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Installed capacity has meaning for hydro power, coal and nuclear. For solar and wind, it is like the relationship between the maximum speed on your car's speedometer vs what the roads and traffic allow.

Here is what all of the wind power in UK is generating in this live grid display:

https://www.gridwatch.templar....

If you look at the tiny graphs under the dials it displays wind power as a blue line in the second column. It peaked at about 5 GW wind production on Sunday Sept 2, and then was nearly zero Monday morning. The concept that the wind is always blowing somewhere is not true for a place as small as the U.K.

Here is a real time G.B. National Grid Status, shows that wind is 15% (as I type).

The G.B. National Grid Status provides an overview of where the electricity is coming from.

I think the biggest issue is getting enough sun on them.

In the UK, we had a bit of weather on Monday, snow everywhere (was brilliant!) so on the day that we needed power the most - as it was bloody cold - all the solar panels were covered in snow, and the sky was cloudy, and as it was a snowy day (ie there was a big high pressure area over the UK) the wind farms were barely turning.

Net result, as seen from gridwatch was that renewables were providing about 5% of our energy demand.

That's the problem with renewables, great to reduce overall yearly carbon contributions, but useless on the worst days, which are the days when we need energy the most. So unless we can provide power from traditional sources, we would be screwed. The renewables lobby fails to appreciate that.

The French burn some coal to generate electricity since it's cheap, producing a few hundred MW on average. Germany burns a lot of brown coal and some anthracite (black coal) because it's cheap, to generate tens of gigawatts on average.

I get the 40GW French nuclear output figure from a near-real-time monitoring webpage at this site (which I referenced in my previous posting).

http://gridwatch.templar.co.uk...

French electricity demand peaks at about 80GW in January when it's cold and dark at which time EdF attempts to have all their reactors on-line to meet the extra demand (hence the refuelling operations being scheduled during the summer). Throughout January this year they produced nearly 60GW of nuclear electricity pretty much continuously. They do burn more coal during winter in part to make up the difference.

Which part of "for nearly all" did you miss?

France burns very little coal through the year to generate electricity, unlike its neighbour Germany which burns over 170 milion tonnes of mostly brown coal each year.

As for hydro yes France also gets a chunk of its electricity supply from that source, mostly from the French Pyrenees, assuming it's been raining or snowing sufficiently. They also have a small tidal barrage power station as well as some grid solar in the south of the country and some wind farms.

Right now, as I type this France's electricity demand is about 50GW. Of that 40GW is supplied by nuclear power and about 8GW comes from hydro. They are getting a grand total of 350MW from coal right now, 3GW from gas and 4.1GW from solar plus some power from other generating sources such as biomass and wind.

http://gridwatch.templar.co.uk...

Yes that does add up to more than 50GW. France is exporting 3.5GW to Spain, 2.5GW to Italy, 2GW to Britain and 350MW to Switzerland while importing about 1GW from Germany. It almost always exports more electricity than it imports by a significant amount because it doesn't cost any more to keep the reactors running at full power since the fuel is cheap. Saying that they tend to refuel their reactors during the summer on a staggered basis as demand reduces so some of their nuclear capacity drops out at that time.

France has a higher demand per capita for electricity than most other European countries since their nuclear-generated electricity is cheap and so they use it for heating homes and other buildings and for industrial processes rather than burning lots of imported gas. That's why their carbon load per capita is way lower than virtually any other comparable European nation.

Oddly enough cock-womble appears to have the march on you. The UK at least uses a lot more power at night during the winter. See http://www.gridwatch.templar.c... As ever a mixture of power sources is likely to provide the best results globally.

So France subsidies nuclear power and meanwhile purchases electricity from Germany?

Not quite. Sometimes France imports from Germany, sometimes it exports. At the moment (14:00 CET, 7/3/2016) France is exporting around 2GW to Germany.

Also, not all French electricity is nuclear, at this moment it's 73% nuke, 13% hydro, 8% gas and 3% coal.

http://www.gridwatch.templar.co.uk/france/

50MWhr is big for a battery, but it's not exactly impressive on an electricity generation scale. Right now France is consuming 45.78 GW, 44.54 GW of which is nuclear.

So one 50MWh battery would last about 4 seconds. You'd need 900 of 'em to power the country for an hour.

(France chosen as an example 'cos I live here and the great Gridwatch site has the numbers)

Right now, as I type this, France is importing 2.5GW of electricity from Germany and 450MW from Switzerland. It is exporting 2GW to Britain, 2.6GW to Italy and 890MW to Spain though, a next export from France of 3GW.

