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34C3 - Saving the World with Space Solar Power

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    34C3 preroll music
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    Herald Angel: The next talks – actually
    two talks – will be about, somehow about,
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    saving the world and saving the
    environment. We will have two different
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    ways of saving them and the first talk is
    "Saving the World with Space Solar Power".
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    It's held by Stefan and Anja and they work
    as space engineers in Berlin at the
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    Technical University. That talk will be
    followed by another approach which is
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    introduced to you by Christoph. He has a
    PhD in theoretical physics and his former
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    work was he was working with higher loop
    perturbation theory and supersymmetric
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    yang-mills theories and now he is doing
    airborne wind energy and that will be his
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    talk also. Please give the three of them a
    warm applause!
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    Applause
    Anja Kohfeldt: Yeah hello! As you have
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    heard today we are trying to save the
    world with introducing you to two very
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    different approaches of sustainable energy
    generation. We are three, the three of us,
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    and we start with Stefan.
    Stefan Junk: Yeah hello everyone. Thanks
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    for having us here!
    Anja: And me with our talk about space
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    solar power. Of course we have an outline
    and I will start the introduction with
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    showing you this very nice picture. Here
    you see the earth at night also known as
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    the black marble. It's a very interesting
    picture because it illuminates you or
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    shows you where people live or at least
    where people have electric energy. But
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    there is more information in this picture:
    When you start comparing these pictures
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    from different years, you also can see how
    certain regions are developing. And you
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    also see where suddenly it gets dark,
    where there has been a catastrophe or a
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    war or something like that. So the
    availability of electricity is an
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    indicator for human development. We still
    have an increasing amount of power. This
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    is also something we can see with that
    picture. But, unfortunately, currently
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    this power demand is largely covered by
    fossil resources. So yes, we need
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    definitely renewable sustainable energy
    such as solar power, wind parks, water
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    plants or even other solutions. The thing
    with terrestrial bound energy plans is
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    that they are bound to a certain location
    on earth, normally, so you either need to
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    decentralize them having a lot everywhere
    or you need a lot of the transfer
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    infrastructure. The other thing is –
    especially when thinking about a wind or a
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    solar power – that the availability is
    very varying and bound to certain
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    conditions. So you need to store the
    energy. When coming, when talking about
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    solar energy of course I mean we have the
    day/night cycle, we have the atmosphere,
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    so we have weather interferences. So why
    not go into space? There are some selling
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    arguments – or some really selling
    arguments – about space solar power: As I
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    already said it's sustainable, because
    it's sun powered. Space generally is very
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    very large, so we can build quite big
    structures without covering any space, any
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    area on earth. We are, it is possible to
    have some sunlight on our satellites up
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    there all around the clock. And we don't
    have an atmosphere, so there is no
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    weather. So space solar power promises to
    have an unlimited, constant and
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    predictable energy source. That's cool!
    Good! In addition, we don't need that much
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    infrastructure to distribute the power on
    earth. For example if you could compare
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    that to a huge solar theater for example
    in the Sahara, you would need a lot of
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    cables in order to get the power for
    example to Europe. This comes with some
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    problems. But also if solving the problem
    of power transmission, you can get energy
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    to very very remote locations on earth and
    you also can get the energy there quite
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    quickly. And of course the intervention in
    the landscape is … let's call it minimized
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    to a certain way. This concept of space
    solar power actually isn't that young.
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    It's there's a pattern from Peter Glaser
    from the 70s who already proposed a method
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    and apparatus for converting solar
    radiation to electrical power. And here
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    you see – you yes there's a small red
    spot, I'm not sure whether you can see
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    that – but you already see that he
    introduces all the components that are in
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    need: Of course we need the earth, we need
    some large area for solar, for sun
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    collection and we need some some antenna
    in order to transmit this power. Since the
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    70s these concepts were actually discussed
    all along. Since then they where
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    discussed. And the state of the art
    approach for that is called SPS Alpha
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    which stands for "Solar Power Satellite by
    means of Arbitrarily Large Phased Array".
