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The universe provides so much power, yet we struggle to tap it and crave more.
Instead of being powerless, let's get off Earth and conquer space.
So today we continue the Upward Bound series and our look at how to get into space cheaper
and easier, and what we can do up there once we can place stuff in orbit more cheaply.
Of course, if you're up in space for a while you'll need a reliable power supply, and
that generally means either solar or atomic.
In terms of the latter, fusion is a good option if we can ever get it working, but fission
is not something folks want in orbit overhead in large quantities.
The big weaknesses of ground-based solar are that it's useless on cloudy days and at
night, but this is an area where being in space is actually a major advantage.
When we refer to the dark void of space, we're being more poetic than accurate.
Space near Earth is constantly lit brighter than the noon-time Sun, and indeed you'd
have to get out beyond the Asteroid Belt before solar stops being as effective there as it
is on most of Earth.
The equivalent of darkness in space depends on your distance from the Sun, or if something's
in between you and the Sun, placing you in the object's shadow.
While any object in a classic Low Earth orbit is spending a lot of its time in the relatively
large shadow of the planet, as you get further away less of your orbital path is in that
shadow.
Additionally, various non-circular obits, or locations like the Lagrange points, have
little to no time in shadow, eliminating most or all of the downtime experienced by solar
panels situated on the Earth.
As for wearing down over time, solar panels on Earth have to contend with dust, rain,
snow, hail, sandstorms, thermal fluctuations and other weathering, none of which are present
in the vacuum of space - and, needless to say, there are no clouds there either.
The total benefit is about seven times more kilowatts-hours per year from a given Photovoltaic
solar panel.
Perpetual lighting also eliminates most of the need for batteries.
All of which makes solar an excellent choice for space.
It's much more attractive than on Earth, and of course we're interested in getting
that energy to Earth, whether beamed down or otherwise, and eventually to other places
in space.
This idea has been looked at a lot for decades, but is becoming increasingly feasible now
that launch costs are plummeting.
For this to be practical though we have to overcome certain issues, and we should start
by laying those out.
First and foremost, getting stuff into space is expensive.
Doing that cheaper is, after all, what this series is mostly about.
A solar panel in space might be several times more effective than one on Earth, but if you
needed to spend hundreds of times more money to get that panel up there, while it remains
useful for powering things up there, it wouldn't really make sense to beam it down.
Not when you can far more easily deploy and maintain conveniently-sized arrays of panels
down here.
But down here you have to add energy storage, which is several times more expensive than
PV panels, if you want to compare apples to apples.
Second, there is the question of how you beam that energy down, and this comes with a lot
of problems.
For instance if you're beaming down with a visible-light laser, it still has to go
through all that air and clouds.
There is also an additional effect called thermal blooming that causes laser light to
be absorbed by the atmosphere over any significant distance, at least for frequencies that interact
with the atmosphere.
You also lose energy at every stage of the process, as you convert sunlight to electricity,
then into lasers, then down to Earth through the atmosphere, into a collector there, and
back into electricity again.
We'll be looking at these problems, some solutions, and some alternatives to visible
light today in greater detail.
But that brings up a third issue, which is safety.
A big giant laser is also known as a death ray, and with any power-beaming system, you
are directing a lot of energy into a potentially small place.
This is a serious problem if your beam goes off target from the collector, and over to
a city, be that as a result of an accident or deliberate action.
So we will be looking at ways you'd be trying to make one safe to use.
It is also worth remembering though that a giant laser in space also has some handy uses,
like blowing up incoming asteroids or space junk, not to mention it's a great way to
push spaceships up to high speeds, so we will also be discussing some of the non-terrestrial
uses of power-satellites later on, though our main focus is getting energy to Earth.
At this point, we have to start considering scale.
At present, humanity uses energy, from all sources combined, at an average power rate
of about 18 terawatts, 18 million megawatts, not including the solar energy used by photosynthesis
and evaporation.
That's about 2400 watts per person, day in and day out, every day, and while we are
getting a lot more efficient with power usage, we also have a lot of people in developing
regions who don't use much yet and hopefully will in the future; hopefully not too much
or too soon though because our main method of power generation has concerns about heating
up the planet.
We should start with a note there then, as folks often worry about power satellites heating
the planet by adding more energy, which of course they do.
The thing is, it isn't our direct use of energy that's heating the planet.
While we use energy at an 18 terawatt rate, Earth receives about 10 thousand times that
energy from sunlight.
