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How Japan Plans to Build an Orbital Solar Farm
- cvbncvbncgbc 13y agoElon Musk's opinion the concept( not this one in particular though ). http://youtu.be/J_af0ow1__E?t=43m12s http://youtu.be/J_af0ow1__E?t=43m12s Let me tell you one of my pet peeves: space solar power. Okay, the stupidest thing ever. If anyone should like space solar power, it should be me. I got a rocket company and a solar company. I should be really on it, ya know. But it's like, super obviously, not going to work because, ya know, if you have solar panels - first of all, it has to be better than having solar panels on Earth, so then you say, okay, solar panel is on-orbit, you get twice the solar energy - assuming that it is out of Earth's shadow - but you've gotta do a double conversion. You've gotta convert it from photon to electron to photon, back to electron. You've got to make this double conversion, so, okay, what's your conversion efficiency? Hmm. All in, you're going to have a real hard time even getting to 50%. [The solar cells are better.] It does not matter, put that cell on Earth then. See, that's the point I'm making. Take any given solar cell, is it better to have it on Earth, or is it better to have it on orbit? What do you get from being in orbit? You get twice as much sun - best case - but you've got to do a conversion. You've got to convert it the energy to photons - well, you have incoming photons that go to electrons, but you - you've gotta do two conversions that you don't have to do on Earth, which is you've got to turn those electrons into photons and turn those photons back into electrons on the ground, and that double conversion is going to get you back to where you started, basically. So why are you bothering sending them to bloody space. "I wish I could just stab that bloody thing through the heart." BTW - electron to photon converters are not free and nor is sending stuff to space. Then it obviously super doesn't work. Case closed. You'd think. You'd think case closed, but no. I guarantee it's gunna come up another ten times. I mean, for the love of God.
- tectonic 13y agoThat's pretty amazing, thank you for posting this.
- deegles 13y agoI could see a space solar power station being used to transfer power to ships traveling to the Moon or Mars. Using a laser (or whatever) for energy transfer would be much more efficient in space.
- chadgeidel 13y agoIgnorant question - what about a solar concentrator - like a mirror - instead of an array of "traditional" solar panels?
- ajuc 13y agoI don't know for power genreation, but it would make awesome weapon.
- jkdearden 13y agoIt actually makes for pretty good power plants, usually they're called some variant of 'solar power towers'. The plants use a bunch of adjustable mirrors that focus sunlight in order to heat water and make it into steam that powers a turbine. There are also ones that use molten salts as a heating element, but that technology is a lot newer.
- JanezStupar 13y agoI remember reading about such a device being planned to "send power" to remote US army outposts e.g. near front lines.
- w1ntermute 13y agoSounds like the Memento Mori (from Mobile Suit Gundam 00): http://gundam.wikia.com/wiki/Memento_Mori http://gundam.wikia.com/wiki/Memento_Mori
- fuzzythinker 13y agoIdea in "Die Another Day", hard to secure it to not be used as weapon.
- api 13y agoIs he factoring in energy storage costs? That's the real problem. Gathering solar energy is easy, storing gigawatt-hours of it at night is not.
- itazula 13y agoNah, they'd be charging all of those Teslas.
- austinz 13y agoIt's not a given that rectification/conversion losses are necessarily greater than, less than, or equal to the gain in base output. A lot of whether that is true depends on how much solid state power electronics improve over the coming decades. In terms of the cost of putting materials into space, isn't that the exact problem SpaceX is trying to solve? Right now, it would be economic folly to build one of these things. In decades or centuries, when we have moon colonies and/or asteroid mining and can do all the large-scale fabrication in situ, SSP could very well be significantly cheaper than other forms of power generation.
- Tloewald 13y agoAssuming you wave a magic wand and get rid of the technical and cost issues, you then run into thermal pollution. You're collecting heat from space and beaming it to Earth and then inefficiently converting it to electricity.
