Order of Kilopi
I hear the UK has just passed 1 Gwatt of
installed solar panels! Yayyyyyy. Then I
hear that Germany installed 8 times as
much this last year. And has 25 Gwatts
total. Those goody goodies.
A Gwatt is a whole power station I suppose.
All that free energy! You know what I mean.
Must be much economic benefit to the germans
while we catch up.
Wonder how the power output drops off over
the years. 5-10% over ten years perhaps?
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you should be more worried about the 100% drop in energy production every evening. solar only really produce at full power a tiny fraction of the time.Originally Posted by peteshimmon
Just to put this into perspective. solar has never and will never replace any other power generating station. it just can't do it because it is not there most of the time. it's just being built as window dressing for coal and gas.
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Well that is a cynical if realistic view of the current state but I think it will not be too long before international solar gets going, with solar systems near the equator, probably heat traps running generators and distribution and storage technologies sorted out and delivering to Europe and North America. Of course it will not be free but it will be clean and serviceable. The major contribution would be a global grid. It is ambitious but I reckon it can be done.
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the claim that "insert renewable of choice here" will get going soon has been claimed for years and years. it's like the fusion claims. just another 20 years and we'l have managed to do it.
I no longer buy that kind of reasoning.
If one is serious about trying to mitigate increasing pollution problems (CO2 is only one factor here) then one must turn to technology that is known to already work and build as much as possible of that right away. I do not want to turn your thread into another nuclear power debate. we already have a couple of those.
But i can tell you. the inherent disadvantages with solar makes it a poor fit for solving the environmental issues we face. global super-grid or not.
Sheesh. a global grid would really be mindbogglingly expensive to build. we are not talking minor connections here. but multi TerraWatt transfer lines more or less crossing the entirety of the globe.
the cost on that would make the Apollo project seem downright cheap in comparison.
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The problem with most renewable energy sources is that we have no good way to store the energy they convert. It needs to be converted to some type of fuel and at a faster pace than what we consume it. Hydrogen is one possibility, but we're really not very close to that.
We do not have the economic capability, nor the engineering knowledge, to build a global solar super grid with TW transmission lines.
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I have the same experience that solar is always just around the corner but at least the technology really is nearly there. The Spanish have been showing how heat collection and generation is more effective than PV. Flow battery technology promises high volume storage and high voltage DC lines offer next generation transmission. Mega costs means employing people, it's all wages really. I see the biggest obstacle to be international mistrust and short termism. Fusion might get there but its still a long way off, and of course a mixed energy economy is a good thing anyway.
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I would think flow battery technology will scale up to very large capacity in the next twenty years.
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I presume you are being ironic. The cost of that solar electricity to Germany is very large. The panel owners are subsidised with high feed-in tariffs, money for which is spread among electricity users, contributing to making German electricity some of the most expensive in the developed world.
They did actually achieve a peak output of 22GW one day in May, which was quite a chunky percentage of Germany's overall demand for that brief period. But overall the load factor I think is less than 10%. German wind turbines have a poor load factor too.
Just think how much more electricity they would have got for their investment if they had installed the panels the other side of the Alps - perhaps twice as much - and built some transmission capacity. In fact they wouldn't need so much transmission capacity because currently there are large net electricity flows in the other direction over the Alps into Italy, which this would set off, at least so long as the sun was shining.
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Solar technology has not really improved all that much the last 10 years. it's gotten cheaper, and more sturdy perhaps, but not really any better power production wise. it is limited by physical constraints after all. we are already pretty close to these physical limits, so don't expect massive improvements to ever materialize either.
The main issue is and has always been the intermittent nature of the source.
Storage is only viable in limited amounts. if you need enough storage for multiple GW over several days worth then it becomes prohibitively expensive to do.
Now onto the employment argument. this is a variant of the broken window fallacy. someone has to actually pay for this make-work. the costs of this mega grid is taking resources away from other aspects of the economy. you cannot just print out money willy nilly and expect money to retain it's value. you would hyper inflate the economy into ground long before getting anywhere with that global super-grid. (ignoring any of the political issues with getting permission to build it in the first place ofc).
However. if we really wanted to get rid of our dependence on fossil fuels we would have to build a ton of energy infrastructure at any rate. but rather than waste money and time on building gigatonnes of wires and install invasive grid control systems (smartgrid) we should focus on building power-plants that deliver cheap power to their local area reliably and on demand.
