A skeptic's take on beaming power to Earth from space
spectrum.ieee.org
spectrum.ieee.org
Thermodynamically speaking, if you transmit electricity from outside the Earth onto the Earth – even if you do it perfectly efficiently – you are, by definition, heating the planet.
Based on that I concluded that it is superior to generate electricity with inputs that are already hitting the Earth… But I’d be very interested to learn more about this.
One could improve the PV by making it highly reflective in the near IR at wavelengths below the bandgap of the cells, while still being highly emissive at the longer wavelengths where it will radiate heat.
But I think using an appreciable amount of the power provided to Earth by the sun is still sci-fi stuff anyway, so we probably can’t make an appreciable dent either way.
Sagan put us at around Kardashev .7, it is a log scale shifted by a constant, apparently we’re under .2%, of what hits the Earth, I guess.
However, it makes sense to have hundreds of ground stations simply to minimize transmission losses on the ground. And presumably utilizing ground stations 24/7 is vastly less critical than maximizing the return on space based infrastructure.
One with a beam that can target distinct areas.
Easy way to fry large amounts of your adversarys telecoms infra.
It will not put you back to the stone age, but 1970-1980 is not out of the question. For wireless communications that is.
At the distance of the L2 point laser power beaming would probably be necessary to keep the transmitter and receiver sufficiently small.
In any case, it won't be worse than releasing a good amount of the captured solar energy in chemical form for millions of years in around a century.
However, this is completely dwarfed by the dynamics of flux in and out of the earth. I forget the exact order of magnitude but I think it's around 100TW, and of course about that amount needs to be rejected to space. The key dynamics that provide us balance are of course the exact and precise quantities of greenhouse gases in the atmosphere, albedo, etc.
And of course, coal and natural gas are releasing stored heat energy too, but their contributions to changes in the atmosphere far exceed the contribution from direct heat energy on the surface of the earth.
Human energy utilization is on the order of 100 terawatts.
Total power used by humans = 16 Terawatts.
https://www.nasa.gov/wp-content/uploads/2015/03/135642main_b...
What we get from the Sun in one hour, is how much we use for the whole year.
All our energy needs can be covered if we can tap into just 0.00001% of energy received. About 100km2 worth of solar panels.
If every residential and commercial building was covered with solar roof - we’d have all our energy needs covered during day time.
It’s free energy if we know how to use it. Plants do and they make up >99.9% of biomass on this planet.
The problem with C02 is it traps the heat. All useful work is done when high energy packets from sun in ultraviolet and visible light get dissipated into heat (infrared).
If we don’t solve greenhouse gas problem, we can’t use more energy since we’d be out of equilibrium.
(forests are only a little less of a "heat island" than an asphalt surface is, and that makes sense, doesn't it? Forests actively try to maximize what they capture from the sun. That tress is capture more is why trees exist in the first place)
I understand the increase in thermal forcing from added greenhouse gases is currently > 400 TW.
You need to get a better handle on orders of magnitude.
The Earth is always almost exactly in a radiative balance with space, except on pretty short timescales. If it weren't, we'd quickly cook. The radiation the Earth receives from the Sun fluctuates orders of magnitude more over solar cycles, but it's debated whether that even has a meaningful effect on global temperature.
It isn't. The amount of energy (and raw materials generally) required to produce a given amount of economic output is not constant. It gets smaller as technology advances. That offsets the effect of increased economic output. Indeed, as more and more economic output becomes information instead of physical objects, the average amount of energy required per unit of economic output will shrink even more.
The notion that economic growth can continue without growth of energy is a short-term illusion created by the transition to an information economy, outsourcing of manufacturing, and perhaps a lack of appreciation for the ongoing growth in energy consumption even within countries like the United States as the economy shifted away from physical goods, let alone the growth in energy consumption in countries like China that ramped up physical manufacturing to make this possible.
My phone uses less power then the one I had 5 years ago, as does my PC.
In fact every industrial manufacturing process today is using less energy then it was in the past.
