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I think solar is a good bet-because it relies on a reliable giant fusion reactor which for which we don't need to spend a single buck for maintenance. Now the problem with electricity is that there is no good way to store it. ... Now I read about a process wherein an electric train on an inclined track hauled a shitload of concrete blocks up the mountain in order to store the energy by simply storing It's potential energy against gravity. ... It's so loving simple. Its simpler than pumping water back up high and running it back through the turbine. zimboe fucked around with this message at 15:51 on May 11, 2016 |
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May 11, 2016 15:46
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What percentage is lost to friction in moving concrete blocks up/down a mountain? Or is that minimal compared to the other losses?
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May 11, 2016 15:51
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Also: Are they only using the storage to buffer lows during the day or is that overnight storage? I mean, you have to use energy not being committed to the grid to get it back up the hill....
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May 11, 2016 15:53
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Quandary posted:What percentage is lost to friction in moving concrete blocks up/down a mountain? Or is that minimal compared to the other losses? Rails are pretty efficient as long as there is little vertical motion.
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May 11, 2016 15:54
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CommieGIR posted:Also: Are they only using the storage to buffer lows during the day or is that overnight storage? I mean, you have to use energy not being committed to the grid to get it back up the hill.... I would guess it's for peaking. Move them up during the night when demand is low, then bring them back down when immediate capacity is needed.
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May 11, 2016 15:58
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Quandary posted:What percentage is lost to friction in moving concrete blocks up/down a mountain? Or is that minimal compared to the other losses? Rails are very efficient for leveling moving loads, roughly 100/ 1. that is, a locomotive with a piston thrust of a ton at the piston radius radius can shift a train with remarkable speed.
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May 11, 2016 16:16
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zimboe posted:Rails are pretty efficient as long as there is little vertical motion. The problem is geography. It's best to do this in wide-open, non-arable land with little environmental impact. This shares synergy with solar/wind power. It does not share synergy with population density. It is impractical to do this near, say, the eastern seaboard.
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May 11, 2016 17:12
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Deteriorata posted:I would guess it's for peaking. Move them up during the night when demand is low, then bring them back down when immediate capacity is needed. That's the long term plan, right now it's just going to offer power conditioning services, helping Cal ISO smooth out reactive power and other fluctuations on the grid. Ramp up is slower than batteries/capacitors but much faster than a gas plant.
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May 11, 2016 17:14
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Quandary posted:What percentage is lost to friction in moving concrete blocks up/down a mountain? Or is that minimal compared to the other losses? It says in the article that they have... 86% efficiency if I recall? It's in the 80% range, which seems REALLY good.
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May 11, 2016 17:17
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Boten Anna posted:It says in the article that they have... 86% efficiency if I recall? It's in the 80% range, which seems REALLY good. That is very good efficiency, but the next question is power density. People like hydrocarbons because even though you only get ~30% efficiency, it's a lot of energy.
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May 11, 2016 17:18
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computer parts posted:That is very good efficiency, but the next question is power density. People like hydrocarbons because even though you only get ~30% efficiency, it's a lot of energy. Yeah they want to do research into steeper inclines which would allow them to use less land and site further east. There will be a lot of useless coal mine sidings in WV soon, that would be a great place to reuse some rail. But even the current style could be really useful for the west.
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May 11, 2016 17:22
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Pander posted:The problem is geography. It's best to do this in wide-open, non-arable land with little environmental impact. The way it reads they don't nessisarily need a stait incline. There are plenty of places where you could fit in a smaller, slightly meandering (and likely a little less efficient) few miles of track on the east coast. Even offsetting 50MWh on a local scale has a big impact. As for steeper slopes I can see them getting this working on some extreme inclines. Rather than use electric motors on the cars the assembly would be lifted from the top by steel cables. The steep incline would allow you to pack enough power into a small area to make up for very short term surges. Say, 1MWh per rail but setup to allow for a 3MW discharge rate. Granted that much concrete falling all the way in 20 minutes would be a pretty dangerous sight. Around 15, 50 tonne cars lifted 500 meters will give you that.
