|
|
Post by patrick on Jul 16, 2014 0:38:23 GMT 9.5
Hi everyone, first post here. Used to be a renewables fan until I started reading some of the information here and elsewhere. Now I'm pretty convinced the only thing that's going to stop catastrophic global warming is nuclear power.
I was wondering it anyone had any data on what is the longest period of no sun and no wind affecting around 1000+ miles. Im trying to determine energy storage needs for a renewables super grid.
|
|
|
|
Post by Roger Clifton on Jul 16, 2014 18:32:06 GMT 9.5
I was wondering if anyone ... Patrick, rather than have us research the question for you, may I suggest you study up on the "European winter anticyclone" and perhaps "blocking highs". These starting points will set you going on a hunt across the Web for the patterns of weather that you are interested in. Then, when you tell us about something you found interesting, there will almost certainly be people wanting to discuss with you. (Then I will delete this comment) PS: DBB, who speaks from one of the "Pacific Northwest" states of the USA provides another clue. |
|
|
|
Post by ppp251 on Jul 18, 2014 0:27:16 GMT 9.5
This was daily generation of wind+solar in Germany in 2013:  www.ise.fraunhofer.de/en/downloads-englisch/pdf-files-englisch/news/electricity-production-from-solar-and-wind-in-germany-in-2013.pdfBased on wind and solar data it is estimated that in the case of 100% renewable grid Germany needs about 35TWh of storage capacity to overcome daily and seasonal gaps (total generation is about 600TWh). Total annual sum of stored energy would be about 70TWh (it is charged multiple times a year). With power-to-gas being 33% efficient (electricity->methane->electricity) that would mean about 210TWh of additional generation. So in 100% renewable grid generation would increase from 600TWh to about 800TWh. That's brute-force way to do it (it could be done more efficiently with smart grids and stuff like that). But these are the numbers. |
|
|
|
Post by cyrilr on Jul 18, 2014 7:52:56 GMT 9.5
35 TWh of utility grade storage, at $200/kWh, would cost 7000 billion $. That's $7 trillion. As in, terra-dollars.
Not bloody likely.
much more likely: endless fossil fuel lock-in for the majority of Germany's power supply.
|
|
|
|
Post by ppp251 on Jul 18, 2014 9:41:56 GMT 9.5
Batteries are not competitive for this particular task. Power-to-gas would be better suited (gas grid and gas turbines are already in place).
A quick calculation:
German gas grid = 200+TWh of gas storage capacity. That's enough.
What is needed is electrolysers and 200TWh of additional electricity to make methane. At €80/MWh (an estimation for long term wind and solar cost, could be lower) electricity would cost €16 billion per year.
Cost of electrolysers is more of a guesswork. Companies say it's about 1200€/kW and could get to 600€/kW in the future. How much you'd need? At 33% capacity factor then about 70GW of electrolysers. That sums up to 42€ billion (I took 600€/kW). Let's say lifetime of one electrolyser is 10 years (a guess), that gives about 4€ billion per year. Let's give another 2€ billion per year for maintenance.
That sums up to about 22€ billion per year for storage. It looks doable (Germany's GDP is in trillions). There are additional costs (gas turbines, grid maintenance), but first estimates go in 'it's possible' ballpark.
|
|
|
|
Post by cyrilr on Jul 18, 2014 15:14:41 GMT 9.5
Batteries are not competitive for this particular task. Power-to-gas would be better suited (gas grid and gas turbines are already in place). A quick calculation: German gas grid = 200+TWh of gas storage capacity. That's enough. What is needed is electrolysers and 200TWh of additional electricity to make methane. At €80/MWh (an estimation for long term wind and solar cost, could be lower) electricity would cost €16 billion per year. Cost of electrolysers is more of a guesswork. Companies say it's about 1200€/kW and could get to 600€/kW in the future. How much you'd need? At 33% capacity factor then about 70GW of electrolysers. That sums up to 42€ billion (I took 600€/kW). Let's say lifetime of one electrolyser is 10 years (a guess), that gives about 4€ billion per year. Let's give another 2€ billion per year for maintenance. That sums up to about 22€ billion per year for storage. It looks doable (Germany's GDP is in trillions). There are additional costs (gas turbines, grid maintenance), but first estimates go in 'it's possible' ballpark. If it were that cheap, Germany would not be building coal plants. Sanity check people. Electrolyser efficiency: 0.7. Methanization efficiency: 0.7 (guess?) (n.b. you didn't consider a capital cost here, it is substantial and not done on any large scale today either) CCGT efficiency: 0.6 multiply gives 0.29 cycle efficiency (not even counting gas transport inefficiency). This is too low. For instance, with 80 euros/MWh power, 80/0.29 = 275 euros/MWh of stored energy. That's too expensive. If not for Germany, then certainly for countries like China who have 20-30 euros/MWh coal power. This is the storage conundrum. Storage techs that are efficient are too expensive, the ones that are affordable are made too expensive by poor efficiency. A Watt of solar power is already at a factor of 9x disadvantage in Germany in terms of kWh per year productivity over nuclear and coal. If you then divide by 0.29 the disadvantage factor becomes 31. So you'd need 31 Watts of solar power to match 1 Watt of nuclear power. All because we are ideologically opposed to nuclear. |
|
|
|
Post by ppp251 on Jul 18, 2014 19:42:29 GMT 9.5
Methanization can be 0.8 or higher (insiders say overall process can be improved to about 0.4-0.45), but I get your point.