This is because energy consumption reduction due to efficiency improvements goes -- to be very generous -- as 1/t, and exponential growth goes as e^t, and e^t/t is still exponential for large t.
Per capita energy consumption has not been growing in developed countries like the US. It has been decreasing for at least a couple of decades. Total energy consumption has been increasing because of population increase, but that is expected to level off around the middle of this century.
No, it doesn't, because everyone else is also increasing their economic output. Assuming stable population, one individual's share of the energy supply remains constant.
https://www.tandfonline.com/doi/abs/10.1080/1478644960862084...
https://en.wikipedia.org/wiki/Carbon_dioxide_in_Earth%27s_at...
We currently have an energy budget that's 0.1% of insolation (and compounding growth at 2-5% per year), so if SBSP actually scales to its market opportunity then the effect could certainly be large enough to matter.
This will change when we switch to renewables.
Renewables are still subject to the laws of thermodynamics and other laws of physics.
https://en.wikipedia.org/wiki/Heat_engine#Efficiency
Typical power stations (whether fueld by renewables or not) have efficiencies considerably less than 50% (the examples in this article give 40% efficiency for coal, 48% for nuclear, and 33% for geothermal).
Photovoltaics (not being Carnot-cycle heat engines) aren't subject to these specific limitations, but they have their own problems. Typical efficiencies for current mass-production models are around 20%, while "lab curiosity"-level cells still haven't broken 50%.
Note that this is just the generating side. There are also similar waste heat losses on the consumption side (for example, charging and discharging batteries is anything but 100% efficient, as anyone who's actually tried to use a modern laptop on his lap can attest).
>Photovoltaics... are around 20%
For a fuller articulation of the point HN user thelastgallon is making, see this link:
https://www.sustainabilitybynumbers.com/p/electrification-en...
Well, no. You still have to pay the amortized cost of the installation and real estate, the salaries of the employees, and many other things, all of which would be less if the efficiency were higher than 20%. For example, if the photovoltaics were 40% efficient (the same as coal), you'd need only half the real estate, half the semiconductor-grade silicon, and likely half the cost of many maintenance activities, none of which are free.
> https://www.sustainabilitybynumbers.com/p/electrification-en...
This site doesn't even mention solar or the efficiency thereof.
The reason this matters is because there's a lazy temptation to run the Electrification Calculation merely by looking up the amount of primary fossil energy burned annually, then assuming 100% of this must be replaced by solar/wind/whatever. However this simplistic calculation will over-estimate the amount of renewable energy needed by a factor of roughly 3x.
>This site doesn't even mention solar or the efficiency thereof.
The entire thesis of the article is how mass renewable electrification enjoys large system efficiency gains over fossil fuels. It's pretty evident how solar is a critical enabler of mass renewable electrification.
I'm saying that when states and corporations do their energy reporting, there's no need to report the non-absorbed ('waste') energy from PV. Sunlight striking the ground (and whether it's utilized in a way we appreciate, versus 'just' powering the weather and the water cycle) is not something we include in those numbers.
Heck, maybe we should make a home for your PV 'waste' energy, a new energy statistic that does account for all sunlight striking the Earth. So if you cut down vegetation to make a parking lot, it makes your country's energy numbers get worse. Neat! Maybe that would be useful as an additional metric, but it's far from what we're trying to measure with our existing energy reporting policies. Our existing policies emphasize the (much larger) problems of greenhouse gas emissions and local pollution impacts.
Anyway I think the point has been adequately made, cheers.
Ground solar panels need relatively frequent cleaning due to dust, weather, and plants/animals in some areas. In space the biggest maintenance costs are gone. With the $10-$100/kg launch costs refueling would not be that expensive. Micrometeorites may be an issue, but if the rate of micrometeorite impact is low enough it may not be a concern. The 60-year costs of ground solar panels are actually worse than a large nuclear power plant due to the maintenance, so it is a significant part.
