Many years ago, I read that Iceland has huge hydroelectric power and geothermal power potential-far beyond what a nation of 400,000 people could ever use.
The article said that electricity cold be sent to the UK, via high-voltage DC transmission lines, laid on the seabed. Since the distance is over 800 miles, this would be a very expensive project.
My questions:
-can it be done (at any cost)?
-are present insulation materials sufficient to shield these cables which are miles deep in salt water?
-would such electricity be cheaper than power generated locally in England?
It sonded like a neat idea-and would be zero emission as well?
-can it be done (at any cost)?
Sure. The costs are rather large, but not ridiculously so. You are talking about a line that is roughly the same length as the pacific intertie in the U.S., which is also a high voltage DC transmission line. This would cost a bit more since the pacific intertie doesn’t go under water, but it could certainly be done.
-are present insulation materials sufficient to shield these cables which are miles deep in salt water?
Yep. We’ve got plenty of underwater cables now. There’s a high voltage DC cable under the Baltic Sea that connects Germany and Sweden, for example.
-would such electricity be cheaper than power generated locally in England?
I seriously doubt it.
Two things occur to me:
- Why send it to England, when other parts of the UK are much closer?
- Even if it is a huge surplus for a population of 400,000, that doesn’t necessarily mean it would be of practical interest to a country of 60 million people. It might barely make any difference to the UK’s energy needs.
In case you want to compare this to reality, here’s a description of the NorNed HVDC link, which is currently the longest underwater HVDC link in the world:
(Warning - PDF)
The costs would be the installation and maintenance of the cable and the increased maintenance of the generators used at higher capacity (or new ones if the existing ones are insufficient). So it sounds like you are saying these additional costs, and the losses due to the distance exceed the fuel costs for local generation. Is that the reason for your doubts?
Of course, if fuel costs go up, projects like this start to look more attractive.
There are of course already undersea power links to Ireland and France from the British mainland.
The distance from Labrador to Newfoundland through the strait of Belle Isle is much snorter, Labrador has huge hydro power and the province has not been able to send the power from the one to the other. It is a current campaign promise to build a cable, but it will be quite expensive (some billions). The main problem is that you cannot just lay a cable. It has to be buried deeper than any iceberg will scour. And icebergs in that channel can scour quite deep. I assume that the waters between Iceland and UK (or Ireland) are also scoured by icebergs.
Off the subject, I don’t understand why the Newfies don’t make use of their windswept and essentially uninhabited central mountains to put up wind power. Then they might need the cable in the other direction. But they should at least be able to power the island.
Yeah - it’s a capital cost kind of thing. If a MWhr cost $45 locally in variable costs, and you can get it for say $5 from hydro abroad, then that’s great. But you need to then look the MWhrs per year (let’s say it’s 500,000). [Note that these are totally made up numbers - I’m just trying to show how the calcs might look, dumbed down).
So, you save 40 * 500,000 per year - or $20 million. You would also need to deduct the costs of maintaining the cables from this, but let’s ignore that for now. If you assume a useful life of 30 years, a discount rate of 10%, and a steady $20 million in saving, then the present value of the energy savings would be about $161 million. You might also assign a value to the capacity, depending on the markets and the stability of the generation. Anyway, if the cost of building the generation assets and the trasnmission was less than $161 million, including a risk premium, then you would go ahead and build. If not, you wouldn’t.
It’s a pretty straight forward analysis, so it’s safe to assume that it’s been looked at, and since it hasn’t been built, it’s most likely not econimical. Of course, that can change as fuel prices go up and technology costs go down. And there could always be things like political road blocks and the like. But, based on what I know, my guess would be that it’s probably way out of the money at this point in time.
Why DC? Isn’t an advantage of AC was that it is cheap and easy to send long distances using transformers?
That was the case in terms of the early developement of transmission, but HVDC is now the more efficient means of long distance transmission.
Rather than send off excess electricity, what makes more sense is to move industries into Iceland that require a lot of electricity. That’s what Alcoa has done, building a large aluminum refining plant in Iceland. Alcoa built a new hydroelectric plant to power it. The new plant puts out twice the electricity previously used by the entire island.
