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back to article Solar enthusiasts rays idea of 'leccy farms on MOON, drones

Ever since the Golden Age era of science fiction, space-based power stations have been an object of desire for lovers of the future – but they haven't eventuated, so a Yorkshire-based outfit wants to try droning its solar panels at the more manageable 15,000 metres altitude. The idea, says the trio running the project (and about …

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Anonymous Coward

Why not just run a long extention cable back from the moon?

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Don't be silly, you'd never make an extension cord that long. Plus the electricity would all arrive in one place. I propose a cascading set of those 4 socket flylead thingies. Since they're only around 2 metres long, by the time they get to earth we'd have a socket each.

Brilliant!

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Title

Solar enthusiasts rays idea...

In before some spelling nazi who doesn't get the pun...

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Energy though the atmosphere...

It is not feasible to beam energy through the atmosphere. That said, the energy could be used to power space factories, alternatively, a carbon nano-tube "cable" leading back to earth with a geo-stationary "top" could solve this.

See this study on the effects of the atmosphere on lasers...

http://www.dtic.mil/dtic/tr/fulltext/u2/a518829.pdf

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Trollface

Re: Energy though the atmosphere...

"It is not feasible to beam energy through the atmosphere"
My solar powered calculator begs to differ.

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That picture

That's no moon, it's a Death Star!

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And it's Japanese. What can go wrong!

Excellent! Most excellent!!

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Dark side of the Moon

The idea of placing solar panels in a belt around the moon is pretty daft, because half of the panels would always be in shade! If you put them floating in a geosynchronous orbit instead, they might get occasionally get eclipsed by the Earth, but only briefly, and by fielding several power-generating satellites, the majority would always receive sunshine.

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Re: Dark side of the Moon

Or put several arrays in a narrow loop orbit around L1, where they can get sun 100% of the time. From there, they beam their energy to a network of geostationary satellites which then send it down to receiving stations on Earth.

We already know how to put things into orbit around L1, we use that spot for solar observatories. That's a lot easier than building structures on the moon!

Using multiple arrays we have a bit of redundancy in case one of them gets taken out by a meteor, though not as much as a lunar ring. On other hand, we get 100% duty cycle out of these, versus only 50% for the ones on the moon.

By beaming the power to geostationary satellites, we can send power down to nearly any spot on earth (outside of the poles) even areas directly opposite the sun at the time.

As ever, the hard part of this is the "beaming the power to Earth", which always seems to be accompanied by a lot of hand waving. Hopefully someone much smarter than I can figure that part out someday. If they solve that, my intermediate stage of beaming the power to geostationary satellites should be simple by comparison :)

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Re: Dark side of the Moon

"As ever, the hard part of this is the "beaming the power to Earth", which always seems to be accompanied by a lot of hand waving"

How about focused reflection of sunlight? OK, so this is getting a bit "ant & magnifying glass" for people, but rather than mess about with multiple conversion stages and energy beams, simply use mutiple reflectors to focus on solar power plants on the surface, concentrating to perhaps 5-50x normal sunlight intensity. Not so good for unlucky birds or careless flyboys, but harvesting the energy would be "relatively" straightforward (as in "nuclear power stations are relatively straighforward"). I'm sure that this must have cropped up in sci fi somewhere already, because it is obvious. And the idea of building a series of precisely controlled space mirrors seems closer to our capabilities now than the alternatives.

That "beam" could be multiply reflected to serve the dark side of the planet, could be split or consolidated into whatever made the most sense for the collection plant and power transmission networks. Concentrated sunlight would (?) burn through cloud or fog, and if correctly focused would have limited impact on stargazing romantics.

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Re: Dark side of the Moon

"The idea of placing solar panels in a belt around the moon is pretty daft, because half of the panels would always be in shade!"

Just because the moon's orbit is tidally locked with the earth doesn't mean that the "dark side" doesn't receive any sun. (http://imagine.gsfc.nasa.gov/docs/ask_astro/answers/980302b.html)

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Re: Dark side of the Moon

The idea of placing solar panels in a belt around the moon is pretty daft, because half of the panels would always be in shade!

