Wireless power from space: energy salvation?

Wireless power from space: energy salvation?

Summary: The idea of sending solar power satellites into orbit has been around since the 1970s, but interest has revived in recent years. Japan is wasting no time. The country plans to send its first solar-panel-equipped satellite into space this decade.


Consider this: There's more energy from the sun striking the earth every minute than the amount of fossil fuel used by the world in a year.

Solar power is the most relied on source of clean, renewable energy and ever larger photovoltaic power plants are mushrooming around the world. But there's another way to exploiting solar power, and that is to capture it in space and convey it to the Earth by wireless means using microwave transmission.

The idea of sending solar power satellites into orbit has been around since the 1970s, but interest has revived in recent years. Environmental disasters such as the colossal BP oil spill in the Gulf of Mexico could only work to accelerate support.

DK Matai's report last week about Japan's plan to send its first solar-panel-equipped satellite into space this decade appeared in the Huffington Post. Led by The Ministry of Economy, Trade and Industry (METI) and the Japan Aerospace Exploration Agency, the objective of the project is to first test beaming electricity from space through the ionosphere, the outermost layer of the earth's atmosphere. Matai said that such a satellite could eventually beam Gigawatt-strong streams of power down to earth wirelessly, each enough to power nearly 300,000 homes eco-efficiently. Experts predict this kind of commercial power delivery from space to take 20 years to develop.

Like terrestrial capture, space solar power (SSP) provides a source that is virtually carbon-free and sustainable. The difference is that it bypasses many of the difficulties, including cloudy days, zoning laws, and weathering and degradation in performance. With the satellites positioned in geosynchronous orbit, power collection could occur 24 hours a day. Moreover, delivery of power can be carried out in any type of weather condition when the right transmission frequency is selected.

The challenges facing space solar power are plentiful, and launch cost is chief among them from a practical economic viewpoint. Another hurdle is developing space based assembly techniques to construct arrays. Eclipsing the financial and technical issues are formidable political and societal considerations. A detailed analysis, "Wireless Power Transmission via Solar Power Satellite," lists five more challenges:

1. The mismatch between the time horizon for the implementation of SSP and that for the expansion of conventional energy resources 2. The fact that space power is intrinsically global, requiring enterprise models that give every player a suitable stake and adequate safeguards 3. The potential for concerns over reliability, safety and environmental implications 4. The need to obtain publicly-allocated resources outside the normal purview of the energy community 5. The prevailing mind set which tends to view the future energy infrastructure as an extrapolation of the present one.

In light of these challenges to space solar power implementation, the idea is futuristic now just as it was in the 70s. However, it is now technologically feasible and will eventually become more economically viable. Convinced, DK Matai writes: "The question is not whether we harness power from Space; but rather who will get there first to garner first mover advantage with significant impact on global economic competitiveness."

Topics: Mobility, Networking, Wi-Fi

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  • RE: Wireless power from space: energy salvation?

    "With the satellites positioned in geosynchronous orbit, power collection could occur 24 hours a day."

    I'm not an energy expert, but I don't think you can have both geosynchronous orbit and 24 hour collection of solar energy.
    • RE: Wireless power from space: energy salvation?

      maybe not with 1 satellite, but he did say satellites. Have enough out there and you should be able to collect 24 hours a day.
    • RE: Wireless power from space: energy salvation?

      Quick geometry suggests that geosynchronous satellites would be eclipsed by the earth for a maximum of 45 minutes each day during the spring and fall, but 7 months of the year would be eclipse free.
    • RE: Wireless power from space: energy salvation?

      @TomCarroll Yes, you can. Do the math.

      Hint: Google "diameter of earth" and "Clarke Orbit" - the remainder of the exercise is left for the student as an exercise.
    • RE: Wireless power from space: energy salvation?

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  • Nice misinformation there

    Yes. Sunlight hitting the entire planet each minute is vast, but that's because the earth is big. Sunlight delivers 1 kW per square meter at 1 AU (the earth's distance from the sun). A typical coal fired power plant sitting on 10 acres produces 500 MW of power. A 20% efficient solar power plant would require you to pave over an area 1.5 by 1.5 miles with silicon to get the same power output.
    • RE: Wireless power from space: energy salvation?

      Exactly right, for a power plant. Solar works best if you cover every house and building roof with photovoltaic panels - you can generate a large percentage of your required power without building a new plant, plus you don't have to build new transmission lines to carry the power from a new plant since it's being generated at the point of usage.

      Plenty of problems with solar power, but plenty of benefits too. Solve the problem of energy storage (for times with no sun) and the high cost of the damn panels and you've got a serious contender for delivering enegry independence.

      My favorite solution: Big nukes (2000+MW) for baseline generation, solar wherever it's viable for the daytime peaks. Add in some geo and a little wind (also where viable) and you're good to go.
      • Solar is a great solution for low power requirements

        Where continual energy is not needed. In other words, specialized applications. For pure efficiency, nuclear breeder is the way to go. Of course, with the irrational hysteria surrounding nuclear power, we'll never see it.
    • RE: Wireless power from space: energy salvation?