The savings in grid infrastructure build-out can be used to increase the speed at witch we replace fossil fuels with synthetic ones for transport and industrial processes instead.
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That huge flow of electricity going south is due to italy's own flirt with solar power tho. adding more won't really help any. the entirety of Europe can actually be overcast for as long as an entire week at a time. capacity factors are poor at best. you'd have to move those arrays way down into the Sahara desert if you wanted them to perform while the clouds rule the skies in Europe. There is no high voltage grid connections from there to Germany at present, so that would be expensive. But yeah. Germany being where it is on the globe sure makes it a bad spot for solar.
I think i actually saw a limit analysis for a global grid somewhere some time ago. gonna try and find it again, but i distinctly do remember that even when global distribution is considered with real historical weather data you end up having entire days where none of the facilities produce more than 20% of their average output.
Gonna dig around and edit in a link here when i find it again.
ETA: Here it is: Linky
Last edited by Antice; 2012-Jul-13 at 11:02 AM. Reason: ETA: Adding the link to the analysis i mentioned.
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We work with flow batteries now in some power grids to store excess generation for later use, and the steel mill my company is building right now actually incorporates a form of flow battery on the rotary furnace. I think we need to solve some intermediate problems, mostly that the batteries are overly complex and have a low energy density, before we can scale them to use on any kind of a global scale like this.
Twenty years sounds like a good timetable for that. Of course, twenty years is the timetable for everything in power generation and distribution.
On another note, about five years ago we installed fuel cell power on a residence. This was in southeastern Ohio, which isn't exactly a great solar power area. The engineering was performed by another division of the company I work for, but iirc they used a combination of wind and solar power to electrolyze water. The hydrogen was used to power the fuel cells and the oxygen gathered was stored and then sold. At the time, I think it cost somewhere around 250-300K to outfit one residence with this, and it still wasn't able to be completely self-sufficient. I wish I had more information about it because I think it's pretty interesting, but we sold that division of the company a few years ago and I don't know anyone who worked on the project. But I think it's indicative of the large hurdles we still face in making solar power a viable alternative to fossil fuels and nuclear power.
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very interesting that you have direct experience of flow batteries, I just read the conference papers! We can see the growth of electric vehicles which will load the grids and governments can use fiscal pressures to encourage more distribution. For the long term I guess hydrogen is a contender for flight although there is enough oil for that.
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Hydrogen is such a nuisance to handle tho. has to be kept at cryogenic temperatures at all times and all that hassle. it may be worth it for flight if we get something like this. otherwise synthetic hydrocarbons will do fine. just need a nice stable source of high temp process heat to make em. (nuclear fits that role nicely as well)
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Firstly divide those numbers by 3 or 4 and you'll get how much is really being produced. Secondly Germany's solar capacity is not benefiting the economy but rather is a huge drain on it.
In reality Germany is actually building more coal fired power plants than any other country in the world except China. They say its a stopgap, but seriously those things have a service life decades long. So instead of nukes they go with solar, wind............and considerably more fossil fuels.
About the only area I can see hydrogen making sense is hypersonic spaceplanes/airplanes. Otherwise there's too many disadvantages to make it worthwhile.
Order of Kilopi
What makes you think solar panels are free? What makes you think maintenance is free?
Order of Kilopi
Well I said you know what I mean. The way
solar is being implimented means it is
reducing the power having to be generated
and supplied. So no super grid needed here.
We may be paying through the nose for
it but it is one of the ways the CO2 problem
is being tackled and we find where it leads.
Thanks for the link Antice, I appreciate
the detailed insights that are out there.
Common sense suggests that this "free energy"
is nontheless being used to some economic
benefit somewhere. Utilities have been juggling
supplies for the least cost since the industry
began. Just a continuation therefore!
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I'm not sure how this qualifies as "free". The source is free. The collection, distribution, and maintenance are far from free. We would need a world-wide grid because the far northern and southern latitudes can't get solar energy, and we're probably going to find that it is too inefficient to try this in much of the middle latitudes. That's the problem with something being free when it's not.