The extra heat we add would be trivial on its own.
The concern is with greenhouses gases being released and trapping an additional fraction
of the solar energy, not the extra energy we consume directly.
However, power satellites are solar-powered, so were that a concern you could just have
them block incoming light to Earth, cutting down on how much reaches us.
Not that you'd bother, since you could easily use a mirror to do the job, which is cheaper,
thinner, and a lot less complex for such a geoengineering purpose.
18 Terawatts is a huge amount of power, and even our most efficient experimental solar
panels, those still being worked on in the lab, would only get about 600 watts per square
meter, in orbit.
To get up to 18 Terawatts, you'd need 30,000 square kilometers of our best panels, or a
single panel 100 kilometers in radius.
That wouldn't include any losses in transmission either.
Fortunately, we can assume high-efficiency panels are used, as the single biggest cost
to deploying a power satellite is launch cost, which we'll discuss in a moment.
Solar panels will continue to get lighter, cheaper, more durable, and more efficient
as times goes on.
But for the moment, if we use our top end figures for performance, we can do a panel
with thickness as low as 2 millimeters, massing only about 2 kilograms a square meter and
generating about 600 watts per kilogram in space, constantly.
To get 18 trillion watts out of 600 watts per square meter would require 30 billion
square meters or 30,000 square kilometers, at an approximate mass of 60 billion kilograms.
At current launch costs, that could run nearly a hundred trillion dollars, and doesn't
include any losses in transmission or other associated equipment.
However, these would likely have a lifetime of 20-30 years, and since the energy sector
is several trillion dollars a year, with estimated figures varying widely, spread out over 20-30
years this would already be approaching a competitive cost.
As manufacturing continues to improves and launch costs drop, this could get us into
the economically feasible zone for power satellites rather quickly, and now would seem a good
time to start prototyping to see if this can be made viable as launch costs drop.
However, this is SFIA so we're less interested in the next decade then the next century,
and the earlier episodes of this series discuss many launch systems that we already have the
tech for that can drop launch costs to a tenth or even a hundredth of what SpaceX's Falcon
Heavy can do.
As a reminder, stuff like Jim Powell's StarTram or Keith Lofstrom's Launch Loop or Paul
Birch's Orbital Ring are not all that high tech, they just have a big upfront cost, many
billions of dollars, which only looks big since we don't actually spend our relatively
small space budget on launching truly massive things.
Our annual ground to space launch volumes are tiny compared to a single day's traffic
through any major airport, and same as you don't build an international airport next
to a small village, you don't build these kind of launch systems till you are ready
to up your game and a launch a lot more, not because they are particularly high-tech.
When you are thinking about replacing a multi-trillion dollar sector of the economy, options like
those launch alternatives suddenly become much more attractive and profitable.
See those episodes for details, but even the most expensive of them are offering launch
costs smaller than the production cost of the power satellites.
It's also worth noting that much of their operational cost is electricity, which needless
to say is altered when you're launching gigawatt-sized power generators into orbit.
Additionally, most of the weight of a panel is still silicon, the second most abundant
element on the Moon's Surface, right after oxygen.
Nor are solar panels incredibly tricky to produce, especially when mass and efficiency
isn't much of an issue, and the moon is close enough for us to do remote operations,
so any factories there don't need much personnel physically present to operate, or sophisticated
artificial intelligence.
Before we move on, I should also note that photovoltaics, turning photons into electricity
the way a solar panel does, is not the only way to turn light into electricity.
We could, for instance, just concentrate light on a liquid in pipes so it heats up, boils,
and turns a turbine… a Thermal Powersat, like the prize-winning Flowersat design.
This is a viable way of generating power, provided the light is sufficiently intense,
and sunlight can be made incredibly intense.
Thermal methods are how most power generation occurs, using an atomic or chemical fuel source
for heat instead of sunlight.
If you can't make cheaper solar panels, you can always use a bunch of thin parabolic
mirrors and non-imaging light funnels to focus light on some substance to heat it and drive
a fairly standard heat engine.
Getting rid of the waste heat during the cycle is harder, when you can only remove heat from
a system in space by radiating it, but you can still use cooling by conduction and forced
convection inside it.
The back side of all those mirrors can also be used for radiating surfaces, too.
Even surfaces exposed to sunlight can potentially be used to radiate waste heat, by use of wavelength-selective
surfaces.
Okay, so we can collect it up there, but how do we get it down?