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    It's the best-documented approach in that
    area which comes with a phase one study
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    financed by NASA in 2011 and 12, and they
    suggest a satellite structure based on the
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    geostationary orbit which is non moving
    gravity gradient stabilized. It's
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    collecting the sun with a very very large
    mirror array and a transmitter power with
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    a microwave beam. It looks like that for
    example – or it could look like that, like
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    a whine glass. It could look like a
    puddle, but there is three main components
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    here: So we have the Sun Reflector Mirror
    – this is this very very large shape –
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    these sun reflecting mirrors are made of
    actually solar sail material so extremely
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    lightweight although they are so big. The
    core piece of this installation are the so
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    called hex modules which you see here and
    they host both the solar array, the solar
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    panels and the wireless power transmission
    modules. We come to that later. And then
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    of course you also need the structure
    which holds everything together. In
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    addition to that you need some support
    structures like little robots combining,
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    fixing, exchanging modules and so on, but
    they are not further discussed yet. But
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    the NASA approach isn't the only one.
    There's also an approach from from JAXA.
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    This is a Japanese Space Agency. They call
    their approach tethered SPS. It's also a
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    gravity ground stabilized approach which
    you can see here. The idea is basically
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    the same but they don't have the mirrors.
    Their selling argument is: You know our
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    system is so simple, we're sure it will
    work somehow. But they also say that it's
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    not as efficient as the other approaches.
    In addition there are Japanese scientists
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    involved in the SPS Alpha study. But what
    I think is most interesting there are also
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    a lot of Japanese approaches driving
    forwards the wireless power transmission.
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    Then there's a new – quite new – approach.
    This is from the Chinese space agency of
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    CAST and they suggest a Multi-Rotary
    joints SPS, which you can see here. So
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    here in this the yellow spot over here
    also is the transmission antenna. But they
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    have their solar arrays bound in this
    structure which is approximately 10
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    kilometers wide and they adjust the
    position of their solar panels according
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    to the sun position. So this is how they
    try to increase the efficiency. There's
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    also a paper from Europe which is quite
    old but I'm not aware of a current work on
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    European ground here. If we summarize some
    of the core parameters of these three
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    documented or still discussed approaches,
    we come to this nice table. So we are
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    talking about a power transmission between
    1 and 2 gigawatts. These entire structures
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    have a mass of about 10,000 tons – metric
    tons – or even more. Yes the Japanese
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    approach the antennas are quite big. We'll
    come to that later. This comes with a
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    certain energy density, but the total
    efficiency of this of these approaches are
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    calculated – and there's also a little bit
    of like a small wish list included. This
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    total energy is in the range of more or
    less 20%. I put a question mark behind
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    this 25% of the JAXA approach, because
    they even said that they won't be as
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    efficient as the others are. So don't take
    this number too serious. Maybe we must
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    calculate it. Yes. With that with these
    three approaches, I would say problem
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    solved, isn't it? Applause
    Stefan: .......concepts. But there are some major
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    challenges we want to point out here. At
    first this is the attitude in orbit
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    control so this station is in the
    geostationary orbit. There are several of
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    the TV satellites doing the same and it's
    working quite well, but these TV
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    satellites are about 1.8 metric tons and
    this station we're talking about is about
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    10,000 tons or 9 to 25 thousand tons, so
    this is a huge difference. In the
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    geostationary orbit it's not a big deal to
    rotate. It's very slow. So we just need to
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    point to watch the earth to hit the
    designated point on earth we want to
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    transfer the energy to. And then we have a
    phased array antenna, so these are these
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    little modules you saw before to form a
    beam which points exactly to the receiving
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    point at the earth for the energy. Another
    point is the the orbit control. This means
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    the distance from Earth and the speed the
    station is traveling with. This is another
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    point. This is already for TV satellites a
    little bit difficult to do. And now we
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    have, as I said, this one thousand metric
    tons station to lift up to the right
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    distance or to accelerate. There are
    several forces trying to push us out of
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    the exact orbit and we would lose the
    exact spot we want to point at. And there
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    is the lunar gravity, the sun gravity or
    solar gravity, and the flattened poles of
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    the earth. You know the earth is not a
    perfect sphere, is more imperfect, is more
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    like a donut. You have flattened points at
    the poles which disturb the gravity field.
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    There are solar winds and radiation
    pressure. Solar wind comes from the Sun.