- austinz 13y agoAccording to [1], the surface of Earth receives 89,300 terawatts of power from the Sun on average. According to the stats at [2], world power consumption in 2008 was ~17 TW. So even if we could somehow build the tens of thousands of these power plants necessary to completely supply the Earth's power needs, and assuming that none of the consumed power ended up being radiated back into space, we would only be affecting the Earth's energy budget by 0.02%. [1] http://www.sandia.gov/~jytsao/Solar%20FAQs.pdf http://www.sandia.gov/~jytsao/Solar%20FAQs.pdf [2] http://en.wikipedia.org/wiki/World_energy_consumption http://en.wikipedia.org/wiki/World_energy_consumption
- Tloewald 13y agoSo with a magic wand and an incredible amount of money we'll only make the problem slightly worse. And it's not clear how slightly -- climate change is being caused by accumulation of greenhouse gases during a period of reduced solar output (cyclical fluctuation of 0.1%). BTW 0.02% seems like a lot more when compared to the sun's cyclical variation of 0.1% (which has measurable effects) and suspected historical variations of perhaps 3% that caused ice ages. http://en.wikipedia.org/wiki/Solar_variation http://en.wikipedia.org/wiki/Solar_variation http://science.nasa.gov/science-news/science-at-nasa/2013/08jan_sunclimate/ http://science.nasa.gov/science-news/science-at-nasa/2013/08...
- anateus 13y agoHe's ignoring one constraint: land area. You need to put those panels somewhere. This approach let you perform the concentration somewhere you aren't renting real estate. For an extremely dense island nation like Japan this actually makes a lot of sense. Now, this doesn't refute the issues Musk is bringing up here, but he isn't taking consideration of this factor at all.
- ericd 13y agoInteresting point, they don't have large deserts to drop them in like we do in the western US.
- chc 13y agoIs this actually easier for an island nation than, say, floating solar panels in the surrounding waters? I assume Japan must see some benefit to space, but I'm having trouble working out just what it is.
- mkaziz 13y agoMakes them susceptible to enemy navies, IMO.
- pokstad 13y agoWhat about the ecological effect on plant/plankton life in the ocean blocked by these floating panels? Assuming the cost of producing solar panels eventually comes down and we can cover large areas of the ocean, won't it take a toll?
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- gojomo 13y agoSalt water is very corrosive.
- darkmighty 13y ago
- nickhalfasleep 13y agoIn it's favor, a solar power satellite can get light nearly 100% of the time, while on the ground you are luck to average 50% with rotation and weather.
- cvbncvbncgbc 13y agoIn what orbit, that doesn't require propulsion, do you get constant line of sight?
- danielweber 13y agoThey nearly always call for geosynchronous orbit, because they want to always be over the rectenna on the ground. The Earth will occasionally put such a satellite into shadow, but remember that the Earth is tilted, and so is the equator. Getting up to GEO is hella expensive.
- mikeash 13y agoJust to put some numbers on it, GEO doesn't intersect the Sun-Earth line most of the time. The Earth's shadow touches GEO for a couple of weeks around the equinoxes, resulting in up to 70 minutes of shadow per day in that period. The rest of the time, they're in sun 100% of the time. So, as low as a 95% duty cycle at the worst point in the year, and 100% for most of the year.
- oh_sigh 13y agoL1 reference: http://en.wikipedia.org/wiki/Lagrangian_point#L1 http://en.wikipedia.org/wiki/Lagrangian_point#L1
- Panoramix 13y agoMaybe I'm missing something but in space you can have power night and day if you are using mirrors, and you don't have the atmosphere. Solar power in space is 1300W/m^2, whereas average solar power on Earth is about 200W/m^2, including atmosphere, day-night, latitude, etc. So that's a reasonable difference. It probably doesn't offset the costs of such a project, but damn if I'm starved for some 50's style Massive Engineering projects. Instead all of the brightest minds are focused on optimizing other peoples mouse clicks. Such a thing could be used to power a Lunar base and for sure boost research in power beaming.
- danmaz74 13y agoHaving a stable source of energy at all time is even more important than the conversion efficiency. Case not closed.
- gkop 13y agoWhy not use the solar electricity to mine bitcoin from space?
- mdelias 13y agoJeff Garzik Announces Partnership to Launch Bitcoin Satellites into Space http://www.coindesk.com/jeff-garzik-announces-partnership-launch-bitcoin-satellites-space/ http://www.coindesk.com/jeff-garzik-announces-partnership-la...