You can find real-time details of France's generating capacity, imports and exports at this website, http://gridwatch.templar.co.uk....

I've seen times on this page when France has been exporting as much as 10GW of electricity to other countries (Britain in particular takes 2GW of cheap French nuclear electricity nearly all the time). I don't think I've ever seen a case where France was importing more electricity than it exported.

Up till now Germany has been selling it to (among others) France, for almost nothing.

For example they're currently exporting about 2.5GW to France.

http://gridwatch.templar.co.uk/france/

Yup, I'm going to be keeping an eye on http://www.gridwatch.templar.co.uk/france/

Wonder if we'll see an effect on the German export/import dial?

France right now, at this very second, is fuelling 98% of their demand with nuclear.

http://www.gridwatch.templar.c...

It's not really overstated, but it is very good to have wind power over a wide area.

The main advantage of geographically distributed wind power is that it smooths out the changes.

So it still comes and goes, blows really hard, and drops out almost entirely, but it takes hours to do that, because it takes the weather systems time to move around. Whereas if you only have one small wind farm somewhere, the wind can come and go in a few minutes.

The overall effect is that it makes the power much more predictable, the weather forecasts work better and the slow changes give you a chance to kick in other power sources. But it still comes and go quite a lot.

Here's the UK grid, you can see wind power wobbling around in more or less realtime:

http://gridwatch.templar.co.uk...

You seem to have reduced renewables to just wind and assumed that I think the country should be powered 100% by wind, That is incorrect.

I'm not, but I'm looking at the cheapest renewable. There is some hard (dispatchable), but highly limited renewables, like hydro and biomass. These can make some contribution, but it's rather small. If you look at the fastest growing ones, it's wind & solar.

Tepco lie habitually. Their own statements show they don't know what's going on.

Them not knowing doesn't mean you can just make stuff up and fill in the gaps with whatever you like. The linked article is still over a year old and could indicate a temporary condition. Moreover, it's notably light on radioactivity figures for the contaminated water. When you have a look at an article on the guardian which mentions at least some quantitative measurements, it says "quantities of radioactive caesium-134 and -137 in locally caught fish have fallen to levels close to the government-set safe limit of 100 becquerels per kilogram", while noting that it's "scant consolation". I don't know about other people, but knowing that the level of contamination is falling is indication that the situation is definitely improving. And 100Bq of Cs137 (by far the more active of the two) corresponds to concentrations of 0.22 picograms per kg of water (or less than 1 part in one quadrillion), that's pretty close to the detection threshold of the measurement hardware (which is very low) and means you really don't need to be worried at all. There's shitloads of other much more toxic stuff in much larger concentrations in that water that has nothing to do with radiation - honestly, think about the danger rationally.

Hinkley point will get tens of billions in subsidies at the guaranteed rate of £92.5/MWh - roughly double what will be paid for gas, coal, wind etc.

And I don't agree with that. Did you read what I wrote? I said Hinkley Point C was a bad deal.

If renewables are so unobtainable why are Scotland aiming for 100% renewable by 2020 after having beat their goal of 31% renewable by 2011 set in only 2007.

Because you don't understand how the accounting there works. They look at generation, divide by consumption and declare victory. But last I looked, Scotland isn't an island somewhere in the Pacific. In fact a significant amount of that will be pushed south and reimported from fossil fuel generation later when the wind isn't blowing. But since the overall generation divided by their rather limited population (and thus limited consumption) is high, they can declare "100% victory!" Unfortunately, in the big picture, they are hardly making a difference: http://www.gridwatch.templar.c... <- study these graphs, they're not made up. Portugal is probably the same story with Spain, but I'd have look it up (TBH, I'm not familiar with their grid, I know the UK's and Germany's and I've also studied German renewable growth vs CO2 trends - they won't make their 2050 commitment if they continue at the way they've been going since 2004. In fact, by my estimation after they have expanded to 100% renewables in 2055, they'll still be at 40% of 1990 CO2 levels. Can share the raw data, if you like.).

Iceland is 100% renewable electricity, and much of their heating is renewable.
Norway is 99% renewable electricity.

These two are extremely out of the ordinary examples. Both have very low population densities (Norway 1 order of magnitude less than the UK, Iceland 2 orders of magnitude) and both have specific geographies. Iceland is a highly active volcanic island, so it has ample geothermal resources (and I acknowledged that). Norway has lots of water flows, so it has plenty of hydroelectric resources (and I ackn

I don't see any need to do that, I never suggested that. Just make up some crazy math why don't you.

Oh sure, there's no such thing as a month-long wind lull (by which of course I mean time of very low production). Oh wait, just ignore June.

