The Seagreen offshore wind farm is reported to cost £3bn for 1GW capacity, although wind power is only available on average at ~50% of rated capacity, so the cost works out at £6bn per GW output. However this doesn't include the cost of backup generation or storage, for days when the wind doesn't blow.

The Sizewell C nuclear power plant is reported to cost £20bn for 3.2GW capacity, so the cost works out the same at £6bn per GW output. However this doesn't include the unknown cost of decommissioning.

The nuclear plant will last longer than the wind turbines but I imagine will need more maintenance.

Don't think it's either/or, we probably need both.

Don't think it's all about upfront cost either, otherwise we would choose gas power stations.

https://www.seagreenwindenergy.com/

Posted By: djh

I wondered: what else would 20B buy?

A big pile of insulation
Alot of bikes
Extensive cycling infrastructure
A fair few trees and restored wildlife habitat
Any change can buy garden soakaways for all

Posted By: fostertomHow many centuries wiill old windfarms remain a lethal danger to life on earth

Say what?

Doh, thanks Ed - I must have had a stupid moment there.

Posted By: fostertom"The Hinkley C power station will suck in 29,000 gallons of sea-water every second, heat it up by about 10°C and send it back into the estuary, wasting more energy into the environment than the electrical power it will generate"

Hmm if I have my arithmetic right that's 131,836.61 litres which makes the power 131836.61*4182*10 W or 5.5134 GW

https://www.newcivilengineer.com/innovative-thinking/tunnels-delivering-hinkley-point-cs-cooling-system-16-12-2019/ says its 120,000 l/s so a bit lower but it does seem a plausible number and it does seem an awful lot of energy to dump into a relatively restricted area of water. A lot more than HP B has been dumping.

I read 56t as 56 trillion, not 'only' 56 tonnes - so that's OK then.

Reminds me of this, from my normally anodyne parish mag:

-------------------
Wind Turbines: We Should Know This

Nationally, wind turbines kill 10,000 - 100,000 birds per year. Cats kill 55 million birds per year. If you paint 1 turbine blade black, resulting bird deaths decline by 70% (BBC Science). The RSBP says “in suitable locations, turbine impact on birds is minimal’.

World expert on bats, Dr. C Voight, says that one turbine kills 10 bats per year.

There is no detailed knowledge on turbine effect on insects, but this year, the UK Govt. gave sugar beet farmers permission to use the most harmful chemical (neonicotinoids) against bees!

New generation turbines make the same noise level as a tractor at the same distance from you: a gentle swish (Danish Govt.).

When we buy electricity, we subsidise the electricity company. How much do we pay? Nuclear energy costs nearly £92 per unit. Wind energy costs £45 per unit. Which do you prefer?

Our landscape is beautiful. Let’s keep it that way with sustainable electricity. Climate change is a real issue. The last 7 years were the hottest since records began (Met Office).

When your children and grandchildren ask what you did to slow climate change, what will you say?
-----------------------

BTW, the above is my first (completely faultless) use of newly rediscovered OCR-enabled MS Office Doc Imaging, in Office Pro XP but the OCR omitted in later versions. I knew I used to rely on it but couldn't find it online, anywhere. Eventually discovered my old Office XP install disc - and there it was, happy to run on W10.
Also on same disc is super-capable old fashioned MS Office Editor, with serious old-photo enhancement capabilities, like Despeckle and much more. I processed some old familiar 2 1/2" x 3 1/2" Brownie b/w family pics, printed them at A4 - staggering hi-definition, faces a revelation of their youth (then) and character, not seen in 50yrs!
Look thro those old boxes and drawers, see if you still have your Office XP!

That's Carnot for you! The thermal efficiency is limited by the 2nd Law. That means that only some of the nuclear energy can be used, the rest is too low a temperature, so it has to be dumped somehow. Same idea as the cooling towers on an old coal power station, some of them had seawater cooling instead. Also similar to how a PV panel only turns some of the sunshine into electricity and dissipates all the rest as heat.

5GW of "waste" heat at 20degC isn't much use to anyone in Somerset. If instead it were at say 50degC some could be used, say if Bristol and Cardiff shared a district heating system, but it isn't and they don't! The heat would then be dumped into the air from the roofs and windows, rather than into the sea.

Edit
https://en.m.wikipedia.org/wiki/EPR_(nuclear_reactor)
Suggests the two reactors will produce 2x4500MW of thermal energy, of which 2x1650MW will end up as net electricity, an efficiency of 37%. The rest (63% or 5.7GW) needs to be dissipated as waste heat. That's why it's sited next to the sea!

The core temperature is apparently kept to only 315C to avoid boiling the cooling water, so the maximum possible theoretical Carnot efficiency would be 48%. The real world efficiency is somewhat less than that.

