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Grahamshortuk
2010-Jun-15, 01:37 PM
The Solar wind carries a regular stream of charged particles, and the Earth's magnetic field deflects these and "funnels" them to the poles. When the charged particles collide with the atmosphere we get the auroras.
So...
1) Is it possible to place an object into a geostationary orbit above the poles?
2) If so, would it be possible to place panels of arrays of devices into orbit above the poles that could use these moving charges to generate electricity? The devices in the arrays may use magnetic fields to funnel charged particles appropriately such that electrons generate a current directly, and protons are focused through nano-scale coils to induce an electric current.
3) If so, would it be possible to tether such devices to a ground station at the poles from where electricity could be distributed, (assuming the issues of temperature and weather can be dealt with). Such a tether may make use of carbon nano-tubes, for example.
:confused:

Larry Jacks
2010-Jun-15, 01:57 PM
1) Is it possible to place an object into a geostationary orbit above the poles?

No, that is physically impossible. You could put something into a synchronous (24 hour) orbit over the poles but there is no way to "station" a satellite there.

JustAFriend
2010-Jun-16, 10:14 PM
Anything is >theoretically< possible, but considering how little we can actually throw up into space
(especially once the Shuttle is retired next year), don't hold your breath.
Any device that big would require much more technology and space launch capability than anyone on Earth has.

And you wouldn't have to use a tether to bring electricity back down; the groundwork for beaming power
back from space with microwaves was explored back in the '70s-'80s. But the environmentalists crushed that, too.

Jens
2010-Jun-17, 05:14 AM
1) Is it possible to place an object into a geostationary orbit above the poles?


As Larry Jacks wrote, that is impossible. You may be wondering why, so just as a simple explanation, the poles are not moving, so in order for a satellite to stay above the north pole, it would have to be motionless, so have no orbital velocity. And it's easy to imagine that it will fall back to the earth.

I suppose there is a caveat, which depends really on what you mean by a "geostationary orbit." If you really mean a geostationary orbit, then clearly the answer is no. You may have been trying to ask, "would it be possible to place a satellite in a geostationary position above the pole?" In that case, the answer would be yes, but of course you'd have to keep some kind of a propulsion device running to stop the satellite from falling to the earth. Given an unlimited amount of fuel, theoretically you could maintain a satellite in such a position, just as you can do it with a helicopter.

And as JustAFriend said, you wouldn't need a tether.

I think the key here would be whether there would be any advantage to using the stream of particles modified by the earth's magnetic field, or just the stream of particles that come in any case. I doubt that there would be much, and almost certain it wouldn't be different enough to justify keeping a device floating above the pole.

Jens
2010-Jun-17, 05:17 AM
One other thing: remember that you lose electricity when you transport it. So it's best to beam down the electricity closest to where it's going to be used. Thus, the equator is not a bad choice. But the amount of electricity that humans use near the poles is . . . almost one. If you see what I mean.

korjik
2010-Jun-17, 05:21 AM
The energy density is pretty low, IIRC. The precipitating electrons are also not really in a useful energy state. They are more akin to radiation than electricity

mugaliens
2010-Jun-17, 09:18 PM
I suppose there is a caveat, which depends really on what you mean by a "geostationary orbit."

A geostationary orbit is one where the satellite is directly above the Earth's equator at all times, and it appears motionless relative to observers on the ground. It's subpoint is contant. It's altitude is constant (circular orbit).

A geosynchronous orbit is merely one who's orbit repeats regularly over points on the Earth over time. Thus, polar orbits which repeatedly pass over the same equitorial location are technically geosynchronous orbits, though they're rarely called that.

One interesting version of a geosynchronous orbit is the Tundra orbit (http://en.wikipedia.org/wiki/Tundra_orbit), which has an orbital period of one sideral day. The Sirius radio satellites use the Tundra orbit.

Larry Jacks
2010-Jun-17, 09:39 PM
A geosynchronous orbit is merely one who's orbit repeats regularly over points on the Earth over time. Thus, polar orbits which repeatedly pass over the same equitorial location are technically geosynchronous orbits, though they're rarely called that.