Note that Tepco itself has admitted that 300 tons of highly radioactive water is leaking.

Your reading needs work again: "Hirose stressed that Tepco does not believe all 400 tons of the water entering the sea is contaminated."
Contrast with what you said: "Are you aware that Fukushima is leaking at least 400 tonnes of highly radioactive water every day." Your link doesn't say it's all contaminated, or that it's "highly radioactive" (which I asked you to substantiate with figures again, and of course you can't).

The point is 0.007km3 is absolutely miniscule compared with hundred of massively larger reservoirs around the world which rand from hundres to thousands of km3 which givens them huge pumped hydro potential.

Go ahead, make the investment pitch and start building. Or you might for a second consider that people smarter than you have thought about this and came to a different conclusion, which is why you're not seeing the projects springing up like mushrooms after rain. Why do you think is that?

That would cost a lot more than £450 billion

Bold prediction, considering that's what a utility building the pilot deployment (= expensive) in the US is paying (where median household income is even higher than in the UK). Moreover, when you buy identical products in bulk, you get volume discounts and volume production benefits - that's pretty normal, even in nuclear power. Even using the hugely overpriced £17B Hinkley Point C, you'd still get ~40GW worth of power onto the grid (supplanting all fossil fuel sources) out of a total of 26 reactors. I don't think Hinkley Point C is a good deal for the good people of the UK and I think the government seriously dropped the ball there, but don't try and extrapolate one government's failure on price negotiation on one project to a whole global industry. If the government were serious, set policy so that industry would be reassured that they won't get whacked over the head by undue regulatory burdens down the line and not limit the selection process for political reasons (it has to be European or nothing!), you'd see utilities even in the UK being able to get much better deals, as others already get in other countries.

As of today, the UK is still getting this much from nuclear (19% right at this very moment). The shutdowns don't seem to have really made much of a decrease in the total nuclear supply.

http://www.gridwatch.templar.c...

Taking that many GW-hrs of production offline for that length of time is a serious outage.

It's still summer here, so there's probably lots of space capacity elsewhere. Few homes have air conditioning, the outside temperature tomorrow is forecast to peak at 21C in London. August is the month with the lowest demand.

There are some graphs and dials here: http://www.gridwatch.templar.c...

I'm surprised nuclear power varies over the year -- does anyone know why?

Clearly the price is heavily subsidized, with the subsidy going to the nuclear energy industry.

Ah, so we're into the "we're bad, but look, they're just as bad!" mode of argumentation. I'd ask you to provide evidence of this claim, but I know you won't, so I'll just roll with your assumption.

So subsidies can work both in favor and against a country's self interest - it depends on how they're applied. What needs to be considered is: do these subsidies redistribute taxation income in a manner that hurts the people? Let's look at taxation income and compare: France is again better off than Denmark. Sure that must mean that the extra money they spend on nuclear power means they have less available for important things like healthcare (nope, higher than Denmark, and better results too), military (nope, again higher than Denmark) and I'm sure I don't need to find you tons of links for the amounts of social security and benefits they get (which they are quite famous for). But hey, I found one thing where Denmark spends more: scientific spending. I'm sure the French are crying about it all the way to the bank.

Anyway, even if the French did heavily subsidize their nuclear power generation (which I don't think is the case - maybe a project here or there providing some loan guarantees; that's pretty standard), it's their prerogative to do, if they perceive it as a strategic goal. And regardless, you see the end effect: their economy is healthy and electricity production emits a fraction of the CO2 of Denmark and has done so for the better part of two decades. Meanwhile the heavily subsidized systems like Denmark's and Germany's continue to fail to produce results and are actually trending in the opposite direction or staying static in terms of CO2 production, while electricity prices are exploding. From a purely pragmatic and economic standpoint, I know which I'd choose.

