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.

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.

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

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.).

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 acknowledged that too). Do not for a moment think, though, that you can extrapolate special cases to generalization.

The 30% figure is just plain false (it was actually 25.4%) and is highly misleading, as 11% of that provided by hard renewables (hydro 5%, biomass 6%). Hydro, as I've explained to you, is limited, Germany has already exploited approx. 75% of its viable hydro resources and biomass isn't scalable because it is artificially sustained by extremely high subsidies and results in food crop displacement by energy crops - the German government has in fact already come out as saying they've oversubsidized it and will be cutting it back. The fastest growing, in fact, are wind & solar, both of which have serious intermittency problems. The 74% figure is achievable on certain days or weekends, when they throttle back fossil fuel plants. Just wait until it starts hitting 100% more regularly and the generator curtailing starts. That's when the wind generators (since they're the ones most like to get curtailed first) will start raising such a stink you wouldn't believe it. Mark my words.

Again, you need to look at the breakdown. A majority share of that is hydropower and that has extremely limited growth potential, because there are only so many water flows you can use for it (and most are in fact already developed). If you study the global trends honestly, you'll see that the only thing you're left with is wind & solar and both of those have huge costs associated with their intermittency. Sticking your head in the sand won't help.

Or just stick in an simple power limiter which trips a breaker if you go over the limit :) Trouble is, our current energy system originated in the days of yore when we had to consume significant amounts of fuel (and thus cost) to produce a unit of energy. Our energy markets are geared towards it, our grid control is geared towards and people don't like changing systems with lots of investment behind them and which aren't necessarily broken.
If we were building a new zero-carbon grid green field-style, it might well be cheaper to just lose the stupid meters (and spending time reading them, processing them and collecting the varying amounts), put in a simple circuit breaker and be done with it.

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.

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).

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?

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.

Adiabatic flame temperatures don't mean higher energy release. At best they mean higher heat engine efficiency and you can't just start to run a boiler significantly hotter than it was designed to, or you'll get a rather nasty looking result. Moreover, when you *do* look at the adiabatic flame temperatures of NG and H2 in air, you'll see that a 4% concentration of H2 gives you at best an extra 10C, or about 1% of extra absolute temperature. Using 60% as the efficiency of an idealized Carnot cycle, we see that, assuming 18C cold water cooling, the lowest possible working fluid hot temperature is ~454C. A 1% increase in that gives us ~460C, or an efficiency boost of a whopping 0.3% (ideal best case). In short, not really something to write home about.

Sure, but that'll cost extra, where the entire premise of the original claimant was to utilize the existing gas grid infrastructure (for which we only need to pay for mostly O&M).

Oh yes, my friend, you need to build it to your H2 generator rig and maintain it. You'll need a pressurization substation and an industrial connector. You'll also need to pay for maintaining the existing grid.

Again, you're wrong here. For one, Germany has a very small amount of these, only about 10% of electricity is provided by gas. Seeing as 2/3 of your power would need to be pushed into H2 and subsequently into a gas plant, you'll be deriving ~67% of your overall power generation from gas plants (regardless if burning NG or H2 or pixie dust). So who's going to build those extra 57% worth of capacity? Somebody who expects to make a profit from it, be it an independent utility, or the wind farm operator. If it's the former, they'll be buying your 5%H2-laced gas (let's call it "shitgas" for reasons I'll explain later) at market prices and those are pretty darn low and selling the generated electricity on to the consumer.
The economical calculation for that is pretty simple:
It cost the wind farm X to produce 1 Joule of electrical energy.
They'll convert that 1 Joule of electrical energy and generate a given amount of hydrogen at efficiency Y, which means upon combustion of the generated hydrogen, you get "1 Joule x Z" back AS HEAT ENEGY.
The gas plant takes the heat energy and converts it back to electrical energy at efficiency Z (60% for CCGT, 29% for OCGT) and sell it on to the power grid.
Thus, your original production cost to create Joule of energy is X' = X / (Y x Z). If Y=0.75 (best currently available electrolysis rigs at lab scale) and Z = 0.6 (best currently available CCGT plants), you get 2.22x multiplication of your original production costs (what it costs to provide 1 Joule TO THE GRID). If you take a more realistic Y=0.5 and Z = 0.5 (due to intermittent running), you get a 4x multiplication of your production costs. So effectively, the wind farm is forced to sell its generated electricity (as H2) at a 2-4x higher price in order to maintain the same level of profitability.

