Beaming solar energy from space | Hacker News Reader

Beaming solar energy from space

caltech.edu

67 pointsdanboarder61 comments

I worked on this project a few years back, on the power transmission bits. It's pretty cool from the engineering side; the mechanics need to be very light, and unfold into a large area. The beaming part is just a large phased array. The hardest bit is likely high efficiency, cost effective PV cells that can survive in space, but this is a field that Atwater has been in a long time, and is very, very good at.

Any info on system capacity and efficiency?

IIRC, it took about 50~100 W from a power supply to beam ~2.5W to a target antenna array, but that was fairly early on, so it's likely better now.

Probably a laser would be a much better power transmission method: shorter wavelengths spread out less. You would pick a wavelength that PV panels on the ground convert most efficiently, and pump the laser cavity with focused sunlight, directly. No fooling with PV panels, then. Monochromatic light can be converted via PV with little loss.

Mirrors to focus sunlight weigh practically nothing. Made of alternating layers of different index of refraction, of thickness according to the pumping wavelength, they reflect only that wavelength, and let the rest pass through. So, the laser cavity doesn't get hot, an important detail in space where cooling is hard.

You would arrange so the laser light intensity is no more than of sunlight, for safety.

Of course it wouldn't do much good in the daytime, but would work at night and in winter. Just, not so good through clouds.

Isnt this really a question the reflectivity and amount of absorption in the atmosphere of the wavelength you're using?

I remember this fondly from SimCity 2000, where you could build a "microwave power plant" that would collect beamed energy from space-based solar panels. (If I remember correctly, sometimes the beam would get out of alignment and set fire to nearby neighborhoods.)

With the event being so rare I thought it was a joke...until it happened.

So far every comment on this thread miss the main customer for this tech: the military. Driving fuel trucks along thousand of kilometers where the enemy can bomb your convoy anywhere, just to run the lights and computers, is incredibly dangerous, costly and inefficient (see the wagon equation). Plus, any kind of power source you bring to the battlefield can be captured by your enemy and used against you.

Who cares if beaming it from space is a thousand times more costly than what your local utility company charges you. If it can bring an advantage on the battlefield, army people will research, develop and use it.

And beyond electricity generation, if you can beam enough solar energy down from space to power the military machine in a remote location, it's not a terribly big step to build a fucking space laser to incinerate any point of the planet at will.

I'm excited for the orbital gravity mirror

The Crossbow Project: https://www.youtube.com/watch?v=DTx_qTwQqjU

Solar + batteries + sabotage charges is a fuck of a lot cheaper for the military. Alternatively generators use vastly less fuel than tanks or aircraft etc so logistically it’s not a major issue.

What they might be interested in is drones and missiles. In theory you can make a very lightweight and powerful jet engine using beamed power which then gets unlimited range. Being able to launch cheap Mach 4+ missiles from a gunboat to hit some target 5,000+ miles away is on somebody’s wishlist.

It would also act as high precision targeting system for enemy?

Space is the soft belly of all tactical components. One shotgunshell of a rocket can destroy your whole powersupply and any orbital industry for decades. MAD applies.

https://en.wikipedia.org/wiki/Kessler_syndrome

I highly doubt that any military, no matter how tech affine, would expose itself to this.

Producing fuel in situ with below water solar panels - just off the coast, yes, but not spaced based pre-collection. All you need is industrial strength (chemical/coil) gun and compressed, heat unfolding foil projectiles, to shoot at satellites today.

I don't believe anyone has successfully demoed gun attacks on satellites - and I thought it was infeasible because you'd have to be hypersonic at ground level and lose too much energy.

MAD aside, it seems great for the sort of COIN wars that the US spent the last 20 years fighting. The Taliban don't have anti-satellite weapons.

Yet. With so many sattelites, somebody is going to get sloppy. We already had instances, were people hacked "dead" sattelites. All thats needed is a crash, not something designed to be damaged. Space is the soft underbelly of the soft underbelly that is civilized society.