But if everything was governed by capacity factor then we wouldn't have so many cars. Cars are parked most of the time. They have capacity factor less then 10%. But we still use them.
|
|
|
|
Post by cyrilr on Jul 18, 2014 19:52:21 GMT 9.5
Methanization can be 0.8 or higher (insiders say overall process can be improved to about 0.4-0.45), but I get your point. But if everything was governed by capacity factor then we wouldn't have so many cars. Cars are parked most of the time. They have capacity factor less then 10%. But we still use them. Not a relevant comparison. Cars aren't needed more than 10% of the time for most; yet they are expected to be there 100% of that 10% of the time. If the car doesn't start once a week, its unreliable. Solar isn't there in the winter. Not exaggerating - a 100 Watt solar panel in Germany in december generates 1 to 2 Watts of average power. The alternatives - actually what we have today, the baseline nuclear, gas, coal and hydro plants - don't have this downside. If you could choose between a car that works 350 days in the year or one that only starts 35 days in the year. Which one would you choose? The renewables enthusiasts seem to like their equipment more the less reliable it gets, unlike most other people. What if your car starter motor would not work when its cold? Then it would not get you to work the entire winter! Solar is like that. Wind is more available in winter but even more fickle than solar at the same time, plus on the grand scheme of things wind would not be enough, solar PV is basically what you look for. We're talking about a future German demand of say 100 GWe, needing 1000 GW peak solar PV. That costs $1 trillion at $1/Watt installed. The truth is, if solar PV would operate at 90% rather than 9% we would not be having this discussion. We would all be solar powered and the nuclear and coal and gas people would have left the building long ago. Again, the energy problem is not confined to Germany. Its not even a bit player on the grand scheme of things. We need solutions that are cheap and practical enough for the Chinese to stop building coal plants. |
|
|
|
Post by ppp251 on Jul 19, 2014 0:52:45 GMT 9.5
The point was that not everything is governed by capacity factor. It's the energy we want, not capacity factor. But I do recognize that storage will eventually be needed. Actually, batteries for electric vehicles are needed right now. But they are not needed for the grid yet. We first need to get to 20-30% of wind and solar and that doesn't require storage. China is a little bit offtopic but nonetheless. Don't just ignore the data, wind is scaling faster than nuclear in China. ![]()  cleantechnica.com/2014/03/13/wind-leaves-nuclear-behind-china/ |
|
|
|
Post by cyrilr on Jul 19, 2014 1:26:44 GMT 9.5
And wind and nuclear and all non-coal fuels are growing at a tiny fraction of the growth rate of coal in China!!! Don't omit that important point. Further, don't omit the point that almost all power comes from reliable sources such as nuclear, coal and hydro in China. Thus a tiny amount of wind can grow fast without running into problems. Again, you're completely missing the big picture. China is coal-powered. It won't replace with wind because wind is fickle. What you get is coal plants running slightly less efficient and thus emitting more toxins, more PM10, more CO2, per kWh, for every kWh of fickle wind they must accomodate. As for 20% solutions, that doesn't scratch the problem. Coal use is growing so fast we need a 90% solution in China, a few more decades of growth and we need 95% solution. If all countries achieve 30% renewables, we will end up with MORE emissions due to economic and population growth. www.energytrendsinsider.com/wp-content/uploads/2013/08/Coal-Consumption.png?00cfb7 |
|
|
|
Post by cyrilr on Jul 19, 2014 1:28:34 GMT 9.5
|
|
|
|
Post by ppp251 on Jul 19, 2014 5:17:29 GMT 9.5
Are you trying to say that wind growth is irrelevant because coal growth is bigger?
