How far away are we from viable space-based solar power?

  • Joseph Brown - 2 years ago

    Previous estimates for Space Solar have all died horribly in the teeth of the required cost to launch the system. So far, it has been far to expensive to ever be practical.

    That is changing. Dramatically. Soon.

    SpaceX plans to have the BFR / Starship - Super Heavy operational by 2022 or 2023. The eventual launch cost for that system is supposed to be around US $20 per kilogram to LEO -- and with launch costs that low Space Solar makes much more sense. Expect the military to be an early adopter -- because having an uninterruptible supply of energy even in the remote corners of the world is very appealing to them. More users will mean more supply coming online, lowering prices.

    I think there are some very exciting developments coming in space-based solar.

  • Herman Resto - 2 years ago

    This would never be allowed by other countries. Laser of this magnitude can be used as a weapon.

  • Keith Henson - 2 years ago

    The physics and economics of power satellites have been studied since the early 70s.

    There were two approaches studied. Dr. O'Neills's was to set up (at a huge initial expense) mining the moon for materials. The other was to just haul the parts up from Earth.

    Estimates for the first ran around half a trillion to 2 trillion dollars to set up.

    The least complex method is just to haul the parts into space. Work in Japan, the US, and the UK have determined that the mass of a power satellite would be 3-7 kg/kW.

    The cost per kW for power from a satellite means adding up the rectenna, the parts, and the lift cost. These are estimated at $200 for the rectenna, $900 for the parts. If you have in mind a price you want to pay for the power, then the total should not exceed 80,000 times the cents/kW. So, for example, 3 cents per kWh power can't cost more than $2400/kW. Using the previous numbers that leaves 1300/kW for the lift cost. and for 6.5 kg/kW, the lift cost (to GEO) can't exceed $200/kg. Given that the cost about doubles from LEO to GEO, a target of $100/kg to LEO looks like it would make economical power from space.

    The current cost to GEO is around $20,000/kg. Musk has probably reduced it to $2000/kg and might with his new rockets get it down lower than that. Reaction Engines in the UK thinks they can get the cost down to less than $100/kg with a reusable space plane.

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