Viability Of Solar Power As Grid Baseline

[aerius]

Nuclear is a good solution for that, as it does not emit CO2, which makes it better than coal, oil, or gas. However, in the medium and long term, nuclear energy is an extremely bad fit with renewable sources, as it is mostly incapable of reacting dynamically to demand and production of energy. In effect, nuclear would hinder the use of renewables, once they reach a certain percentage of energy production. Hell, that is already partly the problem, to the point that wind turbines have to be shut down when there is too much wind, as the rest of the energy production capacity is incapable of powering down fast enough to make it viable.

That is a myth. Nuke plants can load-follow just fine. Link
Excerpt:

1.3 CANDU 6 Load Following Capability
1.3.1 Unit Operating Characteristics
CANDU stations operate extensively in the automatic, reactor-following-turbine mode,
where the plant is subjected to continuous small perturbations in reactor power, with no
adverse effects. The digital control systems provide the capability to respond to a
megawatt demand signal generated from a remote dispatch facility. CANDU reactors
operating in the reactor-following-turbine mode can continuously compensate for grid
frequency fluctuations requiring a plus or minus variation of 2.5% full power while
operating between 90% power and 100% power. In addition, considerable operational data
is available documenting successful experience with deep load changes (down to 60% and
back to 100%) in the Bruce B and Embalse stations since 1984 and 1986 respectively.
This provides substantial data to confirm the load following capabilities of CANDU
reactors.
The CANDU 6 can operate continuously in the reactor-following-turbine mode and be
capable of load following that typically involve rapid power reductions from 100% to
60%. The reactor will operate at steady-state at 60% power, and can return to full power
in less than 4 hours.

With regards to the German renewables project, if I'm reading the chart correctly it produces around 4-5MW of power. German electrical consumption is around 580TWh per year which gives a ballpark figure of around 65GW of generating capacity. It only needs to be scaled up 15,000 times to meet power demands. Someone needs to go crunch the numbers to prove it's doable instead of saying "renewables are growing at X% per year, so it will happen". Find the details on the project, how many solar panels did they use, how many wind turbines did they have, how much pumped hydro was involved, get the specs on their biogas facility and prove that all of it can indeed be scaled up at least 10,000 times. I don't see numbers anywhere and until I start seeing them I remain unconvinced.

[D.Turtle]

The pilot project was deliberately made at a 1:10000 scale of the whole of Germany.

Some of the information is available in English at the following site: Kombikraftwerk. Unfortunately the final report is only available in German

The pilot project is now being followed by a number of larger scale projects at a city-wide and regional scale which can be seen at E-Energie.

[Darth Tanner]

The pilot project was deliberately made at a 1:10000 scale of the whole of Germany.

It met a 1/10,000th of the demand with 22.1 gw of renewable capacity and a 1gw pumped storage? Unless I'm mistaken in my googling that is a rather worrying use of resources considering 1/10,000th of German demand was being met by the equivalent of the nearly the entire wind generation capacity of Germany (24gw) while using just under half of Germanys entire pumped storage capacity! Scaling that to supply the entire demand would be ludicrously expensive.

Why do we need to meet the demand now

Because we need to replace existing plants that are reaching their decommissioning dates now? In the UK we already have to extend our existing nuclear plants running life because we have no alternative despite adding lots of wind capacity. We simply cannot build turbines fast enough.

as it is mostly incapable of reacting dynamically to demand and production of energy

As said already some nuclear can scale with demand and all of it can be slowly turned on/off as needed over a few days, however renewables are incapable of doing so at all. You either have wind and sun to run them or you don’t. You can store a tiny amount for later use but you can’t produce wind out of nowhere to supply a spike in demand. Gas turbines are here to stay for such quick changes in generation capacity sadly.

to the point that wind turbines have to be shut down when there is too much wind

It may well be an urban myth but I thought that was because extreme wind speed would damage the turbines. Either way surely it would be easier/cheaper to shut down gas coal plants when demand falls. Gas turbines at least can scale pretty dam fast it the prime reason they’re so prevalent despite the cost of gas.

This does not mean that they were useless, only that their production hasn't been high enough so far.