Please do point me to that miracle grid-scale electrolysis rig, I must have missed it.

Except you forgot that you can at best get a 1% contribution to your energy generation from burning this gas for heating. Heating, however, consumes only about 2-3x as much energy as electrical generation, so even assuming you took all of your surplus electricity (roughly 2/3 with wind) and transferred it into the heat market, you'd essentially be trying to supply ~20-25% of the heating energy from H2, which you simply can't. As we've established, your carbon-free energy contribution to heating tops out at 1-2%. IOW, even if you could convert all of your surplus electrical power into H2 for heating at no extra cost, 90% of your surplus power generation would still be inadmissible into the gas grid.

So you believe in free lunches. Okay, I think I'm done here :D Maybe next time try and ask be baker for free bread, the bus for a free ride and the local utility company for free power and see how that goes for you.

And 78% of the US population believes in angels. Popular vote does not determine reality. Moreover, your reading comprehension needs work again, as had you not cut my sentence off there and torn it out of context, you'd see that I was comparing it to the tsunami that drowned nearly 20000 people.
It is estimated that, assuming linear dose response, ultimately ~200 excess cancer deaths will result from Fukushima over the coming years, most of them in Japan. Are those inconsequential? Of course not. But keep it in context - on that day alone 20000 people drowned, millions have been displaced, their homes gone and vast tracts of shoreline and coastal cities and associated infrastructure have been utterly destroyed. If you look at it honestly, you have to conclude that living in a coastal city in Japan is vastly more dangerous than the occasional nuclear accident. But people aren't rational beings and the media know fear sells news, so guess which story you heard on TV?

Care to elaborate on what "highly radioactive" is? We have ways to measure that. Also, where did you get that crazy figure. I couldn't find it anywhere on any reputable news source, only on some fear mongering blogs. Besides, while certainly not something to be dismissed as inconsequential, leaks of this nature into the ocean get diluted down beyond background levels pretty quickly.
Anyways, stop frequenting crazy conspiracy blogs and listening to professional nutjobs like Helen Caldicott or Arnie Gundersen, it'll rot your mind. Read some research on radiation effects and you'll see that it's far less problematic in the big picture than the media would like to make you believe.

You're comparing current electricity sales prices for wind with LCOE for new nuclear power plants. Good job on comparing apples to oranges.

Uh oh, massive reading fail on your part. The Wikipedia page actually says "28,537,000 acreft (35.200 km3)" - that's thirty-five-point-two cubic kilometers, so right out of the door you're wrong by 4 orders of magnitude - quite an achievement, and it only gets worse from here. In order to be able to use, say, 10% of the reservoir's capacity for energy storage (which is a big ask, considering it's been at ~2/3 capacity since the 90s due to droughts and extensive water use by the population), you need another reservoir (or set of reservoirs) of at least 10% the volume at a suitable lower position close to the dam. The nearest possible suitable reservoir is lake Mohave, unfortunately it's 50km downstream, so that ain't gonna happen. But let's imagine you find some way to blast the mountains right beyond the dam apart to create a nice little reservoir at 100m height difference (the dam itself is ~200m tall, but the water reaches all the way to its bottom and it's not always full, so we'll split the baby and use 100m average water height to simplify the calculation). So how much does that give you?
3.5 x 10^9 m^3 x 100m x 9.81m/s^2 x 0.75 (roundtrip efficiency) ~= 2.575 TWh
That'll give you the power to back up the US power supply for around 4 hours, or countries the size of Germany for about 2 days. Your goal is ~14 days, so you're still about an order of magnitude short. And that's using the largest water reservoir in America.

