This idea, to me, seems both very complicated and simple at the same time. Satellites already use solar energy, and where better to harvest energy from the sun than the place where the sun is located. While what Jaffe has already designed and built is promising, it also will take a significant amount of investment and technology to get it where it needs to be for this to become a reality. Still, this is fascinating stuff and could one day revolutionize renewable energy, at least that from the sun.
@Elizabeth – harvesting energy from the sun is one good way to ensure we use renewable energy. Sun has enough power to power up the entire world. The difficult part is to harvest the energy and transfer it to the earth.
Ha, yes, TJ, it does seem the stuff of scifi and I am sure there will be naysayers that claim it's dangerous and it shouldn't be done. I personally think it's a great idea and, given the fact that we use solar energy naturally anyway, it would be hard to argue that this is dangerous for humans. But I guess you're right in that the transition from solar energy to radio waves that will be "beamed" down will spur panic among some!
@Elizabeth - yes the so called death beams could be very harmful to humans, we might need to create corridor for the beams to travel and ensure that no humans are kept in the area where the beams are received.
I think I am a bit confused by all this talk of "death beams." I know these type of waves could potentially be dangerous (as is sunlight if we are overexposed to it), but do people really think the Navy is doing something that is harmful to humans?
Death rays. Yes the Navy is working on microwave and laser death rays.
"The interest of U.S. Navy in exploring the use of High Power Microwave (HPM) techniques and technologies for purposes of building anti-ship missile defense (ASMD) and command and control warfare (C2W) would likely encourage joint proposals wherein the project would be executed in a Naval Research Laboratory (NRL)/contractor team format to get the maximum amount of research in the most efficient manner."
The design of the solar panel modular system will have to have active steering, and the best way to do that is with phased array tech. That same phased array steering can be used to concentrate the beam and steer it any place you want.
Maybe the Navy will just use it to knock out enemy electronics, but the 1 GW version will cook a person or tank before they can react.
The economics only make sense as a weapons system.
Interesting discussion! Just to put some perspective on this - the power we receive from the sun on a bright sunny day is on the order of 1000 Watts per square meter. Divide by 5, = 200 W/m2, and that's what you can collect from a PV panel. In Iowa, we can count on about 4 hrs of sunlight average per day, so if we had that power on round-the-clock, we'd get 6x what we can get using current technology. That's the minimum bar for one of these systems.
At $3/watt for PV, we would require a space-based system that costs less than $18/watt. A satellite that could deliver 1 MW of power to earth that costs $18M? With transmission losses, optimistically we're talking a satellite(s) that has 4MW of PV panels. I see a few issues with these numbers:
Space-capable PV would have to cost < $4/watt. I haven't priced this stuff, but i'm sure it's much more than that now.
Space-capable PV needs to be replaced every 6 years or so, with a max lifetime of 20 years, and is highly susceptible to meteorite damage.
Avoiding space debris is a full-time job for any orbital platform, and avoiding the junk means moving the platform (have you seen the movie "Gravity"?). Moving the platform means maintaining proper aim of the "power beam" while it's moving.
The ISS has a 1 acre array of about 90 kW. This would have to be 40 *times* that size. 40 ACRES of PV in space - that is capable of being pushed around by rockets to avoid space junk without collapsing on itself. And while maintaining pinpoint aim during the whole maneuver.
This is just for a SINGLE 1MW space-based satellite. By inspection, this is not an $18M satellite; i can't count high enough to give an estimate on what this would really cost.
We can do this job much cheaper, much more reliably, far longer-lasting, and with currently-available hardware today here on terra firma. Space-based power is gee-whiz, but the reality just isn't there.
Thank you for that thorough evaluation of this system, fm. According to your calculations it seems that the economics don't add up, but I suppose that's up to the Navy to find out and decide, and perhaps they have a workable solution to solve this problem.
