CNN:How to harvest solar power? Beam it down from space!

[jpillian]

And finally, someone is listening to you, Larry!

How to harvest solar power? Beam it down from space!

LONDON, England (CNN) -- Jyoti is the Hindi word for light. It's something Pranav Mehta has never had to live without. And he is lucky. Near where he lives in Gujarat, one of the most prosperous states in India, thousands of rural villages lack electricity or struggle with an intermittent supply at best.

Massive solar satellites would beam power back to ground-based receivers on Earth.

more photos » "We need to empower these villages, and for empowerment, energy is a must," Mehta said. "Rural India is suffering a lot because of a lack of energy."

By 2030, India's Planning Commission estimates that the country will have to generate at least 700,000 megawatts of additional power to meet the demands of its expanding economy and growing population.

Much of that electricity will come from coal-fired power plants, like the $4 billion so-called ultra mega complex scheduled to be built south of Tunda Wand, a tiny village near the Gulf of Kutch, an inlet of the Arabian Sea on India's west coast. Dozens of other such projects are already or soon will be under way.

Yet Mehta has another solution for India's chronic electricity shortage, one that does not involve power plants on the ground but instead massive sun-gathering satellites in geosynchronous orbits 22,000 miles in the sky.

The satellites would electromagnetically beam gigawatts of solar energy back to ground-based receivers, where it would then be converted to electricity and transferred to power grids. And because in high Earth orbit, satellites are unaffected by the earth's shadow virtually 365 days a year, the floating power plants could provide round-the-clock clean, renewable electricity.

Click here to read the full article

I really liked this part...

And so has a 2007 report released by the Pentagon's National Security Space Office, encouraging the U.S. government to spearhead the development of space power systems.

"A single kilometer-wide band of geosynchronous Earth orbit experiences enough solar flux in one year to nearly equal the amount of energy contained within all known recoverable conventional oil reserves on Earth today," the report said.

The study also concluded that solar energy from satellites could provide power for global U.S. military operations and deliver energy to disaster areas and developing nations.

"The country that takes the lead on space solar power will be the energy-exporting country for the entire planet for the next few hundred years," Miller said.

The US is the only nation capable of doing this today or in the forseeable future. Wouldn't it be nice for us to be in the position for electricity in 20-40 years, that OPEC is for oil today?

[joeknows]

whats the cost?

not in dollars but in associated problems. im not sure but im thinkin the heat generated by beaming that power down might create an ecological issue ie weather patterns.... i dunno

im just a skeptic though

[Larry]

Wow. Thought I was gonna get to say "I told you so" to a bunch of people who hadn't been paying attention, and somebody has been.

For those who weren't: Link to the first thread where Larry mentioned this idea.

(Maybe they'll name it after me.)

[Thiebear]

So the towers in the desert should work also, easier to work on.

Won't cause the ozone hole?

[Larry]

So the towers in the desert should work also, easier to work on.

1) Very few deserts receive useful amounts of sunlight 24 hours a day.

2) I'll also point out that the article mentions the (outrageously large) area of "A single kilometer-wide band of geosynchronous Earth orbit", which is a surface area of 265K km^2, or roughly the area of Nevada.

Terrestrial sites only receive useful amounts of sunlight for 4-6 hours a day. To compensate for that, you have to creatie several collectors, around the world, each the size of Nevada. (Because pretty much only one of them will actually be receiving sunlight at any given time.)

(You'll also need the power distribution network to allow the United States to get the power, when the sun's over Australia.)

Current technology for converting solar power to electricity are only a few percent effective. (I'm thinking I've heard three percent). So now those sites you've created, all over the Earth, have to be thirty times the size of Nevada. Each.

In space, you can make the receivers as big as you want. Plenty of real estate available, and every bit of it receives sunlight 24 hours a day. (And with very stable weather.)

Won't cause the ozone hole?

The ozone hole was caused by the release of chemical pollutants into the Earth's atmosphere, not by anything having to do with power.

[DCSaints_fan]

I really liked this part...

And so has a 2007 report released by the Pentagon's National Security Space Office, encouraging the U.S. government to spearhead the development of space power systems.

I think they have something in mind besides power. Imagine redirecting all that energy to somewhere else besides the power station. Equivalent power of a nuclear weapon, with no warning, and hence no potential defense other than a pre-emptive strike.

[Zen-like Todd]

1) Very few deserts receive useful amounts of sunlight 24 hours a day.

That's what solar thermal is for.

Terrestrial sites only receive useful amounts of sunlight for 4-6 hours a day. To compensate for that, you have to creatie several collectors, around the world, each the size of Nevada. (Because pretty much only one of them will actually be receiving sunlight at any given time.)