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May 11, 2016 18:54
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M_Gargantua posted:The way it reads they don't nessisarily need a stait incline. There are plenty of places where you could fit in a smaller, slightly meandering (and likely a little less efficient) few miles of track on the east coast. Even offsetting 50MWh on a local scale has a big impact. There is a rock quarry that uses a downhill rock conveyer to generate some small amount of power they use onsite. I think it was probably cheaper to use the energy for power than use energy to slow down the rocks. However, rail generally has very limited incline tolerance. Someone start the funicular equivalent quick!
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May 11, 2016 18:59
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Trabisnikof posted:However, rail generally has very limited incline tolerance. Someone start the funicular equivalent quick! As far as I understood it the incline tolerance wasn't so much the load bearing but the difficulty getting good traction for power transmission. On an inclined winch the cables do all the power transmission and the rails are there as guides and supports for the load cars. Maybe I need to poll a pro from the train thread though?
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May 11, 2016 20:33
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All the more reason to start saving up for a space elevator.
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May 11, 2016 21:59
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The European Union is making noises about throwing some support behind nuclear generally and possibly SMRs specifically. Scared German politicians are throwing a fit over the fact that the German government hasn't started throwing a fit yet, and pointing out that nuclear power plants that aren't getting replaced in part because of scare politics are falling apart without a hint of self-awareness.
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May 17, 2016 11:26
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I CANNOT EJACULATE WITHOUT SEEING NATIVE AMERICANS BRUTALISED!
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Researchers create a module that converts 34.5% of received solar energy to electricity.quote:Researchers at the University of NSW have utilised the light-trapping effects of a simple prism to dramatically boost the efficiency of solar cells. http://www.smh.com.au/technology/sci-tech/unsw-researchers-break-solar-efficiency-record-for-unfocused-sunlight-20160517-gowsgx.html Solar keeps on getting better. This is still a long way from market, but its encouraging.
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May 18, 2016 05:46
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Frogmanv2 posted:Researchers create a module that converts 34.5% of received solar energy to electricity. We've had 40% efficient solar cells for a while now. They are expensive as gently caress.
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May 18, 2016 14:52
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We've  had ultra premium solar for a long time. poo poo that is earmarked for space or research probably has no place here, though.
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May 18, 2016 15:23
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CommieGIR posted:We've had 40% efficient solar cells for a while now. They are expensive as gently caress. The 40% number (actually, it is probably higher than that now) is for concentrated sunlight. This team achieved 35% with unconcentrated sunlight. There are a lot of good things about unconcentrated solar cells which make them more interesting for many solar energy applications than concentrated solar cells. For one, unconcentrated cells are actually able to convert diffuse sunlight in the sky (this is 30% of the sunlight in the sky in the Bay Area in California) into electricity. Concentrators cannot. Concentrator cells at high concentration also require cooling systems, tracking systems, and can be safety hazards--think about how you can use a magnifying glass to fry ants! The good thing about solar energy is how low-maintenance and low hassle it is, and concentrators take some of that advantage away. Potato Salad posted:We've The III-V semi-conductor solar cells often used in concentrator solar systems are expensive, yes, and aren't sold to normal consumers, but I see no reason why they necessarily have to be. If someone here can argue why they necessarily have to be expensive, I'd be pretty interested in hearing their argument. silence_kit fucked around with this message at 15:55 on May 18, 2016 |
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May 18, 2016 15:26
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silence_kit posted:The 40% number (actually, it is probably higher than that now) is for concentrated sunlight. This team achieved 35% with unconcentrated sunlight. There are a lot of good things about unconcentrated solar cells which make them more interesting for many solar energy applications than concentrated solar cells.
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May 18, 2016 16:21
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386-SX 25Mhz VGA posted:Not really understanding here, why would a PVC's efficiency be a function of light intensity At a guess? They probably don't have a linear response to light intensity.
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May 18, 2016 16:59
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Kalman posted:At a guess? They probably don't have a linear response to light intensity.  Like, does the efficiency increase because the efficiency increases at higher temperatures, and higher light intensity tends to raise temperature? I guess that makes sense.