Not quite. An orbit whose period is equal to the rotational period of the body being orbited is called a synchronous orbit. If that satellite happens to be orbiting the Earth, it's called a geosynchronous orbit. It need not be a circular orbit or one over the equator, it just needs to orbit once every 24 hours. If the satellite is in a circular orbit with little or no inclinatio to the equator and a period of 24 hours, it's in a geostationary orbit. Most communications satellites go for this kind of orbit because the satellite appears to be at a fixed location over a given spot on the equator which eliminates the need for a tracking antenna. While it appears to be stationary, it's actually traveling at a substancial velocity (10088 feet per second, IIRC).

If you had a powerful enough booster, you could launch a satellite into a circular polar orbit (90 degree inclination) with a period of 24 hours. Technically, that would be a geosynchronous orbit. However, because it's velocity and inclination, it could never be geostationary over any point of the Earth which is what the OP was asking. That would be physically impossible.

Van Rijn
2010-Jun-17, 11:21 PM
I suppose there is a caveat, which depends really on what you mean by a "geostationary orbit." If you really mean a geostationary orbit, then clearly the answer is no. You may have been trying to ask, "would it be possible to place a satellite in a geostationary position above the pole?" In that case, the answer would be yes, but of course you'd have to keep some kind of a propulsion device running to stop the satellite from falling to the earth. Given an unlimited amount of fuel, theoretically you could maintain a satellite in such a position, just as you can do it with a helicopter.


There is the concept called the statite (http://en.wikipedia.org/wiki/Statite) which could do that: You'd put a solar sail in a powered orbit (which might be over a pole) and use the sunlight to maintain its positon.

Of course, sunlight doesn't give a lot of thrust, so there are significant limitations.

Van Rijn
2010-Jun-17, 11:33 PM
2) If so, would it be possible to place panels of arrays of devices into orbit above the poles that could use these moving charges to generate electricity? The devices in the arrays may use magnetic fields to funnel charged particles appropriately such that electrons generate a current directly, and protons are focused through nano-scale coils to induce an electric current.


I can't see any way to get useful amounts of energy with a scheme like that, even if you could sit a structure up there.

You might be interested in the ideas around space based solar power, or solar power satellites, where there would be a satellite in orbit (often, in concepts, a geosynchronous orbit, but not always) that would convert sunlight to electricity, and then "beam" that down to Earth-side receivers using microwave transmitters or lasers.

The biggest problem with these concepts is cost: It's hard to come up with a space based system that would have a cost advantage over ground based systems.

NEOWatcher
2010-Jun-18, 12:02 PM
A geosynchronous orbit is merely one who's orbit repeats regularly over points on the Earth over time.Not quite.
Not quite? Note the bold. It makes it absolutely right.

Larry Jacks
2010-Jun-18, 01:02 PM
For Earth-orbiting satellites, the definition of synchronous or geosynchronous requires an orbital period of 24 hours. It says nothing about orbiting regularly over points on the Earth. You can get that with a Molyniya or sun-synchronous orbit but they're not geosynchronous.

NEOWatcher
2010-Jun-18, 01:15 PM
... It says nothing about orbiting regularly over points on the Earth. You can get that with a Molyniya or sun-synchronous orbit but they're not geosynchronous.
I guess that's the point I'm missing. So; "around" the Earth is important.

HenrikOlsen
2010-Jun-18, 04:56 PM
I guess that's the point I'm missing. So; "around" the Earth is important.
24 hours orbit is the point you missed I guess.

In one sense the Molyniya orbit is still geosyncronous, since it does have an apex hover over the same spot every 24 hours.
That it has another spot offset by 180 degrees and 12 hours where it also hovers every 24 hours is just a bonus. :D

Hop_David
2010-Jun-18, 08:36 PM
24 hours orbit is the point you missed I guess.

In one sense the Molyniya orbit is still geosyncronous, since it does have an apex hover over the same spot every 24 hours.
That it has another spot offset by 180 degrees and 12 hours where it also hovers every 24 hours is just a bonus. :D

Molniya's period is .5 sidereal day. The word for this orbit is semisynchronous. An orbit with a period of one sidereal day is geosynchronous. A circular, equatorial geosynchronous orbit is geostationary.

mugaliens
2010-Jun-18, 08:48 PM
A geosynchronous orbit is merely one who's orbit repeats regularly over points on the Earth over time. Thus, polar orbits which repeatedly pass over the same equitorial location are technically geosynchronous orbits, though they're rarely called that.