Yes, and runs dry in about 7 hours, so it holds ~12.6 GWh. The UK uses ~1 TWh per day, so to provide 2-week long backup, you'll need about 1000 of these. Nevermind the fact that there probably aren't enough sites around the country to put them and let's ignore those pesky environmentalists, by the time you're done, it'll have cost ~£450 billion, or approximately 2/3 the UK national budget for the entire year. Such a steal! And don't forget the transmission grid upgrades, since you need to feed large amounts of power (far in excess of what the current grid can support) from wind farms from the windy southeast to the mountainous northwest - that'll set you back even more. Oh and you know how much CO2 you will have displaced by that investment? Zero, because this is storage, not generation. And this is the cheapest you can do, any other grid storage tech is more expensive than pumped hydro.
Or here's an alternative that isn't completely crazy. Take less than 1/3 of that money, spend it on buying Westinghouse AP1000 reactors (which cost ~£4.25 billion a pop if you look at the Vogtle 3&4 project), build about 30 of them and generate all the baseload power the UK needs without emitting any extra CO2 and requiring no new transmission lines (since the plants would simply displace existing coal & gas plants at their existing sites). Of course use hydropower and geothermal where the resources are available - they're fantastic, dispatchable zero-CO2 sources. And if you happen to have a rich wind resources somewhere, plug that in to capture the tops of the load curve and feed it into the few pumped hydro plants there are to capitalize on the high daytime prices.
You see, when you have an honest look and don't zealously discard options out of hand, the UK could have a zero-CO2 electrical supply before the year 2035. France has already done it.

Yes, we haven't, because it's simply not economical. Your estimates were orders of magnitude off of what is actually achievable because your biases put distortion glasses before your eyes. You see commas where there are decimal points and you can't grasp the scale of the construction projects you propose.
Perhaps they can become reasonably affordable in the long run, but they are just not viable today. All of today's intermittent generators work by externalizing the cost of their intermittency onto others. If you forced them to internalize these costs (e.g. by forcing them to be reliable and dispatchable - same as everybody else), they'd collapse before they got off the ground.
And as for availability of nuclear fuels - there is more of that than you think. Increase the price a little, dig around a bit more and you'll see we have thousands of years worth of that stuff - I'd hope that by that time fusion or wind&solar would finally become viable. Ultimately, we all agree that nuclear fission is a bridging technology for the next few hundred years at most to a really limitless power source.

Not necessarily. Fuel costs consist of several components, for Uranium it's mining, refining (yellowcake production), enrichment and fuel fabrication. It depends on the breakdown and efficiency of use that dictates price contribution to operation, so it'd probably far less (I've heard estimates where a 5x price hike on raw uranium would only result in about a 2x bump on the fuel price). What you also neglected to consider is that at around 3-5x current mining price, we'd probably have tens of thousands of viable reserves, so the 10x is quite a high margin. Lastly there's the usage efficiency. The LWR once-through cycle is pretty inefficient. With higher burnup or higher breeding ratios (all reactors breed some fuel, just typical LWRs don't do it much), all of which are achievable in modern reactors, the cost goes down. Or we could use fast breeders for which the only cost is the initial fissile load - after that they run on depleted uranium, of which there is a heck of a lot (100x more than fissile).

Well, the "sooner or later" might in fact be quite a ways away. Regardless, I broadly agree with you, but there's no need to rush things or exclude one path over another. I'd like to see us invest in anything and everything that reduces CO2 emissions - that's the real pressing issue - be it renewables, nuclear, carbon sequestration or burning dung for power, for that matter. R&D being currently invested in all of these is currently peanuts.

It doesn't have to. We have ways to burn down the waste to short-term stuff. We just have to use it.

That's a bit of a pessimistic way to look at it. We've had a pretty good half century, generated shitloads of zero-CO2 energy with it and only managed to cock it up a few times (and while each of these was serious, they pale in comparison to the number of deaths you see in, say, transportation, every year). Don't you not think the cavemen that discovered fire have not burned themselves quite often and wanted to throw away that dangerous thing? But their curiosity prevailed and we today couldn't imagine life without it. "Nuclear fire" is kinda similar, we're new to it (we didn't even know atoms could fission before 1938 - the TV is older than that), learning and making mistakes, but ultimately I'm an optimist and largely believe in the ingenuity of humanity to master a wonderful new power source and use it for good.