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    These are particles hitting the station
    and pushing it out of the orbit. And there
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    is radiation pressure, the same that comes
    from deep space. This station is huge. So
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    you have a huge surface. This is different
    from the most TV satellites. So we have to
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    overcome this. Luckily, we have nearly
    unlimited energy with this station, and we
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    can use electrical thruster. So we don't
    need any fuel or propellant. Maybe a
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    little bit propellant to bring up to the
    station. Another point is the power
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    transmission. I think this is the most
    critical point. As I said, it's in a
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    geostationary orbit and I have an example
    here. I chose the MR SPS because the
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    numbers are so round, but most of the
    concepts are similar, as you saw before.
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    So I think about a 1GW output station. And
    in the picture on the right and chopped
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    you can see the yellow point is the
    standing antenna. This would be about
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    1.000 meter in diameter. So this is about
    110 soccer fields placed in space. This
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    antenna is sending a microwave beam with
    2.45 GHz or 5.8 GH. These frequencies are
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    chosen because of the low attenuation or
    damping in the atmosphere. We want to
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    transfer the most energy. And this beam
    hits at the receiving antenna, or in the
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    literature called the Rectenna. And this
    Rectenna is going to be about 5.000 meters
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    in diameter. This is 2.750 soccer fields,
    or about 20 times the Messe Leipzig area.
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    So you can imagine this is a big deal. If
    you think about wind parks are ugly, then
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    maybe you think about this area. OK, so
    you can read more about if you like in the
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    references. We have a link to this. Now, I
    guess you wonder about the efficiency of
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    this. Anja talked about it already a
    little bit. I have the subsystems here
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    including, and I think the most important
    part is this microwave beam. This is the
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    third position, and this is actually not
    tested. So this is just a calculated
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    number. These 85% or 90% to 95% is just
    from the studies we read. Current tests
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    are more in the area of 1% or a few
    percent. And most studies are not really
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    certain about the total efficiency. So we
    have 18% to 24% with these numbers. And
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    from other studies we have 13% to 25%. So
    this is most calculated. So now you would
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    wonder if wouldn't laser work for this? Or
    microwave beep sounds nice and you have
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    this nice receiving antenna. But a laser
    would be much smaller, I guess. So, yes,
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    basically you could use laser for this.
    And it would have a much higher energy
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    density. So you could hit a really smaller
    spot on the earth to receive the energy.
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    You don't have this 5 kilometers receiving
    antenna. But most of the research
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    institutes don't want to talk about
    lasers. I think it's just a little bit too
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    obvious that you have some …
    Laughter
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    Stefan: OK, so this is the most technical
    things, I think.
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    Anja: The other question is, who is gonna
    pay for that? And if we talk about this
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    extremely large structures that have to be
    built, and since they're also are meant to
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    be in the geostationary orbit where we
    have a certain radiation force, and we
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    want these components to operate for quite
    a long time, they are usually quite
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    expensive and geting all the certification
    for sending them up there is also very
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    expensive. Somehow the SPS Alpha approach
    has thought about that, and they are
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    aiming at, although the numbers are
    varying very much, at a material cost of $
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    250 per kilogram, which still is some
    billion dollars. And it is also a wish
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    list. So they are aiming for this number
    in their third approach where they think
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    that they already have the mass
    production, and have the certification,
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    and the engineering and development cost
    all covered up already. There's another
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    thing and this is the launch cost. So we
    are talking about a structure which is
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    maybe 10 thousand tonnes large, or heavy.
    Again, the SPS Alpha guys, they hope that
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    they could launch a kilo for $600 into the
    low-earth orbit, and continue from the
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    low-earth orbit into the geostationary
    orbit with electrical truck trusters. OK,
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    maybe if the BFR rocket will be available
    for the price of the Falcon 9, maybe. But
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    this also would take some time. Just a
    reality check right now, for the prices
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    the SpaceX provides on their site, the
    Falcon Heavy which was erected today, I
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    don't know whether you have heard that, so
    also the Falcon Heavy has not flown yet.
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    But SpaceX hopes that they could sell the
    the Falcon Heavy for 90 million dollars in
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    order to lift 26 tons into geostationary
    orbit. But that would be approximately 400
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    launches for such a structure as the SPS
    Alpha, and also would cost some tens of
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    billion dollars. Additioned to that, there
    are some other costs like the initial
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    orbit installation cost which comes with
    11 billion dollars, and an operation of a
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    100 million a year. So it's quite
    expensive and probably this is also one of
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    the reasons why we don't have space solar
    power, yet. But still, I mean, we have
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    technical problems, this is just money,
    maybe it's also solvable, isn't it?