The traditionally suggested method is microwaves, in a beam, which worries folks a bit since
we all use those to heat up our food and they'll heat up a person, or a city, just as well.
We'll get to the safety issues in a bit.
First, why microwaves?
They are not the only option, but in terms of our spectrum, the atmosphere does a very
good job keeping out virtually all gamma and X-ray radiation, and the overwhelming majority
of Ultraviolet too, so they're not great wavelengths to use to get our energy past
the atmosphere.
Visible light goes through pretty well, obviously, but much is still lost even in an open sky,
and clouds obviously are murderous on visible light transmission.
Don't discard it just from that though.
Power satellites all around the planet can just re-target their beams to collectors not
obscured by the clouds, and only on the cloudiest days would we not have clear sky windows which
some powersats could use to get an angle on the ground-based collectors.
I should also note that we always want other power generation methods and energy storage
in any power grid anyway, so that some ground based collectors being blocked by clouds sometimes
is not really a deal-breaker for visible light.
Nor do you necessarily need to beam light down as a laser.
A big parabolic dish concentrating light on ground-based collectors is an option, too,
which gets around thermal blooming that happens when a high-powered laser enters a medium,
like air, that's absorbing some if it and heating up and scattering the beam a lot.
This, by the way, is a really big issue for using ground-based lasers to intercept missiles
or using lasers for ultra-high-bandwidth data transmission over long distances.
Since part of the point is to get power down at night, using the visible range of the spectrum
in broad diffuse beams could cause a lot of light pollution, though in some places this
might be advantageous.
Of all the spectrum, radio waves are the ones that basically ignore the atmosphere and clouds
the most over all, and microwaves, which are shorter than radio waves in wavelength, which
is where the name micro comes from, are quite good at going through our atmosphere, clouds
or not.
You might wonder about the danger of this, but if you are accessing this episode over
a wireless network, I should note that those use microwaves too and the same frequency
as your microwave oven.
There's nothing very special about that frequency by the way, it just in a small band
the FCC leaves free for non-broadcast purposes.
Equipment operating at these frequencies is also pretty efficient at converting between
electricity and microwaves, especially compared to lasers.
You can do better than 75% with a magnetron converting electricity into microwaves whereas
laser efficiency, as much as it's improved, is still generally more like 50%.
Our best new laser designs can almost match that, but historically, lasers have been much
less efficient.
Microwaves remain better, but not by the same overwhelming margin.
Here's the thing though, a Rectenna, a specialized type of antenna for absorbing these microwaves
and turning them back into electricity, has an efficiency of at least 85%, much better
than our best solar panels.
This means that any side-effect environmental heating from beamed-in microwaves will be
much less as well.
Now as to safety concerns, the general notion is to beam the energy in at about 100 Watts
per square meter, non-coincidentally what OSHA says is the maximum safe workplace exposure
amount.
To get 18 Terawatts, and keeping in mind 15% is lost in conversion by the Rectennas, would
require about 200,000 square kilometers of rectenna collector surface area.
Sounds big, and indeed it is, that's about the size of Nebraska.
Not that you'd be putting them all in the same place.
More to the point, that doesn't really seem much better than covering huge chunks of land
with solar panels.
Of course you could just increase power density, and fence the place off, but you'd still
be blowing birds away left and right and potentially have a doomsday weapon.
Though, realistically you could ramp the beam intensity up an order of magnitude without
producing too much of either problem.
Birds would tend to avoid them as uncomfortable or be able to swoop through before being hurt.
This is mostly just raw heat damage like being too near your fireplace, after all.
However, the neat thing about a Rectenna is that you can use multiple of them to cover
a wide area, and this area is not entirely lost to you, as a Rectenna is a mesh more
like chicken wire than an opaque glass panel, and tougher too.
Indeed you could beam it right down on a city and provide wireless power, though obviously
you'd want to be careful about concentrating it too much.
Incorporating solar panels into roads and parking lots obviously has extreme issues
with durability, while sticking a layer of chicken wire over farm fields or grazing land,
isn't difficult, nor is it that hard to concentrate such beams to such sizes and keep
them on target, nor will they torch a fiery furrow through the landscape as they go.
But the optical considerations of microwaves mean that rectennas receiving gigawatts will
necessarily be large, usually several kilometers across.
Safety is easily achieved by having the emitter and collector handshake, and the beam just
shuts off if it goes off target.
I should probably note that an optical version of this, using nanotech and metamaterials,
called the Nantenna, shows promise of achieving a 70% or higher conversion of optical light
frequencies to electricity.