But not the same half all the time. The moon only shows one face to the Earth because it's tidally locked, which means that when the moon is between the Earth and the sun, the "dark side" of the moon is lit by the sun.

If it's comparable in cost to build and ship those panels (or ship a robot up to the moon and have it build the panels there?) rather than shoot up satellites with a little over half as many panels and then burn energy maintaining their orbit and ensuring their panels always point directly at the sun, and that they don't collide with the other satellites in geosynchronous orbit, then the moon option is still a contender.

There is no dark side of the moon, really. As a matter of fact, it's all dark. -- PF

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Anonymous Coward

Re: Dark side of the Moon

Nah, just shift the moon a bit to put it into geostationary orbit.

It might annoy those people who never get to see the moon any more though.

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Re: Dark side of the Moon

And you put your receiving station somewhere like the middle of the Sahara or Australian desert so that, even if there is any spillover/lack of tracking you're not actually burning up cities/grassland/holiday camps while the techs work to either shut down or reposition the beam.

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More importantly...

.... will it be staffed by robots who start their own religion and praise the energy converter with songs composed by Delilah Derbyshire?

http://www.youtube.com/watch?v=jetzY-W78gg

Kudos to you if you get that reference without having to look it up.

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Re: More importantly...

Yes, but without complete dedication — they've all got second jobs policing the White Void.

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Blinded by the light

Beaming energy towards earth at any sort of "optical" wavelengths sounds like a great way to kill amateur astronomy stone dead. Whether the energy was beamed from the Moon (easily avoided) or satellites (not so much).

Although radiation densities would (you'd hope) be made safe for normal eyeballs to gaze upwards, the added collecting power of a telescope could make stargazing as hazardous as turning your telescope sunwards. The normal advice given to those who might be tempted to try is "Do not repeat this with your remaining good eye".

It might be a good time to invest in white-stick makers.

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Re: Blinded by the light

The systems I've seen proposed using light, use lasers. That means a very, very narrow band and very easy to filter (like filtering out low pressure sodium lamps). They also have quite a low power density to make them eye-safe, including for binocular users (viewing a very large telescope by eye, I don't know).

The systems are done to get 24hour power (except 70 minutes during the equinoxes), and use lasers rather than huge mirrors because the conversion efficiency in space is better than on Earth, and the final conversion efficiency on Earth with a very narrow wavelegth range can be quite good.

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Re: Blinded by the light

FFS!

low power density for the transmission of power?????????????????????????????????????????????????

?????????????????????????????????????

okay thats a lot of question marks, but it's a pretty big fucking question.

AFAIK we'd want to use IR lasers for this, trouble is, apart from amat observers, there's nitrogen, co2, h2o and a whole shitload of other stuff in the way each of which have their own absorption spectra, which would seriously fuck up any power link. Further complicated by the fact that not every wavelength is available.

Look at the anti missile tech as the state of the current art, consider the bigness (not to mention inefficiency) of the laser, the smallness of the target, the puny-ness of the distance, and the relatively piddling amounts of power transferred. Multiply all that by a couple of orders of magnitude then design me a heat-sink that will allow the laser to run continuously... in space.

piece of piss really!

(not saying impossible, but very very very hard)

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Anonymous Coward

Re: Blinded by the light

So either you go low power density, and have a pretty useless form of energy transmission, or you do high power density and end up frying entire cities when something goes wrong. And it will go wrong eventually, either by accident or deliberately.

So many people are against space based weaponry but here we are proposing just that, only on a larger scale than any military organization would ever dream of.

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Unhappy

Anyone done some actual *calculations* on this?

15km drops air pressure roughly 75%. The differenece between Air Mass 1 and Air Mass 0 solar constants (1296-976) is 320W/m^ so probably there would be a measurable improvement on energy generated at that altitude

Microwave systems can give conservative energy transmission efficiencies of 80% and ruinously expensive triple junction solar cells have efficiencies of > 44%.

