Solar farms in space could be renewable energy’s next frontier

Posted: March 9, 2019 by oldbrew in Energy, innovation
Tags: , ,


Maybe there’s some military angle to this. As the report says, it ‘will be difficult and costly’. Capturing the sun’s power will be cloud-free, but when transmitting to the ground the clouds are still there.

China wants to put a solar power station in orbit by 2050 and is building a test facility to find the best way to send power to the ground, reports MACH (NBC News).

As the green energy revolution accelerates, solar farms have become a familiar sight across the nation and around the world.

But China is taking solar power to a whole new level. The nation has announced plans to put a solar power station in orbit by 2050, a feat that would make it the first nation to harness the sun’s energy in space and beam it to Earth.

Since the sun always shines in space, space-based solar power is seen as a uniquely reliable source of renewable energy.

“You don’t have to deal with the day and night cycle, and you don’t have to deal with clouds or seasons, so you end up having eight to nine times more power available to you,” said Ali Hajimiri, a professor of electrical engineering at the California Institute of Technology and director of the university’s Space Solar Power Project.

Of course, developing the hardware needed to capture and transmit the solar power, and launching the system into space, will be difficult and costly.

But China is moving forward: The nation is building a test facility in the southwestern city of Chongqing to determine the best way to transmit solar power from orbit to the ground, the China Daily reported.

Continued here.

Comments
  1. spetzer86 says:

    Wonder how many GW you’d need to be pumping down from the heavens before you’d basically have an energy weapon? A concentrated microwave beam wouldn’t be dangerous, would it? Maybe just a really intense laser?

  2. JB says:

    Lotsa problems with this very old idea. Low ROI and EOL disposal to start with. Then energy transfer efficiency. Maintenance cost.

    From pie in the sky to blight in the sky.

  3. A C Osborn says:

    spetzer86 says: March 9, 2019 at 2:29 pm
    There was an old Sc Fi Book or film about that, a person would not want to be in the way of those microwaves.
    The theme of the book/film was terrorists taking over the Satellites and Micowaving the Cities.
    If they are powerful enough to transfer electricity through the atmosphere they would cause untold damage to a human body.

  4. dscott says:

    One would think beaming microwaves to the ground, no matter how weak would heat the moisture in the air and cause…global warming. Just saying. Your microwave oven heats food by heating the water molecules in the food. /snicker, snicker/

    Applied to powering stuff on the moon or in orbit, say a space station, this might be cost effective.

  5. Curious George says:

    Most grandiose energy schemes have that famous “then a miracle happens” box at their heart. Chinese are actually trying to make it happen.

  6. oldbrew says:

    The Sun already transmits to the surface of the Earth. Can a device out in space do it better?

  7. Gamecock says:

    Additional energy sent to the earth would cause global warming.

  8. BoyfromTottenham says:

    How many more crazy, unworkable ideas are we going to hear about ‘space to earth’ power transmission? Simple physics says that electromagnetic signals are atttenuated by the inverse square law. Even ‘low earth orbits’ are in the order of 2000 km, so the losses (watts transmitted to watts received) are enormous. These losses can be minimised by focussing the sent and received signal with high-gain antennas, but even then they are so high as to render the concept totally unworkable.

  9. gbaikie says:

    “How many more crazy, unworkable ideas are we going to hear about ‘space to earth’ power transmission? Simple physics says that electromagnetic signals are atttenuated by the inverse square law. ”

    The main thing is you have to lower launch to GEO.
    Chinese could do this by using a nuclear orion:
    https://en.wikipedia.org/wiki/Project_Orion_(nuclear_propulsion)
    “The Orion concept detonates nuclear explosions externally at a rate of power release which is beyond what nuclear reactors could survive internally with known materials and design.

    Since weight is no limitation, an Orion craft can be extremely robust. An unmanned craft could tolerate very large accelerations, perhaps 100 g. A human-crewed Orion, however, must use some sort of damping system behind the pusher plate to smooth the near instantaneous acceleration to a level that humans can comfortably withstand – typically about 2 to 4 g.

    The high performance depends on the high exhaust velocity, in order to maximize the rocket’s force for a given mass of propellant. The velocity of the plasma debris is proportional to the square root of the change in the temperature (Tc) of the nuclear fireball. Since fireballs routinely achieve ten million degrees Celsius or more in less than a millisecond, they create very high velocities. However, a practical design must also limit the destructive radius of the fireball. The diameter of the nuclear fireball is proportional to the square root of the bomb’s explosive yield.”