Not quite. An orbit whose period is equal to the rotational period of the body being orbited is called a synchronous orbit. If that satellite happens to be orbiting the Earth, it's called a geosynchronous orbit. It need not be a circular orbit or one over the equator, it just needs to orbit once every 24 hours.

Not quite. First, it's a sidereal day, so it's 23 hrs, 56 mins, and 4 secs. Second, any such orbit would, by definition, "repeatedly pass over the same equitorial location."

I did forget to mention "once per day."

Jens
2010-Jun-19, 04:44 AM
I think we're getting a bit off topic. I don't think the OP meant to ask a question about what a geostationary orbit, but rather whether it would be possible to put a satellite over the pole. I think it's been well enough answered, that you would need to expend energy to keep it there. I don't think the question was really about orbital mechanics per se, but whether such a scheme if feasible.

Hop_David
2010-Jun-19, 04:39 PM
I think we're getting a bit off topic. I don't think the OP meant to ask a question about what a geostationary orbit, but rather whether it would be possible to put a satellite over the pole. I think it's been well enough answered, that you would need to expend energy to keep it there. I don't think the question was really about orbital mechanics per se, but whether such a scheme if feasible.

I think some orbital mechanics is needed to answer his question. In an orbit, a satellite is keep aloft by so called centrifugal force, the "force" you feel on a merry-go-round. When you stand in the middle of the merry-go-round, you feel no tug. The axis of earth's rotation is the center axis of a giant merry-go-round. An object fixed above the north pole would be on the axis and therefore feel no centrifugal force.

You could counteract earth's gravity with a solar sail that's tilted 45 degrees to earth's axis as well as 45 degrees towards the sun. The force exerted would be opposite earth's gravity. Van Rijn mentioned statites earlier in the thread.

Since we're not relying on centrifugal force to hold it aloft, an ~36000 kilometer altitude isn't necessary. So possibly this tether could hang from a lower altitude and thus be less massive than the conventional beanstalk. Even so, plausible solar sails able to hold it aloft would be difficult, if not impossible (I haven't bothered to crunch any numbers, that's just a hastily formed opinion).


Not quite. First, it's a sidereal day, so it's 23 hrs, 56 mins, and 4 secs. Second, any such orbit would, by definition, "repeatedly pass over the same equitorial location."

I did forget to mention "once per day."

Rats. I know this is off topic but this post needs correction.

An inclined orbit crosses earth's equator twice each period, once at the ascending node and once at the descending node.

If an inclined geosynchronous orbit is circular, or if its line of apsides lies in the equatorial plane, these crossings would occur each .5 sidereal day.

In this case, a geosynchronous orbit crosses the same equatorial location twice per day.

A circular semisynchronous (approx 12 hour orbit) would cross 4 equatorial points in a day, each point spaced 90 degrees from it's neighbors. For this orbit, each equatorial point would be crossed once per day.

Murphy
2010-Jun-19, 07:15 PM
And you wouldn't have to use a tether to bring electricity back down; the groundwork for beaming power
back from space with microwaves was explored back in the '70s-'80s. But the environmentalists crushed that, too.

Rubbish. On what do you base that statement? I'm an environmentalist and I'm 100% in favour of beaming clean energy from space based solar power satellites.

The reason it wasn't done in the 1970s has nothing to do with any political objection, but that the technology simply didn't exist then. What was the efficiency of solar cells back then about 1% to 5%? Today it is about 25%, and likely to go to 50%+ within a few decades. This technology is only now becoming possible and you'll find that it is actually supported by a great deal of environmentalists.

Ronald Brak
2010-Jun-20, 12:15 AM
Then there's the fact that we beam microwaves generated from solar power down from space all the time. Or did fat hippies crush all those satellites while I wasn't looking?

ravens_cry
2010-Jun-20, 01:23 AM
Unless we get to the point where the launch costs are better then building twice and some more (for light absorbed by the atmosphere and for cloudy days) size solar power stations on two antipodal spots on the ground, I don't see how this could ever be practical.
And you're talking to a strong believer in space based industry and infrastructure.

Antice
2010-Jun-21, 09:32 AM
With the time and money you would spend on building just one solar power satelite for beaming down power, you can build 10 times the capacity of power production down here on the ground in the form of nuclear power. That is in the end the only factor that really counts when you have competing technologies making the same end product.

