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A little sunshine on a rainy day...
April 5, 2013 11:33 AM   Subscribe

The Virtual Power Plant: "Critics of renewables have always claimed that sun and wind are only intermittent producers of electricity and need fossil fuel plants as back-up to make them viable. But German engineers have proved this is not so." A pilot program funded by the German Federal Ministry of the Environment offers a rebuttal to critics who claim renewable energy sources have an insurmountable variability problem.
posted by saulgoodman (24 comments total) 6 users marked this as a favorite

 
It's a pretty huge stretch to assume that there is an abundance of sites that are suitable for pumped storage. A thought experiment about "100% renewable" energy production is pretty easy if you've got a huge resorvoir on top of a mountain that you can drain and fill at will. You're essentially using the water in the reservoir as a giant battery or buffer for the other power sources that can't generate energy with good consistency. Just make sure that you've got enough wind/solar power to run the pumps to keep the reservoir filled.

It's cool to see that these guys have formally envisioned such a system, but it's not easily reproducible, unless you've got the exact right geographical topography. I don't think that anybody really doubted that this sort of thing would be possible, given the exact right geographical and economic conditions.
posted by schmod at 11:43 AM on April 5, 2013


David Roberts had a great post recently about this very subject, which pretty much says that in the long term these are problems that can be overcome by more expansive adoption of renewables, but in the short and medium term gas-power plants are required to continue creating energy to deal with the variable energy output (since it is the only type of plant that can be turned on and off quickly). Thought I'd leave the link here for discussion.
posted by Weebot at 12:00 PM on April 5, 2013 [1 favorite]


The Combined Power Plant links 36 geographically-dispersed wind, solar, biogas, and hydropower facilities in Germany into one jointly-controlled networked virtual power plant. Rohrig, deputy director of IWES, tells Undine Ziller, writing for Monitor Magazine for Electric Safety,

Not sure I understand schmod's criticism related to siting above. I understand the point of this approach to be that the different renewable power sources can be widely geographically-dispersed. So you would just site each kind of energy source (or storage) wherever it's practical and they would all work together to power the grid as if from a central source. If it's transmission distances you're wondering about, there may be an issue there, but that's out of my depth. The system also uses bio-gas as an additional supplemental energy source if needed.

Here's a link to a PDF of some technical specs for the project.
posted by saulgoodman at 12:04 PM on April 5, 2013 [1 favorite]


So you would just site each kind of energy source (or storage) wherever it's practical and they would all work together to power the grid as if from a central source.

Right, as I have previously mentioned and cited, it doesn't have to be pumped water storage and can be old salt mines/chambers and compressed air. Glad to see positive light shined on renewable options, even cynical me has hope that it's not too little too late.
posted by RolandOfEld at 12:09 PM on April 5, 2013 [2 favorites]


It's almost as though some people had vested interests in maintaining the status quo, inflating every shortfall into a disastrous deficit, and every gap into an uncrossable chasm.

"Oh noes, solar won't work - what will you do at night, Mr. I-Don't-Want-To-Live-On-A-400-Degree-Planet?"

"Well, we can use batteries, pumped water reservoirs, molten salt, compressed air, alternative energies as supplements..."

"Oh yeah? Well, what if those batteries cost too much? Huh? What then?"
posted by IAmBroom at 12:20 PM on April 5, 2013 [3 favorites]


"Oh yeah? Well, what if those batteries cost too much? Huh? What then?"

"And what about my SUV, how will compressed air drive it around huh? I have a kid I need that space for, you know..."
posted by RolandOfEld at 12:22 PM on April 5, 2013 [1 favorite]


What about flywheels?! The tech is coming along nicely...
posted by markkraft at 12:25 PM on April 5, 2013


The tech is coming on nicely...

Can't tell if sarcasm or...
posted by RolandOfEld at 12:27 PM on April 5, 2013


Yeah, and fossil is totally unvariable. Price-wise, availability-wise, political-wise, big-chaotic-unpredictable-war-wise. Solid as a rock.
posted by telstar at 12:45 PM on April 5, 2013 [1 favorite]


saulgoodman: "Not sure I understand schmod's criticism related to siting above. I understand the point of this approach to be that the different renewable power sources can be widely geographically-dispersed. So you would just site each kind of energy source (or storage) wherever it's practical and they would all work together to power the grid as if from a central source."