Right, that's forgone revenue.

So you take your invested $ to generate this power, divide it by the efficiency of your H2 generation rig, and that's what you get back. Oh and you also just expanded your capital costs by the cost of an industrial-sized H2 generator, a gas pipeline and a gas plant.

See, you understand how forgone revenue works. Instead of losing all of the power from curtailed wind turbines, you only lose ~3/4 of it by using the energy -> H2 -> energy conversion method, in effect increasing your cost to produce it by a factor of 4. And you add capital costs for an H2 generation rig and gas grid and gas plant operations. Also, selling into the gas market means you're competing with the NG providers, so you'll be selling at whatever they're selling at (and they tend to sell _really_ cheap).

Wow, that 1% reduction is really going to save the planet. Remember, you're limited by a volumetric concentration of 5%.

So what's worse is you're just selling a natural gas substitute produced at massive expense :D

Whoa now young man, that's a bold statement. I suppose you're not familiar with the acronyms ROI (return on investment) and O&M (operations and maintenance), but in the world of actual projects that cost money to build and run, they reign supreme. Lost production for a wind farm is as serious as it is for anyone (your investors expect a return and profit - try and tell them your ROI is maybe 3-4x as long as you had originally planned and they'll eat you alive).

You know that sounds about right. If we take the high estimate (75%) to be for a reactor operating for a relatively short 40 years at a cap factor of 0.8, a 1 GW unit with a levelized purchase price of $9 billion would cost $32/MWh, so adjusted to 100% this comes to roughly $42/MWh. The remaining 25% is fuel, O&M and decommissioning costs. Of course this significantly depends on what deal you get on the unit and unfortunately real reactor purchase prices are a closely guarded secret of the manufacturers. Prices can range from the sensible (Unit 1 costing about $3B in inflation-adjusted present day dollars and Units 2&3 being constructed for about $4.5B a pop) all the way to the downright insane (honestly the idiots who approved this project ought to have their heads examined, if AP1000s can be had in the US for over twice as cheap, as can be VVER-1200s and ABWRs).

Well, that remains to be seen. Current wind installation prices are getting close to leveling out. The future will show more.

The $44/MWh is for existing operating plants, whereas $10c/kWh is for new builds and takes into account things such as uncertainties in licensing, delays and a host of other potentialities for cost-rising elements. Financial prognosis is a black art.

I agree that Hinkley Point C should have been sent down the drain, the single most expensive power plant on the face of planet. For that matter, Areva's EPR is turning out to be a massively overpriced unit, at least the way it's being built outside of China. My guess is they're probably trying to save Areva from the massively overpriced fiasco that is Olkilouto 3 (the cost overruns there are largely being absorbed by Areva), in order to preserve what little nuclear industry is left in Europe. Don't know the details of the deal, but personally I'd tear the idiots at Areva a new one.

That's because it doesn't include the cost of providing zero-CO2 storage and current investment confidence is high. Add the storage and Hinkley Point C will seem cheap. Of course that cost doesn't materialize until wind gets fairly high in the generator percentages, so it'll take a while for it to materialize.

Hanford was a military weapons production installation, not a power plant. Don't be dishonest in including it in these.
As for Fukushima - we'll see how new plant designs do. Had they been running an ABWR or even an AP1000 at Fukushima, dick all would have happened (and that's mostly what did happen, but thanks to mass hysteria it got blown wildly out of proportion; never mind the 20000 tsunami-drowned suckers, NUCULAR ACCIDENT!!111!). Oh and Chernobyl was just a criminally bad design in an almost completely unregulated and curtained state-controlled industry. By that logic you could try and paint the nuclear power industry with the legacy of nuclear weapons. Oh wait, you already did (Hanford). Well, never mind then. ;)

