Energy interconnectors. What's all the fuss?

What are energy interconnectors?
Energy interconnectors are high capacity cables or gas pipelines that connect two energy grids, with the aim of balancing supply and demand across two or more geographic areas.

They're typically between two countries, like the East West Interconnector, the 500MW electricity cable that links Ireland with Wales. But they can also link two islands of the same country, like the 500MW Moyle cable that links Scotland and Northern Ireland.

Interconnectors are typically laid on, or beneath, the seabed, like the 40 inch IUK gas interonnector that links the UK with Belgium. They can also run within bridges or - like the 2019 Anglo-French 1GW ElecLink cable - through a tunnel.

What's all the fuss?
Interconnectors based on advanced technology aren't especially new. The first link between two countries - at least in Europe - was the 160MW cable linking the UK and France, which opened in the early 1960s. Like its 2GW successor, which opened in 1986, it was bi-directional and based on low-loss High Voltage Direct Current (HVDC) technology.

No, the fuss relates to their role in the low carbon energy transition that we're currently going through. Interconnectors are a key enabler for making this successful, as they allow energy to flow between two systems, bridging the variability of renewables in localised areas. The independent advisers to the British Government, the Committee on Climate Change, suggest that greater interconnection with other grids will be key to decarbonising the power system.

They do this in two ways:-

1) enabling electricity grids to prioritise renewables and nuclear power when balancing supply and demand across long distances. Countries with a high dependency on intermittent renewables, as the UK is increasingly becoming with wind, will need to be able to export their excess power to neighbouring countries when wind resource is high, and conversely import it (e.g. nuclear from France) when the resource is low.

2) enabling natural gas to flow between countries. Whilst natural gas is a fossil fuel, gas turbines are a lower carbon alternative than thermal backup from coal plants. With strong demand from households with gas boilers during cold winters putting pressures on domestic gas supplies, gas interconnectors with neighbouring countries - especially those with electrified domestic heating (e.g. Norway) can be key to powering gas turbines. They're an alternative to topping up networks with Liquified Natural Gas (LNG), which is increasingly converted from fracked gas at huge energy cost.

Recent large scale interconnector programmes
There are a considerable number in the pipeline right now. Sorry. Here are some examples.

• Nemo Link is a new 1GW cable between Great Britain and Belgium. The two countries have traded across a gas interconnector since 1998, but this is the first power connection. (Wikipedia)

• IceLink is a proposed connection linking Great Britain to Iceland. At just over 1,000km long, it would be one of the longest seabed cables in the world, and would have a capacity of between 800MW to 1.2GW. As you'd imagine, such a long and deep cable, power cable takes considerable planning and IceLink likely won't be live until the late 2020s. As Iceland has considerable, 100% renewable, power generation but only c.360k residents, IceLink is a great example of how diverse renewable resources (mainly hydropower and geothermal) could be transmitted to a larger consumer via interconnectors. (Icelandic homepage)

• North Sea Link and Viking Link will run from Great Britain to Norway and Denmark, respectively. Already under construction, they aim to be live in the early 2020s, and will each carry upto 1.4GW over about 750km. Similar to IceLink, they would allow the relatively small populations of Norway and Denmark to export their (respectively) hydropower and wind generated power to the UK. Likewise, if the UK wind resource was high, but dam and wind levels were low in Scandinavia, then there is the potential for the flow to be reversed. (Wikipedia: Viking Link and North Sea Link).

• Sun Cable is a project in development. Amazingly, its being mooted to connect solar farms in Australia's Northern Territory to Singapore, some 3,800km away. I estimate about 800km of that would be on land in Oz, so its possible that they're talking about a staggering 3,000km on the seabed - three times longer than the proposed IceLink. Despite the Top End being home to some of the world's best solar irradiance levels, the scale of the project (suggested to be 3GW) and its skeleton staffing give it the appearance of wishful thinking. Similar desert-based long-distance schemes have been suggested before and come to nothing, with the defunct Sahara-Europe project Desertec (Wikipedia) a classic example. It makes sense that Singapore would want to reduce its reliance on pricey Liquefied Natural Gas (LNG) but you'd think Singapore could be supplied far more effectively through solar deals signed with neighbouring Malaysia and Indonesia. (Sun Cable website and The Guardian Australia).

• Another Asia Pacific project is Asian Super Grid (ASG), which aims to link a least China, Japan, Russia, Mongolia and South Korea. Despite being longer (up to 36,000km), high capacity (up to 10GW) and clearly more complex than Sun Cable, ASG has a greater chance of being at least part-realised due to it being founded and chaired by Masayoshi Son, the billionaire founder of SoftBank Group. (Asian Super Grid site and Wikipedia).

• Finally, there's the Celtic Interconnector, slated to connect Cork, Ireland to France. It's planned for 700MW, around 600km and should be up and running in the mid-2020s. It's to be owned by the public grid operators of the two countries. (Wikipedia).