Again, that's what solar thermal is for.

(You'll also need the power distribution network to allow the United States to get the power, when the sun's over Australia.)

Umm.. no.

Current technology for converting solar power to electricity are only a few percent effective. (I'm thinking I've heard three percent). So now those sites you've created, all over the Earth, have to be thirty times the size of Nevada. Each.

No. The most efficient solar cells are about 10x as effective. And as for solar thermal, they have demonstrated 30% efficiency as well (Stirling).

In space, you can make the receivers as big as you want. Plenty of real estate available, and every bit of it receives sunlight 24 hours a day. (And with very stable weather.)

A 96x96 mile array in the Southwest (in reality it will be a series of somewhat smaller arrays throughout the southwest) would supply all of the electrical needs for the United States, at a far, far lower cost.

It would be fairly easy for a country such as China to hold us hostage over such an energy infrastructure, by attacking the array in space. Distributed, land based generation doesn't have this problem.

That said, it's not a horrible idea. It will be used, but the initial user will be the military. They will use it on a much smaller scale, in order to deliver power to remote outposts/forward operating bases without infrastructure.

[Larry]

I think they have something in mind besides power. Imagine redirecting all that energy to somewhere else besides the power station. Equivalent power of a nuclear weapon, with no warning, and hence no potential defense other than a pre-emptive strike.

The beam they're talking about has an energy density (the amount of power per area) comparable to what's used now for microwave communications like long-distance telephone. That's why, for example, it's not dangerous to birds (or aircraft) flying through the beam.

Yeah, the power exists. So I suppose that the guys on the satellite could divert power from the microwave transmitter to the Phasers. But only if the satellites have Phasers.

(And there are other ways to use space for a weapons platform. Dropping rocks, for example.)

(And there are other ways to use this technology as a weapon: If the world is dependent on the US for energy, then the threat to turn off Iran's power (by shutting down the satellites that are beaming power to them) becomes a valid threat. Even if there are no weapons on the satellites whatsoever, the fact that we control somebody's power is a weapon on it's own. it's just not a destructive weapon.)

[Larry]

That's what solar thermal is for.

Uh, unless you've got something I'm unaware of (quite possible), "solar thermal" is a way of converting sunlight to power.

It doesn't magically convert darkness to power.

No. The most efficient solar cells are about 10x as effective. And as for solar thermal, they have demonstrated 30% efficiency as well (Stirling).

OK, so your sites only have to be three times the size of Nevada.

A 96x96 mile array in the Southwest (in reality it will be a series of somewhat smaller arrays throughout the southwest) would supply all of the electrical needs for the United States, at a far, far lower cost.

I'm certainly not claiming to be an expert, even when it comes to space based options. (I'm just a Trekkie fanatic hobbyist). So I'm certainly not qualified to claim that your claim is impossible.

But I've never even heard of anybody claiming that, before. Got any links?

It would be fairly easy for a country such as China to hold us hostage over such an energy infrastructure, by attacking the array in space. Distributed, land based generation doesn't have this problem.

Uh, OK. China has the ability to destroy thousands, maybe hundreds of thousands, of space-based structures, each of them roughly 100 square miles in size. But doesn't have the ability to hit what you're describing as several ground-based, outdoor, facilities. (Every one of which, I'll point out, will have to have a single, fixed point where the facility ties into the power grid.)

Allow me to also point out that, if we're considering indestructibility as a design factor, that any attack on the space-based portion of this idea, will be visible from thousands of miles away. Whereas a ground-based structure can be approached as close as wherever the security fence is without detection.

So, as long as we're considering vulnerability to hypothetical threats: Which do you think al Qaeda is more capable of attacking? A ground-based facility, or one in Earth orbit? :halo:

That said, it's not a horrible idea. It will be used, but the initial user will be the military. They will use it on a much smaller scale, in order to deliver power to remote outposts/forward operating bases without infrastructure.

I'd agree that there's a market application for portable, wireless, power (for lots of things.) But I'm not certain this is it. While the beams are of low power density, that doesn't mean that simply beaming the entire US with microwaves just so people's cell phones can recharge themselves might have long-term health or environmental effects.

[Zen-like Todd]

Uh, unless you've got something I'm unaware of (quite possible), "solar thermal" is a way of converting sunlight to power.

It doesn't magically convert darkness to power.

Solar thermal, as opposed to photovoltaic, provides for cheap and efficient energy storage. In solar thermal, a fluid (water, or salt) is heated, and a perfectly typical turbine is heated via steam. Molten salt storage is cheap and simple. You simply store the molten salt, and draw down its heat to run the turbine overnight.

OK, so your sites only have to be three times the size of Nevada.

