The greenness of geothermal power is pretty variable. It's low carbon, but if it's extracted at a rate higher than the rocks' recharge rate (as is often the case) it's far from sustainable. I don't know what rate the Icelanders are extracting heat at currently, but I'm concerned that coupling them to a much larger market such as the UK (and therefore the rest of Europe) would put a lot of economic pressure on them to up it substantially.

The losses on a 1500km undersea cable would be pretty gnarly too.

Having said that, I think on the whole it's a good idea, if it can be done economically. More interconnectors are a good thing in general IMO.

HVDC is used in Quebec where some of the connections are over 1500km long. End-to-end losses (including conversion) are less than 6%. Conversion losses are pretty low. The advantage of using DC is that it protects you against grid disconnects if your frequency goes out of whack (this is part of the reason HydroQuebec had to put in HVDC for the interconnections to the US grid - their frequency regulation for AC wasn't good enough apparently).

See http://www.abb.ca/industries/ap/db0003db004333/87f88a41a0be97afc125774b003e6109.aspx for a 1500km link from Radisson in the north of Quebec to Boston

Paul in Montreal.

It's all intended to be part of the pan-European super-grid that will also link in North Africa and the serried banks of pv as per...

Ref pps 178/179 of 'Sustainable Energy — without the hot air'.

See... http://www.youtube.com/watch?v=TqJPreSAFOM

Not much more than that in the GB grid overall, and the bulk is in distribution. Transmission losses average at ~2%.

And even if we did 'waste' 20% of the energy in transit, given the lack of fuel that went in, and compared to losses in heat engines such as conventional thermal generators, would that be so bad?

Rgds

Damon

UK politicians are soooo stupid for not making a deal with iceland for access to their geothermal and hydro resources in exchange for the icelandic bank 'debt' to the UK.


This link is IMO absolutely vital if the UK (and Scotland in particular) is to have anything like the levels of onshore and offshore wind that's planned, as it will enable us to use Iceland as part of a buffer system to take excess wind generation and supply back up to that wind in lull periods.

This should actually work very well for Iceland as well, as it means their geothermal and hydro should have better chances to recharge during the periods when UK wind is supplying Iceland. It also boost the resilience of Iceland's power grid, which is vital to the Icelandic economy as they're now hosting several server farms, and in the running for more I believe.

Posted By: tonyIceland dont need us for energy! They are more than self sufficient have access to virtually unlimited heat and plentiful sources of electricity.

they don't need us in the same way that we need them, but data centres that need 100% guaranteed reliability will view this favorably.

Has anyone considered the heating impact of cables on seabed plus the of rapid increase in coastal based biomass powerplants dumping two thirds of the energy into the sea? We are told rising sea temperature is the main climate change concern, just a thought!

Posted By: tonyone million billionth

Is that a definitive number

Easy enough to work out, so simple in fact that I am not going to bother

Energy loss in cable* SHC of cable *Mass of cable*(Temperature of cable-Temperature of sea)

Stick on the upper and lower bounds of the energy losses, impurities of the cable, the mass of the cable, the sea temperature and I would start to think that 1 part in a 1000 trillion is a gross estimate

I like these big engineering projects, let's just do it, we only need to import about 20% of our current energy usage at the moment, so if it all goes horribly wrong and the cod start spawning too early or too late, we can turn it off and pop in some more insulation.

Tony?

Ed...

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Posted By: BrianwilsonHas anyone considered the heating impact of cables on seabed plus the of rapid increase in coastal based biomass powerplants dumping two thirds of the energy into the sea? We are told rising sea temperature is the main climate change concern, just a thought!

somewhere between miniscule and negligible.

Actually, this is a more detailed reference on what I'm saying.

http://physics.ucsd.edu/do-the-math/2011/07/galactic-scale-energy/

Posted By: tonyNo, we are a ball orbiting in space which is very cold, the sun keeps us warm, even if we tried we could not generate sufficient energy to boil ourselves as as or temperature increases so do our heat losses, this is a fourth power relationship as discovered by Stefan...

Exactly.

Current human energy use is about 2000 W / person with 7 billion people so 14 TW. If that grows at 2.3%/year for 450 years (sorry, misremembered the exact number of years) we'd be using 14 * 1.023⁴⁵⁰ = 389191 TW.

Current solar input is about 1000 W/m² * pi * R² (radius of the Earth, roughly 6371000 m) = 127516 TW.

So if we used all the solar energy available then got the rest from fusion or something then we'd be roughly tripling the heat the planet has got to radiate.

The current average temperature is around 15°C. The new temperature would be:

Math.pow(Math.pow(15 + 273, 4) * 3, 0.25) - 273

(I.e., current absolute temperature to the fourth power, multiply by three, take the fourth root and convert back to Celsius.)

which comes to 106°C.

Of course in reality we wouldn't get to that point. My minor near-parenthetical point was that, though the heating effect of the losses from a cable of this sort would be negligible, in the much longer run such heating would ultimately become a concern even if nothing else bit us first.

Posted By: Ed DaviesIf that grows at 2.3%/year for 450 years



Of course in reality we wouldn't get to that point.

Indeed we wouldn't. When considering resources and growth, it's a mistake to think you can model it simply as continual geometric or exponential growth. That was were Malthus went wrong. Things like the logistical model have turned out to be more accurate, where even if the growth looks exponential in the early stages, there may be influences that are too small to notice which significantly restrict growth later on. In short: s-shaped growth.

I suspect energy use, like population growth (and largely linked to it) will plateau at some point.

Peak oil, shmeak oil. Demand will keep growing, when oil gets too expensive it'll just push us towards other energy sources. I have zero faith in humanity's ability to keep demand under control over the next hundred years. There's just too much growth coming from the developing world.

Energy use will be largely determined by population and economic growth. It'll only stop growing when the population stabilises and the majority of the world's economies have reached the point where economic growth decouples from energy use.

Ah well, I'll only be seeing temperatures like that when the conveyor takes me into the crem's furnace. And no, ST, I don't believe in the other place either, so don't go wishing me there.