      SSPs would actually be much more efficient than land based power plants due to 2 main reasons. 1) SSP gather more concentrated light, since the light will be collected before it is diffused by the Earth's atmosphere. 2) The emptiness of space will act as a giant heat sink allowing for more efficient PV panels (heat gain is one of the leading barriers to higher PV efficiencies).
      • The 1 kW per square meter is the amount of

        energy arriving at earth through the vacuum of space. Diffusion by an atmosphere is irrelevant.

        Space is actually a very efficient insulator. Getting rid of heat is one of the major challenges in spacecraft design.

        The laws of physics are immutable. Space-based solar power is just as impractical as ground-based solar power.

        If you want cheap, abundant energy, go nuclear.
      • It is a very poor heat sing.

        @Caffeinated85 <br>The only means of eliminating heat is through blackbody radiation. If that were enough for high heat, we would not need cooling systems in space suits.<br><br>TripleII<br><br>TripleII
      • RE: Wireless power from space: energy salvation?


        I disagree with frgough on the efficiency. The energy available in space > the energy available on earth surface

        But he is very correct about heat. Vacuum is a very good insulator. So you would have to disperse the heat. However converting the waste heat to additional transmittable energy is feasible.

        I think we should pursue solar and continue alternate power sources such as nuclear, fossil, wind, fusion and wave.

        Nuclear though isn't cheap, it costs a lot to build a plant.
  • RE: Wireless power from space: energy salvation?

    The old Sim City had solar collectors, and every so often the satellite would go crazy and drag the beam across the city, causing fires. This would make a great weapon!
  • RE: Wireless power from space: energy salvation?

    Power from space is otherwise known as microwaves. The environmentalists will love that until the first bird fries on the wing. Not to mention the tin foil hat brigade.
    • RE: Wireless power from space: energy salvation?

      Right on the nose. Firing a gigawatt microwave beam (a laser, maybe) from geosync orbit to a power station on the earth sounds like a great idea until you consider that 1) the atmosphere will make the beam lose some coherence, so you'll get a somewhat spread out beam, and 2) microwaves also cook your food. Get too close to the incoming beam and >phoosh!<, crispy critters.
      • RE: Wireless power from space: energy salvation?

        @doodlius: Given that the frequencies of microwave radiation that would make birdies go *phoosh* are water-resonant frequencies that would increase scattering and losses due to water vapor in the atmosphere, I think it is highly unlikely the future power satelites would use them. The water-resonant frequencies are actually rather specific, and typically the ones you see in wireless networking, specifically because they get attenuated, so their applications are only short range (this is also why your microwave can mess up your 2.4 GHz wireless devices).

        On the other hand, power sats are going to need to find (make? via the FCC) a nice big hole in that part of the RF spectrum so that you don't have any devices that rely on that frequency to go *phoosh* if they get anywhere near the beam.

        OTOH, given tin-foil's wide bandwidth, wearing a tin-foil hat near the beam would likely result in a hair-raising (singeing?) exerience.
    • RE: Wireless power from space: energy salvation?


      Yes, microwave ovens cook by exciting water molecules and are specifically tuned to that frequency, but you can get burns at just about any RF frequency. For instance, in the US, OSHA refers to 29 CFR 1910.97, which limits RF exposure in the range from 10 MHz to 100 GHz to 10 mW/cm^2 during any six minute period, and the FCC has 47 CFR 1.1310, which covers the range from 300 KHz to 20 GHZ and has limits around 1 mW/cm^2 per 30 minute period at microwave frequencies.
  • RE: Wireless power from space: energy salvation?

    Bussard's Polywell fusion completely sidesteps the necessity for this. Look it up, it works... and for a fraction of the cost of that waste of a project in France.
    • Polywell may work?

      @Vailhem@... <br><br>If Polywell fusion is got to the practical stage it will be useful, how useful is not certain until it is operational.<br><br>It sounds a lot more promising than the practicality of putting up a massive field of solar panels, which would then have to beam the power through the atmosphere they were trying to avoid in the first place.<br><br>The big issue with solar panels and beaming is that you are still facing all the issues that ground based solar is facing, along with the added losses in converting the power to the transmission method and then back to electricity on the ground. Every added conversion introduces loss.<br><br>Combine this with the massive area needed to collect the microwaves safely, I believe the area is 10km2 to be practical.<br><br>Also the shading effect of the solar panels as the satellites transit the sun is going to be an issue, unless the panels are in an orbit near the poles.<br><br>Lots of problems to solve for space based solar unfortunately, I once thought it was a good idea until I thought through the issues.<br><br>Let's hope that fusion of some kind is made to work practically, and soon.<br><br>Right now it makes more sense to use a large area of our rooftops as solar collector arrays, why do we need to throw that power away?<br><br>And probably it always will make sense to collect energy where we currently waste it, which is all over the place. Better than introducing a no fly zone, even if the frequency is not water heating, which is unlikely, it will heat something and will also generate currents in any conductive material in it's path.

      I should add that the issue for me is not can this be done, but can it be done practically on a large enough scale without creating hazards.

      I know there have been tests of systems for microwave transmission that report no issues, but when you ramp this up to the tens or hundreds of megawatts needed there are likely to be issues. Laser may work eventually, but 40%-50% efficiency is not enough, and the beam is definitely a no fly area.
      • Forget fusion

        fission is here now. It works, it's reliable, it's safe, and it produces gads of power. Of course, human beings are often completely irrational beings, so we'll never actually see it put into play.