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May 18, 2016 17:09
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386-SX 25Mhz VGA posted:That just seems weird to me from what I know about light and the photovoltaic effect, but I guess I'm not a solarcellomatologist Under constant non-time varying illumination, solar cells produce constant electrical power. The formula for constant electrical power is Power = Voltage x Current. So solar cells need to generate both a voltage and a current to be able to generate electrical power. The exact shape of the solar cell current-voltage relationship under different solar illumination intensities is complicated and I won't get into all of the details, but it pretty much can be summarized as the following statements. When a good solar cell is properly loaded in the power generation circuit: 1) Current generated is roughly proportional to absorbed sunlight intensity. Solar cell scientists understand this part very well and within the fundamental limitations of the popular solar cell schemes, good solar cells (those with >20% efficiency) do about as well as they possibly could in this aspect. Photons in -> electrons out is done at very close to 100% efficiency in good cells. Current is easy. Voltage is harder. Actually, even a lot of solar cell scientists do not understand the voltage very well. 2) Voltage generated is roughly proportional to the logarithm of absorbed sunlight intensity, at least until you get to really really high solar intensities. Upon solar illumination, excited-state photo-generated electrons accumulate in the solar cell. The reason why the voltage increases when illumination intensity increases is because at higher solar intensities, the electron concentration increases, the excited state electrons occupy higher energy levels in the semi-conductor, and so the electrons can be extracted from the solar cell at higher voltages. The output voltage of the solar cell is the part of the solar cell that needs to be improved upon for current solar cells to achieve their theoretical efficiencies. The way to improve the voltage is to carefully study the various mechanisms in the cell by which photo-generated electrons are converted directly to waste heat in the cell and engineer those mechanisms out. TL;DR: Since Power = Voltage x Current, and Voltage is proportional to the logarithm of solar intensity and Current is proportional to solar intensity, the efficiency ( = Power/(Solar Intensity x Cell Area)) increases with the logarithm of solar intensity, and efficiency increases under solar concentration. silence_kit fucked around with this message at 16:40 on May 19, 2016 |
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May 18, 2016 19:38
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386-SX 25Mhz VGA posted:Not really understanding here, why would a PVC's efficiency be a function of light intensity PV efficiency goes down as temperature goes up. Concentrated Photovoltaic (CPV) uses dual-axis trackers using lenses to concentrate direct sunlight onto a multi-junction cell, usually at a few hundred times normal solar intensity, then use heat sinks to keep the cell cool. Diffuse light can't be concentrated as light coming from many different directions can't be concentrated well with lenses. This new cell is a multi-junction cell with a prism attached at front to capture and somewhat concentrate diffuse light. The prism prevents it from needing a tracker as there are many directions light can enter a prism from and be directed to another face. As a result it doesn't need tracking or cooling.
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May 19, 2016 04:34
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http://arstechnica.com/science/2016/05/heat-from-misaligned-mirrors-at-solar-thermal-plant-causes-electrical-fire/ ivanpah is done, csp is done
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May 22, 2016 03:28
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StabbinHobo posted:http://arstechnica.com/science/2016/05/heat-from-misaligned-mirrors-at-solar-thermal-plant-causes-electrical-fire/ Sim City 2000 predicted this!
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May 22, 2016 03:36
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StabbinHobo posted:http://arstechnica.com/science/2016/05/heat-from-misaligned-mirrors-at-solar-thermal-plant-causes-electrical-fire/ Eh, let's see how Cresent Dunes goes before declaring csp dead. Startup energy costs in the morning have been a big part of what really doomed Ivanpah. Overnight energy storage is a big difference in the design at Cresent Dunes. Edit: looks like China just signed a deal to build 1GW of CSP with the same company that build Cresent Dunes: http://cleantechnica.com/2016/05/17/shenhua-solarreserve-1-gw-solar-thermal/ Trabisnikof fucked around with this message at 03:49 on May 22, 2016 |
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May 22, 2016 03:42
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silence_kit posted:TL;DR: Since Power = Voltage x Current, and Voltage is proportional to the logarithm of solar intensity and Current is proportional to solar intensity, the efficiency ( = Power/(Solar Intensity x Cell Area)) increases with the logarithm of solar intensity, and efficiency increases under solar concentration. Ouch, my brain. Voc is essentially governed by the band gap of the solar cell material. A bandgap of 1.1 eV is going to get you (less than) 1.1 V of potential, mostly from the problems of recombination and the like that come with a doped semiconductor. I'm sure you can get a huge logjam of excited states in an unconnected solar cell device until the rate of recombination balances out with the rate of generation of electron-hole pairs saturating the conduction band of the material, but, uhhh, then you don't have it doing anything and nobody gives a poo poo. Voltage from a solar cell depends on the band gap, like so:  Though the practical voltage you get will always be lower than the ideal.
