient than AC over even longer distances. Additionally, it allows to connect two asynchronous networks (basically when two networks wiggle out of phase), which is exactly what is needed when connecting those poor islands gone astray from the mainland! If I completely lost you in the last few lines, just take home as the next pub-quiz trivia knowledge that modern interconnectors are HVDC links, and that it’s pretty cool.

Aaaaaaaanyway, these cables connecting all these bits of land with each other have acquired even more interest over the last few years with the increase of variable and not-so-easily predictable renewables in our grid. What to do with all that wind when no one needs it at 02:00 AM? Or how to still heat up my dinner at night when the solar panels on my roof are pretty useless?

Well, again, the natural wind and sun ressources are different throughout the day and in different regions across Europe. By connecting all these renewable sources together in a mega-grid, it smoothens out the individual variability and allows to provide renewable energy for everyone more continuously. So after all, those dreams of isolated communities relying on their own solar panels to grow their quinoa in greenhouses (I’m not sure how you grow quinoa to be honest) might be a bit counterproductive, and we would be much better off sharing all that renewable energy.

Secondly, some specific geographical differences between countries can be exploited. The most striking and exciting example is the North Sea Link currently being built between the UK and Norway. In the UK, especially in the Northern parts, the grid often experiences times of wind power overproduction which no one needs. Norway on the other hand generates 98% of its electricity through hydroelectric dams thanks to its mountainous topography and high amounts of rainfall (at least some people can be thankful for their shitty weather!). Hydroelectric dams have the very interesting property that their turbines can be run backwards at times, essentially working as pumps to store the water high up. With the North Sea Link, the overproduced wind power from Scotland can then be used to pump the water up the reservoirs in Norway, to then be used later on in the hydroelectric dams the other way around when there is a shortage of production in the UK. Essentially, these hydrodams work as massive energy storage solutions, which are to date the cheapest and largest energy storage option available.

This example out of many shows the benefits which can be extracted from collaboration between different countries through interconnectors. And while some people might moan about the oppressive bureaucratic nature of the EU, I hope examples such as these will remind them that it’s not all bad and that differences within Europe is what makes the strength of this place. I’ll stop here before this gets too emotional, but thank you for reading this far and see you soon for another topic I’ll probably have randomly chosen the night before!