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 …
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
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.
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 :)
"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.
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.
"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)
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
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.
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.
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)
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.
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?
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.
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.
" 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".
"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.
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).
"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?
"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.
"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?
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. "
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.
"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.
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.
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.
"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.
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.
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
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'
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?
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.
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.
The technical challenges aren't the issue. The funding is going to be what squashes this idea. That seven year ROI as part of their funding pitch is going to be really hard thing to ignore. That's a perfect world, pie in the sky kind of pitch that startups use all the time and they get mad if they can get funding. It's highly unrealistic and a bad sign of managements capabilities. Investors would rather hear about the big challenges and how you plan to deal with them, not about how great it will be if everything goes exactly according to plan.
The actual science involved in beaming power from space is beyond me, but building things to accomplish never before tried things isn't, that's our business. The realities of building things from scratch, especially things that go into space, are really, really expensive. Even companies that regularly put things into space fudge in 2x+ R&D because they know it'll all go pear shaped several times before a rocket ever touches the launching pad. If you aren't a space regular the problems are even more expensive.
I hope they can get this to work, I really do. But the truth of the matter is this is a perfect project for a government to be funding, not private investors. Governments are the only organizations that can absorb the massive losses in proving a concept, private money really isn't well suited to extremely expensive pilot programs.
"Governments are the only organizations that can absorb the massive losses in proving a concept, private money really isn't well suited to extremely expensive pilot programs."
Tell that to SpaceX and Elon Musk. Ooh, and go tell it to the private investors who bankrolled the invention and construction of most of the rail networks in the UK or US, or did the same for motor transport, or built the first decent roads in Britain after the Romans left (the turnpikes for anyone not paying attention), or developed aircraft in the face of governments blustering that these things were of no use. Obviously we don't remember all the things that didn't work, but I think you're wrong to believe that government is the best answer to funding, organising or delivering major R&D programmes.
The roads in the UK I know nothing about, but every single other item on your list was piloted and underwritten by governments. Big outside investment eventually came along, but only when the technical issues were understood and governments had agreed to assist with governmenty issues.
Railroads in the US were only partially funded by private investors, and then only when the government made the property issues go away, overlooked insanely bad work conditions, funded 'work ships' full of Irish and Chinese disposable labor and used the army to move the pesky Indians out of the way. The government also completely underwrote the expansion of steel mills and saw mills and timberland purchases for track building. The mill owners committed to certain quantities of output and funded the labor, but the capex was 100% government.
Even the SpaceX project is only feasible because they've got a financial commitment from the government as well as 60 years of government funded research to build off of as well as guaranteed loan underwriting at great rates (you didn't really think Musk was risking his own money did you?) If the project succeeds it'll only be making incremental improvements to existing, proven, processes (cool yes, but without government subsidies it would never happen). The project being discussed here is hugely unique and will require unbelievable amounts of never before tried infrastructure.
Now, I'm the first to say governments everywhere are the single most inefficient organized bodies on the planet, but they are also the best suited to absorbing the costs of huge programs that benefit all of society. It's actually what governments are designed to do, gather resources and redistribute them where the greatest good can be had. I am not saying they currently redistribute those resources the best way, but programs like this is what they're structured to do.
I'm not a huge fan of most government activities, but at the same time it is foolishness to ignore the massive contributions they make to big projects. Everything from the research of the core principals to subsidizing the infrastructure is taxpayer funded and has been for a very, very long time.
"Now, I'm the first to say governments everywhere are the single most inefficient organized bodies on the planet, but they are also the best suited to absorbing the costs of huge programs that benefit all of society. It's actually what governments are designed to do, gather resources and redistribute them where the greatest good can be had. I am not saying they currently redistribute those resources the best way, but programs like this is what they're structured to do."
Put it this way. There are some things you can't trust the private sector to do right because money isn't the right motivation (at best, it distracts; at worst, it actually interferes). That's why I don't trust the private sector when it comes to medicine. This is one industry where the money angle interferes with the greater goal of improving health (think treatment regimens vs. permanent cures/vaccines).
The roads in the UK I know nothing about, but every single other item on your list was piloted and underwritten by governments. Big outside investment eventually came along, but only when the technical issues were understood and governments had agreed to assist with governmenty issues.
Not at all my dear chap.
