Space Based Solar Power - Revision history

Strangelv: Reworking start of article a little.

2019-04-09T19:51:48Z

Reworking start of article a little.

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2019-04-09T19:38:35Z

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2019-04-08T14:44:17Z

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Jburk: Created page with "The Wikipedia's take on the topic is here https://en.wikipedia.org/wiki/Space-based_solar_power = What are Power Satellites? = The history is covered in the Wikipedia articl..."

2018-06-20T05:57:13Z

Created page with "The Wikipedia's take on the topic is here https://en.wikipedia.org/wiki/Space-based_solar_power = What are Power Satellites? = The history is covered in the Wikipedia articl..."

Exoplatz.org>Hkhenson: /* What are Power Satellites? */

2017-06-22T01:24:11Z

What are Power Satellites?

Exoplatz.org>Hkhenson: /* Methodology of This Work */

2017-06-18T18:32:34Z

Methodology of This Work

Exoplatz.org>Hkhenson: /* Common considerations */

2017-06-09T00:11:09Z

Common considerations

Exoplatz.org>Hkhenson: /* Photovoltaic (PV) and Concentrated PV */

2017-06-08T23:21:44Z

Photovoltaic (PV) and Concentrated PV

Exoplatz.org>Hkhenson: /* Parts energy */

2017-06-08T23:19:58Z

Parts energy

Exoplatz.org>Hkhenson: /* Cost allocations */

2017-06-08T23:14:55Z

Cost allocations

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+'''Space Based Solar Power''' is the concept of moving the collection of energy from [[Sol]] to Earth orbit in order to increase collection efficiency, eliminate weather, time-of-day, and seasonal outages, and reduce needed land usage.  Energy collectable from orbit is a major factor in the first level of the [[Kardashev Scale]].
 ==What are Power Satellites?==
-The history is covered in the Wikipedia article above.  The 1968 work by Peter Glaser is briefly mentioned in the video here: https://www.youtube.com/watch?v=VEkZkINrJaA
+<!-- The history is covered in the Wikipedia article above.  The 1968 work by Peter Glaser is briefly mentioned in the video here: https://www.youtube.com/watch?v=VEkZkINrJaA
+-->
 They are a way to collect solar power out in space, usually GEO where the sun shines 99% of the time.  Solar power on the ground has the problems of intermittency from clouds, night and the sun being low in the sky. Typically, ground solar in good locations averages about 20% of its peak rating. Power satellites are subject to short eclipses (up to 70 minutes) near the equinoxes around midnight.  Because demand is low, the interruptions can be tolerated.  With deep market penetration, the microwave beams can be crossed if the demand exceeds the capacity of the surface grid to redistribute power east to west or west to east.

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 The history is covered in the Wikipedia article above.  The 1968 work by Peter Glaser is briefly mentioned in the video here: https://www.youtube.com/watch?v=VEkZkINrJaA
-They are a way to collect solar power out in space, usually GEO where the sun shines 99% of the time.  Solar power on the ground has the problems of intermittency from clouds, night and the sun being low in the sky. Typically, ground solar in good locations averages about 20% of its peak rating. Power satellites are subject to short eclipses (up to 70 minutes) near the equinoxes around midnight.  Because demand is low, the interruptions can be tolerated.  With deep market penetration, the microwave beams can be crossed if the demand exceeds the capacity of the surface gird to redistribute power east to west or west to east.
+They are a way to collect solar power out in space, usually GEO where the sun shines 99% of the time.  Solar power on the ground has the problems of intermittency from clouds, night and the sun being low in the sky. Typically, ground solar in good locations averages about 20% of its peak rating. Power satellites are subject to short eclipses (up to 70 minutes) near the equinoxes around midnight.  Because demand is low, the interruptions can be tolerated.  With deep market penetration, the microwave beams can be crossed if the demand exceeds the capacity of the surface grid to redistribute power east to west or west to east.
 They potentially scale to more than ten times the current energy needs of the human race.  Started soon and pushed hard, they could end the build up of CO2 in the atmosphere and even reverse it.
 == Methodology of This Work ==
-The specifics in this study are less important than the analysis methodology.  Important concepts include levelized cost of power, specific mass in terms of kg/kW, lift cost, ERoEI, and payback times.  The attempt here will be to analyze specific examples but the details of choices such as PV vs thermal are less important than the analysis proceedure.
+The specifics in this study are less important than the analysis methodology.  Important concepts include levelized cost of power, specific mass in terms of kg/kW, lift cost, ERoEI, and payback times.  The attempt here will be to analyze specific examples but the details of choices such as PV vs thermal are less important than the analysis procedure.
 = Power Satellites and Energy Economics =

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 == Methodology of This Work ==
-The specifics in this study are less important than the analysis methodology.  Important concepts include levelized cost of power, specific mass in terms of kg/kW, ERoEI, and payback times.  The attempt here will be to analyze specific examples but the details of choices such as PV vs thermal are less important than the analysis proceedure.
+The specifics in this study are less important than the analysis methodology.  Important concepts include levelized cost of power, specific mass in terms of kg/kW, lift cost, ERoEI, and payback times.  The attempt here will be to analyze specific examples but the details of choices such as PV vs thermal are less important than the analysis proceedure.
 = Power Satellites and Energy Economics =