I'll also note this altitude is nowhere near high enough (about 835Km too low) to deliver near continuous (IE 24 hr) output.

So the question has to be who wants this?

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I think the Japanese company is called Shimizu, not Shimzu. (Although they seem to be using 'Shimz' as their logo.)

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Anonymous Coward

OK I get the laser bit ...

... but how will they keep the sharks alive? Water is dense, you know

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Re: OK I get the laser bit ...

I saw no mention of sharks in the article.

And that's just wrong.

I want to know how they propose to have lasers on the moon without sharks.

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Cameron

How about sponsoring sending Npower and that Cameron crony up to the moon.

Anyone want to power it via kickstart ?

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Stop

The Clue....

...is in the words "MASTER PLAN" on the graphic.

I bet he has a white cat!

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Final demand

Please pay your overdue energy bill promptly.

Note that our Death Ray\\\\\\\\\\\\\ Energy Transfer Beams are notoriously difficult to keep focussed on our receiving stations, we would not like an accident to occur.

Yours....

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not rocket science

Solar power is not viable on earth, even though we have huge areas of worthless empty desert where the sun shines every day and where the cost of delivering heavy equipment and maintaining it is minimal.

Adding in a million dollars per kilo to get plant to the moon, plus the massive costs of maintenance (think Hubble Space Telescope servicing mission x 10 or x 100) is completely bonkers from an economic perspective even if you get 3 o4 4 times the amount of power.

The sun already beams energy right to us in electromagnetic waves, we need better ways to collect it on earth, not ridiculous moonbases or whatever else.

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Re: not rocket science

I think you'll find that solar PV IS viable on earth, or very close to it, when in the right place. Even without the massive feed-in subsidies it's getting close on a domestic scale in the cloudy UK. And covering a few hundred square miles of desert/mountain/tundra with panels will be extremely economically viable within a few years, and a whole lot cheaper, simpler, safer, more secure, more maneagable etc than lasers in space.

Current solar cells in a clear sunny location near the equator can generate at least a kWh per square metre per day. A square kilometres of panels can generate a terawatt hour per day. Global electricity consumption is about 20,000 TWh per year. So 60 square kilometres of PV cells could match the entire global electricity needs, and 500 square kilometres (25 milliWales or a couple of Liverpools) would match total global energy needs.

A massive job to set it all up, very expensive, but still cheaper than beaming that much energy down to ground stations.

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Re: where the cost of delivering heavy equipment and maintaining it is minimal

You clearly have no idea of what maintenance means in a desert environment.

Here's a clue : fine grain sand and mechanical gears of any type do not mix well.

Come to think of it, fine grain sand doesn't mix well with electronics either - something about static charge buildup that's really fun in the vicinity of a motherboard.

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Re: not rocket science

" So 60 square kilometres of PV cells could match the entire global electricity needs"

That's what the Desertec consortium reasoned, and reckoned they could build in North Africa to supply Germany. Unfortunately German energy policy is even more misguided and chaotic than our own (not by much, mind you), and the prospective energy company participants no longer have two pfennig to rub together, financial backers look at the energy policy death zone that exists across all of Europe and concluded that such schemes were not a safe investment, and the existing German plan of subsidising solar and wind in not-quite-so-sunny Germany met a fair chunk of demand that might have made Desertec viable, but in a less efficient manner.

The UK made a similar mistake to the Germans of supporting build out of immature, sub-optimal renewables, although in our case by promoting vast amounts of low output on shore wind, when (if you must have wind power) the answer if not "small, crappy, onshore" but "vast, efficient, offshore".

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Re: not rocket science

"Current solar cells in a clear sunny location near the equator can generate at least a kWh per square metre per day. A square kilometres of panels can generate a terawatt hour per day."

I would like to know where you obtain these figures. Because I have a counterpoint.