No, as I already said, you need less than a 100x100 mile array to provide enough electricity to power the entire country.

I'm certainly not claiming to be an expert, even when it comes to space based options. (I'm just a Trekkie fanatic hobbyist). So I'm certainly not qualified to claim that your claim is impossible.

But I've never even heard of anybody claiming that, before. Got any links?

Sure you have... it's been posted on the board before.

http://www.sandia.gov/news/resources/releases/2004/renew-energy-batt/Stirling.html

That references the 100x100 figure from a few years ago.

http://www.ecogeek.org/content/view/991/

That one references a more recent 92x92 calculation.

Uh, OK. China has the ability to destroy thousands, maybe hundreds of thousands, of space-based structures, each of them roughly 100 square miles in size. But doesn't have the ability to hit what you're describing as several ground-based, outdoor, facilities. (Every one of which, I'll point out, will have to have a single, fixed point where the facility ties into the power grid.)

Allow me to also point out that, if we're considering indestructibility as a design factor, that any attack on the space-based portion of this idea, will be visible from thousands of miles away. Whereas a ground-based structure can be approached as close as wherever the security fence is without detection.

So, as long as we're considering vulnerability to hypothetical threats: Which do you think al Qaeda is more capable of attacking? A ground-based facility, or one in Earth orbit? :halo:

One in earth orbit, by far. Think about it. Take your time. :halo:

I'd agree that there's a market application for portable, wireless, power (for lots of things.) But I'm not certain this is it. While the beams are of low power density, that doesn't mean that simply beaming the entire US with microwaves just so people's cell phones can recharge themselves might have long-term health or environmental effects.

Eh? Not sure I made any comments to that effect. Just on the simple reality of the situation that if this goes anywhere, the initial effort will be small scale, and at a high cost. The sector that is most easily able to absorb this cost, and has the greatest need for such an application is the military.

[Larry]

Sure you have... it's been posted on the board before.

http://www.sandia.gov/news/resources/releases/2004/renew-energy-batt/Stirling.html

That references the 100x100 figure from a few years ago.

http://www.ecogeek.org/content/view/991/

That one references a more recent 92x92 calculation.

(Reading first link.)

Huh. The solar thermal that I'd been seeing involved hundreds of mirrors reflecting energy to one heat sink. That approach would seem more efficient to me, for several reasons. (One being that, that way, you only have to build one heat receiver/turbine system, and it doesn't have to move. That also would mean that your tilt-and-swivel system only has to be heavy enough to handle the weight of a mirror.) And I would assume that one big mechanical-to-electric system is cheaper and more efficient than 100 smaller ones.)

But I'll freely admit that there are lots of folks who know a whole lot more about it than I do.

(Including, apparently, you. )

(Checking second link)

They do claim to be able to generate power at night. (Their mention seems to be purely hypothetical, but I'll also admit that nobody's beamed any power from space, either. It's only been done in laboratories.)

Although this part does jump out at me:

Despite the optimistic results of their calculations, they warn that a plan like this requires a complete revamping of the current electric infrastructure. The country's AC grid would have to be converted to High Voltage DC in order to decrease transmission loss from 50% to around 3% while moving the power from the sunny Southwest to the power-hungry North East.

Although if the only problem you've got is transmission losses, then there may be other solutions besides replacing the entire national power grid. Like, maybe, generating some of the power on the east coast. Or, generating twice as much power and letting transmission losses eat half of it.

Still, I'm a lot more optimistic about this than I was half an hour ago. Sounds like we should be looking at this idea a lot more.

[Thiebear]

Just to get this straight... (only interested in the U.S. right now) the rest can pay to play.

Lets do both... If some country or solar ray or meteor or comet blows it away you have a backup.

But that whole constant beam of energy from solar to earth seems bad....

Lets not forget Nuke plants to match 50%.

Energy as we've seen to date should never be in one basket.

[Larry]

Oh, if that "one bucket" is the Sun, I'm not too worried. Seeing as if it ever does fail, we're effed, anyway.

If our energy comes from a distributed system of receivers who get their energy from the Sun, then that seems to be enough redundancy to me.

(And let's face it, It'll be decades, if ever, for all of our energy to come from a source like this. For example, why would you ever retire Hoover Dam? It's already been built, so the marginal cost per KW to keep it running is about as close to zero as you'll ever see.)

(Now, I wouldn't have a problem with funding space, ground solar, and nuclear for the next decade or so. Not as protection against failure, but as protection against "Oh, we just discovered that this one solution we picked won't work without dilithium", or "Oops, I guess it does produce this one exotic kind of pollution that we didn't predict". Obviously, as long as both kinds of solar are still in the "never been done in big enough scale to count" category, then you study competing technologies.)