I'm not sure what you mean by utilities juggling supplies for the least cost. In any case, it would be incredibly irresponsible of them to not try to achieve what they do in the most cost-efficient manner possible. Conventional coal-fired plant construction costs can reach as high as $3500 per kilowatt of capacity. Solar energy equipment costs around $9000 per kilowatt of capacity, and that's not counting the extra trillions of dollars it would cost for changes to our distribution system, worldwide, that would be needed to make this viable. We can't measure the cost of solar power on a KWH basis like we do for fossil fuel power, but it really doesn't matter at this point because the set-up and distribution problems are very daunting. With worldwide daily energy consumption at around 15TW and climbing, we have a lot of work ahead of us and it is not even close to being free.
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Would there be any advantage in building large solar power farms in desert regions that tend to ring the globe at around 30 degrees latitude I think? IIRC that's where the cooler dry air from the Hadley cells decends to the surface.
They tend to have clear weather and receive more direct sunlight than the more northerly or southerly regions, countries like Saudi Arabia could become solar power exporters instead of oil in the future. You would need to provide some sort of protection from extreme weather events like sand storms, and transmission lines to distant consumers.
Also for storing solar power would flywheel technology be appropriate?
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It would make sense if transmission of power and maintenance was free. But as you yourself mentions. sandstorms is a big issue, but also counter intuitively enough, so is access to water. solar concentrating mirrors and solar cells need to be kept extremely clean to function. even a couple of micron thick layer of dust can cut their efficiency severely.
I'm not entirely certain that building big solar power arrays is even going to make any economic sense for the saudi arabians own use. those desert conditions are harsh on anything man made.
Flywheels is one interesting storage technology. one that has it's own set of advantages and dis advantages. one is cost. it takes a lot of mass to store energy in the form of movement. (kinetic) another is that flywheels are never going to be 100% friction less. that means that they are unsuited for longer term storage like a couple of days, rather they are well suited to help balance second to second variability. like pumped hydro it actually works better if you pair it with a reliable baseload generator like coal or nuclear. in that role the flywheel is used to smooth out ramping rates so that the base-load generators can run more evenly, and hence at a better overall efficiency. whenever a power-plant has to load follow rapidly, efficiency takes a major hit.
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Interesting question about the flywheel. You can find a little information about it here: http://en.wikipedia.org/wiki/Grid_en...orage#Flywheel
As you can see, they have a limited range of applications, and our current flywheel technology isn't up to this. We use flywheels more like capacitors than batteries.
As for building large solar farms at certain latitudes.... almost anything is possible in theory. But besides the difficulty of simply constructing such a system, there are also two other problems. One is that a lot of the countries in that area around the globe are pretty unstable. Concentrating world wide generation in a <relatively> small area as opposed to having generating facilities spread over the globe also gives terrorists a great target.
You also need to consider I^2R losses over the lines themselves. In order to minimize loss, we need to step up the voltage. But at voltage potentials around 1800KV or more between the transmission lines and ground, corona discharge losses become severe and that limits how much we can step up the voltage. Transmission conductors are mostly aluminum because better conductors are too expensive. Using conductors with a larger cross-sectional area will also make losses smaller, but that adds significant cost and weight to the system. Simply put, there is a limit to how far we can economically transmit electricity. I don't know how the distribution engineers calculate it, but the last I heard it was not economically feasible to transmit AC power more than 3000 miles from source to load. All of our transmission lines today are considerably shorter than that.
I think if we want to distribute power long distances it is going to have to be in the form of a fuel that can be easily moved. I'm a big fan of hydrogen, and would like to see more research in that direction, but there are people here who are way more knowledgable about that than what I am who are not fans of hydrogen.
Last edited by primummobile; 2012-Jul-13 at 08:54 PM. Reason: clarity
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When economies grow they use more energy, when they are in recession they use less energy. So what you're talking about is basically a permanent recession.
Which is basically taking an already uneconomical source of energy and making it more uneconomical. That reminds me of the "Sahara Solar" idea, which is thoroughly debunked here
Order of Kilopi
There are advances to be made, certainly, but flywheels may be better used at a smaller level, such as for neighborhoods or in each house, itself perhaps having a solar PV roof or panels placed elsewhere. An integrated solution can be widely distributed instead of centralized.