Ivanpah is the largest solar plant in the world, at 5.5 square miles. It's about to come online. And note this plant is solar-thermal (using molten salts) so actually CAN still generate electricity at night unlike photovoltaics. It's rated generation is 392MW, enough to power about 150,000 California homes (thing is, California is the most populous state in America--over 12 MILLION homes alone). So may I ask where you numbers come from? And how is night accounted for?

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Happy

Re: not rocket science

"That's what the Desertec consortium reasoned, "

I think you'll find that Desertec's plan used solar thermal, which is an efficient way to harvest all of the solar spectrum by heating a working fluid to high temperature and hence drive a pretty conventional steam turbine.

Large scale but (mostly) conventional technology. BTW being in a desert peak sun was about 2x that of less arid areas.

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Re: where the cost of delivering heavy equipment and maintaining it is minimal

Moondust is just as bad as desert sand, but it's still a lot easier to maintain in a desert.

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Re: not rocket science

Ivanph is in the desert, too, and is solar-thermal. Thing is, despite its size (5.5 sq. mi.), it's estimated to only provide enough power for just over 1% of California's homes, to say nothing of big energy sinks like heavy industry (and let's not start on industries like aluminum smelting which specifically requires lots of electricity due to the smelting techniques involved---at least steel smelting can use non-electric sources).

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Re: where the cost of delivering heavy equipment and maintaining it is minimal

"Moondust is just as bad as desert sand, but it's still a lot easier to maintain in a desert."

At least the moon has no atmosphere and therefore no WIND. Sand by itself doesn't do much until air picks it up. It's not sand that raises the maintenance costs but sandSTORMS.

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Re: not rocket science

"I think you'll find that Desertec's plan used solar thermal, which is an efficient way to harvest all of the solar spectrum by heating a working fluid to high temperature and hence drive a pretty conventional steam turbine."

Can you point to a study that supports this? I would think the "thermal" in solar thermal implies that the energy absorption would be concentrated on the low end of the spectrum (particularly in the red to microwave ranges--this includes infrared, the wavelength we most commonly associate with heat). What happens to the higher frequencies like green, blue, violet, and ultraviolet?

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Re: where the cost of delivering heavy equipment and maintaining it is minimal

Moondust is just as bad as desert sand

Moondust is far worse than desert sand. It's like slow-motion grey goo and abrades anythingsoft parts of the machinery:

What a little Moon dust can do

Lunar dust is extremely abrasive -- and unavoidable -- as astronauts quickly learned during the Apollo missions of the 1960s and '70s. Within hours, the dust covered the astronauts' spacesuits and equipment, scratching lenses and corroding seals. "Dust is the No. 1 environmental problem on the moon," said Apollo 17 astronaut Harrison Schmitt, who reported having a severe allergic reaction to moon dust during his mission in 1972. "We need to understand what the (biological) effects are, because there's always the possibility that engineering might fail."

AFAIK it ate through all the rubber seals used to keep it contained in a box.

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Re: not rocket science

"I think you'll find that Desertec's plan used solar thermal, which is an efficient way to harvest all of the solar spectrum by heating a working fluid to high temperature and hence drive a pretty conventional steam turbine."

I know (my employers were a founder member of the consortium), my shorthand simply referred to the idea of solar energy capture in desert locations.

But to take issue with your comment, harvesting solar by thermal means may collect a greater proportion of the spectrum, but end to end it is not really that much better than PV - the cost, complexity and losses of solar thermal are big offsets, when pv is simply a "fit and clean" solution with minimal maintenance requirements.

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Boffin

Re: not rocket science

of course, any Sahara based PV farm would need a DC grid to its main market - Europe, north of the Med.

http://smartgrid.ieee.org/questions-and-answers/902-ieee-smart-grid-experts-roundup-ac-vs-dc-power

There's something in New Scientist about DC grids that I could not find. A DC grid will 'join up' the various renewables more efficiently that AC systems.