Hydro: already maxed out in the west. Pumped hydro: calculate the scale involved, it ain't pretty. Wave power is so expensive it's not funny, as is solar thermal. Solar PV is intermittent - see linked graph again, it won't cut it. CAES has some potential, but is as yet much more expensive than pumped hydro. Biowaste accounts for a drop in the bucket - there's simply not enough of it. Batteries are horribly expensive at grid scale and environmentally very damaging (Ever seen a lithium mine? Or maybe you prefer lead-acid? And Vanadium redox is still more expensive than pumped hydro). You forgot to mention flywheels.
The point is, you need to understand the problem quantitatively. Run some calculations on the system cost and scale and post them - it's a sobering experience. And don't forget to include the developing world, they want power too, you know.

So CO2 emissions from gas and fracking are a-OK? You do realize that natural gas still emits around 50% of the CO2 per unit of energy, not to mention that any small methane leak is also a serious source of GHGs, right?

This is grossly oversimplifying. First you need to understand the relationship between cost and recoverable resources. In general, double the cost, you increase recoverable resources 10-fold. Even using today's nuclear power designs (which I'm not a big fan of, but consider them a necessary evil on the way to better designs), the fuel cost is only about 10% of the TCO of the plant (the rest being construction, O&M and decommissioning), so if you double their raw fuel cost, their LCOE grows only very modestly (a good chunk of their fuel cost is also enrichment and fabrication). So if you accept, say, a 5% increase in their LCOE, you'd have enough Uranium to power all of the world for another 200-300 years. Now you might say that's not enough for fusion to come along, so read on.
The real prospect, is for new reactor designs that either breed fuel from fertile uranium (of which there is approx. 100x as much as directly fissile uranium) or use the existing stock a lot more efficient (e.g. the denatured molten-salt, not a breeder, but a lot simpler than the LFTR being hyped around the net). Breeders are not paper reactors, they exist and are operating. They have their challenges, but give a significant improvement. The molten-salt ones pile a bunch of very attractive safety on top.
Should we *only* do nuclear and not invest in renewables like wind, solar, geothermal and tidal? Absolutely not! We should do all of these! Use what's appropriate where it's appropriate. Iceland is a geothermal bomb, so nuclear there is stupid. Arizona has lots of solar, with a little improvement in salt storage, that could pan out. And where nothing else works really exceptionally well (like central Europe :D), use a mix of nuclear, hydro and whatever else you can lay your hands on.

I do understand that, but it's financial storage that loses around 3/4 of your stored product. That means that whatever power you time shift will come out around 4x as expensive. For example, say you are running a 100% wind-based grid (it's a little more complicated, but just for simplicity's sake). Since wind has around 1/3 cap factor (actually around 25% in Germany, but whatever), that means you need to overbuild by about a factor 3x in terms of MW installed relative to the average MW of consumption. That means about 2/3 of your produced energy will come from times when there's too much of it (i.e. you need to store it). Now if your wind plant has a cost of producing a unit of energy of $X/kWh (this is referred to as LCOE), then only 1/3 of that value can be directly fed into the grid at any one time and on average 2/3 of it you need to time-shift. Given that the time-shifting technology inflates the cost of the production 4-fold, it means that your LCOE is in fact 3x higher than if you didn't have to do the time-shifting in the first place. *That's* the hidden cost of intermittency and that's assuming the time-shifting system is free (i.e. doesn't cost anything to build & maintain). Add that to the equation and it starts to look like a pretty bleak proposition.
This problem starts to occur in general (not just specific to H2-production) once intermittent sources hit a market penetration about equal to their capacity factor. This is not the case in Germany yet, but it's starting to become one. They're at ~15% now (rest being hydro & biomass), but once they get to around say 20-25%, you'll start seeing the weeping and gnashing of teeth as grid operators will start to curtail intermittent generators - after that, they'll be either forced to discard unrealized production (in economics this is a loss called "foregone earnings"), or forced to pay for its time-shifting. In short, intermittent renewables get cheaper with volume only up to a point, after which the problem of their intermittency slowly grows until it becomes overwhelming.
Now this is only a simplified model, but it gives you an idea of the mechanics at play here.