IsaacKuo
2010-Jun-21, 01:56 PM
There can be other factors. For example, nuclear power technology can't be freely exported. So, it may make sense for Japan to invest in solar power satellite technology because they can export solar power but they can't export nuclear power. If you take a long term view of things, you realize that a consumption based economy isn't really viable--you've got to produce something exportable.

Antice
2010-Jun-21, 02:42 PM
Japan cannot afford to build any solar power sat's, so for japan that would be an impossible investement. Japan already have nuclear capability for domestic use, and would be better served to expand that capacity to drastically reduce it's dependence on imported oil. you may not get an "exportable" product. But the trade balance would still get a major shift towards independence. not a bad thing imho. Japan could export the same things they do today.

IsaacKuo
2010-Jun-21, 02:52 PM
Japan is spending $21 billion on a project to build a gigawatt class solar power satellite. It's not impossible.

dgh64
2010-Jun-21, 04:09 PM
If you ask me, what we need is not space-based energy generators, but high-temp superconductors and storage systems. All the solar energy we need is already on the ground in places like the Sahara Desert and the western US, and there's also wind and tidal energy all over the place. All we have to do is figure out how to store and distribute it efficiently.

Antice
2010-Jun-21, 09:40 PM
21 billion for a single GW. you could get 2GW nuclear for that money. A westinghouse AP1000 is priced at 11 billion, but china is deploying a licensed version a lot cheaper than that. fourth gen reactors using thorium as fuel will have access to enough thorium to power our society at ten times our power consumption rate for a million years easy. The US alone has enough Thorium sitting around as spoils from rare earth mining to power itself for a mighty long time. this stuff is so common on earth as to make it equivalent to renewable as far as sustainability goes.
A tonne of thorium is enough to generate 1GW/yr.

Or to put it another way. the entire life time electricity consumption of a single average individual living the "modern" lifestyle can be generated by fissioning a roughly golf ball sized volume of thorium.(80 to 100gram) The resultant nuclear waste would fit in a soda can. and it's radioactivity is reduced to background levels within 300 years.

there is plenty of energy to be had with the right tools. there is no need to fill any coastlines with windmills or any pave over any desserts with solar panels to harvest really diffuse energy sources. especially not when there is such a wonderfully dense power source present in the mineral content of common rock.

IsaacKuo
2010-Jun-21, 10:11 PM
21 billion for a single GW. you could get 2GW nuclear for that money.
As I noted already, there may be other factors. For example, Japan could freely export that single GW, while they could not freely export 2GW worth of nuclear power plants.

Also, the price of energy varies throughout the day. The price of on-peak electricity can be 10 times higher (http://www.greentechmedia.com/articles/read/connecticut-power-light-proposes-10-1-ratio-for-peak-power/) than the price of off-peak electricity. While 2GW worth of nuclear is good for base load, it can't be ramped up to provide more power where/when it's most expensive. Space based solar power could be used to beam energy to where it's most expensive (dawn and dusk, assuming the target market already has solar power; dawn to dusk if the target does not). In principle, 1GW of space based solar could provide up to 5 times the revenue of 2GW of nuclear power.

The US alone has enough Thorium sitting around as spoils from rare earth mining to power itself for a mighty long time.
For whatever reasons, the US nuclear power industry is not really interested in thorium. This is a technology where the USA may fall terribly behind India and China.

dgh64
2010-Jun-21, 11:04 PM
Wow. I didn't realize Thorium was so abundant. How come we're not using it already?

I'm a strong proponent of nuclear energy, but I don't think it's the ONLY thing we should invest in. Everything has advantages and disadvantages, so I think we should cast a wide net to try and get as many options as we can.


While 2GW worth of nuclear is good for base load, it can't be ramped up to provide more power where/when it's most expensive. Space based solar power could be used to beam energy to where it's most expensive (dawn and dusk, assuming the target market already has solar power; dawn to dusk if the target does not). In principle, 1GW of space based solar could provide up to 5 times the revenue of 2GW of nuclear power.

This is why we need the high-temp superconductors. They would significantly decrease the on-peak and off-peak problem because energy could be moved around with almost no loss -- a nuke plant on the east coast could feed cities on the west coast during part of the day and vice versa during other parts, and the plants would only have to ramp up and down a little. If everyone has a plug-in hybrid car, then their cars could also act as an energy reservoir, further decreasing the ramping up/down problem.

