# Thread: Solar Energy from Space

1. To explain what people see in space solar power, the idea is that in space, there is no atmosphere to absorb solar radiation, so more can be collected and transformed to a type that can be sent through the atmosphere without interference. There are of course a lot of inefficiencies and problems in thjis approach, but that is the general idea. (There is also more room in space.)

2. This also seem incredibly assumption loaded (Have you already designed the system in your head, decided it is the only way and made the cost estimate based on that?). Yes, the manufacture of one solar panel will cost more than the manufacture of many, generally speaking (though at the scales we're talking about, even that is probably not true. There are reasons why silicon wafers aren't giant, you know.)
Even IF you disagree than launching redundant parts of a network would be cheaper (and perhaps there is some element that scales really poorly), the reality is that 200,000sq meters of panels = 200,000sq meters of panels. The core of the cost remains the same. That was the point - the scope of the project is identical. Small contributions add small contributions - for a high cost. The relative cost is not changed significantly.

It's a simple problem - you need a certain amount of "floor space" to generate a certain amount of energy. Efficiency isn't even the problem here, you could bump it up beyond 100% in some strange removal of the laws of the universe and it would still be large.

Do your analysis on cell-phone and GPS research the same way you did for this, and see if you come up with them being feasible at the time. System and component research have to go on in parallel, because components don't magically create a system. If you want your ROI for component research, you need a system for the components to plug into.
You mean like how radios, short wave radios, microwave relays... or the other side, like triangulation, atomic clocks etc were all proven in advance?

I see the analogy as being perfect... unless you are talking about building cell phone networks when the radio was invented, which would of gathered the same arguments in miniturisation and data/binary transmission.

Who says we have to replace current coal or Nuclear power plants?
That's like asking "Who says we have limited resources?". We have limited resources and they should be directed towards the most important projects. This would replace another power system or it would be a waste of resources to build.

The gov't give "future carbon credits" to companies that aim to implement parts of this sort of system (perhaps even maintain partial rights to carbon credits of future users, etc.)
This is the same reason I used nuclear power as an example. There are current options that could be subsidised.

This is an engineering project, not a science project. We ought not wait for our 'anti-gravity' module to proceed with conceiving of different system implementations and trying to make that as cheap as possible.
Again, the cost of generating one system equivalent to one nuclear power plant is way way out of whack. Every nuclear generator could remove coal/oil/ugly fossils. Or build a wind farm, or a wave generator, or a gound based solar farm...

Did you read the second link in the OP? I am wondering where you are getting your numbers.
I skimmed it. What I saw was the ground station would cost 8-15 billion for 250mw. I saw no size estimate for the GW production floating in space. I see no reason to even believe these numbers either, unless they aren't including the space segment.

Since there is no background on how they got this information, I looked up the the current state of solar panels and their efficiencies and sizes. Maybe there is a gigantic difference in space, but looking at the "current" (older, I suppose) panels, to generate power, I'd be generous to say 200,000sq meters. It's closer to 300,000 based upon the ISS power generation. And of course, that's not even including the loss from beaming.

I'm not sure what number they got for sending stuff into space, but it seems unusually low... about \$470/kg. I don't know what the current cost is, but I remember it is being... a whole lot higher (wasn't the commercial launch in April somewhere around 15,000?)

3. Just surface intuition gives me the impression that this project is a very bad idea. No way in hell we're making a space solar power station that actually makes economic sense...

I'd much rather see money pumped into this project personally.
Even if their claim of "making break-even fusion" is a pipe dream, it's a better step in the right direction than space-based solar power, IMHO. Why capture energy from the sun? Bring the sun right here to earth.

4. The second link in the OP has referring, and referenced articles linked at the top for those interested in how they derived their numbers/

A lot of the criticisms (including comparison to nuclear power, and terrestial solar power) are addressed in this wikipedia entry.

We can make up whatever numbers we want to prove our case. But needless to say the costs of taking things to space is coming down, and having reusable transport means (as-opposed to one-time satellites launches) can give us economies of scale.

Dismissing the idea outright, seems like a hasty conclusion. Costs are based upon the designs themselves, and since solar power from space will provide steeper return on investments than terrestial sources (quite a bit more energy), doing it in smaller chunks would be a way to have it pay for itself (IOW, increasing our limited resources). The power from these systems is going to be ~20 time more expensive (but you still get power) that fossil fuels, but economies of scales are expected to bring that down into fossil fuel range over time. The added benefits are all the externalities we derive from making this investment.

You can read this article: FirstScience - Solar Power from Space as well.

I have HW to do right now, but I may answer in more detail if I have time.

I still think this is the best thing I've heard proposed for getting us off of fossil fuels. It is a solution based on renewable sources. The power is a clean source as well. It makes use of things we already know how to make/do (no new discoveries are needed for its possibility, but perhaps for its feasibility, so it is an engineering project not a science project, like cold-fusion, and therefore has means to pay for itself over the long run). There are many who believe it feasible (again you can quote numbers from wherever to prove one way or another).