Well, it depends on the exact technology used. The most efficient numbers you quote are high-temp electrolyzers, but they require a readily available heat source (not the case for wind farms, unless you heat it with electricity, which diminishes efficiency again, or use NG heating, which makes it not zero-CO2). The really cheap ones use inefficient electrodes that degrade. The 50% number is a rough ballpark estimate of what can be achieved with sort of run of the mill readily available large-scale equipment.

And that's one of the fundamental problems I find with discussing renewables with wind & solar proponents. Reducing CO2 has to be the first and primary goal, not installing tons of renewables. Installing renewables *might* be the answer to the task, but it has to always be moderated by the question of how to most efficiently reduce CO2 emissions. All too often though I find renewable advocates such as yourself forgetting what the question was and latching onto one particular solution. "I don't care what the question was, I forgot the question, but the answer is definitely more wind & solar!" And then when I show them that France has effectively and successfully decarbonized its electrical production 20 years ago by going for nuclear in a big way (CO2 per capita today at ~1/10 of Germany despite using ~5% more per person), they usually stick their fingers in their ears and go "lalala".

And do you expect these wind guys to do it out of the goodness of their hearts? Of course not, the equipment costs money and they want their money's worth out of doing it - they've got wind farms to write off, loans to repay and profit to make. And as I've shown you, the product they make to do this is costs them about 4x more to produce than the electricity they started with.

Dude, by saying "considering that XYZ" I'm just reiterating our points of agreement. I'm agreeing that it's less than 5% here. The point comes later, in that it's just not good enough, because it's just a drop in the bucket of the ultimate goal of reducing CO2 emissions to zero.

No, I assume the same amount of energy for heat will be consumed, regardless of which source it comes from. I've shown to you that at 5% concentrations, you will at best offset ~1% of CH4 use, and thus achieve an emissions reduction from its use of at best ~1%. I did assume the H2 production is zero-CO2. It's just simple thermodynamics. Volumetrically H2 has lower energy content, which has the effect of lowering the energy content of the overall mixture, thus in order to achieve equal energy output, you'll need to burn more of the mixture. Here's the math (check me please):
let us assume 25 MPa nominal gas pressure
let E_total be the total amount of heat energy required
let V_total be the total amount of pipeline gas consumed
let ED be the energy density (energy per volume at nominal gas pressure) of the gas when combusted.
V_total = E_total / ED
The value of ED above depends on the molecular composition of the pipeline gas. If you look here, you'll see 100% NG gives 9 MJ/L, whereas H2 only gives ~2 MJ/L.
Hence a pipeline gas composed of 100% NG at 25 MPa has an ED_ng = 9 MJ/L, and pipeline gas composed of 5% H2 and 95% NG at 25 MPa has a ED_mix = 8.65 MJ/L.
Since E_total is assumed in both cases to be equal to produce a direct comparison of gas consumption, the change is in V_total:
V_total_mix = E_total / ED_mix
V_total_ng = E_total / ED_ng
Given that ED_mix = (8.65 / 9) x ED_ng = 0.96111 x ED_ng we get:
V_total_mix = E_total / (0.96111 x ED_ng)
Rearranging the coefficient of the density term we see that:
1.0404 x V_total_mix = E_total / ED_ng
Substituting V_total_ng for the right-hand side we get the ultimate result:
1.0404 x V_total_mix = V_total_ng
Hence, it takes ~4.04% extra pipeline gas composed of a 5/95 H2/NG mixture to provide the same total amount of energy of a pipeline gas composed of 100% NG. But since the mixed pipeline gas is still composed of 95% NG, we have effectively consumed 0.95 x 1.0404 = 98.84% or roughly 99% of the original volume of NG. Thus, a 5% concentration of H2 in the pipeline has offset only ~1% of NG consumption and CO2 emissions.
What's worse is if the gas gets then used for electricity production in, say, a CCGT. Since your typical electrolysis rig is only ~50% efficient, and current state of the art CCGTs are up to 60% efficient, this is kind of pipeline-stuffing of H2 generated from wind power represents at least a good 70% energy loss of surplus production. In fact it could be a lot more, since gas backup peakers are often OCGT (CCGT have around 40-60 minute startup times, so they're not good for backing up gusting wind) with at best ~30% efficiency, so perhaps even more than 85% losses. An alternative would be to run-up the CCGT ahead of time prior to your forecasting predicting a lull and quickly disconnecting during a gust, but this means that some of the time the turbine will be in spinning reserve and burning unused gas, which will lower its efficiency, so a quick set of my pants estimate would be about 75% losses from the turbine blades to electrons flowing onto the grid a few hours later.
At this point you have to just be honest and considering that only a very small concentration of H2 is allowable in the gas grid, the expenses of operating a gas plant intermittently and the associated wear & tear and maintenance and the 75% energy loss due to intermittency; and conclude that it's either pumped hydro (25% losses, no excess wear & tear from intermittent running, but much more expensive to buy and site) or building a generator that is dispatchable, baseload capable and zero-CO2 (this would be your nuclear, biomass & hydro dams) and using intermittent sources like wind only as a supplemental technology to capture the peaks when possible - and this is exactly what I advocate for.