The impact of this emerging technology on solar panels, ground or space based, might
be immense and very near at hand.
Again though, this is SFIA.
In this series, it's only been a few episodes since we were talking about Orbital Rings,
the great big rings around planets for getting into space once we want to be moving millions
of people and megatons of cargo back and forth between space and the ground on a daily basis.
An Orbital Ring is far cheaper, kilogram for kilogram, than any other options and you can
scale it up immensely if you want to, unlike rockets, where that kind of throughput would
also produce enough pollution and heat to mess with your climate.
If you want to do a lot of travel from ground to space, and you love your planet, you should
put a ring on it.
While the massive drop in launch costs is certainly handy, the orbital ring also brings
some benefits from being directly connected to the planet below.
You can run tethers and lines down to the surface without making them of super-materials
like graphene.
Though you may still want to use graphene in particular, since recent improvements are
being made in producing it in bulk, and it's quite a good conductor of electricity.
But the important point is that tethers going from the ring to the planet need only be reasonably
strong, not space-elevator strong, and don't have to be rigid or run in straight lines.
Because of this, they can be built with some extra features in mind, such as transmitting
power, bringing people or cargo to and from the cities near the ring, and can do so without
a lot of the hassle of something like a rocket.
You can't launch a rocket anywhere near a city, or any sort of spaceship meant for
that kind of speed and acceleration, not without damaging the city or even killing people,
so you'd have to commute to a launch pad far from that city and any of its suburbs.
Alternatively an Orbital Ring tether can leave from any terminal in that city as easily as
a train or subway, allowing direct transport of people from a city up to the Ring.
And for that matter, they can also transport up heat, something we might discuss more in
the future, but this is interesting in the context of Ecumenopolises, planet-wide cities,
or their little brothers, arcologies, in that it means space based power generation is actually
better than fusion, because a fusion reactor is still producing a lot of waste heat in
the process of making electricity.
Power plants generally lose over half their energy to heat loss in making electricity,
even before it hits the power grid, where even more is lost to resistance on the lines.
But a solar panel in space running electricity right down a cable to a city, or for that
matter a reactor in space doing the same, is not producing one extra drop of heat on
Earth that isn't in the grid.
So no heat is being produced due to electricity production waste, though of course all that
electricity will end as heat, either in the wires or at your house, it's just not leaving
half or more back at the power plant.
Orbital Rings a major investment, and they also aren't local, you have to encircle
the whole planet.
We do have another option, which can be done strictly at one location, and that is to build
Karman space-towers.
I call them that because they reach the Karman line, which is the generally accepted line
between our atmosphere and space.
Even with our material science today, we can build such a lightweight structure using Carbon
fiber materials.
We might even squeak by without having to resort to newer construction techniques too.
As many of you will be aware though, here at SFIA, we are very much in favour of using
active support systems to build higher and stronger.
See our episode on space towers, and particularly the Atlas Pillar, for how to do that.
As a brief recap, we support the tower by a series of fountains of material propelled
through the tower.
Our Karman towers are lightweight Atlas Pillars poking above the atmosphere with an energy
collector at the top.
Now, the atmosphere does not abruptly end as you go into space.
At the Karman line, which is 100 kilometers up, the air density is about 2.2 million times
less than at the surface.
That's handy for power generation, as we'll see.
Should you have trouble building quite that high, much of the advantage remains from going
shorter, but taller is better.
Atlas Pillars take a lot of power to keep them supported, how much depends on your efficiency
regenerating the momentum of the support material, in theory that could be a 100% efficient closed
loop but we're not there yet and these would use a fair amount of power.
You might ask what is the point of having a Karman Tower that consumes some of the power
it produces when you could just beam the energy to ground instead?
The answer is the energy collector is in space.
Having the collector in space handily gets around a lot of the transmission losses and
other problems we discussed, like thermal blooming, light pollution, hazards to animals,
and that trade off of concentration for safety.
You can skip a lot of the steps by just having big mirrors and parabolic dishes that can
point at a large array of solar collectors fanned out on top of that tower and flood
the panels with as much light as they can handle, and those mirrors can bounce light
to night side collectors just fine as well as filter out any frequencies we can't use
well or which might degrade the panels.
You stick one just north of a city so it never shadows it and run a low resistance power
line down it and now that city has a good power supply and a popular tourism spot, since
looking down from 100 kilometers up gives a breathtaking view of everything for a thousand
kilometers around.
