Another advantage to DC is that it can be shipped around in “bulk” so to speak and there’s no issue with matching frequency and phase. With AC, just traveling a long distance will make the phase lag - the speed of light is very fast, but after 1,000 miles of wire, there will be a significant difference that needs to be corrected before the power can be added to the local grid.
Also, the wiring for DC can be smaller (and cheaper) than for AC as at these crazy-high voltages, AC wants to travel on the surface of the wire, rather than completely in the wire. This is a phenomenon called skin effect. DC will flow through the entire cross-section of the wire and make more efficient use of the conductor.
It sounds like they already have more than enough capacity, or close. They’re going for energy independence by 2050, but it’s mostly transportation fuel oil they need to replace at this point right? I thought they do have, or easily can have, excess capacity they might as well sell.
My question is, once they get lines to the UK and Norway for instance, is there a limit to how much further they could sell electricity?
They certainly have (or could have) excess capacity. But you want to make sure that that excess capacity is equal to or greater than the maximum amount that could be trasnported on the largest line available to be built (because the largest ones are the most economical in terms of being able to support recovery of capital costs, at least when used at max capacity). I don’t know the exact numbers in terms of what kind of capacity is readily available there, but it’s a consideration.
In terms of your question - yes, the limit is caused by a combination of engineering and econmics. There are three major considrations - line losses, capital costs, and maintenance. The longer the line, the higher they become.
[all numbers below are made up for point of illustration / how to do the calculation]
Say you wanted to go X distance and the line losses were 10% and maintenance costs are 0.5 million per year. If the variable costs of operation were $7 per Mwhr, you had a capacity of 1,000,000 MWhrs / year (which means you deliver 90,000 after lossses), your initial capital costs were $500 million, your discount rate is 10%, the useful life of the asset is 30 years, and you assume flat prices and costs in terms of generation costs and purchase price. Under these assumptions, you would need to be able to sell the power at $66.44 / MWhr in order to have a NPV positive project.
But, if you wanted to go distance Y - and that increased the losses to 12%, the maintenance costs to 0.6 million per year, and the capital costs to $550 million, keeping all other variables the same, you would now need to be able to sell the power at $78.04 / MWhr in order for the project to be NPV postitive.
So, the length is limited by the econmics - basically you want to find the mix og the best market at the shortest distance.
Of course, other utilities can always ‘wheel’ the power across existing lines, but losses will be greater than a HVDC line and the economics of existing ties will alway be incorporated into the LMP prices of wherever you’re deilvering to, so it doesn’t really mean much.
At a guess, I would suggest that the weather is very very unreliably horrible. Based on my experience here, my suspicion is that you would spend as much time maintaining the damn things as you would generating power.
I’ll look into an actual informed answer when I get a chance.
Put simply the evil Icelanders owe us £3.5 billion pounds as punishment for forcing us to put all our money in Icelandic banks. How dare they! I surmise that if this cable existed, and Iceland supplied most of the UK’s energy needs, the boot would be on the other foot. They could turn off the power and laugh as we freeze during the winter. Damn them.
And of course if they can build a cable, they could probably build an underwater tunnel through which legions of Icelandic stormtroopers would invade the UK. They would start with Scotland - the hardest part - and then work south. I tell you, war is inevitable; we need to build a large metal fence around the north of Scotland, quick, before the Icelanders get ideas. They beat the Royal Navy in the Cod Wars, Bjork conquered the pop charts, it’s only a matter of time before they actually literally try to actually conquer-conquer the UK. And make us all Icelandic.
Do you have a source for this? I was under the impression that the separation of Eastern and Western grids occurred because the grid growth followed population growth which came from East and West coasts and that as the local grids became interconnected the phase strength of the two large grids became too strong to connect them. It would be like trying to tie two ocean liners together with thread. One thread could not synch to ships together.
The third Grid ERCOT (Texas) was actually somewhat political in that during the time when local grids were creating interconnects with each other the Texans were wary about any action which might place their rich local energy product (oil) into the domain of federal transportation. The Texans had some control over transport of their oil but feared that they would lose some of that if the feds could convert it to electricity and ship it out. Texas also had issues with federal reliability requirements and that keeping their grid in-house they avoided those issues. Just like the other grids, by the time that those issues were less important, the Texas grid was too large to synch over one tie or a few ties.
I don’t refute your claim. I’m just interested in this stuff and want to read more.
I’m skeptical as well. They’re transmission lines, so radiation from current flowing in one direction is canceled by current flowing the other direction on another conductor. Also, any unbalanced current will tend to be canceled by image currents in the Earth at these frequencies.
There is an issue with a large system, though, in that resonances can develop. At 60 Hz, a half-wavelength is about 2500 kilometers. With a system that large, energy can “slosh” from one side to the other, with bad effects. As the system get larger, those resonances get harder to suppress.