I misspoke in the earlier post when I said "metals or bearings", I meant "metals or seals". Sorry.

H2 will not sit and only start to embrittle metals or bearings after some time. It will start diffusing into the metal right away. Now of course damage depends on exposure length, but if used at scale, there's always going to be some of it present, hence the danger. Below a few percent you could mix anything into the gas grid and have it work fine. But the question is at-scale production.
Here's a thought experiment: looking here, if we estimate about ~1GW of surplus wind power for 8 hours (easily achievable with the fluctuations, in fact 10x this would be quite normal), you'll need on the order of 12000m^3 of pipe volume for the pure hydrogen at 25 MPa, or about 61km of pipe at 0.5m inner diameter. Now if you don't want to exceed 5% concentration in the network, that means you need ~1220km of piping of that diameter.
But that's just to give you a taste of the piping scale. The real problems start when you look at where this gets us in terms of real CO2 offsetting. Since at identical pressure methane has 4.5x the energy content per unit of volume than hydrogen does, that means that in order to keep concentration below 5%, you'll still be using about 99% natural gas for heating energy (and this ratio cannot improve - it is dictated by the maximum concentration of H2 vs CH4 and their energy content by volume). Even if half of the gas in the mix were molecular H2, you'd only be getting 10% of the energy from it, so you'd only offset 10% of the CO2 emissions from natural gas use.
Put simply, I have to concur with Elon Musk here, H2 is great for upper stages of rockets, but it's a dog almost anywhere else (loosely paraphrased, he was talking about liquid H2 use for transportation, but the problems apply roughly equally badly to home heating).

Up to a few percent perhaps, which is almost certainly not going to be enough to do much of a difference (see back of the napkin calculation above). At best it might offset your intermittency economics by a few percent - not exactly a huge change. As for CO2 emissions offsetting, it's utterly inconsequential.

Right, so it's not usable for liquefaction and transportation use (horrible in ICB vehicles and a less so in fuel cell vehicles). I was using that only as an illustration of what might happen if you tried to do it.

I assume you've got access to some internal planning documents then? If not, then you've only got news articles and press releases, same as everybody else.

Construction schedules cannot account for unplanned construction halts due to unforeseen government interference, simple as that. When that happens, you have to adjust your original estimate. They have been delayed due to government action for about a year. They're starting up about a year later. Period.

Construction schedule is not a train schedule. There are error bars on all parts of it, hence why it's called an "estimate". On first-of-a-kind projects, the error bars are going to be large. Besides, even a train schedule has error bars below which a train is not considered to be late.
This is all just word games, really. Their construction process was on-time, they just got an unplanned interrupt. Frankly, I won't hold it against them, just as I don't hold bad weather conditions at sea (which are actually a lot more predictable than government action) against offshore wind projects. You do whatever you want.