Even at Jimbo's Truth Emporium, we learn:
The railway system of Great Britain, the principal territory of the United Kingdom, is the oldest in the world. The system was originally built as a patchwork of local rail links operated by small private railway companies. These isolated links developed during the railway boom of the 1840s into a national network, although still run by dozens of competing companies. Over the course of the 19th and early 20th centuries, these amalgamated or were bought by competitors until only a handful of larger companies remained (see railway mania). The entire network was brought under government control during the First World War and a number of advantages of amalgamation and planning were revealed.
In other words: it worked until the big intra-european massacre which Britain though it could participate in for frankly unclear reasons (now being retconned to "protecting the freedoms"), at which point frank socialization occurred, as one never should let a good crisis go to waste.
When "governement" does something, it does not "contribute". Government is also not structured to do anything (otherwise there would be no wars and decisions would either make sense or be followed by firings). It ignores economic calculation. Destruction of economic well-being necessarily ensues, otherwise the Soviet Union would have been the splendid land of proletarian freedom, so glowingly presented to us by the starry.eyed press of the 20s. Ah yes.
All those people investing in canals and railways and roads, and Musk-in-spaaaaace et al had a concept of a 'long term investment' that extended more than a few years down the road.
Given the highly dysfunctional state of the markets these days i cant see anyone a) investing in actually making anything b) making something that wont show a return for decades.
(Mr musk is an outlier - an enthusiast with unimaginably deep pockets)
It also probably helped there was a very concrete goal in mind when canals and later railroads were built. In both cases, the main goal was speedier commerce: moving more stuff at a time at a faster rate than one could before overland.
But then again, think back to the great age of sail. Who underwrote most of those transoceanic voyages? As has been said, once you have the basics down, private enterprise can build upon them, but when you're trekking into the great unknown, where the goal itself, let along its attainment, was anything but certain, you probably need backing from an entity for which money isn't the first priority.
"I cant see anyone . . . . making something that wont show a return for decades"
I think you'll find the Chinese have been doing that for years, particularly in Africa. 'Let us build you some new roads and a hospital or two, maybe some schools. No, no rush to pay us back, just remember who did this for you when the time comes'
In the West we want payback as soon as we can get our hands on it and bugger what happens in 20, 30 years time, which is one reason we fucked up our empires so badly. The oriental approach is to look at what the long term gains/effects will be.
A Western corporation which promised its shareholders a return in 50-100 years time would soon have its board voted out.
Start with the fact that photovoltaics is a crude parlor trick using one-time, one-way molecular erosion process that never produces the energy required for it's manufacture. See "Green Prince of Darkness...EXPOSED" on this 'sustainable' fraud. Then compound that STUPIDITY with the losses of converting photovoltaic 1.5 volt DC to usable AC high voltage, then losses to convert to three phase. Then compound with losses converting to laser or microwave. Then fry every bird or airplane that strays into the transmission path. Then losses converting laser or MW back to electricity.
To even discuss this multilevel HOAX is proof that the inmates are in charge of the institution.
So, we import extra energy just so that we can breed more. Jeez, Agent Smith was right.... we are a virus! Welcome to earth in 2100. Nobody cares about CO2 any more because the sheer heat produced by 12 Billion people consuming 10Kw each has melted all the ice and nobody can live within 20 degrees of the equator. CO2,.... that was such a 21st century problem.
What about the old THE ARTEMIS PROJECT of doing fusion on the moon? The lunar surface hold more He3 that any source on earth; and is in fact abundant there. Their is less gravity so holding a magnetic field to confine the plasma is easier too. Since the moon always faces the earth, never moving a smidge out of sync - using laser/microwave transmitters would be a no-brainer. Solving the fusion problem is a brainer though. Excess neutron radiation? Who cares? Its the moon! It would be a robotic power plant - no one would care if it blew up! Except maybe Homer Simpson.
The moon may always face the earth, yes, but the Earth rotates under the moon approximately once per day (it's off by about 1/28th in one direction--forget just which way; does the moon orbit with or against the Earth's rotation?). So there's still the matter of aiming a beam back down to Earth (and with that, the inherent risk of mishap--or worse, sabotage).
The Register 
Biting the hand that feeds IT
Copyright. All rights reserved © 1998–2024