No one is arguing that renewables don’t produce energy, but the simple fact is to actually run the grid off of them would take far more than we can reasonably build within our lifetimes. Thats not a reason not to build them where the economics support them but to argue against building other forms of energy generation in favor of renewables is foolish when we know those renewables are not going to be in place to take over the needed capacity. Hence why Germany is building coal and will contineue to give France money for its nuclear capacity.

What it shows that is currently possible to expand renewable sources a lot before the variability of their production becomes a problem.

But surely if the renewable cannot be relied upon it must be backed up, either by pumped storage or conventional generation. Thats going to cost regardless of how much renewales there are but if the majority of the generation capacity can not be relied upon to keep working then the cost of providing the backup is going to skyrocket.

Oh, and you will of course show where the tripling of the energy bill comes from?

I concede that as I was spewing hyperbole out of my arse. However plans to switch over to renewables are going to increase energy bills as well as taxation in general if their subsidies are kept in place as the sector grows, they simply cost more than coal or nuclear, sadly we cant get away from that.

[D.Turtle]

It met a 1/10,000th of the demand with 22.1 gw of renewable capacity and a 1gw pumped storage? Unless I'm mistaken in my googling that is a rather worrying use of resources considering 1/10,000th of German demand was being met by the equivalent of the nearly the entire wind generation capacity of Germany (24gw) while using just under half of Germanys entire pumped storage capacity! Scaling that to supply the entire demand would be ludicrously expensive.

You misread. It met 1/10,000th of demand with 22.1 MW of renewable capacity and ~1 MW of pumped storage. In the final report they mention that meeting storage demands for the whole of Germany would require roughly a tripling of available power and a doubling of storage capacity. Alternatively it could also be met with increased use of import/export of electricity.

Because we need to replace existing plants that are reaching their decommissioning dates now? In the UK we already have to extend our existing nuclear plants running life because we have no alternative despite adding lots of wind capacity. We simply cannot build turbines fast enough.

I already mentioned this problem, which is part of the reason that apparently older coal plants in Germany are being replaced by newer coal plants which have greatly increased efficiency and thereby lower total CO2 output. As the production of renewables continues to ramp up, that will be no longer necessary and then they can start replacing older plants.

As said already some nuclear can scale with demand and all of it can be slowly turned on/off as needed over a few days, however renewables are incapable of doing so at all. You either have wind and sun to run them or you don’t. You can store a tiny amount for later use but you can’t produce wind out of nowhere to supply a spike in demand. Gas turbines are here to stay for such quick changes in generation capacity sadly.

That is where biomass/gas comes in.

It may well be an urban myth but I thought that was because extreme wind speed would damage the turbines. Either way surely it would be easier/cheaper to shut down gas coal plants when demand falls. Gas turbines at least can scale pretty dam fast it the prime reason they’re so prevalent despite the cost of gas.

Most wind turbines are shut down when there is extreme wind - at wind speeds of about 25m/s. This high speed is not achieved very often. In contrast the problem of too much production is quite common.
The problem is that many conventional power plants are not made to quickly shut down or ramp up. There are several studies here (German) that look at the required conventional power generation as the amount of available renewables increases. The effect is that base load power plants are required less and less (to becoming completely unneeded by 2040 or so), while there is an increased need of middle load and peak load power plants. They calculate for one scenario - an optimistic one - which has renewables supplying about 47% of electricity by 2020 here in Germany, that unless using pumped-storage to try and mitigate the variability of output by renewables there would be no requirement of power plants running 100% of time - instead even the lowest amount of conventional power would be required to switch off and turn back on at least 84 times in a year. Using pumped-storage to change that, would still only allow a grand total of 1.8 GW to run 100% of the time. Anything higher than that would have to be turned off and back on every few days and more. Power generation that would run at least 7000 hours a year would have to cycle up to 250 times a year.

No one is arguing that renewables don’t produce energy, but the simple fact is to actually run the grid off of them would take far more than we can reasonably build within our lifetimes. Thats not a reason not to build them where the economics support them but to argue against building other forms of energy generation in favor of renewables is foolish when we know those renewables are not going to be in place to take over the needed capacity. Hence why Germany is building coal and will continue to give France money for its nuclear capacity.