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May 22, 2016 04:31
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StabbinHobo posted:http://arstechnica.com/science/2016/05/heat-from-misaligned-mirrors-at-solar-thermal-plant-causes-electrical-fire/ Even if power tower csp were done, parabolic trough csp is still around.
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May 22, 2016 07:31
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fermun posted:Even if power tower csp were done, parabolic trough csp is still around. I like to pretend all trough csp anywhere is part of the SEGS
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May 22, 2016 07:40
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America's achieving great strides in transitioning to renewable energy. http://thinkprogress.org/climate/2016/05/16/3778542/grid-70-times-renewables-natural-gas/ quote:
Europe's doing even better. This is great geopolitical news for the west and terrible for Russia and its petrostate economy. The Russians won't be able to blackmail Western Europe by threatening to shut off the pipes anymore. http://cleantechnica.com/2016/05/16/renewable-electricity-replaces-natural-gas-europe/ quote:Renewable Electricity Replaces Natural Gas In Europe Portugal smashes records, running the whole country on renewable energy for four straight days. Portugal is a small country, but it still has over 10 million people. http://www.theguardian.com/environment/2016/may/18/portugal-runs-for-four-days-straight-on-renewable-energy-alone quote:
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May 22, 2016 12:56
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Charlz Guybon posted:http://www.theguardian.com/environment/2016/may/18/portugal-runs-for-four-days-straight-on-renewable-energy-alone This is the most notable one. To what extent did they overproduce and dump into the Spanish grid at low prices though?
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May 22, 2016 13:00
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Holy poo poo! Go, Portugal!
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May 22, 2016 13:14
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Claverjoe, you are quoting me out of context. I was explaining to someone why solar cell efficiency can increase under solar concentration. You pointing out that the solar cell open-circuit voltage often tends to go with the semi-conductor energy gap is neither here nor there. The voltage doesn't have to go with energy gap though. Plenty of people have made junk solar cells with high energy gap semi-conductors which have had worse open-circuit voltages than silicon. quote:I'm sure you can get a huge logjam of excited states in an unconnected solar cell device until the rate of recombination balances out with the rate of generation of electron-hole pairs saturating the conduction band of the material, but, uhhh, then you don't have it doing anything and nobody gives a poo poo. Under solar concentration, the photo-generated electron and hole concentration in the cell should be higher than when under 1 sun, and so the quasi-Fermi level splitting (this is Voltage) should be greater than when under 1 sun. This is certainly true at open circuit but it is also true when the cell is at its operating point. This is why the voltage of a solar cell often increases and so the efficiency often increases under solar concentration. silence_kit fucked around with this message at 02:31 on May 23, 2016 |
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May 22, 2016 15:36
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StabbinHobo posted:http://arstechnica.com/science/2016/05/heat-from-misaligned-mirrors-at-solar-thermal-plant-causes-electrical-fire/ Isn't that intended behaviour of the orbital death satellite that ISPP is funneling power to?
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May 22, 2016 22:40
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OwlFancier posted:Isn't that intended behaviour of the orbital death satellite that ISPP is funneling power to? It's what would happen if one of those fantasy orbiting solar power satellites were to become misaligned with their microwave base station.
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May 23, 2016 03:10
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And why we should just stick with coal until 2050 when we get fusion.
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May 23, 2016 03:15
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I was making a fallout joke.
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May 23, 2016 03:15
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The rest of us are old enough to be making Sim City 2000 jokes. 
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May 23, 2016 03:17
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