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Comment by fmajid | Hacker News Reader

There's this incredible project to build a 10GW solar farm in Morocco (1/3 of UK peak consumption) and bring the power to the UK via HVDC cable. Amazingly they estimate only 10% losses despite being over 3800km long:

https://xlinks.co/morocco-uk-power-project/

Surely HVDC links between Scotland and England could be built?

And then there are pumped hydropower storage project like this one with a proposed storage capacity of 200 GWh and 1.5GW of power:

https://www.coireglas.com

In the worst case, couldn't the excess power simply be used in electrolyzers to generate hydrogen? They may not be very efficient but it's better than throwing free energy away.

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> "Surely HVDC links between Scotland and England could be built?"

Absolutely. One HVDC link between Scotland and England (actually, Wales) has already been built:

https://en.wikipedia.org/wiki/Western_HVDC_Link

And more are planned:

https://en.wikipedia.org/wiki/Eastern_HVDC

> Surely HVDC links between Scotland and England could be built?

The article covers this and explains why it's not enough. Provisioning time for the links exceeds projected generation capacity increases in the Scotland.

It seems like the planning isn't so great, though. They expect to have another 4 GW of links by 2029, which is enough for the wind overshoot today, but there will be a lot more wind by 2029... so, double the investment and build 8 GW of links by 2029.

I'm sure the people in charge of the project wish they could snap their fingers and double their budget.

The dumb thing is that electricity transmission and distribution are usually fixed. This already doesn't make sense because it's peak demand that drives the capex. Opex is peanuts.

But the retail buyer doesn't usually see the negative/low electricity prices of high-supply+low-demand time periods for their "inefficient" uses that should still be economic.

> "But the retail buyer doesn't usually see the negative/low electricity prices"

There are electricity suppliers in the UK who offer prices linked to the wholesale price, including actually paying you to use electricity if the price goes negative. Quite useful for flexible loads such as EV charging!

https://twitter.com/DanielColquitt/status/139539635553586790...

> Surely HVDC links between Scotland and England could be built?

why would this be necessary when the entirety of Great Britain is one synchronous grid?

Strangely there already is one between Scotland and Wales and two more are proposed (see the article).

I suspect NIMBYism is a big part of the explanation. Airborne AC links are efficient but ugly. Underwater AC links are tolerated by Nimbies, but inefficient. So you end up with underwater HVDC links.

HVDC links are more efficient than terrestrial AC transmission lines over long distances.

Also a lot more expensive. The UK is not big enough for it to make technical sense.

> The UK is not big enough for it to make technical sense.

The UK market maybe not, but the UK could make a truckload of money selling their wind power to France to aid their old, barely running NPPs.

And that is happening. There are multiple cross channel HVDC lines and more on their way. These make perfect sense.

The equipment costs (eg: converter stations) for an HVDC link are more expensive, but by running under the sea you save on a lot of other costs (ie: civil engineering, land acquisition, etc).

Building any new transmission line through densely-populated England is extremely expensive. Even if you can secure the necessary land and wayleaves, nobody wants them running near their house and spoiling the views, so significant segments have to run underground in tunnels, greatly increasing costs.

Besides, the UK is not that small when linking England and Scotland. The proposed Eastern Green Link 2 (EGL2) is 440 km long: there are many existing HVDC connections much shorter than that around the world!

Most of these issues are not technical so I stand by my assessment.

You are absolutely right. Building pylons through much of England means dealing with highly organized NIMBYism - from people who care a lot about their local 'environment' but very little about catastrophic floods or fires in other countries, and highly opportunistic landowners who can name their price for use of their land.

DC links are usually built to better control frequency in grids.

They are expensive things, and typically not something left to popular vote.

> "why would this be necessary when the entirety of Great Britain is one synchronous grid?"

Because there are bottlenecks in capacity on the synchronous grid that restrict the amount of power that can be moved from north-to-south (or vice-versa).

It works out better/cheaper/easier to bypass those bottlenecks with efficient undersea HVDC links than to try and build more terrestrial AC transmission lines.

I hope they will have good anti-submarine defences. And one more strategic dependency on another country.

Are you referring to Morocco or a potential future independent Scotland :-) ?

I am not too worried about Russian submarines meddling with the undersea cables between england and scotland…

Did you read the article? The Eastern HVDC will run from Peterhead to Drax via the North Sea.

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