You will of course prove these statements. The fact is that even conservative scenarios see up to 80% of power generation by renewables by 2050. And once again, new coal plants (and natural gas) replace some old coal plants while renewables continue to ramp up. As for France, Germany has generally generated a surplus of electricity. The reason that France exports so much electricity is quite simple: Their nuclear plants are not able to follow the load requirements enough, so they have to use exports to react to that changing power requirements. If France would not export so much energy, they could not have as much nuclear power as they have.

But surely if the renewable cannot be relied upon it must be backed up, either by pumped storage or conventional generation. Thats going to cost regardless of how much renewables there are but if the majority of the generation capacity can not be relied upon to keep working then the cost of providing the backup is going to skyrocket.

That depends on the cost of those backup power plants sitting idle.

I concede that as I was spewing hyperbole out of my arse. However plans to switch over to renewables are going to increase energy bills as well as taxation in general if their subsidies are kept in place as the sector grows, they simply cost more than coal or nuclear, sadly we cant get away from that.

They currently cost more than coal or nuclear. Their costs are coming down rapidly. What subsidies do is make that happen faster. Once their cost is low enough that they are competitive with conventional power even without subsidies, then those subsidies will be lessened and then eliminated. Several studies that have looked at the effect of renewables on electricity prices have come to the conclusion that they will not significantly increase the electricity bills (on the order of 20-30€ a year for a typical household).

[aerius]

The pilot project was deliberately made at a 1:10000 scale of the whole of Germany.

Some of the information is available in English at the following site: Kombikraftwerk. Unfortunately the final report is only available in German

I looked at the tech summary, scaling up is going to be fun. You'll need about 10GW worth of pumped storage hydro, which according to this is more than twice as much as much as your entire existing hydroelectric base. Biogas production will use up nearly 1/5 of your agricultural land. That's going to be a problem.

[D.Turtle]

Germany currently has about 7 GW of pumped-storage hydro (German wiki). At least another 2 GW are currently in planning, with a plant in Atdorf with a planned capacity of 1.4 GW being the largest part of that.

[Singular Intellect]

Germany currently has about 7 GW of pumped-storage hydro (German wiki). At least another 2 GW are currently in planning, with a plant in Atdorf with a planned capacity of 1.4 GW being the largest part of that.

Good old Germany, showing the world that renewables is viable, practical and not 'too expensive'. To quote Hermann Scheer (R.I.P.): "The argument is over. What can be done in Germany can be done anywhere. Arguments against solar have nothing to do with science, only mythology.". Hermann Scheer quite accurately pointed out that the only major hurtle to a 100% renewable energy is policies and political willpower. Arguments against renewable energy being able to meet all energy needs are based upon ignorance, lies and personal incredulity. Period.

To further your point D.Turtle, the examples of solar energy storage such as pumped storage, molten salt, rechargable batteries, etc are merely the transitional examples of the upcoming solar power grid baseline. Much like how hybrid vehicles are merely a step towards the end goal (full electric vehicles), not the final solution. Here's a small list of the future technologies that will be used for storing solar energy and rapidly revamping the existing power grids to accomodate renewable energy sources:

Nanocomposite paper batteries
Organic battery technology
Graphene enhanced Li-Ion batteries
Technological improvement of electrostatic capacitors
Super capacitor developments for renewables and electric vehicles
Virus built battery technology
Graphene enhanced super capacitors
Graphene supercapacitors beat batteries
Ultracapacitors as battery alternatives

Never mind what even more impressive advancements will be achieved in the next ten to twenty years.

Rapid technological advancement is taking place across the entire spectrum of industries, not just solar panels or computer chips. You need to look at the bigger current picture, not cite decade old analysis reports of solar panel payback or attack strawman positions like molten salts being able to meet all energy storage needs. The renewable energy infrastructure is rapidly being put into place and will continue to rapidly improve it's results, capacity and efficiency.

Like I said before, there is no convincing argument or evidence for a 100% renewable energy infrastructure for opponents to the idea. It's 'impossible', 'too expensive' and will not be accepted until they're literally in their homes running off solar/renewable power grids. The current conventional power companies are going to get steam rolled by the renewable energy sector. They're not stupid, they know their own end, they're just interested in postponing it as long as possible.

