So first off my opinion
Interconnectors are one of those parts of the electricity system I knew existed without ever really thinking about them.
Britain produces electricity.
France produces electricity.
Norway produces electricity.
Obviously we can move electricity between countries.
Job done.
Except once I started thinking about what that actually means for an electricity grid, interconnectors became much more interesting.
Because they’re not really just big cables.
They’re a way of connecting different electricity systems together.
And that means connecting their generation, demand, weather and electricity markets as well.
So what actually is an interconnector?
At its simplest, it’s a high-capacity electricity connection between two electricity systems.
For Britain, that generally means very large subsea cables connecting us to neighbouring countries.
Electricity can then flow across them.
If Britain needs electricity and another connected country has electricity available, we can import it.
If we’ve got electricity available and somebody else needs it, we can export it.
Already that changes how I think about Britain’s electricity supply.
Our generation fleet doesn’t exist completely on its own.
It’s part of a much larger connected system.
France is interesting
France has a large nuclear fleet.
Britain has a large amount of wind generation.
Norway has enormous hydroelectric resources.
Those are very different generation mixes.
And they don’t necessarily experience the same conditions at the same time.
If Britain has lots of wind, we might have electricity available for export.
If our wind generation drops, electricity from somewhere else may become more valuable to us.
Norwegian hydro is particularly interesting because water stored behind a dam is effectively stored energy.
So connecting different countries isn’t just connecting wires.
We’re connecting different types of energy assets.
But it works both ways
This is something that’s easy to forget.
An interconnector isn’t an electricity tap.
We can’t simply turn it on whenever Britain wants some cheap electricity.
The country at the other end has its own demand, generation, grid constraints and electricity prices.
If electricity is more valuable somewhere else, power may flow in that direction instead.
So an interconnector gives you access to another market.
It doesn’t give you ownership of another country’s power stations.
That’s an important distinction.
Then there are the cables themselves
Moving huge amounts of electricity over long distances isn’t trivial.
Many interconnectors use High Voltage Direct Current — HVDC.
That’s another rabbit hole I’ve ended up disappearing into.
Our domestic electricity networks largely use AC.
But for long-distance subsea transmission, HVDC can have some significant advantages.
That means you’ve also got converter stations at either end converting between AC and DC.
So what looked like:
Britain → Cable → France
is actually a substantial piece of electrical infrastructure.
And like every other bit of infrastructure, it generates data.
This is where it gets interesting for me
Imagine you’re trying to understand Britain’s electricity system.
You can’t just look at generation.
You need imports and exports as well.
Then I start asking questions.
How much electricity is flowing across each interconnector?
Which direction?
What’s the capacity?
Is the cable operating at full capacity?
What’s the electricity price on either side?
What generation is available in both countries?
Are there planned outages?
Are there constraints on either grid?
What’s the weather doing?
Suddenly we’ve got engineering data, market data and operational data all interacting.
Which is exactly the kind of problem I enjoy.
An electricity shortage might actually be a data story
Imagine wind generation suddenly drops in Britain.
Demand remains high.
Electricity prices increase.
An interconnector begins importing heavily.
Looking at any one of those datasets gives you part of the story.
Put them together and you can start understanding what the electricity system actually did in response.
That’s the bit I think is important.
Data engineering in energy isn’t just moving numbers between databases.
Sometimes we’re reconstructing the behaviour of a physical system.
And the physical system doesn’t stop at the British coastline.
So where is my head at?
Interconnectors make a lot of sense to me.
If neighbouring countries have different generation mixes and different peaks in supply and demand, connecting them allows those differences to be useful.
But I don’t think they should be thought of as generation.
They’re infrastructure that lets us access generation somewhere else.
That means their value depends on what’s happening at both ends of the cable.
Which also means Britain’s electricity system is probably more international than it looks when you just look at a map of British power stations.
That’s where my head is at the moment.
Gareth Winterman