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PostPosted: Jul 19, 2015 6:31 am 
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Joined: Mar 22, 2014 2:34 pm
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Location: Germany
A week ago i thought why not putting solar cells into the sky above all clouds and weather.
I searched the net and found a company called http://www.stratosolar.com The CEO is Edmund Kelly.
I am really stunned why there are actually so few companies working on that or debating on that since it sounds way more realistic than space solar power and delivers
100% predictable solar irradiation rates,averagin 12h a day per year.
It delivers almost twice the energy one could harness in deserts, even in the UK.
But what is more mind boggling is that it places the desert to almost every place on earth, only with varying but highly predicatble seasons.
THe discrepancy between solar summer irradtion and winter irradiation in many countries like for example germany is really high. In summer time you get almost 7x more energy than in winter time. The imbalance is just too bad and makes the whole renewable energy concept a bit crappy.
The only little downside with this concept is the interference with air traffic. But it could be diminished by accumulating f.e. 500 GW of power into a 30 by 30 km area that would be clarified to a no fly zone and would ly in the center of a country. From there HVDC lines would transmit power and gas(only for heating) to all sites. In a country like Germany those lines would have to be a few hundred km long.
A country would only need 12-16h of electricity storage. Most of the energy would be stored as gas as most countries have incredible gas storage capabilities already and we need so much of it. The easiest way to store huge amounts of energy over a longer period of time very cheap. The creation of new gas storage structures is also very cheap. Washing out salt domes kms beneath the earth surface.
With 500GW of power and 2500 TWh generated energy Germany could be totally energy independent.



https://www.youtube.com/watch?v=dZlaweoZDiU Moonshot Google X Edmund Kelly

Other good news are that monocrystaline cells can now be made as thin as they only need to be.(4micron) http://www.raytonsolar.com
So that you have already today all the solar silicon (282,000tons)you need to turn the whole world stratospheric solar powered in jsut 10 years if you only would make the cells ultrathin.
Because with this technology silicon gets used 100 times more efficient.


Actually everything is fusion powered. But people just don't complain because we have that protective atmosphere and magnetic field around us.
Maybe it would the best solution to put all nuclear plants onto the moon and then beam the energy down to earth. XD


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PostPosted: Jul 19, 2015 12:48 pm 
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Joined: Nov 14, 2013 7:47 pm
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Location: Iowa, USA
The reason we don't see more solar power is cost. I was on the solar race car team in college and that was quite the eye opener in the limitations of photovoltaics. Solar panels work well on only a fraction of the light spectrum from the sun, the rest of that spectrum produces efficiency killing heat. Light cloud cover actually improves PV performance since it takes a lot of the heat out of the sun but leaves the useful spectrum for power production.

PV cells are also complex electricity sources, they don't follow Ohm's laws. To get the most out of a PV panel there must be an expensive electronic system called a "maximum power point tracker" that manages the load seen by the PV cells and convert that to something that can feed the given load. Those little PV panels that you can buy to charge your cell phone either have very simple, and very inefficient MPPTs, or do away with them completely and rely on a battery to just take what the cell can give, meaning shortened battery life from the abuse.

Since the sun moves through the day the PV panel must move to track it or put up with the lower power output. Moving a panel is usually quite difficult, and therefore expensive. People will usually make up for the lost efficiency with larger panels, larger storage, or combine the solar with other sources of power, such as wind, water, or burning fossil fuels.

PV panels are also quite sensitive to dust and other debris that can land on the panel. Dirt can accumulate to reduce efficiency. Shadows from a larger object, like a leaf, can produce hot spots that can damage a cell. A damaged cell can short out an entire panel.

Put a PV panel on a large lighter-than-air craft and it must deal with high winds that inhibit keeping proper attitude with the sun. There's reduced atmospheric protection of damaging radiation. I understand that at some altitude there is increased risk of micro-meteors, small little rocks from space that like to punch holes in PV panels and gas envelopes, not something conducive to PV panels on top of a balloon. Do they get high enough that meteor impacts is a concern? I don't know but I'd like to find out. There's not likely to be a concern of leaves falling on the panels but the winds at that altitude would turn any dust into a sandblasting.