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 For economic analysis, 50%.  The loss chain might be a little better with technical improvements, but not much.  It means you generate two kW in space for one kW on the rectenna bus.  That's been assumed in all the analysis here.
+== Transport Methods Surface to LEO ==
 ====Falcon Heavy====
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 Combustion of hydrogen is 286 kJ/mol.  Mole is 2.016 gm, so 496 moles in a kg, 143 MJ/kg or 39.4 kWh/kg.  That's quite a bit less.  The rough analysis have also been using 20 kWh/kg to liquify the hydrogen.  That's way off.  If you Google for "A Future Energy Chain Based on Liquefied Hydrogen" Berstad and go down to page 20, they cite a number of ~6.5 kWh/kg.  We might do a little better because we can use warming the LNG to cool the hydrogen.  That makes the energy content of the LH2 about 46 kWh/kg.  It's hard to say exactly where you should measure the input energy, but the process to make hydrogen from natural gas is efficient, and it only uses about 1.7% of the energy in a kg of NG to liquify it.  I.e., measuring at the well head will not make a great deal of difference.  Still, this Wiki article needs to go into the thermodynamics of steam reforming.
 The current LEO to GEO hydrogen consumption (using electric propulsion) is 4000 tons to get 15,000 tons to high orbit.  On average, that makes a 15 ton Skylon payload 11.84 tons cargo and 3.16 tons of hydrogen reaction mass.  At launch the average Skylon has 59 plus 3 or 62 tons of LH2.  That makes the hydrogen per ton of payload 62/11.84 or 5.25 kg/kg of payload.

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 == Photovoltaic (PV) and Concentrated PV==
-Most designs for power satellites since the 1970s have been PV.  PV has advantages, long experience powering communication satellites being important.  However, PV suffers from relatively low efficiency (20%) and degradation from radiation.  There are proposals by Robert Forward and Robert Holt on draining the van Allen belt [http://en.wikipedia.org/wiki/HiVolt]; however, just the presence of a substantial number of power satellites in GEO is expected to greatly mitigate the radiation from particles trapped in the Earth's magnetic field.  (The particles are stopped by running into the power satellites.  There are only about 3 kg of protons trapped in the belts.)
+Most designs for power satellites since the 1970s have been PV.  PV has advantages, long experience powering communication satellites being important.  However, PV suffers from relatively low efficiency (20%) and degradation from radiation.  There are proposals by Robert Forward and Robert Holt on draining the van Allen belt [http://en.wikipedia.org/wiki/HiVolt]; however, just the presence of a substantial number of power satellites in GEO is expected to greatly mitigate the radiation from particles trapped in the Earth's magnetic field.  (The particles are stopped by running into a power satellite.  There are only about 3 kg of protons trapped in the belts.)
-There are PV cells that range up to 40% efficient, but they require concentrated light and cooling.  The work on thermal power satellites makes CPV possibly attractive, though there are problems with the limited supply of gallium which is used to fabricated the multi junction cells.
+There are PV cells that range up to 40% efficient, but they require concentrated light and cooling.  The work on thermal power satellites makes CPV possibly attractive, though there are problems with the limited supply of gallium which is used to fabricated the multi-junction cells.
 == Thermal ==

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 time) to repay the energy used to build it and move it to GEO.
-That's a three month energy repayment time.  There are no other renewable
+That's a three-month energy repayment time.  There are no other renewable
-proposals that are even close.  The energy from a power satellite is available 99% of the time.  (There is up to a 70 minute eclipse around the equinox.)
+proposals that are even close.
-If the power satellites last 30 years, you get an ERoEI of 120 to one.
+If the power satellites last 30 years, you get an ERoEI of 120 to one, as good as early shallow oil wells.
 This is subject to adjustment as we settle on more accurate numbers in
-the design phase, but it is good enough to justify investigation in more detail.
+the design phase, but it is good enough to justify investigation in detail.
+In his book on power satellites, John Mankins gives a payback time of 8 weeks.  John uses the energy from physics, about 12 kWh/kg from the surface to GEO) (IIRC, it's actually 14.75 kW/kg)and doubles it twice for his estimate.
 = Power Satellite Types =

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 *$900/kW for the cost of parts and minor labor in space and
-*$1300/kW (6.5 kg/kW[[https://spacejournal.ohio.edu/issue18/thermalpower.html]] and $200/kg) for the cost of transport to GEO.
+*$1300/kW (6.5 kg/kW[[https://spacejournal.ohio.edu/issue18/thermalpower.html]] and $200/kg) for the cost of transport to GEO.  (add pointer to sustech 2014 paper)
 These numbers are targets which future work will firm up.  If they go too high, something (like the cost charged for the electric power) will have to be adjusted.  Of course, if they go too high, the entire idea needs to be reconsidered.