Credentials: I have been working space solar arrays for over 35 years. My college project was Space Solar Power Systems (SSPS) later called SBSP originally suggested by 1941 Asimov SF and later made credible by Peter Glaser in a US patent for "practical" application. (See Wiki for more in depth). SiliconGreybeard is right, low power microwave beamed to earth surface receiver/converters (rectenna size:square miles) was the generally agreed upon technique for safe delivery and conversion. Jaffe of NRL is correct in a key need was a distributed beaming capability which will subsequently need to be synchronized to avoid nulling of the beamed power at the receiver. I have designed and built solar arrays (S/A) which have lasted on orbit for over thirty years with graceful (predictable) degradation in Geosynch orbit where these should be parked. That's not an issue. But fm and Daniyal_Ali are also right. Here is the challenge: at 0.10/ kWhr, and 30 years of perfect operation, it leaves only $26.2/watt to build and deliver the complete system (not including amortized nonrecurring costs). The industry shows space rated arrays typically cost between $600 to $5000/watt. Current terrestrial solar panel technology which might be capable for space use may get to $4/watt, though the terrestrial ones are looking to eventually <$1/watt wholesale, but space is tough! To go from $600/W to $4/watt for space S/A is beyond current technology. Next, the cheapest cost to space at Geo is ~10000/lb, though SpaceX hopes to get that in the realm of $1000/lb. Space S/A weigh 14 to 36 W/lb, though there is some hope to get to 180 W/lb eventually. That is $.05lb/watt or $50/watt for launch. Launch cost would need to get below $200/lb ($10/W) to make the system feasible. Then you need to pay for the ground based rectennas and all the balance of system with the $26-$4-$10=$12/W left over. Possible? Yes. Near term (next 30 years)? No. Should we do it? Ultimately for the species, yes. More cost effective than terrestrial solar? In 50 years? That's TBD.
Elizabeth, one thing you don't mention is how much energy the proposed array will produce. What is the efficiency of the whole system?
On another note, why use robots to assemble this. Why not the International Space Station (ISS)? It has a robotic arm and people to do the work. This would have lots of benefits. First, there is cost. The whole robotic assembly is not a part of the technology of power generation. It is a whole other program requiring diffent skills and really raises the cost and complexity of the system. I expect that a demonstrator would be built (a single satellite) and then a larger array, then the full envisioned array. That's a lot of steps. Getting rid of the robotics in the early stages would speed things along.
Lou, those are good questions, but as to your first I don't think the research has gotten that far. I would have to check with Jaffe. I think the answer may be a bit further down the line, as it hasn't really been tested yet.
And as for the robots, that's also a question for Jaffe. I am sure he has a good reason for including robotic assembly, but I completely see your point that it seems like a lot of effort for something that doesn't contribute to the ultimate goal of the system.
I agree with Lou too. Do get the answers from Jaffe and share them with us when you get time. Being actively involved in the Renewable Field myself i can say this with great confidence that at the end, the cost effectiveness and overall output yield is the only thing that settles the issue of implementing something at a larger scale or rejecting it completely, even if the idea is unique. Perhaps as time passes we will be able to manufacture a better technology to cater such ideas with much cheaper and environmental friendly solutions. The main slogan of Solar Panels is to produce environment-friendly energy, isn't it ironic if we use Solar Panels to generate beams that result in harming the environment? I am eagerly looking forward to more details about this project which would make things clearer.
I hate to be so negative, but this is a terrible idea, and seems like just a way to get money from the taxpayers to make space based death rays.
From placing panels in space you gain, 4x over ground based if you can keep it out of the earth and the moons shadow.
You lose at least that much converting rf and back. You lose 75%. You have to keep the RF below about 100 watts per meter squared, that's only 50Watts after conversion. Earth based solar panels would produce 200Watts dc/4 or about the same 50W, and they would do it on our rooftops, without the 10,000 dollars per lb it costs to launch sufficient space! As for getting solar power during a hurricane, that's some fancy pr. just convert wastes to fuels and use them in your backup generators and peak generators when you need it.
Other folks have pointed out this could make a great death ray from space too. I agree. That's why the Navy is backing it.
Thanks for your comment, Trenth. I see your point, but I am not sure what you mean by "death rays." I am pretty sure this isn't the Navy's intent, but I would be interested to hear more about what you think.