I'd expect them to do better in the summer with more sun-time, if the angle allows enough of the suitable wavelengths through. In the winter you know it won't operate, so put it in storage and go with something else, like nuclear, and use a combined Heat and Electricity solution to make it even more efficient.As for building large solar farms at certain latitudes....
Et tu BAUT? Quantum mutatus ab illo.
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That's pretty much how we use flywheels now. They are usually at the point of service. Where I said that we don't use flywheels all that differently than capacitors, it was meant to point out that they can't supply long-term power like a battery. In most applications, an electric motor turns the flywheel to get it up to speed and maintain that speed. An electric motor and a generator are basically the same thing. In fact, many motors can be used as generators. That's what happens in most flywheel systems. The kinetic energy of the flywheel turns the rotor of the motor which induces a voltage in the stator that can be used. The problem is that unless it is a very well designed and expensive system that kinetic energy is gone in seconds. The momentum of the flywheel makes it cost effective for the motor to keep it up to speed. But I've never seen a flywheel that can function as a secondary power source for anything other than momentary needs. I think what you're talking about would require a more massive flywheel than you think. I'm not saying it is impossible, just that it may not be the solution.
Last edited by primummobile; 2012-Jul-14 at 03:58 PM.
Order of Kilopi
A single electric cell doesn't hold much power either. Hence the reason we put them in battery.
Et tu BAUT? Quantum mutatus ab illo.
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This doesn't mean that flywheels are maintenance free. They have moving components, and are still relatively expensive. I worked in a hard drive array testing facility. They had a flywheel for uninterrupted power, but it was only to hold until generators kicked in. The only reason this was done was that the cost of interrupting formats and tests and possibly crashing thousands of drives in a power outage... made it worth it.
I remember seeing the suggestion for cars, but personally I think sodium borohydride could be a good choice for utility level hydrogen storage. It could make a solid, low volatility long-term storage system for hydrogen at large scales. (I think its application to cars is wrong, I'm starting to lean toward interchangeable battery-electric in cars for another reason: it simplifies cars people have to maintain.) But at industrial scale, I could see having a pressurized tank of "ready" hydrogen to last a half hour or more of peak output, then a vast storage field of sodium borohydride that gears up to meet demand.
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Thanks, that answers some of my questions.
Order of Kilopi
Interesting article. I didn't think Germany was that great for solar. So apparently that 20 gigawatt figure is peak output, which is very misleading. Up to a point, solar can offset the need for peaking plants in summer use, which can make a fair bit of sense where air conditioning is a big factor. But that doesn't work for peak use in winter (usually after dark, electricity used to prepare dinner). As solar increases as a percentage of total electricity production, storage becomes a critical requirement for the day-night cycle and weather variations. Storage also substantially raises cost, both because of the additional hardware that needs to be built and maintained, but because there's no 100% efficient storage, requiring more input.
Anyway, the point is that the sweet spot for solar as a percentage of total generation is maybe 5-10%, depending on where it is (you could do better in Arizona than Germany, for instance), but it becomes much less economical as you push beyond that. Ultimately, you'll need a lot of spare capacity to handle the variations. Maybe if solar gets really cheap with thin film solar panels that could work, but despite the improvements it's still quite costly.
I say there is an invisible elf in my backyard. How do you prove that I am wrong?
The Leif Ericson Cruiser
Order of Kilopi
Then there are the non-technical issues with the Sahara solar idea: Do you really want to be reliant on other countries for your energy again? That would be an issue both economically and politically.
I say there is an invisible elf in my backyard. How do you prove that I am wrong?
The Leif Ericson Cruiser
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Yeah, it's really to bad we don't have any technology to store energy...
Order of Kilopi
True; Every solar project that I have heard of relies on being on the grid.
For example, In Florida, there is a project called "Babcock Ranch" claiming to generate more than it uses. But:
There is a project in Abu Dhabi to run a city entirely carbon neutral and off the grid (Masdar City).. But; the entire city is designed for drastic energy savings which would be nearly impossible for anywhere else without completely rebuilding.Babcock Ranch's solar power plant will connect to the main grid so a consistent energy supply can be maintained by importing power on overcast days and exporting it on sunny days
From what I infer in the article, they will be making hydrogen off the solar and wind to burn in thier "world's largest hydrogen power plant".
Also notice the latitudes of both projects.
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