1. Zero realistic cost-analysis. Wind doesn't blow? No problem, solar is here to save the day! (Except that just doubled the cost in installed generation capacity). Wind AND solar not there? No problem, geothermal/hydro/whatever! (Triple the cost.) And how do you site so much geothermal or hydro capacity, considering most places either don't have them (geothermal) or are already maxed out (hydro). Also hydro can't produce for one week at a crack, most dams are limited to 6-8 hours at full power. So gas peaker backup? (Quadruple the cost?) See these are the problems when you intend to build a grid with a reliability higher than that of some 3rd world country.
2. A demonstration of one ideal week is a sham. You need to look at worst case scenarios, not best case. And those are the things that dictate capital expenses, as you pay for installed capacity and only earn for delivered energy. If power plants (either fossil or hydro or geothermal) don't operate a considerable amount of their lifetimes, they'll either never ROI (i.e. go bankrupt or just won't get built at all) or they'll have to be operated at a loss to the utility, which will again just make electricity more expensive.
3. Transmission grids are only to temporarily even out partial outages of a small portion of generation capacity or sell of some small portion of excess capacity in one locality to another. What intermittent sources require is lots of high-capacity bi-directional transmission, i.e. tens of GW across long distances. These simply don't exist and constructing them will cost A LOT, not to speak of the amount of pushback from land owners.
4. Prolonged wind lulls and Solar non-production are commonly experienced on country-wide scale. Notice the . Where's that gonna come from? Are we supposed another 60 GW of solar just to cover this eventuality? And during those times that it's not needed, what will we do with it? Who's gonna pay for this?
5. Forecasting does absolutely nothing when your forecast is for a 2-week long wind lull. You can't just tell your users "sorry, no power for this week, wind ain't blowing". You have to do something. And we know what countries like Germany are doing: firing coal at record rates, increasing, not decreasing their CO2 emissions.
6. And all of this before we get into issues such as sub-synchronous resonance on the electric grid due to tens of thousands of turbines.

I'd also recommend, if you understand German, a talk by Hans Werner Sinn about the upcoming failings of the German Energiewende: http://youtu.be/m2eVYWVLtwE?t=... He calculates, taking real wind & solar daily production figures from 2011, that even if you take the seasonal opposite trend of wind & solar together and wanted to provide power at 99% reliability, it'd take an additional 100 billion Euros just to provide an extra 5 GW of reliable power (i.e. replace around 5 nuclear reactors which would have cost less than a quarter of that) through 450 new pumped hydro installations (Germany has ~35 of them now and new constructions are being protested everywhere), for which Germany probably doesn't even have the places to put them; or about an additional 254 billion Euros if you were to use the batteries of EVs (not the EVs themselves, just the batteries!).

In short, the problem is a lot harder than you think and a lot harder than that pretty video you sent me tries to make it out to be. These things look pretty from a semantic point of view unless you come down to real brass tacks, commit the numbers to paper and start making hard investment decisions. I'm on Bill Gates' team here and think that people deeply underestimate what a hard problem it is to rework the entire electrical grid to work reliably with these unreliable inputs.

France's overall price of electricity with tax is lower than Denmark's untaxed price, meanwhile emitting >30% less CO2 per capita with a very similar GDP per capita (to within 5%). If we limit our consideration to electricity, France has ~75% lower emissions per MWh generated than Denmark; and over 80% lower than Germany, the renewable powerhouse of the continent. In fact, they have so much zero-CO2 electricity that they can afford to offset the CO2 emissions from many of their neighbors via transmission. Also keep in mind that France has had this CO2 per kWh value for the better part of two decades because its power mix has always been ~70-80% nuclear and ~15% hydro (the rest being filled in with things like gas, hence why this CO2/kWh number isn't a flat zero).

The OECD average is so high mostly because of heavy polluters like the US, being the about 1/4 of the population of the entire OECD (not just the high-income bracket), but twice the per capita CO2 emissions of, say, Germany.

To preemptively dispense with the "we can't build it fast enough" criticism of nuclear, I again present the example of ... France. They initially started construction in 1974 and finished installing >50 reactors, hitting over 70% of generation capacity, within 15 years. So don't believe the renewable industry talking points of "it can't be done on time". It has been done before and it can be done again. If it had the political and popular will, Denmark could hit its CO2-reduction targets for electricity for 2050 some 20 years earlier.

You should calm down a bit and educate yourself on wind production stability a bit: http://www.gridwatch.templar.c...

The UK has better than 10GW of installed on-shore and off-shore wind over a geographical area >1000 km across and yet over the latter half of the month of June overall average production was

You trash engineers as too stupid when they tell you this is a serious unresolved problem, but then call on them to find a solution? Have you ever considered the possibility that the grid engineers have a bit more knowledge on the subject than you and so they understand the magnitude of the problems better? Of course not, because they're all in cahoots with "big coal" or whatever anti-corporatist conspiracy theory floats in the blogosphere this week.

Except that only works while there's a fairly small amount of solar on the grid and the government is meddling in the market by imposing regulation such as giving hard preference to solar at the expense of other operators. At higher proportions things stop looking so rosy (recommend you read this nice paper on the real costs associated with intermittency - the reason you're not seeing them in your bill is because of government forcing the price offset onto other users, in effect subsidizing you while taxing others).