[aerius]

Germany currently has about 7 GW of pumped-storage hydro (German wiki). At least another 2 GW are currently in planning, with a plant in Atdorf with a planned capacity of 1.4 GW being the largest part of that.

Thanks, seems like my link from the German Ministry is a bit out of date.

---

Getting back to the latest batch of bullshit links posted by SI. Seriously, do you even read and understand the crap you post? Let's take a look at this one since it's the only one with hard numbers. Look at the energy density, it's the same as NiMH batteries and less than half of lithium ions. Would you like to know how many megatons of nanotech energy storage materials are required to provide large scale energy storage? Actually, just work out the fucking numbers yourself, I'm sick of doing your research and math homework for you.

[D.Turtle]

Thanks, seems like my link from the German Ministry is a bit out of date.

No problem. The numbers aren't out of date, they just counted the amount of hydro-power generation separately from pumped-storage. So there are about 4.7 GW of hydro-power and 7 GW of pumped-storage.

[PeZook]

SI, you have ignored people's points about advanced solar panels using rare earths which are in short supply. You can't just post links to articles about superior new technology existing somewhere. Your position ("Solar power will run the entire world, no need for nukes or coal") requires that technology to be physically possible to implement.

Arguments that producing enough panels and batteries would eat the entire world's production of rare earths and still not be enough should therefore be adressed if you are to defend your position.

I would also instruct both sides to use more citations instead of "several studies have shown that...". I really hate it when that sentence shows up in any sort of technical debate.

[Singular Intellect]

SI, you have ignored people's points about advanced solar panels using rare earths which are in short supply. You can't just post links to articles about superior new technology existing somewhere. Your position ("Solar power will run the entire world, no need for nukes or coal") requires that technology to be physically possible to implement.

Regarding conventional power plants, I assert they will become obsolete. I'm not asserting we shut them down tomorrow or stop current projects of building more conventional power plants. Indeed, building additional ones makes sense to meet growing energy demands and gives time for the renewable sector to grow and prove itself.

As optimistic as I am about solar power and renewable energy projects and projections, I'm not naive. The energy industry is neither small nor simplistic in scale.

Arguments that producing enough panels and batteries would eat the entire world's production of rare earths and still not be enough should therefore be adressed if you are to defend your position.

I already cited sources indicating the development of plastic solar cells, IBM's production of non rare material solar cells, etc.

They've been ignored already and I see no reason why they wouldn't be ignored again.

Molecular assembler technologies are also rapidly developing and will begin to render 'rare material' concerns obsolete as well, although that's delving into another debate in itself and I'm already getting weary of this one. Nothing can be as convincing as time playing out what I assert will happen (or more accurately, myself independently confirming what others are beginning to assert will happen).

Could I be wrong? Absolutely. Do I think I am? Not in the slightest, but only time can tell.

I would also instruct both sides to use more citations instead of "several studies have shown that...". I really hate it when that sentence shows up in any sort of technical debate.

I'm not referencing simple 'studies', I'm referencing actual working technologies that have been developed. Generally, the only hindering factors are things like cost and mass production methods. Which inevitably come down and get addressed, or have already been addressed for both those concerns during development. Some will work out, some will not. That's a given, but there will be multiple solutions, not 'one shot wonder fixes everything' nonsense.

Technological breakthroughs like the ones I'm referencing aren't magical. You can't just expect mass production and deployment months or a couple of short years after the concept has been proven. These things take time, no matter how viable and practical they are. Especially when faced with ridiculous criticisms and the fact they are attempting to invade the most powerful, influential and rich sector of our civilization which any idiot should know would have a strong vested interest in downplaying and hindering such a take over for as long as possible.

And since I'm here, I'll throw out some more informative links about energy storage mechanisms in the works:

New molten salt sotrage technology
Hydrogen Storage breakthrough
Home based energy storage systems

As far as I'm concerned, it's a foregone conclusion renewables are the future and will win out. I'd literally be shocked if that turns out to be incorrect.

[PeZook]

Regarding conventional power plants, I assert they will become obsolete. I'm not asserting we shut them down tomorrow or stop current projects of building more conventional power plants. Indeed, building additional ones makes sense to meet growing energy demands and gives time for the renewable sector to grow and prove itself.