    To work one would need detonate many nukes in the atmosphere- something US will not or can not do for political reasons.
    And China does not have such political limitations.
    Technically, it’s quite feasible, but it would have significant radioactive pollution.
    The radioactive pollution would not problem if operating within the space environment, but the present problem is getting off Earth, and that would would be a problem particularly if launching a lot of them. And to be cheap enough the Nuclear Orion would reusable and one have to have a large number of launches and returns to Earth surface.

    Another possibly would be having very large chemical rocket, like a Sea dragon:
    https://en.wikipedia.org/wiki/Sea_Dragon_(rocket) :
    “The rocket would have been able to carry a payload of up to 550 tonnes (540 long tons; 610 short tons) or 550,000 kg (1,210,000 lb) into LEO. Payload costs were estimated to be between $59 to $600 per kg.”

    It probably have to be better than $59 per lb to LEO
    Currently launch cost to LEO is about $1000 per lb and you have to get to GEO which is 2 to 3 times more than LEO.

    But if you make it all on the Moon and then ship to GEO, the launch cost from the Moon can very cheap. But roughly to make it on the Moon, one has first lower the cost energy on the Moon.
    It seems unlikely to me that the Chinese could make Sea Dragon type rocket cheap enough or make electrical power on the Moon cheap enough. So it seems to me a Nuclear Orion is probably the easiest or only pathway for China.

  10. oldbrew says:

    It could all be a figleaf for some military stuff.
    – – –
    According to Chinese and U.S. estimates, China has the world’s largest shale gas reserves, an estimated 31 trillion m³.
    https://cen.acs.org/articles/93/i3/China-Backpedals-Shale-Gas.html

  11. Stuart Brown says:

    Gbaikie – always been intrigued by Orion since reading ‘Footfall’ (Niven & Pournelle) many years ago. Quite some trick to make something capable of withstanding repeated nuclear explosions close up, but apparently do-able, according to George Dyson in his book and TED talks.

    Since the object is to generate energy and the Chinese have quite a bit of experience letting off nuclear explosions at the bottom of deep holes in Lop Nur, perhaps a better way would be to line the hole with boiler tubes and stick some steam turbines at the top. Then just keep chucking the Orion style nuclear explosives down the hole!

  12. Gamecock says:

    Another ingenious solution to a non existent problem.

  13. gbaikie says:

    “Since the object is to generate energy and the Chinese have quite a bit of experience letting off nuclear explosions at the bottom of deep holes in Lop Nur, perhaps a better way would be to line the hole with boiler tubes and stick some steam turbines at the top. Then just keep chucking the Orion style nuclear explosives down the hole!”\

    Well perhaps these holes could contain some of the radioactive pollution.
    A general idea is one has to get lower density air of atmosphere in order to attain the higher velocity needed to gain orbit.
    Or another way to look at it, is one use cannon to get to space, but it’s upper limit is around 6 km/sec and one could think of cannon as “first stage of rocket” and would add the remaining 1.8 km/sec with solid rocket [or some kind of rocket] to attain the 7.8 km/sec velocity needed for orbit.
    The reason 6 km/sec is the limit is that going the dense air of lower atmosphere is sort like through a solid wall or water at +100 mph.
    Or in rocketry there is a term called Max Q, wiki:
    “The max q condition is the point when an aerospace vehicle’s atmospheric flight reaches maximum dynamic pressure. This is a significant factor in the design of such vehicles because the aerodynamic structural load on them is proportional to dynamic pressure. This may impose limits on the vehicle’s flight envelope.”
    https://en.wikipedia.org/wiki/Max_q
    And:
    “During a normal Space Shuttle launch, for example, max q occurred at an altitude of approximately 11 km (35,000 ft). The three Space Shuttle Main Engines were throttled back to about 60-70% of their rated thrust (depending on payload) as the dynamic pressure approached max q;”
    So Shuttle gets to 11 km elevation and going about 700 mph, it reduced it’s thrust so the shuttle structure could withstand the dynamic load from the fairly dense atmosphere, but as gain higher elevation and less dense air, it can return to full throttle.
    And all rockets have Max Q. And with cannon max Q is once it leaves barrel of cannon- if too fast the projectile just explodes.
    And with a cannon, the projectile experiences very high gees [100 or more gees]. Btw if in car accident one can experience about 50 gees without dying. And with flight suits one can survive about 9 gees for a couple minutes without blacking out [or jet fighters train to such levels of gees].
    Also modern cars have crumple zone which are basically about lowering the gee forces in a car accident- or you can total the car, and you can walk away from it- and also air bags.