Space is also vast, Kessler syndrome is mostly a threat to a small percentage of orbits. The bottom of LEO blurs the line between space flight and aircraft because nothing can stay there for long without active boosters.

At the other end there is a vast mostly empty space above, below, and around geostationary orbit.

A Kessler syndrom is a exponential thing. Shrapnell hitting shrapnell, becoming smaller all the time, some of those shrapnells will recieve sufficient energy to be sling shotted into higher orbits. Also, several parties have threatened a kessler syndrom indirectly, the last being the russians atm:

https://en.wikipedia.org/wiki/Anti-satellite_weapon

Space is vast, but orbits cover vast distances regularly, making it a thing of propability and syncing up cycles. Throw a dice often enough and you win this lottery with certainty, because with every hit you get exponential more lottery tickets.

So, to sum it up, its not about if unless action is taken, its about when..

There is a minimum size of shrapnel that’s dangerous. Micrometeorites are already common and not a major issue. That means there is a finite maximum number of dangerous particles a satellite can break into and those particles are limited by the energy before impact.

So, Kessler syndrome is something we can model to say where it is and isn’t a problem.

It would be unbelievably easy for any modern military to take down a satellite like this.

Solar farms in space might beam electricity to Earth - https://news.ycombinator.com/item?id=33426956 - Nov 2022 (7 comments)

Space-based solar power is getting serious - https://news.ycombinator.com/item?id=33273144 - Oct 2022 (208 comments)

Europe Is Getting Serious About Making Space-Based Solar Power a Reality - https://news.ycombinator.com/item?id=32644013 - Aug 2022 (50 comments)

Solaris: ESA Says Space-Based Solar Power Is a Real Option - https://news.ycombinator.com/item?id=32513122 - Aug 2022 (5 comments)

On beaming solar power from low earth orbit - https://news.ycombinator.com/item?id=28426262 - Sept 2021 (86 comments)

California utility bets on space-based solar power - https://news.ycombinator.com/item?id=28225254 - Aug 2021 (3 comments)

$100M donation powers decade-long moonshot to generate solar-power from space - https://news.ycombinator.com/item?id=28106957 - Aug 2021 (3 comments)

Beaming Down Space Solar – Air Force Research - https://news.ycombinator.com/item?id=27334259 - May 2021 (3 comments)

UK government considers space-based solar power for 24/7 Solar Generation - https://news.ycombinator.com/item?id=26674956 - April 2021 (28 comments)

A solar panel in space is collecting energy that could be beamed to anywhere - https://news.ycombinator.com/item?id=26262524 - Feb 2021 (5 comments)

China wants to put a solar farm in space by 2025 - https://news.ycombinator.com/item?id=19190620 - Feb 2019 (59 comments)

Scientists are working on space-based solar panels - https://news.ycombinator.com/item?id=10310307 - Oct 2015 (11 comments)

Harvesting solar power in space and sending it back to Earth - https://news.ycombinator.com/item?id=6294565 - Aug 2013 (80 comments)

Space Solar Power System - https://news.ycombinator.com/item?id=2197108 - Feb 2011 (11 comments)

Will the stars align for space-based solar power? - https://news.ycombinator.com/item?id=698859 - July 2009 (6 comments)

New Company Looks to Produce Space Based Solar Power Within a Decade - https://news.ycombinator.com/item?id=487316 - Feb 2009 (6 comments)

... and what the hell:

A Material That Throws Heat into Space Could Soon Reinvent Air-Conditioning - https://news.ycombinator.com/item?id=15249089 - Sept 2017 (25 comments)

Efficient Air-Conditioning Beams Heat into Space - https://news.ycombinator.com/item?id=15176721 - Sept 2017 (187 comments)

Material Cools Buildings by Sending Heat into Space - https://news.ycombinator.com/item?id=8684647 - Dec 2014 (18 comments)

Cooling panel sends excess heat back into outer space - https://news.ycombinator.com/item?id=5556564 - April 2013 (14 comments)

This same tech was on the cover of a 1971 IEEE Spectrum magazine. I don’t see any advancement since then.