No, the statement that spawned this thread was that you are not concerned with the death of nuclear power because the world would soon be powered entirely by solar power (not renewables: you said solar power). You can concede that position and try to take a new one, but you don't get to shift the goal posts mid-stride.

I already cited sources indicating the development of plastic solar cells, IBM's production of non rare material solar cells, etc.

They've been ignored already and I see no reason why they wouldn't be ignored again.

Point them out again ; If they actually address the problem and people ignore them, they will be called out on it.

I am not here to take sides in the debate, as that would preclude me from properly moderating it due to the inevitable conflict of interest. I am merely trying to ensure proper standards are observed.

I'm not referencing simple 'studies', I'm referencing actual working technologies that have been developed. Generally, the only hindering factors are things like cost and mass production methods. Which inevitably come down and get addressed, or have already been addressed for both those concerns during development. Some will work out, some will not. That's a given, but there will be multiple solutions, not 'one shot wonder fixes everything' nonsense.

I was not referring specifically to you. Which doesn't mean I will accept vague statements from you while denying that to your opposition.

In fact, you can start right now, as aerius demanded you show basic viability of these new power storage technologies. An order of magnitude estimate should do.

[aerius]

And since I'm here, I'll throw out some more informative links about energy storage mechanisms in the works:

New molten salt sotrage technology
Hydrogen Storage breakthrough
Home based energy storage systems

As far as I'm concerned, it's a foregone conclusion renewables are the future and will win out. I'd literally be shocked if that turns out to be incorrect.

I'm still not seeing any fucking numbers. Watt-hours per kilogram. What the fuck are they made from? Is it that fucking hard? I can look this shit up myself but frankly that's not my job, it's yours. You're the one claiming it can be done, I want to see the hard numbers to prove it.

[Sky Captain]

In northern climates like most of Europe solar as baseload is not possible unless you place the solar plants in Sahara and build power lines thousands of km long or have energy storage of ridicolous capacity that can store locally produced surplus solar energy during summer for usage in winter. In such places investment into wind energy would give better return because winter when energy demand is the highest also tend to be more windy. Wind turbines also don't require exotic materials, just steel, concrete, fiberglass and some copper and plastic.

[aerius]

Wind is better but it still has a pretty low capacity factor. From a quick search on Google, Germany has something like 25-27GW of installed wind power capacity. Going by this chart those wind turbines generate 37.5TWh of electricity per year giving a capacity factor of a bit over 16%. A modern nuclear plant is a bit over 80%, or about 5 times better. Meaning you'll need about 5 times as much installed capacity for wind power as you do for nuclear, plus the energy storage to even it out. Pumped hydro which is the most efficient way of storing energy is about 75-80% efficient overall, so add another 20% or so for process losses. The numbers aren't looking too good, it's possible in the sense that you won't use up the entire world's production of certain resources, but it's a hell of a big project and a crapload of land is going to end up underwater.

[Sky Captain]

Meaning you'll need about 5 times as much installed capacity for wind power as you do for nuclear, plus the energy storage to even it out.

That's another significant issue. Suppose you want to power Germany mostly from solar and wind. In another thread it was said Germany consume ~80 GW of power. To generate that from solar and wind would require ~400 - 500 GW installed capacity. When there is windy and sunny day there would be 5 - 6 x more power generated than actually needed so you would need energy storage of massive scale that can eat it or you would have to shut down most of solar and wind farms to avoid overload and lots of energy that potentially could be generated would be wasted. Upgrading the grid to a level it can handle 5 - 6x more power that has to be moved from solar and wind farms to pumped storage sites also would be major investment.

[The Big I]

So what do you think of this I think that it is doable if someone had the political guts to do it. http://www.energy.unimelb.edu.au/upload ... ort_v1.pdf

[aerius]

Yeah, good luck with that. They want to build gigawatts worth of solar with molten salt thermal energy storage. As I worked out on page 3 of this thread it would only take the entire yearly world production of sodium nitrate to run a 1GW plant for 12 hours, and they want build about 40GW worth of solar thermal with 17 hours of storage. They'd better find another kind of salt that's more abundant and mined and/or produced by the tens of millions of tons every year. But according to page 46 of the report, they're using 40/60 mix of potassium nitrate and sodium nitrate. Yeah, that's not happening, considering that the all-time production peak for sodium nitrate was 3 million tons a year back in the early 20th century.