Space solar may not be effective initially, but I think it could have its place similar to SMRs. Power could be generated 24/7. The ability to allocate power as needed across a whole hemisphere would allow us to optimize power grids without megatons of power cables. These could also beam power to moon bases or even mars bases eventually.
Also bringing up Musk was unnecessary. The space industry is bigger than one person and many of "his" ideas predate his involvement with the industry and have teams of many scientists and engineers doing the actual work. It would be a shame to throw out ideas that could facilitate human progress simply because we didn't like one personality.
TBH though I'm very much not qualified to debate about this type of technology, so I acknowledge that perhaps this could have no moving parts and if so maybe maintenance is less certain than I thought.
Its not immediately obvious that a mass produced solar satellite could not scale better than thousands of individual legal jurisdictions and eco systems.
I haven't followed developments in solar cells or power transmission closely, but I get the sense that there's only been minor, incremental, improvements. The math still doesn't work.
The proposal for rectenna arrays was grids over farmland which could be used for cattle grazing with illeffects to the cattle - simply not enough EM can be absorbed by them for it to matter.
Furthermore, microwave antennas are mesh, not solid. You won't have full sun under it, but neither will it be dark.
That being said, there's a fundamental issue here that without huge improvements in launch costs it's simply not viable unless made out of lunar materials.
And note that it doesn't have to be in a synchronous orbit so long as you permit some movement of the antennas. Put say 25 stations out there and 24 ground stations--they keep hopping to the next station as the Earth rotates underneath, the 25th station is offline because it's in shadow.
A single solar power station can be taken out by a cloudy day.
A million little solar power stations spread across an continent average together into an even power source that provides power for longer than daylight hours.
The higher you run the voltage the more corona loss, the higher you run the current the more resistance loss. And there's a limit to how close you can put the wires to each other before they interfere. The band of land required for the massive power bus is gargantuan.
A panel in space can capture maybe 3x as much energy as one on the ground over a 24 hour cycle. But there are losses in transmission and huge costs to get the thing into space.
They can't get you through a month of Dunkelflaute in Germany (that's a 1-in-100 years event), when the normal renewable energy generation is less than 10% of the nameplate capacity.
The German grid mix very obviously crushes back down to being fossil fuels every night.
Here is an example: https://energy-charts.info/charts/power/chart.htm?l=en&c=DE&... - for about a week the renewable generation crashed in Jan 2019.
And it can happen for almost a _month_ of sustained low performance.
No, it's not. The long-term hydrogen storage demonstrator is not even completed yet. There is essentially no electrolyzer capacity, and long-distance hydrogen pipelines are even scarcer.
Sorry, but for now, hydrogen is nowhere close to reality in Germany. That's also why it's _subsidizing_ 10GW of new natural gas generation. After signing a 15-year LNG contract with Qatar.
[1] https://www.linde.com/clean-energy/our-h2-technology/hydroge...
BTW, hydrogen has a 100-year GWP of 12, so leaking 2-5% (the current figures) is not acceptable long-term.
Oh, and let's not forget what happens when one too many power plants have to undergo maintenance while a few others have to shut down temporarily due to a heat wave... There is no such thing as perfect one-fits-all solution to stable and sustainable energy. Oh, and btw. "baseload" is a term from the 70s - there's not much energy intensive heavy industry left in Europe to keep that term meaningful and relevant these days.
> Oh, and let's not forget what happens when one too many power plants have to undergo maintenance while a few others have to shut down temporarily due to a heat wave...
Let's actually forget it. The largest nuclear power plant in the US is in a freaking _desert_ and is cooled by evaporating treated wastewater. Nuclear power plants can work just fine during the heatwaves, the plants just need to be designed for that.
That's two key issues here that you just carelessly tossed aside. For one, central Europe doesn't have deserts or any large uninhabited regions for that matter. The US has a population density of 33.6 ppl/mk², compared to 236/km² in Germany. All nuclear power plants in Europe are therefore located near rivers and cooled accordingly.