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    Stefan: Yeah, so you know about the
    concept, you know about the challenges,
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    and let's assume we can overcome these
    challenges, and someone is funding this
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    big station. I think, there are some
    considerations about if we want to do
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    this. And at first, so this beam is, you
    need a precision of about one 10.000ths of
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    a degree plus minus to hit the spot at the
    earth. So this is like you want to hit a
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    hazelnut of a 100 meters from a station
    flying with 3 kilometers per second. If
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    there's something goes wrong and the beam
    is hitting the wrong spot, maybe, you
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    know, it's not a good idea. Or if some of
    the antennas are not working well, the
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    beam is not forming right, and it's
    straying somewhere. So this is one point.
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    Let's assume everything works well, and
    the beam is still going through the space,
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    and it's going through the atmosphere. And
    there are some other satellites going.
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    Maybe, for an accident, they go through
    the beam. What happens then? Or, if you
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    can't, or by accident, and the airplane
    goes through the beam. So it's not even
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    allowed to turn on your phone on the
    airplane. You can imagine what happens if
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    this beam with 50 watts per square meter
    hits the airplane. I don't want to sit in
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    this. And then you can't avoid the
    animals, birds, insects, whatever go
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    through the beam. And maybe you have a
    same imagination like I have, or we have.
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    Soft laughter
    Stefan: And it looks a little bit like
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    this maybe.
    Laughter
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    Stefan: It sounds pretty scary, I think.
    Doesn't it a little bit sound like an
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    energy weapon? So we thought about: OK 50
    watts per square meter; it's not like a
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    nuclear weapon, but still it could harm a
    lot. There is a high energy density, and
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    you can really fast readjust this beam. So
    you can point it in 1 second to the
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    receiving antenna, and the next second,
    you can just point it to some city, and a
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    second later, you point it just back. It's
    really fast to change. It's not really
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    defendable. I mean, you can sit in the
    bunker and try to hide, and maybe put your
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    aluminum hat on. After all it's useful.
    Applause
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    Stefan: But still, this thing is 24/7 on,
    so it could hit your bunker all the time.
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    And last year, there's a lot of interest
    from military institutions. So this is, I
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    think it's a bit scary. OK. And then you
    would ask: But it's legal to install this
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    kind of application? So basically, yeah.
    You see, there is already the United
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    Nations Outer Space Treaty. It was first
    signed from the Russian Federation, and
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    the United Kingdom, and the United States.
    And now it's in the United Nations
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    treaties and most of the other countries
    signed it, too. It's about all the
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    activities of States in the space. What
    does it say about this case here? And it
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    says, there are no nuclear weapons or
    other weapons of mass destruction allowed
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    in outer space. As always, there's a
    backdoor. If you install a military object
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    in outer space with a scientific reason,
    then it's allowed again. So another point
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    is in this treaty you must not influence
    the earth environment at all. There are no
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    real studies about this. I have a feeling
    it's going to influence somehow the
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    environment, but I'm not sure about this –
    I'm not a lawyer. So finally this all this
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    funding and this technology and the
    knowledge is necessary, so it's only
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    possible by some few states to build
    this. And how do you prevent that certain
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    leaders of states or whoever's want to
    build this is misuse this technology. So I
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    can't give you an answer on that, but I
    think there are some who shouldn't have
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    this. Yeah and you maybe you can think
    about this after the talk. And now we have
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    some take-home words for you from Anja.
    Anja: So yes, the concepts are existing
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    and we don't say that they should not be
    discussed and that they are entirely evil.
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    They it's technologically feasible – at
    least that that's proposed some studies –,
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    but I mean it's still challenging: The
    technology is not there yet, but the moral
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    questions are still open. So yes it's
    still pretty science-fiction and as I said
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    we don't say it's we should not do that at
    all, but at least we should think about it
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    and be critical with this kind or also
    with other new technologies. So but right
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    now, maybe, we should think about: Is
    there another solution to this energy
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    problem? Maybe a more realistic, maybe a
    less problematic one I mean?
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    Interrupted?
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Title:
34C3 - Saving the World with Space Solar Power
Description:

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Video Language:
English
Duration:
25:43

English subtitles

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