[Sky Captain]

How abundant are potassium nitrate and sodium nitrate? Are these salts currently mined at low amounts because there is low demand or because they are difficult to find and extract? If the former then it is concievable a mining operations could be ramped up if demand for thermal storage grows.
Suppose you switch from coal to solar thermal. A lot of coal mining capacity would become spare some of that could be tasked to help to mine required salts.

[PeZook]

They're not mined, they're synthesized. Both compounds are important ingredients in industrial fertilizer and explosives. They are also toxic to humans if ingested or inhaled.

Incidentally, the production process for both is really environmentally unfriendly. Considering the viability of solar power should take into account the environmental impact of producing both compounds in the required amounts,and any technologies that could be used to reduce it if they exist.

[aerius]

From what I can tell sodium nitrate production is anywhere from 60,000 tons a year to 700,000 tons, I'm guessing that some of the sources are counting the mines alone while others are counting both mines and what's produced in chemical factories. Potassium nitrate I can't get any numbers on, I can only find numbers for Potash which includes all potassium salts; that's around 33 million tons a year. How much is nitrates I have no idea, nor do I know if the other salts can be economically converted to nitrates. Potassium salts at least looks possible on a supply basis, we have billions of tons of reserves and a crapload of production every year. If the solar thermal plants can be made to run on a 90-100% mix of potassium salts then we're in business (farmers might be pissed though) but as long as the salt mixes are around 50%Na 50%K it's not happening unless we find a way to seriously increase sodium salt production.

[Napoleon the Clown]

What kinds of fire hazards would you see with molten salts storage? Would these things simply burn down or would they potentially explode rather violently? If they run a higher risk of catching fire than you see with current power plants I would imagine that that would be a pretty big drawback, especially because they're gonna have more nasty shit around than just the various salts used to store the energy. As has been said, the panels themselves have some really nasty chemicals.

[madd0ct0r]

Wind is better but it still has a pretty low capacity factor. From a quick search on Google, Germany has something like 25-27GW of installed wind power capacity. Going by this chart those wind turbines generate 37.5TWh of electricity per year giving a capacity factor of a bit over 16%. A modern nuclear plant is a bit over 80%, or about 5 times better. Meaning you'll need about 5 times as much installed capacity for wind power as you do for nuclear, plus the energy storage to even it out. Pumped hydro which is the most efficient way of storing energy is about 75-80% efficient overall, so add another 20% or so for process losses. The numbers aren't looking too good, it's possible in the sense that you won't use up the entire world's production of certain resources, but it's a hell of a big project and a crapload of land is going to end up underwater.

Meaning you'll need about 5 times as much installed capacity for wind power as you do for nuclear, plus the energy storage to even it out.

That's another significant issue. Suppose you want to power Germany mostly from solar and wind. In another thread it was said Germany consume ~80 GW of power. To generate that from solar and wind would require ~400 - 500 GW installed capacity. When there is windy and sunny day there would be 5 - 6 x more power generated than actually needed so you would need energy storage of massive scale that can eat it or you would have to shut down most of solar and wind farms to avoid overload and lots of energy that potentially could be generated would be wasted. Upgrading the grid to a level it can handle 5 - 6x more power that has to be moved from solar and wind farms to pumped storage sites also would be major investment.

These numbers don't add up. Both of you ought to check you figures and reasoning again.

Aerius: so you need approx 5 times the installed capacity for wind as you would for nuclear, OK?
Why then do you need to add 20% for energy lost to storage inefficiencies? are we putting 100% of the energy generated into (or through) storage? I think you need to figure out how much storage capacity is required to 'smooth' the energy coming in. It ain't 100% unless germany is only windy 1 day a year.
Be careful with your numbers, you've been pulled up on this a few times already.

Sky Captain: sigh.
So, Aerius decides we need to build 5x the nuclear capacity to ensure we generate the 1x power figure. Your figure is 80GW. You go from there to 400W-500W. ok. a little higher then 5x but I'm sure you can justify that. Then you assume that we need to store 100% of the theoretical maximum energy produced, despite knowing 6.25-5% production capacity is all that is needed to meet the annual demand.