I would think that robots would be far more desirable than humans because of the added cost and risk associated with life support. This is supported by our government use of aircraft drones. These drones are actually robots controlled by humans, as would be the robots constructing the space array. The space station certainly is not designed to perform array construction, and it would be far to difficult and costly to manuver its own solar arrays around a huge construction site.
I think this is the general idea, jhankwitz. The robots would be controlled by humans but save humans from actually having to go into space to deploy the satellites. I think in the long run it would be more efficient and cost effective, even if there is a lot spent in initial R&D and cost.
Robots are much cheaper to support in space than humans. Humans need food, water, air, companionship, and an environment with tightly controlled temperature range and air pressure. All of this means a lot of weight being sent to space consistently which is really expensive. Robots are more durable. Robots can withstand greater temperature ranges and higher levels of exposure to radiation. Robots don't get tired, bored, or disgruntled. Robots don't have to be brought back to Earth after a relatively short stay.
How is the energy harvested to be transferred? Solar panels have greater efficiency and longer life due to lack of atmosphere. However, is it enough to outweigh the efficiency lost in transmission through the atmosphere?
Can we deliver the sun's energy to earth more efficiently than nature does now?
It looks like most of the other posts broach the question, "how much power?". This is certainbly a valid question. I also wonder about the cost figure of 10 cents per Kwh. I'd certainly like to see how this was calculated ... i.e. what assumptions were made. On the logistics side, I think it might be imprudent to quickly discount the "death rays from space" argument. The article talks of RF and then seems to move on to microwaves. If this is the case, then I must logically conclude that there would be a transmitting antenna array/dish for directing the energy toward some receiving station on the ground. What will be the size of the energy "beam"? Probably most important, how accurately can/will this be directed between orbit and the ground? Let's consider some numbers. In the desert SW of the US (and even sometimes in the SE regions), the insolation can reach 1000w/(sq meter). In space, where there is no atmospheric attenuation, that number will certainly be higher ... but let's just use 1Kw/m^2. If the collector array is 1Km x 1Km (implied from the article), then we could expect an array output of 1Mw. For the sake of argument, let's also assume a DC power - to - beam conversion efficiency of 25%. Further assuming a uniform distribution of power across the beam cross section, that would give us a total cross sectional beam power of 250Kw. For a beam diameter of 1m, the power would be approximately 333Kw/m^2. This number would go up for smaller beam diameters and down for larger beam diameters. The positioning of such a beam would need to be VERY carefully controlled.
It isn't clear what type of beam will be used. RF does not seem very efficient as there is too much atmospheric loss, the beam power you calculated is way beyond the capability of any present day RF amplifier, which would need power to operate. Such a process would require a passive device that can convert the collected energy and convert it into a beam (like a magnifying glass).
On another note, what are the environmental effects of the beam in question?
I was surprised that the most important aspect was ignored in the article. How do you get the energy from space to earth? The atmosphere is a very lossy conductor. Then again, you'd need to either set aside a large area for a receptor, or the beam has to be very narrow.
Now, what happens if a flock of birds flys through the beam? Is there a special on fried 'chicken' at McDonalds? Does everybody's TV flicker? Then there are clouds.
Now, how about the orbit of these things? If it's not geo-synchronous, you'll lose contact at least half the day, then another half, the beam is going though even more atmosphere due to a poor angle. If it is to be geo-synchronous, do the satellites always see the sun, or will there be blackouts?
It seems to me a lot of things have to be thought out before you start designing hardware.
Hank-4: death rays are exactly what this would become. This is probably the main reason it will not be done. I have seen examples of technicians working on large radar systems on Navy ships. Generally there is a bar placed in the mechanism that stops the antenna from rotating. In rare cases something happens to this and there have been cases where the technicians have been fried. What will happen with such a large source in space? As for fried bird, that is a real possibility. Just look at the latest concentrated solar power (CSP) plant built. It is responsible for killing lots of birds already, and that is just from mirrors. We also have the problem with wind power killing birds.
On the price issue, I fully agree. There is no way this is 10 cents per Kwh. Jaffe is supposedly a spacecraft engineer. He should know that this is not in the realm of possibility.