The point is that there aren't many places on earth that are well-suited for pumped storage. The geographic requirements are incredibly specific. You need room for a huge upper reservoir, and a steep enough elevation gradient that you can also connect to a huge lower reservoir without needing to build hundreds of miles of pipes.

The assumption that pumped-storage can built "in an appropriate region" is kind of like assuming that we can just pull oil out of the ground "in an appropriate region."

Geothermal and hydroelectric are pretty great too, and we'd use those everywhere if we could (but we can't). Pumped storage potentially also has a lot of the same environmental pitfalls as hydro.

Geographical dispersion also has its limits. Transmission losses are not insignificant, and wire isn't exactly cheap.
posted by schmod at 12:47 PM on April 5, 2013


inflating every shortfall into a disastrous deficit

It's always the same guys who either shake their heads in disbelief or fall about laughing at the prospect of alternative energy that simultaneously are creaming their pants about how capitalism took us to the moon in 1969 and can literally do anything. Except sustainable/responsible/new ideas about energy, because obviously nobody can do that.

I've heard the same guys talk about how we'll live on another planet soon because capitalism can solve that problem. But not wind/solar energy.
posted by colie at 12:54 PM on April 5, 2013 [7 favorites]


Wave and tide are consistent sources, yet solar and wind are the hot commodities. I don't know why. Great swaths of energy users are near Coastal regions.
posted by mightshould at 12:57 PM on April 5, 2013 [1 favorite]


You only get tidal power on coasts, there's a heck of a lot more area that can support solar and wind.
posted by Zalzidrax at 1:02 PM on April 5, 2013


Wave and tide are consistent sources, yet solar and wind are the hot commodities. I don't know why.

I've pondered this before myself, both as someone who grew up and now resides less than 1 hours drive from an ocean and as a mechanical engineer by education. The only thing I can come up with is that the taming of the ocean's forces (be it tidal or wave) is a unforgiving and difficult to manage nightmare due to the mix of unpredictable circumstances, insane power/strength/scale, and corrosive tendencies on the equipment.

That's my wag at it because the energy contained in a single wave is immense and the desire to harness that, or the tide, is indeed a no-brainer.
posted by RolandOfEld at 1:03 PM on April 5, 2013


The question is not whether you can get 100% of the electricity from renewable sources, the question is the cost. Already residential electricity rates are $0.34 per kWh in Germany vs. $0.12 per kWh in the U.S. That's a huge difference that this plan will only further increase the price of electricity in Germany.
posted by stan.kjar at 1:16 PM on April 5, 2013



It's always the same guys who either shake their heads in disbelief or fall about laughing at the prospect of alternative energy that simultaneously are creaming their pants about how capitalism took us to the moon in 1969 and can literally do anything. Except sustainable/responsible/new ideas about energy, because obviously nobody can do that.


The ad hominem attacks on anyone with serious criticism of implementation issues in alternative energy need. to. stop.

There are clearly greenwashers and shills for conventional energy/captilaism/fascism etc out there. There are also serious non-bought-off environmentalists, scientists and engineers with real critiques.

The task that faces us is MASSIVE, and "wishing it were so" about the perfection of against the Man-ness of Every green-sounding resource ain't going to cut it.

Serious societal and technological engineering on this scale needs to be feasible, or it will be just another giant sinkhole for the earths dwindling resources.
posted by lalochezia at 2:03 PM on April 5, 2013 [9 favorites]


Here's a detailed exploration of pumped storage from Do the Math. It sounds about as feasible as one of Randall Munroe's What If? articles.
posted by nixt at 3:07 PM on April 5, 2013 [2 favorites]


Wave and tide are consistent sources, yet solar and wind are the hot commodities. I don't know why.

Coastal areas tend to be desirable for other purposes, as well as generally being rather delicate ecosystems that might not benefit from large scale deployment of wave harvesters.
posted by ook at 4:39 PM on April 5, 2013


Also bear in mind with pumped storage, a lot of the economical sites are already used to buffer load - base load plants that can't quickly be spun up or down (nuclear in particular) continue to generate at least some power at night into pumped storage lakes etc, which is then used to provide quick generation capacity when needed due to spikes of demand, such as the early evening, as an alternative to firing up the gas burners. So you'd need even more sites to swap out for the base load plants going at full whack at peak demand.

