Harnessing Solar Power in Space

[GeeKay]

Assuming for the moment that the technology will be available in the not-too-distant future, could the Earth's energy needs be met entirely by solar power one day? By this I mean having the Sun's energies directed from space down to us on Earth via microwave beams, say.

 

As a follow-on question, are there any practical limits to how much energy could be harvested from the Sun? I have in mind an array of gigantic solar panels orbiting the Sun at fairly close quarters - the ever-present threat of solar flares and CMEs notwithstanding. But there may be other solutions about which I am entirely ignorant.

 

Finally, is the physics concerning the above already in place, if not the technology and political wherewithal?

 

Many thanks.

 

 

 

 

[Danijel Gorupec]

I guess... if you start transferring really large amounts of energy toward the Earth (say, and I am just making a wild guess, 100 times more than we currently use) then you will start heating the Earth surface noticeably. So, I guess there are practical limits on how much additional Sun energy we can deflect toward Earth (in any form).

 

On the other hand, there are probably not practical restrictions on how much energy can be harvested from Sun (at least not for some 1000 years in future, possibly much more). There is enough energy there to vaporize our planet many times.

 

(lol, I once had a silly SF idea to make huge, super-light paragliding wings that will float near Sun on its light and solar wind, and at the same time reflect light and focus it on Mars to heat it up.)

[Acme]

Assuming for the moment that the technology will be available in the not-too-distant future, could the Earth's energy needs be met entirely by solar power one day? By this I mean having the Sun's energies directed from space down to us on Earth via microwave beams, say.

...

Finally, is the physics concerning the above already in place, if not the technology and political wherewithal?

SPACE-BASED SOLAR POWER (SBSP): Solar power directly from space may arrive sooner than you think

 

...You can't collect solar power at night. Well, at least not on Earth. Since it's Space Week, we thought it'd be appropriate to look at one promising, but futuristic, idea that could change the face of solar power generation: Space-Based Solar Power (SBSP). While the Energy Department is not actively researching SBSP, we hope you'll take a moment to learn about this far out concept.

 

The idea of capturing solar power in space for use as energy on Earth has been around since the beginning of the space age. In the last few years, however, scientists around the globe -- and several researchers at the Energy Department's own Lawrence Livermore National Laboratory (LLNL)-- have shown how recent technological developments could make this concept a reality.

...

[swansont]

I guess...

 

No need to guess.

 

Take the US, for example, and looking only at generation. Our current electrical generation capacity is about 1000 GW, with a small fraction already being solar, and that's to accommodate peak loads in summertime. So you need less than 24,000 GW-hr/day. Even in winter there are places one can generate around a kW-hr/m^2 each day, and that would be more in summer. Let's use 1.2 kW-hr/m^2 each day

 

We need 20,000,000,000 m^2 of panels to do this. That's a square 141 km on a side, and that's peak production, so the area is actually smaller for actual demand, assuming you can store the excess and use it when needed. You also need spaces between the panels so they don't shade each other, so you need more land area than this. But that's only around 0.3% if the area of the contiguous US, and some fraction of this could be placed on rooftops. No need to add the complication of energy transfer from satellites.

 

For the whole planet, the number is around 260 km a side (YMMV depending on the assumptions)

http://www.dailykos.com/story/2014/06/25/1309388/-Solar-Panel-Acreage-Needed-to-Power-the-Entire-Planet-158-mi-x-158-mi#

[pavelcherepan]

 

 

Assuming for the moment that the technology will be available in the not-too-distant future, could the Earth's energy needs be met entirely by solar power one day?

 

Below is the link to a video, where Elon Musk is presenting Tesla Power Wall. I've linked to the section starting at 2:41 where he talks exactly about how much area you'd need to provide solar power for the entire world with some pictures too.

 

https://youtu.be/yKORsrlN-2k?t=2m41s

 

At about 4:50 he talks about how much space is required for batteries (since solar power is useful only for half the time).

[Enthalpy]

The physics for energy from space exists for a century, the technology for decades and it has been demonstrated in La Réunion.

 

Though, transmitting energy has very serious drawbacks: size of the transmitter and receiver, danger for birds and aeroplanes, cost. So I too wonder: why do it in space, not on the ground? Storage is being solved presently, and the losses and cost of transmission pay easily for the land and cell area.

 

Sidenote: a normal font suffices, I have my glasses.

[GeeKay]

Yes, my apologies about the "shouty" font. I must have hit the wrong button.

 

Re solar power issues, I do wonder if Earth-based systems will always be sufficient, given our soaring energy needs. The last time I looked we were, globally speaking, consuming around 500 exajoules per annum, and while there will always be dips due to recessions etc, the trend, for all its sawtooth profile, remains remorselessly upwards. So much so it seems that unless there is a global catastrophe of some kind, or else a radical shift in thinking, it will continue to soar. I accept that new technological advances in the nearer term - both with regards to solar energy gathering and the perennial problem of energy storage - may satisfy our needs for quite a while longer yet, and so keep the industry down here on Earth. And, yes, I share the concerns about microwaves beaming down from space. I suppose we will first need to become a true spacefaring species before we learn to harvest all the energies that requires from the environment of space itself. I don't know if this is putting the cart before the horse, or whether the horse is having a free ride, but I'll let posterity decide about that.

 

Many thanks for the links and helpful responses. The Elon Musk link is a gem.

[Mike Smith Cosmos]

No need to guess.