What this whole thing strikes me as is an attempt by NASA to get involved in solving the energy problem. They would want to do that becuase it is getting more attention than space exploration. Energy is a DOE responsibility and they have the expertise.
This is a rather old idea; I remember talking about when I was in school, so over 35 years ago, but I think it was an old idea then. The system design has been done so that it all works out on paper, it's safe for birds or small planes flying through the RF fields, or kids who'd wander into the antenna fields. IIRC, C band (approx 4-6 GHz) worked out well. I've seen design approaches that start with acres of solar cells on the moon, because the weak gravity of the moon provides advantages. It also has the disadvantage of two weeks of darkness out of every four weeks. I think satellites, in deep space worked out best.
The beam can be as strong or as weak as you want it to be. Microwaves can be focused very well; high gain antennas that can be deployed in space have been in use since at least the late 1970s and reaction wheels for stablizing the satellites are probably older than that. The safe power exposure level of RF for the general public is around 1 mW/sq.cm, so the receiving antenna array has to be large: think square miles, not square meters. (Fun fact: the lowest power limit the FCC issues is 200 uW/sq.cm for the FM broadcast band, where the average person is close to 1/4 wavelength tall and so a very effective receiving antenna. Just sit down to tune yourself out of band.) Above some fairly low frequencies, you get lower losses by transmitting through the air than by trying to use cable. It's the reason the phone companies went to microwave links on towers decades ago.
In fact, think square miles of solar cells, square miles of antennas, and the "Microwave Power Amplifier Designers' Full Employment Act". The questions about whether it can be done technically are over. Of course it can. The rough questions are whether it could be done without massive amounts of government spending, when virtually every government in the world is on the verge of default from overspending as it is.
I don't understand why people keep thinking this is a viable thing. In order to be useable you'd need to construct a system capable of delivering 500GW to 1000GW of electricity on Earth, comparable to a standard power station, otherwise, what's the point. First off the space based panels would have to be made of galium arsenide to withstand the radiation in space. Ordinary silicon panels would die after 6 months to a year. Galium Arsenide panels are 50X more expensive, even if they are 40% efficient. At an overall system efficiency of about 7% (panel efficiency = 40%, convert to microwave = 75%, atmospheric losses 50%, receiving antenna losses = 75%, convert to 60 Hz AC = 60%) .4 x .75 x .5 x .75 x .6 = .67) we'd need a huge solar array. At 100% efficiency we'd need the total panel size to be 1000GW/1400watt per foot = 714,000 sq ft. At 7% overall efficiency the panel size would be over 10 million sq feet. That's 2/3 of a mile on a side. And what keeps the panels all in the same plane? A giant truss of some kind. Currently the solar panels on the ISS are the largest we have in space. Do any readers recall the frequent problems they've had? These are microscopic compared to our sci-fi panels! And how will you keep something this large pointed at the sun? It becomes a giant solar sail.. constantly being pushed away by the sun. It would have to be in geo-synchronous orbit and sending it's 1000GW microwave beam through the path of thousands of satelites in lower orbit. And how do you maintain it? What about space debris.. this thing will make a nice target! And how do you even get it up there in the first place? We'd be talking about 1000's of launches!! And you want robots to assemble it? What robots? This thing would probably cost more than the GNP of the entire world!! I could go on and on. This whole idea is ridiculous!
Next thing we know, someone will propose putting solar panels on roads! Yes, I know, they already have, and if you believe that will work, I guess you might as well believe this too.
Sorry for being so sarcastic and perhaps exagerating a tad.. but I just get tired of these crazy schemes! I run an engineering company and it seems half of my time is spent explaining to clients why some things are just not practical!!
If you don't believe me, perhaps you'll believe Elon Musk! http://www.popularmechanics.com/how-to/blog/elon-musk-on-spacex-tesla-and-why-space-solar-power-must-die-13386162
notfred, your points are well taken and yes this seems a bit far fetched. But I think people thought that about putting somone on the moon way back when. Maybe it is a bit out there but with one of the top scientists in the world on it, I think maybe someday it could be viable. Of course, you are an engineer and I'm just a writer, so I could be wrong! This is why it's great when our readers weigh in on stories to provide real-world perspective.
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