Also this:

http://theenergycollective.com/rogerrethinker/204396/ac-versus-dc-powerlines

" But DC lines were not developed initially to be capable of higher voltage, nor to be able to move more power than AC lines, but rather to make it possible to put high capacity power lines underground (for security) or under the ocean (to bring power to islands initially).

To understand why undergrounding HVDC lines for great distances is feasible, while undergrounding HVAC lines for more than about 40 miles is not, it is necessary to consider the capacitance of air-insulated overhead lines versus cables, which are typically surrounded by polymer insulation and soil. "

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Holmes

A solution in search of a problem

Title says it all.

There are more than enough lower cost and easily implemented solutions right here on Earth. The first being solar on rooftops. The second being rooftop wind.

The third being ever rising efficiency.

The distant fourth being wind and solar farms.

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Re: A solution in search of a problem

"There are more than enough lower cost and easily implemented solutions right here on Earth. The first being solar on rooftops. The second being rooftop wind."

Solar isn't low cost in the UK, largely because the output is so dismal. Perhaps you confuse the subsidies and redistributive effects of policy with the underlying economics. And rooftop wind is a joke anywhere. Not only will the roof itself and adjacent buildings interfere with the local wind field, such devices will be far too close to the ground and suffer severe boundary effects and low wind speeds, being on land there will be strong diurnal variations....but even ignoring those the size of rooftop wind collectors will be pitiful. This could be why the cutting edge technology for wind turbines is 500 ft diameter rotors on 330 foot masts, located well offshore.

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Re: A solution in search of a problem

Ledswinger; you also forgot to mention that putting a turbine on the rooftop tends to propagate all sorts of nasty vibrations into the structure of the building, which then tends to fail with parts crumbling away and cracks appearing. For me that is a more serious problem than low efficiency.

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Re: A solution in search of a problem

You're right, but there were even more problems that didn't get a mention - the short life of wind turbines, the harm to wildlife of such a close mix of habitat and bird & bat death machine, plus noise, weight and dynamic load even before vibrations. And then there's the high cost of property-specific installations, and the rubbish output. There was some amusing news recently about the Welsh Assembly installing a £48k wind turbine that churns out a stonking £5 or electricity each month.

There's some interesting stuff in this link for those still hoping that a small scale wind turbine might answer their prayers - a little dated, but the physics and the fundamentals haven't changed since:

http://www.theoildrum.com/node/6954

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Re: A solution in search of a problem

Ah but you see what you have failed to do is drink the renewables koolaid!

if you are going to think practically about the reality of implementing these ridiculous garden shed schemes then we'll never get anything done.

also i'll see your 'vibrations will destroy your house' and raise you a 'the whole embedded generation pipe-dream is ruining the grid we already have'

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Trollface

Re: A solution in search of a problem

£5 a month!

Sir your data is out of date!

modification of the system has increased the output by 80%

so that's now £9 a month.

put's a whole different perspective on it i think you'll find.

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fpx
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Store the energy and dump it occasionally

How about ... drone goes up to 15km, collects energy, stores it in batteries (electrical, flywheel, compressed gas, electrolysis, whatever), and occasionally comes down to land for de-fuelling. Or have its full batteries regularly serviced by a second sort of drone aircraft.

Would there be enough extra sunlight at 15km to offset the conversion losses and the service drones?

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Re: Store the energy @fpx

No. Volumetric and specific energy density of any known form of energy storage would make the aircraft too heavy. If you look at the existing solar powered "aircraft" you'll see that they struggle to stay airborne overnight, and that's with the craft made of string and paper. If the most energy you can bring back is sufficient to fly what is barely more than a glorified glider for a eight hours then this won't be supplanting even land based solar or wind ever.

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Re: Store the energy @fpx

Saying eight hours makes me think all of these solar-powered aircraft were flying widdershins (east, against the sun), producing shorter day-night cycles. I wonder if anyone's built one with enough lasting power to fly sunwise (west, with the sun): longer days but longer nights, too.

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