I have yet to hear a better proposal.

5. While I'm all for solar power and renewable resources, and I see nothing wrong in pursuing this as a problem in engineering, I don't think this is likely to solve the major energy problems that we face now. As PTGatsby says, the scale of power generation isn't too impressive compared to existing technologies (I'm thinking nuclear in particular) and there's a LOT of overhead in deploying and maintaining things in space - it's likely going to be hard to get things to a point where the extra efficiency of receiving solar energy outside of the atmosphere overrides the inefficiency of operating in space and beaming it back to earth. Point in case... need to replace faulty/broken panels? How much more does it cost to send an astronaut repair crew up to repair this thing than it would to send a guy in a truck out to a desert-based solar array? It's not like the earth's suffering from a lack of solar radiation - like PTGatsby says, what's wrong with cheap(er), plentiful solar arrays on earth?

The cynic in me says that this is simply a ploy to redirect funds allocated for renewable resource research and development into a project more in line with the goals of (here it comes, the cliche of conspiracy theories...) Eisenhower's military industrial complex. If I remember right, one of the main reasons for this plan is to deploy energy to mobile military units in the field. I'm seeing a cash cow of major proportions to defense contractors - with corresponding reductions in R&D that's actually going to address energy concerns.

While it's an interesting engineering problem, I'd much rather see resources put into decreasing the costs of getting things into orbit (and beyond), and development of a less fossil-fuel-centric energy infrastructure, in particular more efficient ways to store energy generated from nuclear/solar/wind/etc. power generation (be it fuel cells, etc.).

6. I dunno, my biggest issue here is the fact that we're beaming it across such a large distance. Since any transference of energy induces loss, I am a firm believer that it's best to collect or produce the energy closest to the place of consumption. I would believe in widespread rooftop solar panels of high efficiency before I'd believe in space-based centralized solar collection/distribution.

If we have a significant orbital presence some day, where spaceflight becomes cheap and orbital development surges, a central solar array like this would be a great idea, beaming power between orbital platforms. But down to the planet... just doesn't sound sensible IMHO.

Nuclear fission in its current form (in much of the USA anyhow) is ridiculously fuel-inefficient and dangerous; there are better designs out there (pebble bed, Integral Fast Reactor although dev. on that was halted) but I am leaning towards either solar and/or (if we see any breakthrough) fusion as the ideal power source for our future. I have a feeling that solar won't do the trick for our growing and increasingly energy-hungry society: while solar is plentiful, at some point the power-per-capita ratio will outpace our ability to efficiently collect solar energy to meet those demands, especially as our average quality of life becomes more dependent upon advanced technology. It is this reason I propose nuclear (fusion, ideally, if not, the best form of fission we can employ) as the best solution for our future energy growth.

One thing is for damned certain: we need to STOP using ground-sourced chemical fuels for our electricity needs. Problem is, chemical fuel is still the best way to transfer power for power-hungry portable machinery (eg cars/trucks), and that won't change for a long time. Electricity storage technology still sucks for high-energy portable applications, and even if we did have advanced batteries (or supercapacitors) to power our vehicles, the public utility power grid was not designed for transferring arbitrarily large amounts of power to residential sites (this is the true "long-term" problem with "all electric vehicles", IMHO)

Fun fact:
Did you know that by pumping 10 gallons of gasoline in 5 minutes, you are transferring raw potential (chemical) energy through a hose at a rate of roughly 4.3 MEGAwatts (computed from 131MJ/gal)? It's incredible how much power our vehicles use in comparison to the electronics we're accustomed to in our households. Bear in mind though, our cars typically only get to extract about 15-25&#37; of that from the gasoline; the rest is wasted as overhead or vented out as heat.

By comparison, if you were to operate your house's utility power at full current, balls-to-the-wall, you'd be lucky to get 48 KILOwatts out of that. (computed from 240VAC * 200A = 48KVA, actual wattage will be lower. I got the 200A figure from the mains breaker in the circuit breaker panel down in the garage of my roommate's house)

7. Originally Posted by spirilis
I dunno, my biggest issue here is the fact that we're beaming it across such a large distance. Since any transference of energy induces loss, I am a firm believer that it's best to collect or produce the energy closest to the place of consumption. I would believe in widespread rooftop solar panels of high efficiency before I'd believe in space-based centralized solar collection/distribution.