 

Take the US, for example, and looking only at generation. Our current electrical generation capacity is about 1000 GW, with a small fraction already being solar, and that's to accommodate peak loads in summertime. So you need less than 24,000 GW-hr/day. Even in winter there are places one can generate around a kW-hr/m^2 each day, and that would be more in summer. Let's use 1.2 kW-hr/m^2 each day

 

We need 20,000,000,000 m^2 of panels to do this. That's a square 141 km on a side, and that's peak production, so the area is actually smaller for actual demand, assuming you can store the excess and use it when needed. You also need spaces between the panels so they don't shade each other, so you need more land area than this. But that's only around 0.3% if the area of the contiguous US, and some fraction of this could be placed on rooftops. No need to add the complication of energy transfer from satellites.

 

For the whole planet, the number is around 260 km a side (YMMV depending on the assumptions)

http://www.dailykos.com/story/2014/06/25/1309388/-Solar-Panel-Acreage-Needed-to-Power-the-Entire-Planet-158-mi-x-158-mi#

Well I must say that article is very impressive. It certainly shows how it would be possible to give what is needed from land based solar panels ,if that is the way you want to go .

[DrP]

Seems like a better idea than beaming rays down from space imo... they are already coming and can be harnessed. Solar cells are improving in efficiency too as time goes on, so this is good too.

 

 

I quite liked the 'solar roadways' invention that there was a video about a while back too.

 

It was all solar powered and had sensors and LEDs.... so the road could light up to tell you if there was a moose on the road around the next bend for example (by using pressure sensors in the road panel to detect the moose and the driver and to work out where to put the 'Slow Down' warnings... which would actually appear on the road itself, powered by itself.

Edited July 2, 2015 by DrP

[swansont]

 

I quite liked the 'solar roadways' invention that there was a video about a while back too.

 

Last time I visited NIST in Gaithersburg I noticed they had solar panels over the some parts of the parking lots. Generates electricity and keeps your car in the shade

[DrP]

Nice idea.. could do with keeping the car cool over here at the moment - heatwave yesterday. Our company has recently fitted solar panels on all the roofs. I was quite pleased and impressed. Did you see the vids I was talking about? The cells clip together real simple and have little chips in them to connect to the whole network of them.

[Harold Squared]

 

No need to guess.

 

Take the US, for example, and looking only at generation. Our current electrical generation capacity is about 1000 GW, with a small fraction already being solar, and that's to accommodate peak loads in summertime. So you need less than 24,000 GW-hr/day. Even in winter there are places one can generate around a kW-hr/m^2 each day, and that would be more in summer. Let's use 1.2 kW-hr/m^2 each day

 

We need 20,000,000,000 m^2 of panels to do this. That's a square 141 km on a side, and that's peak production, so the area is actually smaller for actual demand, assuming you can store the excess and use it when needed. You also need spaces between the panels so they don't shade each other, so you need more land area than this. But that's only around 0.3% if the area of the contiguous US, and some fraction of this could be placed on rooftops. No need to add the complication of energy transfer from satellites.

 

For the whole planet, the number is around 260 km a side (YMMV depending on the assumptions)

http://www.dailykos.com/story/2014/06/25/1309388/-Solar-Panel-Acreage-Needed-to-Power-the-Entire-Planet-158-mi-x-158-mi#

BIG assumption there, Mr. Cost Estimate Guy. What is the price tag for all the handwavium you are going to build the storage out of? Where are all the handwavium mines anyhow?

Nice idea.. could do with keeping the car cool over here at the moment - heatwave yesterday. Our company has recently fitted solar panels on all the roofs. I was quite pleased and impressed. Did you see the vids I was talking about? The cells clip together real simple and have little chips in them to connect to the whole network of them.

So how is that working for you so far?

The physics for energy from space exists for a century, the technology for decades and it has been demonstrated in La Réunion.

 

Though, transmitting energy has very serious drawbacks: size of the transmitter and receiver, danger for birds and aeroplanes, cost. So I too wonder: why do it in space, not on the ground? Storage is being solved presently, and the losses and cost of transmission pay easily for the land and cell area.

 

Sidenote: a normal font suffices, I have my glasses.

Storage is being solved? More details please. While we do have electric aircraft at present none are of trans oceanic or transcontinental range. They are only in the experimental or ultralight category.

 

Similarly, one can power a remote cabin with solar and batteries, but not a city, nor yet a nation.

 

I need not remind you that demand for illumination increases as the sun is unavailable, and all those electric cars looming in our oh-so-green future will be recharging during this time period as well. In Minnesota. In the winter. When it snows, ya know.

 

So storage is a big deal for those residing at higher latitudes, and you will understand my curiosity.

[DrP]

So how is that working for you so far?

 

 

I haven't delved into the figures.... but we produce our own electricity and feed excess into the national grid and get paid for it. It's clearly the way ahead, especially as solar cells improve in efficiency and flexibility and become more cost effective.

[swansont]

BIG assumption there, Mr. Cost Estimate Guy. What is the price tag for all the handwavium you are going to build the storage out of? Where are all the handwavium mines anyhow?

 

Cost estimates were not part of the question being asked. I crunched actual numbers and provided a link (things to which you appear to be allergic), so what hand-waving are you alluding to?

 

Storage is being solved? More details please.

 

http://www.scientificamerican.com/article/tesla-s-elon-musk-unveils-solar-batteries-for-homes-and-small-businesses/

 

So storage is a big deal for those residing at higher latitudes, and you will understand my curiosity.

 

Generation does not have to all be local. Just like it is now, with conventional electricity.

While we do have electric aircraft at present none are of trans oceanic or transcontinental range. They are only in the experimental or ultralight category.

 

So? Why bring this up?