Secondly, building nuclear power plants takes a shitload of money and time. Case in point:
* Hinkley Point C UK - significantly delayed, to date 50% cost overrun; only continued after the UK government gave long term guarantees, including fixed minimum electricity prices
* Olkiluoto Nuclear Power Plant Unit 3 Finland - 13 years delayed, 45% cost overrun
* Flamanville Nuclear Power Plant Unit 3 France - 12 years behind schedule, a staggering 5x cost overrun
* Plant Vogtle Unit 3-4 USA - massive delays and 2.4x cost overrun, Westinghouse filed for Chapter 11 due to losses from its nuclear business during construction
* etc.
So no, Germany didn't need _more_ nuclear.
Which is furthermore tightly coupled with other grids such as the UK/Ireland and Nordic countries.
This feels low to me (not an expert at all). So many advantages in space. much longer sun exposure, no atmosphere or weather to deal with, etc?
I really would love another sentence or two on this. I can't immediately think why that would be, e.g. don't Maxwell's equations apply at very large scales? Any ideas?
In general, you'll want your mesh to have subwavelength distance between points, and perhaps even less in regions with complicated geometry or parts of your geometry you're particularly interested in. In the microwave regime, this means mesh points will typically have tens of centimeters or less between them. However, given that the receiving antennas in satellite-based solar power are orders of magnitude larger than that, trying to simulate such a large structure and still keep your mesh points relatively dense is just asking for the curse of dimensionality to bite you.
In other words, it's certainly possible with enough compute time, but we have better things to do with our GPU cores, especially since the whole point of antenna simulation is to assist with design by allowing you to run a bunch of simulations to tune your design without having to fabricate a bunch of DUTs. Again, I'm not really an expert, but my understanding is that this kind of multiscale problem is a hot research topic right now, not only in computational EM but in many other areas of physics simulations, especially those governed by nasty PDEs (e.g. fluid dynamics) or those which involve complicated structures at multiple scales (e.g. VLSI design).
What are the consequences if, for some reason, the aim becomes not-so-precise?
It seems that practicality and efficiency concerns limit the beam at between 10% to 30% of the solar intensity. Every single design falls in that range.
Unfortunately, most of these impossible proposals lack any form of passive failsafe. Plus, the insurance liability question maybe an unsurmountable unknown.
The "receiver" is more-or-less a field "covered" by a spiderweb of bent coat-hanger wire. That doesn't block the sun, and making it huge (low power/sq. m) is quite cheap.
Since you don't want clouds/rain/fog to block the microwaves, the frequencies you use are ones which water does not absorb well. So if the beam hits a person...he probably can't even notice it.
And Wikipedia is only talking about humans, not about electronics, which are much more sensitive to microwaves. Want to fry the enemy's electronics? Just focus that "civilian" microwave transmitter with a few GW power tightly on where you want it to be.
I am really surprised nobody talks about this whenver space-based power transmission is mentioned.
2) Beam can be used as a weapon if you will just point it and light it up and thus deploy would be sooner or later heavily restricted or outright banned like nuclear weapons in space are banned.
No heavy transmitters or PV cells. No new ground-based infrastructure that has to be built before you can do anything useful.
(also wouldn't the appropriate word be "goddess"? Interestingly in ancient German tradition the sun is female and the moon is male)
Personifications of the sun and moon in ancient German lore had better make them respectively female and male, because otherwise the assignment would clash with the grammar, which has them as "die sonne" and "der mond".
- Space-based solar power is not a thing: https://caseyhandmer.wordpress.com/2019/08/20/space-based-so...
- No really, space based solar power is not a useful idea, literature review edition: https://caseyhandmer.wordpress.com/2019/09/20/no-really-spac...