A CCGT runs much hotter, so is more efficient, but the economics are different - the CCGT must be efficient with its expensive fuel, whereas the nuclear station must run within conservative operating limits due to its expensive hardware.

So it is slightly unfair to compare the "wasted energy" from a nuclear plant against that from a fossil plant, or even a wind turbine or PV panel - different economics apply if your 'fuel' is cheap or free.

The prices quoted in FT"s parish news for nuclear of £92/MWh look like a bargain when gas electricity is £180/MWh, like it is this week, but who knows what it will be in future. The price quoted £45/MWh for wind is continuing to fall. But those prices miss out large "externalities" of emissions (gas), decommissioning (nuclear) and backup/storage (wind).

Posted By: WillInAberdeenThat's Carnot for you! The thermal efficiency is limited by the 2nd Law. That means that only some of the nuclear energy can be used, the rest is too low a temperature, so it has to be dumped somehow

Oh that - I get it. They've written it to look like all the power generated, plus more from elsewhere, goes into running the pumps.

Posted By: WillInAberdeenBut those prices miss out large "externalities" of emissions (gas), decommissioning (nuclear) and backup/storage (wind)

and 'forever' storage and military guarding of radioactive waste.
http://www.greenbuildingforum.co.uk/newforum/extensions/InlineImages/image.php?AttachmentID=6087

Posted By: fostertommilitary guarding of radioactive waste.

FWIW, nuclear waste is not guarded by the military (at least at the front line). It's a civil police force job.

Posted By: SteveZ
I would rather we spend the money on developing a molten salt reactor

That, and scale up the energy amplifier for useful processing of nuclear waste whilst extracting more energy:
https://en.wikipedia.org/wiki/Energy_amplifier
It might need a bit more than £10B though.

The proposed tidal lagoon at Swansea Bay would have a capital cost more than 3 times as much, per unit of electricity, as the Hinkley Point C nuclear power station and is much smaller but also doesn't need wind but isn't continuous either.

Interesting read:
https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/719189/tidal-lagoon-programme-factsheet.pdf

Isn't this a bit of cherry picking? Is it really cheaper when you add the construction costs, running costs, decommissioning costs, waste storage costs and incurred security over thousands of years. I really cannot see how it is.

As for if the lagoon could be a continuous producer I don't see why it could not be designed to be.

Nuclear is an old technology that despite having ridiculous amounts of money thrown at it has never really produced the goods. Time to consign it to the dustbin where it belongs.

As I mentioned, "those prices miss out large "externalities" of emissions (gas), decommissioning (nuclear) and backup/storage (wind)."

Just for clarity, the tidal lagoons referred to are proposed in Swansea Bay, which has nothing to do with the defunct Severn Estuary tidal dam proposal, it's 50 miles away up the M4.

The unpriced externality for a tidal lagoon is that you need to keep another significant power source on standby, used twice a day, as a lagoon cannot produce continuously at peak times. That standby could be another lagoon further up the coast, where the tide times are different.

Another unpriced externalitity for a tidal dam is that it trashes a lot of estuary habitats, which are turning out to be significant carbon stores.

UK has recently licenced 33GW of offshore wind farms, so all the publicity around a single 3GW nuclear station would normally seem disproportionate, except that the wind farms are intermittent and will be critically dependent on backup power.

The backup power stations can be : Nuclear; or fossil fuels with CCS; or TWh-scale storage. As of now, only one of those technologies exist in the UK. The others could/should probably be developed, but meanwhile there is not much scope to be choosy!

Possibly, but peak demand in the UK (5-7pm UTC) is after nightfall in most of the Sahara, so storage on previously-unimagined scales would still be required, as well as transmission.

I'm quite keen on imagining the previously-unimaginable, but time is running out (has run out?) so we also need to build things that already work at multi-GW scale.

But there's certainly a strong case for trading UK wind power for Algerian PV and Austrian hydro (or Australian hydrogen) for political as well as environmental reasons.

Edit: on the cost comparisons - wind and nuclear are now seen as cheaper than tidal power, but that is partly because taxpayers subsidised decades of their technical and commercial development phases (FITs etc). There could be an investment value in paying over the odds for the first few tidal lagoons (wave farms, electrolyzers, CCS projects) if one of those gives us cheaper energy options in future.

Posted By: Jonti
I understand that there is a problem with destruction of habitat and carbon storage/release but there has to be balance where by yes a habitat might be destroyed but it might also lead to the saving of many others. Doing nothing is not an option that has a good outcome so it might be a case of the lesser of two evils

There are many examples where wet habitats recover very quickly and thrive after civil engineering messed with their water levels, contrary to what many predicted. I am not saying we should just go ahead with whatever and count on nature recovering but as you say there is a balance to be struck.
Unfortunately it is really hard to predict or model how habitats would change, nevermind account for the net CO2 effects of those changes.