And just as a sidenote: these energy charts are often misleading, because they include wasted energy. Actual electricity generation is more accurate.
Oil and liquid fuels are a whole another set of problems.
|
|
|
|
Post by patrick on Jul 20, 2014 5:18:25 GMT 9.5
Thanks for the replies so far; this has been interesting reading. However, I still don't have an answer to my original question. I've been scouring the internet but haven't turned up anything concrete so far. I'm just trying to determine how many days you would need to get 100% (or close) of your power from energy storage with a super grid (Europe, Australia, or the US) given a worst case weather scenario of no sun/wind. What is the longest stretch of days in history where close to all of the US/Europe/Australia has had no (or very little) sun or wind? Finding raw data relating to this question has turned out to be pretty difficult.
|
|
|
|
Post by ppp251 on Jul 20, 2014 6:55:42 GMT 9.5
patrick, it depends on area considered. The larger the area, the less storage you'll need (but more grid connection). Note that what is relevant is not just longest period of no wind/no solar, but longest period before storage capacity can be recharged again.
It doesn't help if you have 2 weeks of storage, then you discharge it, then you have 1 week of good weather (but not good enough to recharge storage), but then you have again 2 weeks of bad weather. Obviously in such case you need more than 2 weeks of storage.
Installed capacity is also relevant. If you massively overbuild wind capacity, then less storage is needed. 100% renewable simulations often contain some amounts of spilled energy.
The answer to "how much storage?" depends on these assumptions. But I doubt you'll get it without in-depth simulations.
|
|
|
|
Post by cyrilr on Jul 20, 2014 16:48:14 GMT 9.5
The answer is simple. Weather is a natural process, which follows log normal distribution of events. As such it is always possible to get a worse weather situation. 3 week lulls of wind in winter across europe are very rare but not impossible. But so are 4 or 5 weeks so you will always need fossil backup no matter how much storage you have.
|
|
|
|
Post by patrick on Jul 21, 2014 5:57:48 GMT 9.5
patrick, it depends on area considered. The larger the area, the less storage you'll need (but more grid connection). Note that what is relevant is not just longest period of no wind/no solar, but longest period before storage capacity can be recharged again. It doesn't help if you have 2 weeks of storage, then you discharge it, then you have 1 week of good weather (but not good enough to recharge storage), but then you have again 2 weeks of bad weather. Obviously in such case you need more than 2 weeks of storage. Installed capacity is also relevant. If you massively overbuild wind capacity, then less storage is needed. 100% renewable simulations often contain some amounts of spilled energy. The answer to "how much storage?" depends on these assumptions. But I doubt you'll get it without in-depth simulations. Thanks for this answer. I've been debating with a renewables advocate at cleantechnica and he kept demanding that I supply the hard data demonstrating a two week lull of little/no sun and wind across the entire US. I had claimed that you need roughly two weeks of energy storage for a super grid to be prepared for the worst case scenario. This claim was just a ballpark figure based on what little I know of weather patterns. I can see now, however, that his demand for data was nothing more than a red herring. |
|
|
|
Post by Roger Clifton on Jul 21, 2014 8:12:17 GMT 9.5
...you will always need fossil backup no matter how much storage you have. The more insurance a renewable economy installs, the more outages it evades, the less prepared it will be when happenstance eventually brings the angry climate indoors. PS: By "insurance" I meant "storage". It would protect them from occasional unkind weather but not the very worst. |
|
|
|
Post by David B. Benson on Jul 21, 2014 9:56:08 GMT 9.5
patrick --- The Pacific Northwest is part of the Western Grid. There are a few very weak interties to the Eastern Grid. There are three other grids in North America, leaving out south of Mexico. As the interties between girds are weak, it suffices to consider each grid separately. But worse, the Pacific Northwest is an electricity producer which wheels a lot of power to California; the Californians never reciprocate, being short of generation. So when the wind does not blow for weeks on end in the fall here in the Pacific Northwest, the power comes solely from hydro and thermal sources.
|
|
|
|
Post by cyrilr on Jul 22, 2014 23:43:54 GMT 9.5
...you will always need fossil backup no matter how much storage you have. The more insurance a renewable economy installs, the more outages it evades, the less prepared it will be when happenstance eventually brings the angry climate indoors. Insurance? What a tactical euphemism for burning fossil fuels! I must congratulate you on your marketing skills. You could probably sell a refrigerator to a polar bear! |
|