Imagine if you could tell your car that it only needed 30% charge during the week because you were only going back and forth to work, so the other 70% could be sold back to the grid for a profit. The car and the smart grid automatically negotiate. On Friday the car makes sure it gets up to 100% so you can take that long weekend drive.

Sell back to the grid? If I had an electric car, I wouldn't be inclined to wear out the batteries (which have a finite life in terms of number of charge cycles) doing this.I once did a back of the envelope calculation using typical lifespan data for Li-ion batteries - I'd have to sell back at a ridiculously high price to justify the loss of battery life. And even practical storage schemes like pumped storage hydro need to sell at a higher price than they buy - a cost that typically isn't included in the cost of electricity estimates of wind and solar (which is fair enough as it's too dependent on other factors, but something that needs to be considered). Moot point though, as electric cars will stay uneconomic unless there's an huge and unexpected drop in battery costs or oil prices skyrocket.

We can only predict demand for large regions, not locally.

That's all we need, thanks to the grid averaging out demand fluctuations over space. The high reliability of the current grid is evidence for that.

Thing is that is never, every does die down for hours or days. At least, not everywhere.

Really? I've seen it happen on UK grid monitoring webpages (e.g. here)- wind generation under 10% of total installed capacity for hours at a time is quite common. In fact output varies quite savagely, presumably due to the cube-law dependence of output on wind speed. People often claim that "the wind is always blowing somewhere", but the data suggests "not enough it isn't".

With something like wind and individual turbine failing will drop maybe 20MW. Wind speed changes slowly, so if it is 20 knts now it won't be less than 18 or 19 knts in 20 minutes time, giving plenty of opportunity to spool up other sources.

Which other sources though? Renewables (except hydro and biomass, which are limited) can't be spooled up, they either generate or not depending on the availability of the resource. You can predict that you won't have power, but then you need to do something about it. Turning fridges off will only help on a much shorter timescale.

In contrast, handling a power station failure is a solved problem with the existing grid, as are demand surges. Solving problems that have already been solved isn't a compelling reason for something.

1) Depends on a large number of factors. First thing you need to understand is the concept of heat flow. The absolute temperature of an object depends not only on how quickly heat is being added, but also on how quickly it's being removed. A quick glance on the wikipedia article on "Decay heat" says that after 1 year decay heat is around 10 kW/t of original material and 1kW/t after 10 years. Unfortunately, UO2 fuel is a ceramic, which has pretty poor heat flow properties, so I suspect active cooling may be necessary for several more years, possibly up to 10 years total.
As for sustaining a criticality, the answer is an unambiguous "no". Water-moderated reactors have a very carefully controlled neutron budget and moderation environment to achieve criticality at all. Melting the core essentially messes this up completely. Remember nuclear reactions do not at all depend on the temperature of the fuel, only on the geometry of the fuel elements and overall neutronics of the surrounding environment (neutron moderation, absorption, neutron leakage, etc.).
2) Reactor containment would probably heat up considerably, making cleanup operations very difficult, not to speak of the hard radiation the corium would emit (the water is as much radiation shielding as it is coolant).
3) See answer to point 1 - possibly for many years to come (depending on when the fuel was put in). Again, possibility of achieving criticality: zero.
4) Frankly, I'm not too worried about anything serious going on at this stage. What I really worry about is that because the public is easily susceptible to fearmongering and soundbite arguments, they won't take the time to examine all of the complex issues surrounding power generation and they'll agree with feel-good measures that ultimately, though, have an almost negligible impact on CO2 emissions. Just the other day I was reading articles on some enviro-power site about how Japan should switch over to wind power, completely ignoring the tiny intermittency problem and hailing the low-low prices of solar at 30 pence per kWh (about 5x that of coal and that's without the intermittency accounted for, which will more than double the cost if it were to come from zero-CO2 sources).

Bah! Just the power consumption of some uninteresting company, here is the real time power consumption of an entire country.

Not every plant is coal. The electricity grid has a combination of baseload plants (things that can only change output slowly, like a PWR nuclear plant or a large coal generator) and peaking plants (natural gas etc). A natural gas power station uses basically the same turbine engine as an airliner, minus the fan (many industrial turbines are identical to ones on airliners, right down to the part numbers). Just like an aircraft engine, gas turbine power plants can throttle up and down very quickly. So if a bunch of load goes away, the gas turbine stations can easily throttle back. Pumped storage can be throttled back. Hydroelectric can be throttled back etc.

However on a large electrical grid it's extremely rare to suddenly lose so much load in such a short space of time that you have to do that, electrical load is pretty predictable. The grid operators also do a lot of work to forecast demand.

Have a look at a real time view of the UK grid: http://www.gridwatch.templar.co.uk/