IsaacKuo
2010-Jun-22, 01:46 AM
Wow. I didn't realize Thorium was so abundant. How come we're not using it already?
Obviously, it's not so easy to just use thorium. You need a different kind of reactor, and that requires R&D. India, in particular, has been investing heavily in thorium reactor research.

This is why we need the high-temp superconductors.
High temperature superconductors still need liquid nitrogen cooling, which makes them impractical for long distance power transmission. Currently, the most promising approach is HVDC--high voltage DC. But even so, long distance transmission of power will be expensive and limited.

If you mean room temperature superconductors, then...good luck. We've been reaching for that holy grail for decades. Who knows? Someone might stumble on the magic formula tomorrow. Or maybe no such beast exists.

Jens
2010-Jun-22, 02:22 AM
The question is about the feasibility of putting a satellite above the poles to generate electricity and beam it down to earth. If people want to discuss nuclear power, why not start a thread on that?

dgh64
2010-Jun-22, 03:53 AM
Actually the original post was about using a tether to wire the electricity down, and it was answered in the next few posts: No, you can't have a satellite hover over the poles without expending a constant stream of rocket fuel. A geosynchronous orbit over some point on the equator is possible, as is a polar orbit that repeatedly crosses over the same two 180-degree-apart lines of longitude (or is it lattitude?) on its way between the north and south poles, but hovering over one pole isn't.

An equally (I think) important question is this: Why would we want to? That's where the discussion of other (not just nuclear) energy sources is relevant, just to provide a cost comparison to show how it'll probably be way more expensive launching generators into orbit than using what we already have here on Earth's surface.

Antice
2010-Jun-22, 06:43 AM
France is already cycling their nuclear reactors for load following. instead of cycling the reactor core you cycle the electrical output by dumping the excess into pumped hydro, or simply by dumping electricity into load resistors. The LFTR design i like to promote is capable of load following with the best of them, it's a self regulating reactor core.
Wind and ground based solar is not capable of load following at all, in fact you cannot control it's output at all without power dumping, so without massive storage you end up increasing the stress on the system by causing the non renewable part of the mix to ramp up and down more than with a nuclear/hydro mix. hydro power is really good for load following, capable of ramping up and down in a minute or less depending on the generator. Nuclear can deliver the base-load power, and hydro can deliver the rapid load following capability.
This is a much cheaper option than building big solar power sats. not to mention the maintenance headache a solar power sat represents.

Despite the issues of intermittent supply, there are places where solar and wind are a better option. especially in remote locations where there is no grid connection, and there is no need for the large power output of nuclear. but storage is an obligatory part of the system.

IsaacKuo
2010-Jun-22, 12:46 PM
Dumping the excess into load resistors is possible for any technology but it doesn't reduce operating costs at all. It's not an example of load following, it's a kludge that proves that your technology isn't capable of load following.

Putting the excess into pumped hydro is also possible for any technology, and it's certainly one option to consider if you are limited to nuclear, solar, and wind. It's even more critical for solar and wind than it is for nuclear. Still, it's not a practical option in all locations, and it's more expensive than power on demand because of the losses in energy storage/retrieval.

If $21 billion buys you 2GW of nuclear power plants, it does NOT buy you 2GW of nuclear power plants plus 1GW of pumped hydro...that will cost extra. And it's still not something that you can freely export.

dgh64
2010-Jun-22, 03:54 PM
What we need is to get the Smart Grid up and running -- network the sources and loads together for better management, and then you don't need expensive pumped hydro or other storage systems.

Once electric cars, plug-in hybrids, and hydrogen vehicles become a significant portion of our energy economy, the load balancing problem becomes a lot easier -- just tell the charging stations and hydrogen production facilities to turn up/down as needed. So, imagine your car is charging at let's say 5 kW, if the grid suddenly needs to dump some excess then it could go up to 6 or 7 kw (and so would all the other cars in the area, adding up to however much excess you have). Then when the grid can't supply enough, your car's charger might only do 2 or 3 kW for a while while the power plants ramp up. The same thing could work for facilities like water treatment plants, and even stuff in your home like water heaters and air conditioning: Your AC doesn't absolutely have to come on the instant your thermostat tells it to and stay on until the thermostat says stop. The Smart Grid could tell the AC to turn off for a couple minutes if it can't supply enough power, and then turn it on again later once the sources have ramped up sufficiently. And instead of letting everyone's air conditioner turn on at the same time (say, when the sun first comes up and hits the whole town at once), instead have them networked so only like a third of them come on, run 5 mintues, and then shut off while the next third runs, then they shut off and then the final third takes its turn. It'd be sort of like the rolling blackouts they had in California a while back, except it's just your air conditioning. Most people wouldn't even notice.