Which is not to say it's unsolveable, but it's a non trivial problem, and good pumped storage sites are not that common.

Hopefully some of the big battery tech improvements in development will pan out - they don't need to scale to small sizes for this application (which is often one of the problems) - and rare earth metals to make them are more common than the name suggests, so with any luck that will drastically help with the implementation of renewables.
posted by ArkhanJG at 7:42 PM on April 5, 2013


Already residential electricity rates are $0.34 per kWh in Germany vs. $0.12 per kWh in the U.S. That's a huge difference that this plan will only further increase the price of electricity in Germany.

How much of our energy is coming from coal or nuclear? There are costs associated with each and they are not being paid for up front.
posted by psycho-alchemy at 12:24 AM on April 6, 2013 [2 favorites]


Hi guys. I am an engineer living in Germany, and working on smart grid / smart home type stuff and energy storage. Great post! If you want to see what the status is of some pilot Virtual Power Plants and the development of the smart grid in Germany, you should check out this page (in German) from E-Energy. Those six projects are not theoretical or simulated virtual power plants, but smart-grid pilot projects that worked and are laying the basis for what is to come in Germany.

First things first - forget about pumped storage. That has such a minor part to play. Hydro is pretty much tapped out and nobody is pinning their hopes on that. Compressed air is cool and all, but as mentioned above, there are only a few places where you can do it and, realistically, even with highest tech system around, your roundtrip efficiency with CAES is pretty dismal (even compared to say, mundane lead batteries).

Now, virtual power plants are not about simply integrating storage. They are about combining (1) overcapacity of renewable energy with (2) an information exchange system and (3) the control of those renewable generators using that IT infrastructure . What commands? Well, you can't turn renewable energy production up at will, but you can turn it down whenever you like. So most of the commands are about whether or not you should turn off over-producing solar panels and wind turbines. Other commands are about setting electricity prices, and still others are about routing power (i.e. with high voltage dc) from regions with a surplus of energy to those with a deficit. All of that, in real time.

So, sure, there is some storage involved (like pumped hydro and CAES and batteries and even flywheels), and it plays its part, but it's not the big saviour. I mean, yes, we are expecting to see a lot more residential batteries in the coming years in Germany, especially if this subsidy finally kicks in (they keep changing their minds about the criteria and when it will begin). So yes, storage is important. But the plan is not to have sort of, half storage and half renewables. The more important thing in smart grids within a 100% renewables scenario is that there is a lot electricity consumption that can be shifted. In industry this is pretty obvious, for example with smelters who intermittently require huge amounts of electricity, but who are flexible about what hour of the day they use it. Or, a power-to-gas plant that produces methane (i.e. natural gas) from electricity but only operate when there is a surplus of electricity available (i.e. the cheap stuff). But even in the residential area, at home, consumers can adjust their electricity consumption based on the current price. Air conditioners, electric water heating... even when you turn your washing machine on. Maybe you do it yourself because you are conscientious, or maybe you have a "smart device" that can make a "good" decision about when it should turn itself on (or up or off or down).

So, virtual power plants, along with this whole smart grid thing, are all about answering the question: if we have overbuilt our renewable energy capacity, what should we do when we produce more than we need? Do we try to increase consumption? Do we send the electricity to a different region? Or do we just turn off some turbines and solar panels? That last option... kind of a bummer right? Why throw away free energy? But that's exactly what Germany is doing right now. Over and over again, solar production is too high and we are turning off solar panels. In a virtual power plant, you can (a) predict when a surplus or deficit is coming and (b) communicate with other regions and provide (or receive) as needed, and (c) communicate with the smart grid to try to encourage individual consumers to use more (or less) electricity in order to balance everything out. When it comes to residential batteries, an increase consumption is just the battery charging, and a decrease in consumption can be achieved by consuming from the battery (instead of the grid).

Remember, the idea here is that we are going to significantly overbuild our peak-capacity. Even on low-producing days we manage to meet most of our needs (and can adjust our needs to get even closer to balancing out). And on high-producing days we again adjust our needs, and with the help of a few batteries, a bit of pumped storage, and most-importantly, good real-time communication between regions and among consumers and producers, everything should work out just fine.