Roland Emmerich's first from 1984!

https://en.wikipedia.org/wiki/The_Noah%27s_Ark_Principle

100 km of atmosphere in the way of any 'beaming' makes the economics unviable even with recent drops in launch prices.

It will likely have to be assembled in space from materials mined in space to ever work out.

Microwaves pass through atmosphere with negligible losses.

The losses certainly are not negligible, they're >> 10%.

That’s why Bruce banner was experimenting with gamma rays. It’s a shame what happened to him.

Infrared laser in wavelengths between 8 and 13 micrometers? The inverse of radiative cooling?

https://news.ycombinator.com/item?id=15176721

Clearly the answer is to run high tension cables

Electrify the space elevators.

mining things in space is something we could concievably do in the next 100 years or so. constructing things, like for example a 3-core electrical cable? don't hold your breath.

There's been all sorts of improvements since then, reusable rockets, better PV, the list goes on and on.

Still doesn't make any sense because alternatives, like ground based solar and wind have also advanced considerably.

In fact, if you use the best available alternative source of electricity as the benchmark, it's regressed noticeably since the 1970s.

https://caseyhandmer.wordpress.com/2019/09/20/no-really-spac...

(from linked previous post)

"My view is that space-based solar power is impossibly expensive and will never be used on Earth."

I agree. In radio the size of the aperture across which the currents flow is inversely proportional to the size of the antenna main beam. The pattern is literally the fourier transform of the currents. The bigger the smaller. There's no getting around needing to have a giant antenna surface (or array).

In order to have the required extremely tiny main beams (high gain), to not instantly lose most of the power to spreading losses, LEO beamed power at reasonable microwave frequencies requires ~5km wide aperture.

We cannot build 5 km things in space yet. It is not really something worth discussing till we're doing that regularly. Space based power isn't that much more available than ground based so there's not much value added to the huge increase in cost orbit requires.

Henry Spencer (https://en.wikipedia.org/wiki/Henry_Spencer) a couple of months ago run a presentation of current state in space power. Land antennas (rectennas) were in this size, ~5km diameter, made mostly from chicken wire. Cheap, and you can still grow vegetables or anything under it. Not much risk walking under it either. Space antennas are an order of magnitude smaller, ~250 meters (for gigawatt-class power stations).

To me, this all seem to need a lot of data and some careful calculations :) .

They discuss they would build a 3.5 mile array using unfolding tiles. They seem to appreciate the challenges and are researching how to overcome them. Isn’t this how we turn “cannot” into can ?

> at the end of the day, power is cheap and rapidly getting cheaper on Earth, while it remains expensive in space.

Only a couple of years max before this becomes obvious to everyone so if you have any mad schemes that rely on high energy prices then your window of opportunity to land some funding is closing.

I disagree. The currently envisioned approaches are impractical due to in-orbit assembly needs, but there are other options.

Lunar solar, with panel foundries on the Moon, resulting energy beamed to Earth.

yes. Dr. Gerard O'Neil figured this out in like 1978.

Then, OPEC decided to demonstrate just how temporarily infeasible they could make it, by manipulating global oil prices (far from the first time).

The only place this might make sense is at high latitudes where solar power is essentially unavailable for months on end when demand is highest.

In temperate and tropical latitudes it’s unlikely to be economically competitive with solar panels on the ground.

24-hour or near 24-hour power delivery would be a big advantage to these space-based solar systems, compared to only mid-day daylight for terrestrial solar.

Not as much as you'd think.

A modest amount of storage (for which there are a variety of options including conventional batteries, flow batteries, and pumped storage), as well as demand management (run your heat pump hot water and charge your EV in the middle of the day) is more than enough to deal with the intra-day mismatch between supply and demand.

That storage isn't cheap but is likely much cheaper than launching the equivalent amount of solar array into space, where the constant supply of power still means you need to either overbuild the array or build storage to supply peaks in demand.