Antice
2010-Jun-22, 08:40 PM
there are operating expenses and there are operating expenses. load following in general does not entail any benefit on operating expenses. Power plants needs to have it's operators present regardless of wither it is making power or not. Nuclear has the advantage in that the fuel costs is so low that wasting some of the power produced does not have much of an economic impact.
French nuclear power do load follow. albeit not rapidly. they can ramp up and down over a few hours when needed. thus they load follow no worse than coal fired steam plants. gas and hydro are the best load followers around. capable of ramping up within minutes. No other power plant types has this capability. they either dump into load resistors or ramp slowly based on projected power demand.
I.E. we know that at some times per day a lot of equipment is turned on at once. so what they do is ramp up and dump (spinning reserve capacity) for a time while they wait for the expected demand spike to arrive.
Your solar sat does not deliver load following capability at all. it will be delivering a variable output based on where it is in it's orbit. if the power is unneeded at the time it is delivered it ends up in the dumping resistors.

Then there is that export issue again. if you want to export power. At a profit no less, then you need to have a system that makes power at a competitive cost. SBSPS has a lot of things going against it on the cost basis. first off there is the capital costs. this has to be paid back in a reasonable timeframe. for nuclear that timeframe is 20 years. or about one third of the service lifetime of a nuclear powerplant. how long can a SBSPS go before you have to replace it? the answer i guess lies in factors like station keeping propellant requirements, Solar panel degradation rates and some other factors I havent thought about.
The onus is on the proponents of SBSPS to show that they can make power at a cost that is competitive with the alternatives.

Ronald Brak
2010-Jun-23, 01:41 AM
Putting the excess into pumped hydro is also possible for any technology, and it's certainly one option to consider if you are limited to nuclear, solar, and wind. It's even more critical for solar and wind than it is for nuclear.

In warm locations solar generally matches demand quite well and is growing as a means of meeting peak demand. Of course, if 100% solar is being used, energy storage becomes pretty important.

Ronald Brak
2010-Jun-23, 02:10 AM
Nuclear has the advantage in that the fuel costs is so low that wasting some of the power produced does not have much of an economic impact.


Because of the high capital costs of nuclear power, not being able to sell all the power generated can make a nuclear plant terribly uncompetitive. In a free market excess production very rapidly drops of the price of electricity down towards zero. A coal or gas plant can save significant amounts of money by shutting down durning these periods, but a nuclear plant can't. Putting a price on carbon emissions can help make nuclear more competitive, but it still faces competition from other low emission energy sources. Wind power in particular is very bad for the economics of nuclear power due to its tendency to reduce the price of electricity during periods of low demand.

IsaacKuo
2010-Jun-23, 06:39 AM
In warm locations solar generally matches demand quite well and is growing as a means of meeting peak demand. Of course, if 100% solar is being used, energy storage becomes pretty important.
Right, which is why markets with ground based solar will generally need extra power during dusk and dawn, rather than throughout the day. Of course, there is a literal need for "rainy day" power also.

Supplying extra power during dusk or dawn would be a good match for space based solar power placed in Molniya orbits. Such an orbit would allow a satellite to service both markets in Japan and the US eastern seaboard at their ideal times of day (for example, Tokyo and New York).

