🔌 Connecting grids across continents
How HVDC cables contribute to a more sustainable world by connecting grids.
The sun is always shining on one half of the planet, and the wind is always blowing somewhere, so why can’t we just produce electricity wherever resources are available and send it across the globe? While some grids are interconnected over short distances, some projects have recently gotten more ambitious and are planning to connect gigawatts (GW) of electricity across continents.
In this edition of Seagnal, we’ll explore how High Voltage Direct Current (HVDC) technologies contribute to a more sustainable and interconnected world today, and in the future. But first, we will jump back to a time when connecting continents was a mere dream.
Sea-cable laying, a treacherous adventure
In the 1850s, most of Europe was linked by telegraph lines, allowing for news to blitz across countries, through a well-established Morse code. Using patterns of short and long presses, operators in Berlin were able to let passengers in France know their train was running late within seconds. While the new network was rapidly spreading on land, oceans remained obstacles.
It took ten years, millions of dollars, and five attempts to successfully lay the first transatlantic telegraph cable in 1866. This monumental achievement drastically reduced communication time between Europe and America from weeks to mere minutes. Since then we have continued to increase data transmissions between continents, with now over a dozen fiber optics lines under the Atlantic Ocean.
Mapping sea fiber optics line across the Atlantic - from Submarine Cable Map
We may have mastered the art of intercontinental data transfer, but the same is not true for electricity. Yet, as we will see there are a lot of incentives to create intercontinental grids. Imagine using excess, and cheap, solar electricity in America when the sun is at its Zenith to power the expensive evening European peak load. Indeed, even on shorter distances, the business of connecting grids between countries is proving quite profitable. But first, an overview of how grids and interconnection work.
Grids are like highways
Just as narrow roads enforce lower speed limits while highways allow for faster travel, low-voltage lines transport electricity over short distances with higher losses, whereas high-voltage transmission lines, often carried by pylons, can efficiently transmit large amounts of electricity across entire countries.
Grids from different countries have different standards (voltage, frequency and phase for alternative current (AC) lines), and interconnection equipment allows the exchange of energy between grids. For example, the ElecLink project, finalised in May 2022, transfers energy from the English grid to the French network.
ElecLink Interconnection Diagram, inside the Channel Tunnel
The juicy business of grid interconnection
The English-French interconnection has a capacity of 1 GW, and over its first year of operation, it has enabled more than 6 terawatt-hours (TWh) of electricity exchange. Even more impressive, with electricity price arbitrage, it made €558 million in revenue (EBITDA of €368 million) in 2023 while it only cost €817 million to build. Ask your banker, that’s a pretty good return on investment for an infrastructure project.
Although ElecLink's financial success is tied to leveraging the Eurotunnel’s existing infrastructure, it's no surprise that it’s neither the first nor the last European subsea interconnection.
Mapping Europe’s HVDC interconnections as of 2023, from Wikipedia.
Notably, Europe is also home to the world’s longest HVDC Cable, Viking Link, connecting 1400MW of power across 765km between Denmark and the UK (line number 17 in the map above).
Projects like these not only enhance grid resiliency but also promote sustainability by facilitating the transmission of solar or wind energy to the UK at times when there could be no wind in the UK (as wind power correlations exponentially decrease with the increase of the separation distance). Some international HVDC cables also effectively allow countries to use other countries’ dams for storing excess energy.
However, with the world’s longest HVDC Cable only 765km long, we aren’t connecting continents yet. But this may be about to change.
Mega projects on the rise
The Sahara desert receives 189 times more solar energy than we consume globally every year. Could we power the world with a giant solar farm in the Sahara?
X-Link is looking to start building towards this vision with a wind, solar and battery complex in Morroco, to export electricity to the UK via two (2x) 1.8 GW 4000km HVDC cables. The project is not without its hurdles though, such as the company having to build its own HVDC cable manufacturing and cable laying vessel through an affiliate company XLCC.
SunCable is another project looking to build electricity generation in northern Australia to export to Singapore. The 4300km cable will have a capacity of 1.75 GW, which is about 15% of Singapore’s demand.
With these intercontinental projects, and the vast distances the cables need to cover, current HVDC technologies transmission losses (~ 3.5% per 1000km), become important. Additionally, these projects introduce energy security risks. Unlike gas and oil, where importing countries can build fossil fuel reserves for many days or months, electricity reserves are counted in hours.
So why isn’t there a cross-Atlantic grid?
The historical journey of connecting countries began with laying the first transatlantic telegraph cable in 1866. Today, we have mastered both data transmission across continents and grid interconnection across countries.
Looking to the future, mega projects like X-Link in Morocco and SunCable in Australia envision transmitting vast amounts of solar and wind energy across continents. These initiatives, despite their challenges, represent a significant step towards a globally interconnected grid.
In conclusion, while we do not yet have an HVDC connection across the Atlantic, the technological and economic foundations are being laid, with more profitable and less risky alternatives being carried out first. As HVDC technologies advance, the possibility of an interconnected global energy grid moves closer to reality, promising a more sustainable and resilient energy future.
🔗 - Check these out
Cool links, related or not to sustainability, you might enjoy:
A video retracing the history of the Atlantic telegraph construction.
From San Fransisco 🇺🇸,
Jean
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