Basically solar PV is expensive. That's why we don't see more of it. It's hard to do right only a few feet from the ground, getting it done right 12 miles up just doesn't seem worth the trouble.

_________________
Disclaimer: I am an engineer but not a nuclear engineer, mechanical engineer, chemical engineer, or industrial engineer. My education included electrical, computer, and software engineering.


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PostPosted: Jul 19, 2015 1:21 pm 
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Location: Germany
The temperature in that altitude is -60°C. So the panels or concentrating cells would have enough cooling.
No humidity or dust up there. Air is very thin. 0.12kg/m³. Winds at max reach 180km/h in the winter. Polar vertices. But again the medium is 10x thinner. So it should compare more
to soft/medium winds here on 0km. Worst case scenario. No turbulences up there . very soft horizontal steady loads.
Image

The platform could be build with very many build in redundancy. So that in an emergency case the whole thing doesnt come down like a parachute.
Much like with airplanes which have many vital steering systems threefold redundant.
If PV panels suddenly produce 4x the energy like it would be the case for germany price should come down 4x.
Yeah there could be micro meteorites. But who knows how often that would happen for sure?
The platform therefore should be built modular.
In future those platforms could be also combined with mirrors in GEO so that base load would be almost 24/7. (mirrors in space should also last forever)
500,000 tons of mirrors could be mined on the moon. A good reason to get there. :D
I have heard there could be big frozen lava tunnels that we could use as hideouts.
There is a group working on a moon elevator. liftport.com


These guys here have stolen my invention. A plastic bag containing a mirror coating on the inside. But they invented it in 2009. XD
Image
Those bags could contain the hydrogen. Thousands of them could carry the whole mass.
This specific one here from coolearth solar costs only 2$.

Also the solar radiation should be more up there since 90% of atmosphere is beneath it.
Even on a sunny day we receive only 1000W of the 1367W global radiaton on ground level.


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PostPosted: Jul 19, 2015 4:40 pm 
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0.12kg per cubic metre might mean you have serious problems with cooling despite the very low temperature.
And there might be no turbulence at these altitudes but the air is certainly moving - which will put a major load on the equipment if you want to make it stay in one place.

It also doesn't solve the common problem with solar in the UK.
Peak demand actually manages to occur in the dark, January at about 6pm.


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PostPosted: Jul 20, 2015 4:36 am 
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Joined: Mar 22, 2014 2:34 pm
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Location: Germany
well it would be solar at its best. And not an utopia scenario like space based solar power is right now.
One would need an energy storage for the night. Right.
I consider this concept to be a game changer.
The lift force of the buoyancy hast to be very strong in order to keep it in place.
It could be overdesigned with the help of dyneema ropes and more buoyancy gas.
I can see them standing very firm in the sky just like swimming offshore turbines stand in the utterly rough sea.
For Germany the costs of solar right now are 4 cent per kwh(1kwp=1000€ producing 25,000kwh over 25y, no subsidies). Up there it could cost only 1 cent/kwh. (Price of storing 1kwh of electricity in a battery costs only 1 cent if the battery costs 100$kwh and lasts 20 years and there are actually batteries which can last that long)
At some point in time solar will so cheap without subsidies that it'll produce a major revolution. The demand then will grow bigger and bigger and people will try solutions to get more and more out of it because they are greedy.

Underneath the platforms, in the no fly zone so called energy kites could harvest even more power in that space. http://www.kitegen.com/en/products/kite-gen-carousel/


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PostPosted: Jul 20, 2015 10:11 am 
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You can't just assume 0% capital costs like that.
Even 2-3% will drive those costs through the roof.
Nuclear would be even cheaper on that basis, €3400/kW (~APR-1400) generating 473,000kWh over 60 years. - comes out at 0.72 cents/kWh. (And since you haven't included maintenance or anything like that, neither will I).
And it doens't require thousands of kilometres of dyneema ropes, massive lightweight DC/AC converters, the steering equipment and numerous other bits, the Cost of the PV is just the beginning in this case.
You will also have to take steps to ensure an upwards-lightning strike into the stratosphere (which has been known to happen) doesn't set your envelopes on fire because the hydrogen will certainly result in a huge amount of lost array.

