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Space Energy for Planet Earth

March 14, 2015

This past week saw an advance in our long journey toward energy from spaceAs I have argued, and depict in my Frontera series, energy from space is our only hope for long-term protection of our home planet.

The idea of beaming energy from solar collectors was just that–an idea–back in the twentieth century. But Japanese industry takes it seriously. Mitubishi just reported a significant advance in technology. They managed to transmit 10 kilowatts via microwave across 500 meters. That may not sound like much, compared to the 36,000 km distance that will be required from a geostationary satellite. But it’s an important step forward.

Why is space energy so important? Because all energy use generates waste heat–more and more of it, as more of us do more stuff. And fundamental physical laws limit the rate at which our planet can get rid of waste heat.
Even before the theoretical limits kick in, we can see how upscaling any Earth-based power supply eventually brings disaster.

Solar. Solar power works great on a local scale–every home should have a few solar panels. But scale it up to power cities? Cover the Mohave desert? Black absorptive panels replace white reflective sand. It turns out that large-scale solar may cause half as much global warming as burning carbon fuels. So the planet cooks a bit more slowly. Not a solution.

Geothermal. Geothermal works great to heat your home–even in rural Ohio. We all should go out tomorrow and install geothermal. (After my papers to grade.) But on large scale? Remember when Germany and Switzerland were putting in giant geothermal bore holes. They caused earthquakes.

Wind. Wind is a promising solution for many local areas, from New England to Antarctica. Get used to the turbines–they look as decent as telephone poles. But larger scale wind farms will actually disrupt atmospheric currents, with unknown effects on climate.

Nuclear. Yes it’s clean now, and it’s cost effective–so long as you ignore the next 10,000 years of waste site containment. If today’s ISIL bulldozed the 3,000 year-old Nimrud, what will future crazed groups do?

“Clean” coal, oil, natural gas, fracking. Anything with C in it ends up as CO2. And half of fracked gas escapes, methane, an even more potent greenhouse gas.

Energy in space is where we’ll have to go. And more–we’ll have to spend it there, too, putting all the heat-generating factories there to build our “stuff” and ship it down the gravity well. So let’s get started now.

Looking forward to seeing some of you at ICFA in Orlando.

  1. Alex Tolley permalink
    March 15, 2015 12:34 am

    One of te main issues with SPS is cost. At this time it is nowhere near cost competitive with other power sources. Hopefully in the future, this will change.

    We should also remember that SPSs don’t need to just beam power to Earth. They can be used to power spacecraft too, which will help to open up the solar system.

  2. March 15, 2015 9:20 am

    But doesn’t this also heat the planet? Every bit of energy used becomes entropy, or waste heat, and there has to be some inefficiency in the transmission where we’ll be warming the receiver “lily pad” in your illo, and the atmosphere all the way in between.

    • March 15, 2015 11:31 am

      Yes, energy beamed down will be lost to the atmosphere. That is why it’s not good enough just to beam the energy down; we’ll also need to put the biggest energy users out in space.
      Local solar and geothermal are great to keep a house warm. But the manufacturing plants need to go out in orbit–where they get powered directly by the solarrays, without air inbetween.
      Transportation is a question. Will there be permanent solar-driven planes that never leave the stratosphere? With taxis up and down?

  3. Alex Tolley permalink
    March 15, 2015 7:08 pm

    Beamed power is about as environmentally clean as you can get. That buys you a lot of benefits. One can also compensate for the extra solar energy concerted to heat by using similar technology to reduce the insolation to some extent, offsetting the beamed power heat generation. You can also increase global albedo as another approach.

    In the long term, SPS make the most sense for our energy options. Effectively inexhaustible.

  4. March 17, 2015 3:13 am

    The CO2 cost of putting 1kg of solar panel up there (burning at least 25kg of fuel, so around 75kg of CO2) is pretty bad. Can this generate enough energy over its quite short lifetime (space is a very harsh environment for technology) to make up for this?

    If the concern about solar power down here is that we would absorb too much solar energy, otherwise reflected by the sands, I have a great solution – since we have the beaming technology, why don’t we just beam all the excess right back up? Then the manufacturing plants in orbit can get a planet-size amount of power, rather than what a few paltry space panels can provide.

    • March 17, 2015 9:27 am

      Great questions!
      Putting the panels “up there” will cost; but I think panels can last longer than that. We need self-regenerating materials, and eventually, we need to build them in space, on the Moon or from asteroid material.
      “Beaming back up” is a nice idea (refrigeration?), but thermodynamics gets in the way. How do you collect all the waste heat, without spending more?

    • Alex Tolley permalink
      March 17, 2015 10:59 am

      @Ivan – the answer is that the output from an SPS over 10 years provides approximately a 10:1 payback in energy to launch the panels based on your CO2 estimates (assuming a modest 10 year life time of the panels before replacement). This calc is based on the energy of combustion of methane, the energy delivered by the SPS with around 25% efficiency of conversion.
      This also ignores secondary benefits, such as replacing fossil fuel burning and induced climate warming. Viabi;ity of SPS is primarily dependent on low cost space launchers and ortital transfer vehicles. Harnessing the sun’s output is the only way to power a solar system wide, long term civilization with the energy it will need.


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