Yes - this is almost always a better solution. But sometimes it’s difficult if the end product needs to be shipped further, or if a certain type of workforce or natural resource needs to be located nearby - and, of course, the regulatory environment needs to be competitive in terms of taxes, licensing times, etc.
If you look at some places that were getting into LNG back before shale gas sent US natural gasses prices down - like Trinidad and Tobago - they’ve now switched from exporting via LNG the oil drilling natural gas by-product (that they used to flare-off) to making an effort to bring in industries that require the gas. Much better for their domestic economy. But it took a concerted effort by the government and it was really driven by the decline in the natural gas prices and the lack of US LNG imports. So, if Iceland has that length in clean power - they should try to find a way to use it to attract some energy intensive businesses that could make good use of it.
Why not do both?
Yep, that’s pretty much it. I haven’t tried to crunch any numbers or anything, but I suspect that the cost of all of the equipment involved divided over the life of the system would be more than large enough to offset any potential savings.
The advantage of AC is that you can very easily step the voltage up and down using transformers. An AC transformer is basically just a couple of coils of wire. Stepping DC voltages up and down is much more complicated and involves much more expensive equipment. Back in Edison’s day, DC transformers just weren’t practical. These days we can make them, but they are rather costly compared to an AC transformer.
Once you’ve got the voltage stepped up, though, DC works better for transmitting longer distances. AC is a sine wave, and you have to size your wire and insulators and all of your equipment to handle the peak voltage and current. Effectively, though, you only get the RMS “average” value of power out of it. DC, by comparison, always runs at peak, so for a given wire size, insulation, etc. you can always shove more power across the wire using DC.
AC has inductive, capacitive, and resistive losses. DC has the resistive losses, but eliminates the inductive and capacitive effects. This also makes DC more efficient at longer distances.
DC switchgear is more expensive. High voltages arc. If you try to turn off power on a line with AC, the voltage will arc across the switch contacts. Once you reach a certain distance, though, AC tends to extinguish itself due to the fact that the voltage drops to zero twice during every AC cycle. Since DC voltage is constant and never drops to zero, it is much harder to extinguish the arc and requires fancier switches.
What this all means in practice is that for a given amount of power, the wire is cheaper for DC and all of the equipment on both ends is cheaper for AC. At shorter distances, AC therefore is more economical. Once you get into longer distances where the wire savings beats out the equipment cost, then DC becomes more economical.
If you are going under water, the AC capacitive losses are even worse, which makes long distance AC lines impractical. The NorNed HVDC link I mentioned upthread couldn’t be done with AC. The line losses would just be too great.
Well, if you use the power domestically and you set up the infrastructure to continue to make good use of it domestically - then you are reducing the amount that you can send abroad.
And sending power over long distances ir really a matter of scale - it’s capital intensive. So, if you’re going to commit to spending a lot of money to build the HVDC, you need to ensure that you can use it at nearly maximum capcity, in order to spread the fixed charges over as large of a volume as possible. As you reduce the amount of energy flowing, you increase the cost per MWhr of the fixed maintenace and capital costs that must be recovered on a per MWhr basis - therefore making the project less and less econimically viable.
So, going both routes is not a great choice - if you’re going to invest the capital, you really need to go all out - diverting the energy to other uses will make what is already an unattractive investment even worse.
Now, if you have the ability to ramp up a tranmission line to max capacity and still have excess - then sure, go nuts and develop domestically as well.
At least part of the way between Iceland and England, the ocean is over 6000 feet deep.
Dumb question, but if one wanted to move power from Iceland, aren’t there parts of continental Europe that would be closer than the UK?
Quoth engineer_comp_geek:
Once you get up to continental-scale distances, radiative power loss also starts becoming significant with AC. This is why the US is divided up into three mostly-separate power grids: Trying to put the whole country on one (AC-connected) grid would basically turn the entire grid into a giant antenna.
You would do a cable from Iceland to the Shetland Islands first. Then split it, and run cables to both Norway & Scotland, which are roughly the same distance away. That gives you 2 markets to sell your excess electricity. (But still rather small markets – the Shetland Islands, northern Scotland and western Norway are all rather sparsely populated.)