You can get into the weeds of the detailed costings, safety, etc, but I think the clearest argument is this:
> The problem with beaming power using microwaves is that the monetizable value per Watt is incredibly low, because essentially unmetered electricity comes out of the walls of every building. The trick is to increase the value per Watt, by increasing the value and decreasing the power. The value is increased by modulating the microwaves with high speed data, and the power can be reduced by a factor of a million or so without hurting this method. Indeed, customers pay only for the data, and not for the transmitted electrical power, which is pathetically low at the receiver. Communications satellites remain the killer app for the commercial space industry
And then you look at the fact that almost every satellite communications company has gone bankrupt at some point. SpaceX with Starlink being a notable exception, but OneWeb which superficially looks pretty similar has already gone bankrupt once. If communications, which is many more orders of magnitude more valuable than power, is not enough to stave off bankruptcy, then there is no possibility of beamed power being economical without a commensurate improvement in the efficiency of space launch. And that's just a baseline as a necessary condition, not actually a sufficient condition for it to be a sensible business.
"There is always a well-known solution to every human problem - neat, plausible and wrong" (Mencken, 1920)
Threat assessment: what if a given technology is wielded by an insane king? ...because all things are eventually... =3
And that's how it's going to be. No matter how technically feasible the idea will ever be, it will never materialize, because the weaponization potential cannot be eliminated.
That said, large scale concentration could still be extremely distributive on a regional scale.
(Speaking realistically, it would not be a weapon. These things take acres of antennas to collect power from.)
Ok. Now imagine you redirect the beam to a random substation somewhere. What's the likelihood some of the transformers will fry? Or you point the beam at some cellular phone network towers?
Russia is at war right now, and they have lots of antennas pointing up, both for anti-air defense and for electronic warfare. All those would be immediately vulnerable to a concentrated power beam coming from the sky. How likely are they to say, "sure, no big deal, as long as you promise to only use that stuff for power generation, we are totally, absolutely fine with it" ?
In other words, the weaponization potential can be eliminated, and doesn't exist in lots of proposed designs.
So you're saying it'd make for an excellent cover story?
Besides, I've always been annoyed that Goldeneye wasn't real. Not so much Under Siege II.
Call it five to ten million metric tons, if we're using ultrathin kapton with sputtered aluminum. Launch costs alone would be in the upper billions to low trillions, combined with construction and maintenance, probably 1-2 trillion as a lowball estimate.
N.B. this only reduces power by a factor of 0.1%, about 1 W/m^2!
Much easier on the ground, too, because you don't need to invent even one single new tech — not even better superconductors because even aluminium will work if you make the "wire" thick enough (scare quotes because, by coincidence, the circumference of the earth, 40,000 km, almost perfectly matches the conductivity of aluminium, 3.8e7 S/m, and you get a 1 Ω line from a 1 square meter cross section, which is a pretty thick "wire").
Plus, once it gets down from a space elevator, you then have to distribute it around the ground anyway.
I'm not saying this will never happen (10% odds Musk tries it), but I don't see that being possible without a single world government, as whoever controls such a system will definitely never fear ICBMs or hostile aircraft.
Put an ablator on the nose of the ICBM. As it approaches burn-through the warhead salvage-fuses. Your defenders have EMP issues, but let's assume they can shield against that. The problem is now the sky is full of electronic ghosts from the first detonation. Pretty soon another warhead comes along through that ghost-filled sky. The defenders have a much harder time locating it accurately enough to fire. And, once again, when it's going to burn through it salvage-fuses. The sky gets worse.
You can stop any given missile. Stopping a whole string of them is quite another matter.
(Same as an aircraft pilot beating an incoming missile. Do it right and you can use the missile's speed against it, forcing it to make a turn it can't. But now you're out of position and can't do it against a second missile coming in some seconds behind.)
Sensing may still be a problem today, especially as stealth is also improving, but detection in general is much easier than it was in the Regan era.
As for conversion: probably some kind of PV, actively cooled.
During takeoff a 747 consumes power at a rate of about 90MW. Having something outside the plane, whether in orbit or ground-based, pumping that much power into the plane while I'm in it, sounds quite alarming. Not to mention issues with aiming, power loss, etc.
To power a plane with renewable sources, it seems most practical to generate power on the ground and use that to produce synthetic fuel.
/s
Ah, he’s European.