I'm not surprised you are so dismissive of solar, your numbers look terrible.

[aerius]

Aerius: so you need approx 5 times the installed capacity for wind as you would for nuclear, OK?
Why then do you need to add 20% for energy lost to storage inefficiencies? are we putting 100% of the energy generated into (or through) storage? I think you need to figure out how much storage capacity is required to 'smooth' the energy coming in. It ain't 100% unless germany is only windy 1 day a year.
Be careful with your numbers, you've been pulled up on this a few times already.

I didn't have anything to work with at the time so I assumed that the vast majority of the energy that's produced would have to stored and came up with a ballpark number.

Since there are now some figures to work with I can come up with a better estimate. It's assumed that the "secure guaranteed capacity" for wind is 5% for onshore and 10% for offshore. I'll skew the numbers slightly towards offshore and call it 8% on average. So, we have 8% which is guaranteed to be available at all times and an average capacity factor of 16%. Problem is we still don't know the what distribution of minimum, average, and best windy days is, it could be a month of weak wind, 6 months of average, and 5 months of strong winds or the other way around.

We could assume a roughly normal distribution and say that 8 months are average so we'll only needs storage for the 2 months on the low side, then since guaranteed power is half of what we need it works out to storing a month's worth of energy production, in which case the process losses are a couple percent or less and not worth counting. Does it work out that way in the real world? Damned if I know, and I'm not paid enough to go find out. So figure 5 times the installed capacity for nuclear, then add a fudge factor of 5% or so to be safe. A bunch of land is still getting flooded.

[D.Turtle]

Actually the whole thing is even more ridiculous.

The idea that you take the nominal power generation and multiply it by the capacity factor in order to find out what the absolute minimum output at any one time is, is patently ridiculous. The capacity factor is a long term average of power generation. Multiplying the nominal power generation capacity by the capacity factor tells you how much electricity they produced in total during the whole year. It tell you nothing about the power generation at any one time. So the capacity factor is completely useless at telling us if we have the 80GW peak-load covered.

So, lets compare the real numbers. According to this study (german pdf) the needed electricity production would be roughly 595 TWh in 2020. Dividing that by 8760 (the hours in a 365 day year), we get 68 GWh. Dividing that by 0.16 - your extremely low balled capacity factor - would mean a required installed capacity of 425GW to cover all electricity production with just wind. Using a more realistic capacity factor of 20% (based on total installed capacity vs actual output - from here) would yield a required installed capacity of 340GW. If we assume that the capacity factor will increase to 25% - which seems quite possible as offshore wind power is expected to expand rapidly and is obviously more efficient than onshore due to steadier winds - we get a total required installed capacity of 272 GW. Taking the numbers from the study cited above, they expected a capacity factor of roughly 0.25 for wind onshore and 0.37 for wind offshore. This means that the total required installed capacity can be figured even lower as the wind power offshore is increased. This to cover all electricity generation purely by wind power.

Obviously reality will look quite different. From the same study (still german pdf) I mentioned above - which is a relatively optimistic study for the renewable energy sector - they envision the following scenario by 2020:
Total installed capacity of all renewables together: 111 GW
Total Electricity production of all renewables together: 278 TWh (47% of total)
Wind onshore: 45 GW installed, 112 TWh generated, capacity factor (CF): 0.249
Wind offshore: 10 GW installed, 37 TWh generated, CF: 0.37
Bioenergy: 9.4 GW installed, 54 TWh generated, CF: 0.5814, available any time
Solar: 39.5 GW installed, 39.5 TWh generated, CF: 0.1
Water: 6.5 GW installed, 31.9 TWh generated, CF: 0.49
Geothermal: 0.625 GW installed, 3.8 TWh generated, CF: 0.6
In addition roughly 13 GW of pump-storage capacity generation.

Again, this would cover almost 50% of all electricity production in 2020.

In addition, a follow-up study (german pdf) was done in which they used the weather data from 2007 in order to look at the feasibility and effects of that scenario. This results in an expected decrease of 36 GW of base-load power generation, and an increase of 4 GW of middle-load and 9 GW of peak-load power generation.