Don't be afraid of smart meters. They are step one in this whole thing.
posted by molecicco at 11:38 AM on April 6, 2013 [4 favorites]


Also stan.kjar, you assume that the price of electricity in germany is high because of renewables. Totally not the case. Renewable haves been decreasing the wholesale cost of electricity, and the utilities and industrial consumers are profiting from this, however residential consumers have yet to benefit from it.
posted by molecicco at 11:45 AM on April 6, 2013


Wave and tide are consistent sources, yet solar and wind are the hot commodities. I don't know why. Great swaths of energy users are near Coastal regions.

The steps to moving renewable energy to commercial and/or technical maturity are complex. Wind kicked off as a useful generating tech in Denmark, experimentally in WW1 and then with limited practical application in WW2. Following the oil crises of the 1970s a lot of countries tried to drive the technology into large scale application (including Denmark, the US, UK, Germany and Sweden) but success was limited. The actual 3 bladed 'Danish concept' wind tech which became dominant came out of a combination of Danish grass roots activists and government scientists building smaller scale turbines and getting them working, then scaling up - the first commercial turbine was 22kW. They had a number of motivations, perhaps the most significant being to come up with an alternative to nuclear. Once the concept was proven then the sector was able to take advantage of subsidies, first in California and after that market collapsed, from the Danish Government, which meant the Danish sector was able to keep innovating and improving the tech. Latterly, an emphasis on RE as a partial solution to climate change drove investment into the sector and other companies also entered, so the market is not as dominated as it used to be by Danish companies.

Solar got its commercial start with the space programme. The tech is different from wind in that it required a higher level tech base, ie one rooted in semiconductor manufacture. It was supported as a potential new industrial sector by countries including the US, Japan and Germany which put a fair amount of support into R&D. The sector has finally started to achieve the cost reductions that were projected from the 1970s. The costs now mean that the niches were solar is cost effective are much larger and the tech can be applied more widely.

Wave energy has been on, and unfortunately off, the R&D agenda for a number of countries since the 1970s. Wave is harder to get working than wind in many ways which has made it a tougher proposition to advance to maturity. There is little potential to develop small generators and then scale them up - most devices in development are in the 500kW-1MW range. Getting to the stage of putting a wave machine in the water costs about £10m and most of the companies are small and cannot easily access that level of funding. The operational conditions for a wave device are far more challenging, sited devices must be able to tolerate very difficult conditions and face additional challenges such as effective mooring of a system which by its nature must be dynamic in order to keep producing energy. The risk of putting something in the water is substantial and with the costs already noted is a massive hurdle, so development has been slow. Projects that have gone in the water have often struggled. Wave energy is realistically about 30 years behind wind.

Tidal stream is a bit more of a recent tech, it really only started to get attention in the last 2 decades. One factor limiting support for it is that although lots of places have coasts not that many places have sites with enough potential to make the tech worthwhile as a national policy priority. Some countries have sites which might eventually be economic but not enough to drive then to provide the stimulus to get the tech working. This means those countries looking to be global leaders are fairly confined. However it has some advantages over wave. The operational conditions are not as onerous. Much has been learned about design from the wind sector. We are already seeing a more rapid move to pilot projects and deployment has seen some success. Potential is relatively limited but I think there is a good chance this tech will move forward at a decent rate.
posted by biffa at 6:02 AM on April 9, 2013 [1 favorite]


The question is not whether you can get 100% of the electricity from renewable sources, the question is the cost. Already residential electricity rates are $0.34 per kWh in Germany vs. $0.12 per kWh in the U.S. That's a huge difference that this plan will only further increase the price of electricity in Germany.

Germany has a very different approach to tax from the US. Taxes were 41% of the total in 2009, which accounts for a big chunk. The state then provides a very substantial chunk of subsidy to the coal sector to keep open what would otherwise be uneconomic mines. This amounted to about €3bn in 2012. RE probably accounts for around 5 cents/kWh, but bear in mind how much electricity it generates and that Germany has taken a gamble on industrial growth in RE as part of its overall energy policy.
posted by biffa at 6:22 AM on April 9, 2013


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