- cvbncvbncgbc 13y agoSo instead of improving the algorithms that support our virtual currency, we brute force the problem with sending stuff to space(!). Sounds like a plan that could destroy a civilization in the long term.
- itazula 13y agoHis "doesn't work" is equivalent to saying "not profitable." But what if that energy is spent within a country whose economy can produce profitable services and products for export, making up for the cost to acquire that energy? Having a non-nuclear source of energy not dependent on other countries might be worth it.
- resu 13y agoWouldn't a structure this large be inevitably hit by debris, whether from our own junk or stuff from elsewhere in space? They'd need a gundam squadron to protect it too.
- Gravityloss 13y agoMost of the debris is in low orbits. So no direct problem. But if you build it in low earth orbit and fly it out on its own power in a slow spiral, then it's going to be a big problem. Flying with chemical rockets only up to LEO and electric propulsion from there on saves mass hugely. Best to assemble moderate pieces and fly them higher after completion.
- grecy 13y agoI was also wondering about the shadow it would cast...
- thret 13y agoI'm sure someone here will do the math, but short answer is that it wouldn't produce a noticeable shadow. Too small, too high.
- cvbncvbncgbc 13y agoThe apparent size of the structure in the sky, is on the order of three magnitudes smaller compared to the size of the moon.
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- commieneko 13y agoIt wouldn't cast an umbral shadow at all. It would cast a incredibly faint penumbral shadow. Look at it this way, at the sizes that are commonly talked about for these, at the orbital heights being talked about, the occlusion of the sun would be on the order of a very minor sun spot, and only for very brief periods of time.
- BrandonMarc 13y agoAnother ignorant question ... so you have a massively powerful microwave beam pointed at a certain spot of your nation. What happens when it misses? Passes over the inhabited land that's infinitesimal fractions of a degree away from the target? From 36000 miles, a few miles is a rounding error. Must take some huge tolerances to keep the beam pointed in the right place. Is this even dangerous, or am I off base? I know they're nervous about nuclear since Fukishima, but unless I'm mistaken there's similar risks with this option.
- trhway 13y agoand a movie about villains hacking in and taking control of the beam. Steven Seagal has similar one ...
- puls 13y agoI can't believe nobody has mentioned this yet: exactly this was one of the standard disasters in SimCity 2000, where "microwave" was one of the power plant types.
- deleted 13y ago[deleted]
- HCIdivision17 13y agoThanks for saving me the trouble. Microwave tech was awesome and cost effective until the first time the satellite got out of alignment and burned half the city down. I've been terrified of the idea ever since: you just can't make a weapon like that fail safe, and if you do manage, then your throughput is too low to make it worth it.
- worldsayshi 13y agoWhat you possibly could do is to not have a single emitter but loads of them for each collector. So that a single satellite getting out of alignment would be harmless. Many emitters would need to get out of alignment pushing the beam in the same direction for it to be harmful.
- csense 13y agoIt seems like the article discusses the challenges of building large structures in space. Maybe the large-scale building techniques developed for this application would be useful for building large space stations. Space would be a lot cheaper if our spacecraft didn't have to use huge amounts of fuel to get out of earth's gravity well, which logically implies production [1] and refueling facilities in space using resources that don't have to be brought from Earth. Which will probably be bigger structures than the ISS, which means the technology to build large structures in space is something which will be useful for reasons beyond solar power. [1] At first, the spacecraft itself will probably be built on earth, and fuel will be the only thing produced in space.
- danielweber 13y agoI really really want to see the numbers on this. 1. How much mass are they putting into orbit? 2. How much is it costing them to put that into orbit? 3. How much energy will that generate? 4. How long will the solar cells last?
- jessaustin 13y agoI don't think there are many power plants on Earth that function unattended and maintenance-free for very long. It will be nice if transport to space will be commonplace enough 25 years from now that sending a regular rotation of maintenance techs will be feasible.
- spiritplumber 13y agoDeath ray. Mwhahaha.
- Fando 13y agoThis idea reminds me of the ION cannon from Command & Conquer.
- e12e 13y agoPfft forget about using this for mere electrical power. Boil the sea to make it rain!