The other thing to keep in mind is that few grids will be purely solar-powered; most large electricity grids will have wind in the mix as well.

Where the equation starts to look a little more appealing is in, say, Canada and northern Europe, where your energy demand is strongly seasonal, and solar output is strongly seasonal precisely the wrong way to meet that demand (unlike, say, Australia, where peak demand correlates reasonably well with solar energy availability).

Amazing Bond plot:

Someone gets ownership of Antarctica, uses Solar panels to raise the temperature of Antarctica and melt all the snow cover, gains control of an entire new continent.

Also Gundam 0083 had the solar system II superweapon, which was just mirrors.

But fundamentally, isn't this increased insolation and on a large scale would accelerate warming?

Man, couldn't we use a bunch of mirrors to locally warm northern climates in Siberia, Antarctica, etc... I wonder if that would be worth it.

This has been researched and found impractical. First you have power conversions solar > electric > microwave > electric. Then the microwave transmission receiver has to grow at the square of the distance. Receivers need to be huge on the order of kilometers. Also to be stationary to the ground the satellites need to be in geo orbit making the distance huge.

What am I missing?

The vision and dedication of a team of Caltech scientists

competition from china. don’t want to fall behind like with the hypersonics and rail guns

Assuming that this technology can advance enough to become practical; are there orbits a satellite can take where it could collect sunlight continuously (i.e. it is not in the Earth's shadow very much) yet still be over a spot where it could deliver energy to a desired point on the Earth for a significant amount of time?

You can look up sun-synchronous orbits; orbits that are mostly polar, but can be set up to continuously face the sun and without ever going into the earth's shadow. For continuous power delivery to a single ground station from such an orbit, you'd need several satellites. (If you remove the requirement to never be in shadow, but just mostly never, there are quite a few orbits that could be set up.) Geo-synchronous orbits would always be stationary above a single point on the earth's surface and could therefore potentially get away with just one solar collector, but you are guaranteed to be in shadow at some point and taking up that much space in the very precious geo-orbit is unlikely.

My first thought on this is why not just build the solar panel on the ground, there must be some major efficiency gain from building this to offset the complexity and cost, or is the main benefit being able to point concentrated power to a different location? (such as a 1m square receiving panel on a moving ship?)

No atmosphere, no land to purchase, and most importantly, no night.

I don't think it will be cost-competitive against alternatives, but it's sci-fi so I like it on that front.

Yes indeed love the sci-fi aspect :)

But these things have to be commercial to work eventually... I wonder what they are seeing as the major competitive advantage. Land, perhaps yeah, but most of the land for solar type systems tends to be out where land is cheapish, but getting that electricity via a cable from a far off location would be something saved.

> most of the land for solar type systems tends to be out where land is cheapish

.. but not the court costs for defending against the environmental lawsuits. There are no endangered species living in outer space (that we know of, anyway).

But I'm not sticking up for this idea. Which one will happen at large scale first?

1) Geothermal

2) Fusion

3) New generation fission

4) Pumped storage hydro

5) Space solar, i.e. this article

6) Other

Modular, decentralized, adaptable, no single points of failure, resilient to degradation, and cost-effective all while providing superior performance?

This is amazing! Are there any downsides? I can’t think of any off the top of my head.

I never understood the point of this. Energy is already beaming to earth from space. Much easier to just let it get to us on earth and collect it there.

Less space constraints in orbit, also this is technology required for the next step, a Dyson Sphere, which allows to gather much much more energy.

What a way to de-democratize solar power!

> Beaming solar energy from space

You mean the sun?

if you can get 100wph from 1m2 of solar panel on earth, how much electricity can you get from space for an equivalent 1m2 space panel ?

i read the no night argument, so if earth panel gets usable 8hr per day, the space panel automatically gets 3x gains, no ?

The article says 8x all in

Interesting but the usual 'moving closer to reality'

Reply on news.ycombinator.com