IsaacKuo
2010-Jun-23, 04:34 PM
An even better orbit would be a 1/3 day Molniya (not sure what the technical term for this would be). It would be able to provide peak demand service to East Asia (Beijing, Shanghai, Seoul, Tokyo), Western Europe (London, Paris, Rome, Berlin), and the Western potion of North America (L.A. San Fransisco, Vancouver).

neilzero
2010-Jun-24, 09:14 PM
We need to pursue all promising alternative energy sources faster than seems prudent except nuclear which has extreme down side if we fast track. The main objection to thorium is even massive funding would require more than a decade to get to the second gigawatt except at high risk. This is especially true as powerful people want thorium to fail.
If the properties of liquid nitrogen super conductors can be optimised, they are likely practical for long distant power lines. Near term, HVDC = high voltage direct current power lines are operational and superior to 60 hertz three phase power lines for up to about 1500 kilometers. We could build a town that uses dc instead of ac appliances, as avoiding the conversion back to ac may reduce losses if not improve cost effective. Can dc wind turbines be operated in series to produce a million volts dc? Likely, but it may be impractical for several reasons. Yes, electric vehicles can help stabilize a dc grid, but the concept is not well established for ac nor for very high voltage dc. The cost is unknown and vehicle owners who decide at the last minute to take a trip will be unhappy, if the grid just halved the range of their vehicle. This will upset most consumers even if it happens rarely.
For SBSP = space based solar power, I like Larry Jack's sun synchronous orbit as the satellite can stay over the sunshine terminator, and thus be able to beam power approximately straight down to cities that are experiencing peak demand. (Ten degrees above the horizon, in all possible directions means the rectenna must have lots more area than for a beam coming from directly above) Early evening is when the power is worth up to 25 times the midnight price. Other advantages are the satellite is at lower than GEO orbit so the aiming is less critical and the transmitting array can be smaller and all the nations of Earth can be served at least rarely by a single solar synchronous satellite in a semi polar orbit. About 12 satellites are needed to provide hundreds of rectennas every late afternoon and every early evening.
Lasers may be available soon as an alternative to micro waves. Existing solar sites can receive, up to several megawatts of laser energy, as small as 4000 square meters = a 64 meter square, while rectennas need to be much larger because microwaves illuminate a larger spot. A receiving site dedicated to the transmitted frequency/wave length will be about twice as efficient, but we can tolerate reduced efficiency for demonstration purposes. Neil

neilzero
2013-Jan-04, 03:00 AM
Back to the op: We can fly an untethered hydrogen filled balloon near the geopole at an altitude of about 30 kilometers, and it will possibly stay inside the Arctic circle for many months. 30 kilometers is possibly high enough to extract a few watts from the aeraborielus, some nights and likely about the same amount of energy can be collected while the sun shines plus some solar energy.That will keep a few kilograms of battery charged. Possibly enough energy to operate the balloon electronics long term = likely little or no surplus energy for either large or small balloons. Higher altitude might produce 2 or 3 times that much energy, but still not enough to be worth beaming to the surface = it does not appear your idea is even close to cost effective. Neil

publiusr
2013-Jan-05, 06:47 PM
No, you can't have a satellite hover over the poles.

You might get away with a statite http://en.wikipedia.org/wiki/Statite http://www.centauri-dreams.org/?p=13631

Now if the thing dangled a tether, might that alone generate power in some way?

Pennine
2013-Jan-12, 10:36 PM
A grain (1mm ) of sand travelling at 0.5c has the kinetic Energy equivalent of 126 litres of petrol (gasolene).
Maybe we ought to go into space an collect them in a bucket ?

neilzero
2013-Jan-13, 03:54 AM
Yes, but how do we covert that kinetic energy to a more useful form at the point of need at less cost than 126 liters of petrol? It is sort of like trying to harnass an avalanche or earthquake or lightning bolt. Neil

Ara Pacis
2013-Jan-13, 07:24 AM
Yes, but how do we covert that kinetic energy to a more useful form at the point of need at less cost than 126 liters of petrol? It is sort of like trying to harnass an avalanche or earthquake or lightning bolt. Neil

Piezoelectric impact plates?

publiusr
2013-Jan-19, 08:05 PM
Now here may be a breakthrough--Thermal optics?
http://web.mit.edu/newsoffice/2013/how-to-treat-heat-like-light-0111.html

"An MIT researcher has developed a technique that provides a new way of manipulating heat, allowing it to be controlled much as light waves can be manipulated by lenses and mirrors."
Space apps
http://forum.nasaspaceflight.com/index.php?topic=30833.0
Superconducting breakthroughs
http://nextbigfuture.com/2013/01/50-tesla-and-other-superconducting.html
http://nextbigfuture.com/2013/01/magneto-resistance-up-to-60-tesla-in.html