Oh and you will only be able to have arrays very much spread out otherwise you will have arrays shading each other during the winter because the sun will be low in the sky.


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PostPosted: Jul 20, 2015 10:43 am 
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Location: Germany
If energy generation costs decreases 4 fold because of the 400% increase then yes it becomes almost negligibly.
And there will be another 60% decrease of costs in the panel production for the future. one example: http://www.raytonsolar.com
The shading effect has already being calculated by stratosolar.com and is said to be not that important. The longest shading time would be in the winter for maybe half an hour.
He talks about that in the moonshot video. In the summer it will be very short much like a passing cloud.
All in all it is not that noticeable.


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PostPosted: Jul 20, 2015 1:06 pm 
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A 3% capital charge raises the repayment to ~€58/years
Which means your energy capital charge is 5.8 cents/kWh, not 4 cents/kWh.

Then you have to do maintenance on the converters and the panels at stratospheric altitudes.
Which will be rather difficult, even if you can avoid the problems with dust on the panels by going to this huge altitude- there will be also losses of hydrogen to consider.
You will have to loft many tonnes of transformer or DC/DC converter.
Unless you are going to put heavyweight compressors on the aerial platform hauling it down will require expending lots of energy on the winches or dumping the hydrogen - which on something this huge is a major loss.
Which means you will have to maintain at altitude, especially considering the problems from temperature changes.

All this is based on the idea of having magical technologies which all work as well as they possibly can as cheap as they possibly can.
That is rather naive - otherwise I could have €1500/kW nuclear and crush you.

This still hasn't solve how you are going to deal with your massive overproduction in summer against massive underproduction in winter (shortest day of the year in Britain is like 8 hours).


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PostPosted: Jul 20, 2015 2:39 pm 
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Joined: Mar 22, 2014 2:34 pm
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Location: Germany
Germany uses per year 80 billion m³ of gas and has storage capabilities of over 22 billion m³.
The construction of new caverns is very cheap and easy.
Conversion of electricity to gas is very efficient and cheap.
There would be no way to heat houses electrically. Because erecting 250 additional GW transmission lines just for heating via very efficient heat pumps would be insanely expensive.
Gas ist the best solution to that since we have already the infrastructure deployed.


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PostPosted: Jul 20, 2015 4:08 pm 
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cerebral wrote:
The shading effect has already being calculated by stratosolar.com and is said to be not that important. The longest shading time would be in the winter for maybe half an hour.


This doesn't make sense. Night is night even at 20km. You might get an extra 30 min at dawn and dusk, if you can point your structure towards the horizon.

Quote:
The construction of new caverns is very cheap and easy.
Conversion of electricity to gas is very efficient and cheap.

Can you support either of these statements?

Electricity to gas conversion is not done outside of the lab because of efficiency losses. Electricity is far more valuable than gas, so why convert it at a loss. If you want to make gas, you want to use heat.

Stratospheric solar power is certainly innovative. Maybe it's even feasible. But it's not yet the proven solution to the world's need for clean energy.

I made the following chart showing the cost of rooftop solar electricity.
http://prntscr.com/7uzxcg
It looks cheap, but this is without storage, and it's more expensive than wholesale prices.


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PostPosted: Jul 20, 2015 4:09 pm 
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cerebral wrote:
Germany uses per year 80 billion m³ of gas and has storage capabilities of over 22 billion m³.
The construction of new caverns is very cheap and easy.
Conversion of electricity to gas is very efficient and cheap.