    Anyhow a mile distance is short distance to accelerate to reach orbital velocity or
    Distance = Acceleration 1/2 times Time squared.
    So 1 gee is 9.8 m/s/s.
    a bit more 1 gee: 10 meters per sec per second for 10 second is
    5 times 100 = 500 meters distance. And attains velocity of 10 m/s/s time 10 second=
    equals 100 m/s [mph = 100 times 3600 second equals 360,000 meter or 360 km per
    hour. And 360 times .62 is 223.2 mph.
    or 100 m/s/s [+10 gees] for 10 seconds is distance of 5000 meter [5 km, or 3.1 miles].
    and be going 1000 m/s [1 km/sec or 2232 mph].

  14. BoyfromTotenham says:

    gbaikie – I was pointing out the futility of trying to transmit useful amounts of energy to earth from a power system in space. The issue of getting the power station up there in the first place is irrelevant if physics says that the generated power cannot be efficiently transmitted back to earth. But please chase rainbows if you wish.

  15. hunterson7 says:

    Lockheed had a concept for this in the 1970s.
    Their idea would have used mirrors to heat a target for a boiler driven generator, or huge solar cells array for direct photon to electron conversion.
    The resulting power would be microwaved to huge lectinear antenna arrays. They would convert the microwaves to electricity.
    The power transmission per sq.meter would be so low as to be allegedly safe. The frequency would pass through the atmosphere and weather with low loss.
    These would be vast satellites, many square kilometers. The orbit would be geosynchronous.
    An amazing huge capital project.
    Could it possibly work?

  16. gbaikie says:

    –BoyfromTotenham says:
    March 11, 2019 at 1:27 am
    gbaikie – I was pointing out the futility of trying to transmit useful amounts of energy to earth from a power system in space. The issue of getting the power station up there in the first place is irrelevant if physics says that the generated power cannot be efficiently transmitted back to earth. But please chase rainbows if you wish.–

    How you transmit the energy harvested in GEO to earth surface is interesting part of it.
    Studies have indicated one could transmit energy by converting it into microwaves or laser light.

    It seems the energy loss of conversions and transmission requires very cheap source of energy at GEO- and this similar with all power plant production on Earth.
    In simple terms wholesale price of electrical power is a lot cheaper than the electrical price you pay for residential power. Or wholesale electrical power might less than 1 cent per kW hour and retail costs can be over 15 cent per kW hour of the electrical power that you use.

    One think of electrical power from space in terms of wholesale or retail. And you can think of it as both. In terms of dollar gross amounts space wholesale electrical power is less than 1/10th of gross income as compared space retail electrical power. Or for each kW hour of space electrical power delivered at earth surface, wholesale gets 1/10th or 1/20th or less of this retail price.
    But as said, this roughly the state of our current electrical market- the large portion of price is distribution or retail of the electrical power which is bought.

    But one could ask, are the wholesale producers getting most of their revenue from their portion of retail price at the earth surface.
    The reality today is that “retail” electrical power in space is about $20 or more per kW hour, or satellites are paying about amount this [or more] for the electrical power- and they have doing this for decades. And if they could get electrical power at 1$ per kW, they would be quite happy and we talking wholesale in GEO at $.01 per kW hour [or less].

    And one could ask, if satellite owner get electrical power at much cheaper price, would consume more electrical power? The trend in satellite electrical power has been increasing. And there about 1000 satellite, now, and one see more 10,000 of them in the future. GEO satellite generally have array of about 10 kW, and if providing them with 100 kW at cheaper cost, they probably could provide much better services.
    Then there are new markets- beamed power. If 1 or 10 MW microwave or laser power was deliverable in space environment, you probably get buyers, not many in beginning, but within decade or decades it could be considerable.
    But basically right now electrical power in space is very expensive and it’s expensive due to high cost getting things in space. And in terms of wholesale [or not earth retail] in within a decade perhaps 1/2 the wholesale gross sales is to market not on Earth surface.
    But that still leaves earth retail as far larger portion of gross sales, and it remain this case for decades or perhaps more than a century.
    In terms of retail, one probably going to start where electrical retail prices are the highest.
    Hawaii and other islands are currently paying about 30 cents or more per kW hour for electrical power. And poor countries tend to be poor, because they have a high electrical costs.

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