If we have a significant orbital presence some day, where spaceflight becomes cheap and orbital development surges, a central solar array like this would be a great idea, beaming power between orbital platforms. But down to the planet... just doesn't sound sensible IMHO.
I agree that I don't see appeal in beaming energy... I mean, what would happen to anything that got between the energy and the station? Couldn't a plane (or the people inside) get damaged? Couldn't it hurt the atmosphere? I don't like to trust solar cells even for my calculator. What if something got between the cells and the sunlight? One or two asteroids is all it would take.
Nuclear fission in its current form (in much of the USA anyhow) is ridiculously fuel-inefficient and dangerous; there are better designs out there (pebble bed, Integral Fast Reactor although dev. on that was halted) but I am leaning towards either solar and/or (if we see any breakthrough) fusion as the ideal power source for our future. I have a feeling that solar won't do the trick for our growing and increasingly energy-hungry society: while solar is plentiful, at some point the power-per-capita ratio will outpace our ability to efficiently collect solar energy to meet those demands, especially as our average quality of life becomes more dependent upon advanced technology. It is this reason I propose nuclear (fusion, ideally, if not, the best form of fission we can employ) as the best solution for our future energy growth.
I was actually thinking research should go into Nuclear development. I just don't know if we can get people to accept it because of all the fallout and radiation risks. People are so opposed to it, despite all the long term risks we take by remaining dependent on oil, that they don't even seem to see. How close are we to developing Fusion? In addition to being a good potential power source, it was my favorite power plant in SimCity 2000.

One thing is for damned certain: we need to STOP using ground-sourced chemical fuels for our electricity needs. Problem is, chemical fuel is still the best way to transfer power for power-hungry portable machinery (eg cars/trucks), and that won't change for a long time. Electricity storage technology still sucks for high-energy portable applications, and even if we did have advanced batteries (or supercapacitors) to power our vehicles, the public utility power grid was not designed for transferring arbitrarily large amounts of power to residential sites (this is the true "long-term" problem with "all electric vehicles", IMHO)
I never thought electric cars were the best idea. Why wouldn't some form of alcohol work to replace gasoline? I think a car can be made to run on some kind of alcohol if I'm not mistaken. In fact, shouldn't any combustible fuel, even something like kerosene, work? I haven't formally studied Science, so I might be wrong. I think all we have to do is find another form of combustible fuel to replace oil.

Fun fact:
Did you know that by pumping 10 gallons of gasoline in 5 minutes, you are transferring raw potential (chemical) energy through a hose at a rate of roughly 4.3 MEGAwatts (computed from 131MJ/gal)? It's incredible how much power our vehicles use in comparison to the electronics we're accustomed to in our households. Bear in mind though, our cars typically only get to extract about 15-25&#37; of that from the gasoline; the rest is wasted as overhead or vented out as heat.

By comparison, if you were to operate your house's utility power at full current, balls-to-the-wall, you'd be lucky to get 48 KILOwatts out of that. (computed from 240VAC * 200A = 48KVA, actual wattage will be lower. I got the 200A figure from the mains breaker in the circuit breaker panel down in the garage of my roommate's house)
Wow. My home uses that little energy? Why does a car need more energy than a computer/monitor or a television? It's such a simple machine with little more than a radio, a few lights, and an air/heating unit. It just needs mechanical energy to propel it... is that where the main energy cost comes from? Having to be propelled forward at high speed?

8. Yes, the mechanical energy required to propel a car is the chief user of all that power. It is enormous.
Case in point:
A typical fuel efficient car may generate a peak power of 115HP (horsepower). Let's assume that for typical highway driving, it has to sustain about 2/3rds of that (~76hp). 76HP represents 56 kilowatts. That can go on for quite a number of hours; so to be fair, those 10 gallons of gasoline will last you a while, but still...
Your home won't come anywhere close to using the maximum capacity of the circuit breaker of course, so the actual power draw will be a mere fraction of that 48KW figure. I wouldn't know what a typical home's power draw is off the top of my head; there may be sites out there detailing that. A typical home power "backup generator" may ride along the 6KW figure though.

Cars can run off alcohol indeed, problem is, the contemporary production processes (corn growing) are very straining on the environment if I've heard correctly... raising the cost of corn, causing extra mass quantities of fertilizer to migrate down the Mississippi river, etc. There are other processes being looked at to produce ethanol which I believe is promising. Hopefully we'll have some traction on some of those processes. Examples include operating vats of genetically-engineered bacteria to process cellulosic waste crop materials, which would be a nice form of recycling... and cultivating algae which can produce it.

9. Originally Posted by spirilis
Examples include operating vats of genetically-engineered bacteria to process cellulosic waste crop materials, which would be a nice form of recycling... and cultivating algae which can produce it.
Has this been done yet in experiments? How sure are we that it's possible? It sounds to me like it might work. In fact, if it's that simple, why hasn't it been done yet? I think they do genetic engineering research all the time. Is anyone working on something like this?

10. I doubt it's quite that simple...

Actually I was mistaken on one thing, the algae are being harvested for oil (biodiesel), not ethanol. USATODAY.com - Algae like a breath mint for smokestacks

This page discusses cellulosic ethanol (hasn't been updated in almost 5 years though): Ethanol From Cellulose: A General Review

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