It also has virtually no footprint on the ground, is very safe if there's a power
loss, offers ultra-high efficiency power transfer, and provides direct access to space and a
launch system.
See the Space Towers episode for more on this.
Another thing that having a direct connection between space and the ground gives us is an
ability to deal with the heat produced at the converter.
In space, the only way to get rid of heat is to radiate it away, which requires giant
radiators.
It's also less efficient than using convection and conduction, which are cooling options
only available on the ground.
If we pipe the heat back to Earth, we can much more easily dissipate it.
We can also use the heat as a source of power in its own right, or use it as a way of desalinating
water with coastal Karman Towers.
Come to think of it, I like the idea of a steampunk solution.
We generate steam at the collector and use the steam pressure as part of the active support
of the tower itself.
We also tap it for energy using turbine generators and then pump the cooled fluid back up to
the collector.
The entire structure could be a giant steam engine converting the steam to electricity
as we go.
Traditionally you do this with magnets, launching material up a mass driver that's slowed
down and deflected back by a receiver up top, but in theory any flow of matter works.
So power satellites seems a much more attractive option, and a potential gateway to space as
launch costs drop.
We've talked about many industries that might fuel a snowball effect to help us get
into space, science, tourism, even filmmaking, but which of these can match energy?
A market making up roughly 10% of our global economy, and the biggest bottleneck on greater
prosperity for humanity in this modern era.
Get power satellite operations down to even just near the price per kilowatt-hour of other
existing sources, and it not only could power our homes here on Earth, but our efforts to
make homes off Earth.
And certainly the power demands to manufacture space habitats will be much higher than that
sized for the habitat's ongoing domestic consumption.
So, even if power generation was the first piece of infrastructure built, additional
power could be beamed to construction projects as needed - or even as emergency power later.
Indeed temporary beamed power for space projects, such as mining and construction could be a
major space industry in itself.
And its applications aren't just for Earth and near Earth.
As we'll see next week, when we continue our discussion of generation ships to colonize
distant stars, one of the hardest parts about traveling in deep space is getting up to the
speeds necessary to do it on reasonable timelines and to provide power to those ships, far from
the Sun, but still needing to keep warm and lit for those who dwell inside.
You can beam power out quite a long way, and you can use it to help ships get up to speed.
Of course slowing down is another matter, and one we'll discuss next week in "Exodus
Fleet".
Electricity is the life's blood of all of our science and industry here on Earth, and
will be for those ships too, and fundamentally, as launch costs drop and solar panels efficiency
rises, power satellites can offer us a virtually unlimited supply of electricity without the
ecological problems or supply bottlenecks of our current energy options.
We had to gloss over a lot of discussion of the basics of electromagnetism, induction,
current, heat engines, and other core topics that explain how power generation and transmission
is actually done, and why some of the methods we looked at today are better than others.
If you'd like to learn more about those topics or just brush up on them, then I'd
recommend the Regents Physics Reviews.
Those courses step through basic physics and some more advanced material in a detailed
and professional fashion, never skipping over terms by assuming folks already know them,
but also not dumbing things down either.
Those are available over at Skillshare, an online learning community that focuses on
assembling classes on technology and has courses on everything from basic sciences to a lot
of modern software, and I've been using a lot of their classes on video production,
audio engineering, and animations to improve the content here on the channel.
If you want to improve your skills, unlock new opportunities, and do the work you love,
give Skillshare a try, and a Premium Membership gives you unlimited access to classes like
those.
If you want to join me and the millions of other students already learning on Skillshare,
we have a special offer just for my listeners: Get 2 months of Skillshare for free.
To sign up, go to S-K-L-dot-S-H slash Isaac.
Again, go to S-K-L-dot-S-H slash Isaac to get 2 months of unlimited access to over 20,000
classes for free.
Act now for this special offer, and start learning today.
As mentioned, next week we'll be returning to our topic of Generation Ships to look at
ways to provide them the power they need to cover huge interstellar distances in reasonable
times and to keep their crew alive during those voyages through the empty ocean of space.
The week after that we'll be teaming up again with Joe Scott of Answers with Joe to
look at some of the potential catastrophes humanity might have to deal with before we
can get out and settle the galaxy, and ways we might avoid those, mitigate the damage,
or recover afterwards.
For alerts when those and other episodes come out, make sure to subscribe to the channel,
and if you enjoyed this episode, hit the like button, and share it with others.
Until next time, thanks for watching, and have a great week!
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