No it isn't.
My primary qualifications are in Chemistry and I have been following development of these electricity-to-fuel processes for years.
They are only 'sensible' in the insane world of renewables.
Mass produced LWRs might be able to justify it for the production of liquid transport fuels or chemicals - but none of these processes will ever be useful for natural gas.

cerebral wrote:
There would be no way to heat houses electrically. Because erecting 250 additional GW transmission lines just for heating via very efficient heat pumps would be insanely expensive.
Gas ist the best solution to that since we have already the infrastructure deployed.

Actually this is completely the opposite solution.
If we can really produce electricity renewably using this system with near zero land area the 'best' solution is probably to build more transmission lines - just run UHVDC east-west (1100kV+ or more) and you will be able to take advantage of time lag with longitude.
With this technology you could even build on random island atolls in the Pacific.

For the record, distribution capacity scales primarily by the number and distribution of subscribers, the amount of energy supplied to each one is almost immaterial (its capital cost is about $30/kVA of capacity).

Also if this energy is anywhere near as cheap as you claim their would be no case for heat pumps as resistive heating will come out cheaper.


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PostPosted: Jul 20, 2015 4:54 pm 
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Joined: Mar 22, 2014 2:34 pm
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Location: Germany
The problem with the excess electricity is the long term storability. Or more the huge amount of energy you need only in winter.
You would need to heavily overbuild the system only for the winter.
Storing it as gas, which we need anyway, is therefore the best solution.

http://vbt.ebi.kit.edu/index.pl/proj_steckb/HELMETH +85% efficiency.


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PostPosted: Jul 20, 2015 6:17 pm 
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85% using the most energy form available (electricity) to make the cheapest form available (natural gas) is a rather bad idea.

Even at 1 cent per kilowatt hour that comes out at something like $3.42 per million BTUs, even excluding the capital cost of the equipment and so on. You would be lucky to get under $5. Especially once you pay for your carbon dioxide capture.

Henry Hub is currently $2.70/MMBTU.
Even more expensive European gas is approaching that level now.

Seasonal heat reserves in houses would probably come out cheaper.
Giant tank of water in the basement or back garden to store heat. (Water is very cheap and we can bury tanks almost anywhere).

There is also the fact that you would, in this post carbon world, be producing any number of products through very energy intensive processes. Calcium Oxide, Cement and Calcium Carbide for example.
Could run a seven or eight month intensive production campaign followed by a depths-of-winter maintenance stand down. Since summer electricity would be effectively of zero price compared with winter electricity.


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PostPosted: Jul 20, 2015 11:50 pm 
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Natural gas produces only about 60% as much CO2 as coal for the same amount of electricity, but it's been estimated that if only 3-5% of the methane leaks out between the well and the power station, CH4's high absorption of infra red will give it a worse global warming effect than coal. Renewables enthusiasts assume hydrogen is a completely harmless fuel, but if it was used in anything like the huge quantities that fossil fuels are now, there would be a certain amount escaping. H2 is a much harder molecule to keep imprisoned than CH4. Any released hydrogen would head straight for the stratosphere and turn to water, at altitudes that used to be very dry. This would be sure to have effects on the earth's heat balance, and possibly also on the ozone layer. Hydrogen leaks from huge ultralight gas bags could be guarranteed.
Most renewables proponents are aghast at the idea of putting sulphur dioxide into the stratosphere, as Pinatubo did, but don't subject any of their own favourite schemes to critical scrutiny.


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PostPosted: Jul 21, 2015 4:06 am 
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Location: Germany
Did you know that plants grow even better in 1000ppm CO2 atmosphere?
Greenhouse owners know that and increase the amount of C02 in their houses. Crops worldwide have increased because of that.
In earths history we had very often concentrations with a few thousand ppm. Fossils tell us that.
There will be NO catastophe apart from a nuclear holocaust.
But people need to be brought into the right mood for The Big New Years Eve.
Right i dont think climate change is an issue.
I am pro solar and wind because i think it can be the cheaper and a better solution than existing solutions. (of course i am also pro next gen nuclear reactors, but politics right now has no interest in them because believe it or not, they cheat on us XD, and that fraud is really monstrous, noone possibly will believe it)


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