Thank you for the kind words, I enjoy the discussion. I love it when people are willing to look at the numbers. Now let's see if I can convince you with this monster post This scenario does not depend on unwillingness to export power by the neighboring countries. We are trying to eliminate coal, nuclear and NG completely, Germany's neighbors are doing the same, indeed, they are being forced to do so by the EU. Even France is building windmills. The situation in which all of Europe is covered by clouds and lacking wind is not uncommon. Solar doesn't contribute much during winter anyway, so a lull is very challenging in itself. In these scenarios, the neighboring countries will be struggling to cope with their own massive losses of unreliable renewable power. Norway might contribute a little due to our gigantic hydro reservoirs, but the problem is the enormous power required. We have lots of stored energy, but only a little bit more generator capacity than we need. Total capacity is about 30 GW, and we need about 25 of those ourselves. Increasing power delivery would be enormously costly and very controversial due to environmental concerns - fish does not like rivers that are a raging torrent one day and a trickle the next, and the insect larvae on the bottom of the lakes die when they're suddenly 10 meters above the water. Norway will not volunteer to become an environmental disaster area, and if anyone tried then you can count on chain gangs and sabotage. The government has met massive problems trying to build a transmission line which is essential to secure supply to Bergen. A forest of power lines for the benefit of Germany is out of the question, and even a tripled export capacity would be a drop in the ocean when all of Europe needs power at once. Germany will have to fend for itself. Good, so NG can fill in, but you need to more than double installed capacity to back up those two weeks. Who will pay for the standby capacity? CCNG costs about 1 billion euro per GW, so you need about 35 billion, not counting running expenses (maintenance, minimum staff). Two weeks of operation per year is not going to pay for the investment. Surely, the unreliable sources will have to pay for their own backup, how does this affect the cost of wind power? There is no way that they can have 60% round-trip efficiency. I bet that's just methane generation efficiency, and if so, it's extremely good, electrolysis is usually said to be about 50% efficient, and these guys add another complex step and increase efficiency to 60%. They're trying to sell the concept, so I'm tempted to think they're exaggerating, but let's use their figure anyway. This means that you need to input 33 TWh to get 20 TWh of methane. But you need 33 TWh of methane to get the 20 TWh of electricity, so electrical input will have to be 55 TWh. You need nine thousand two hundred of those plants. Oh, wait - I forgot transmission losses. Multiply by 1.07. Assume they're about as costly as CCNG plants - add another 40 billion plus running costs. Methaniation requires an input of massive amounts of CO[sub]2[/sub]. You need one molecule of CO[sub]2[/sub] per molecule of methane. This carbon must be captured from either the atmosphere or a biomass plant equipped with a CCS system to be carbon neutral. Is there enough biomass in Germany to provide all that CO[sub]2[/sub]? Biomass for this purpose would also compete with both solar panels and biofuel for the aviation industry. Or you might add CCS to the CCNGs themselves, and feed their own CO[sub]2[/sub] back to the methaniation plants. All of these alternatives are also shockingly expensive. Add another ... 20 billion? Plus a CO[sub]2[/sub] distribution system, I have no idea what that might cost. Further, there is an energy cost to capturing all that CO[sub]2[/sub] that you did not count. This is likely to be about 25%. Now we're up to 80 TWh input to the storage system. But there are no guarantees that there will not be two episodes like this per year. One might want to have some extra methane capacity on hand and the windmills to power it. Now we're approaching the real cost of unreliable energy. I'm counting at least 115 billion euro - in addition to the cost of the unreliable renewable generation capacity itself. These are mature technologies, there are no revolutionary efficiency increases to be had. Power demand management might help a little bit, but don't expect much, BMW will be less than impressed if you tell them that they have to stop their factories for a week. V2G might actually help by a noticeable amount, but this time, the problem is energy capacity. You need two or three weeks of backup, not two days. The price of the backup system alone will pay for 40-50 GW of modern reactors, which would provide 70 to 85% of Germany's power. Together with the renewables already installed, demand management and V2G, this might actually do the trick. I don't care how Germany rids itself of carbon, and coal in particular, it's just that I can't see how it can be done without nuclear. There isn't enough money. I encourage you to take another long, hard look at the Integral Fast Reactor and try to identify its weaknesses. I can't find a single flaw, except for the word "nuclear". That is a significant disadvantage, however. It's an extremely elegant solution, everything has been thought of, no loose ends are left dangling. I would recommend buying "Plentiful Energy". It's a bit repetitive and somewhat dry, but it does examine the design in great detail, and was written by those who know it best. You'll get through it in a week. You can find most of the material by starting at this post at the bravenewclimate blog and following the links, if you don't want to pay those Argonne pro-nuke technofixers for their book (tongue-in-cheek). We need to start building solutions now, we can't wait for the IFR. So take a look at AP1000 and ESBWR and try to find their weaknesses too, under the assumption that we will be deploying IFRs en masse in ten to fifteen years. If you would try your best to shoot down that plan, then I would be happy to try to defend it :biggrin: Take all the time you want responding, I can't keep this pace up anyway. :scared: *edit* Changed from "renewable" to "unreliable renewable". There are multiple types of reliable, renewable power, e.g. hydro, osmotic and tidal power. I'm all for those, they have no hidden costs. Solar energy in the deserts of northern Africa might also possibly qualify as reliable, I'm not sure.