Space Solar Power

[KitemanSA]

There is a lot of thinking between $11,000 and $1.

You betcha, Red Rider! And a lot of fun too!

I suspect the KITE-HASTOL combo might take it down by two of those 4 orders of magnitude. Not a bad first step.

[Soylent]

Mayhaps I do understand. Despite some of the publicity, I suspect they will lose a bit of money on the first one or two (or dozen).

First one or two what? Terawatts?

The fixed costs are spectacular apart from just the launch cost.

You need a ~1 km diameter 2.4 GHz microwave antenna to be constructed in space. You need a ~10 km diameter rectenna on the ground and most likely a buffer of about 10-20 km around the damned thing. In order for the rectenna to get a power density of a mere 100 W/m^2 you need 8 GW of incomming microwaves; in other words it's the same order of magnitude as cumulative world production of solar panels, and you need very lightweight versions. This whole thing needs some decent thrusters to counteract the solar wind.

The solar panels would last only about 20 years on the ground; in space they will be bathed in ionizing radiation and experience large, repetitive temperature swings.

You'll need to invert the low-voltage DC from the panels to low voltage AC, step up to high voltage AC, transmit it to the antenna, step down to low voltage AC, invert to DC, transmit microwaves to rectenna on Earth, invert to AC and finally step up to grid voltage(if you're far from consumers you may have to put in two additional steps and use HVDC).

Then they will start SERIOUSLY reducing those costs and shazaam, it MAY actually become commercially viable. A most exciting proposition, no?

No. I don't think it could ever be commercially viable even if launch costs are effectively free.

[KitemanSA]

Mayhaps I do understand. Despite some of the publicity, I suspect they will lose a bit of money on the first one or two (or dozen).

First one or two what? Terawatts?

Good one
But no, obviously I meant satellites.

The fixed costs are spectacular apart from just the launch cost.

You need a ~1 km diameter 2.4 GHz microwave antenna to be constructed in space. You need a ~10 km diameter rectenna on the ground and most likely a buffer of about 10-20 km around the damned thing. In order for the rectenna to get a power density of a mere 100 W/m^2 you need 8 GW of incomming microwaves; in other words it's the same order of magnitude as cumulative world production of solar panels, and you need very lightweight versions. This whole thing needs some decent thrusters to counteract the solar wind.

The solar panels would last only about 20 years on the ground; in space they will be bathed in ionizing radiation and experience large, repetitive temperature swings.

You'll need to invert the low-voltage DC from the panels to low voltage AC, step up to high voltage AC, transmit it to the antenna, step down to low voltage AC, invert to DC, transmit microwaves to rectenna on Earth, invert to AC and finally step up to grid voltage(if you're far from consumers you may have to put in two additional steps and use HVDC).

Then they will start SERIOUSLY reducing those costs and shazaam, it MAY actually become commercially viable. A most exciting proposition, no?

No. I don't think it could ever be commercially viable even if launch costs are effectively free.

Well, I guess we will have to agree to disagree, but my recollection of the results of many a Space Development Conference was that this could almost be cost effective even with $500/kg to orbit if lunar resources were used for the main masses. Many of the issues you raised have been reviewed and solutions proposed decades ago.

[MSimon]

Mayhaps I do understand. Despite some of the publicity, I suspect they will lose a bit of money on the first one or two (or dozen).

First one or two what? Terawatts?

:o Good one :lol:
But no, obviously I meant satellites.

The fixed costs are spectacular apart from just the launch cost.

You need a ~1 km diameter 2.4 GHz microwave antenna to be constructed in space. You need a ~10 km diameter rectenna on the ground and most likely a buffer of about 10-20 km around the damned thing. In order for the rectenna to get a power density of a mere 100 W/m^2 you need 8 GW of incomming microwaves; in other words it's the same order of magnitude as cumulative world production of solar panels, and you need very lightweight versions. This whole thing needs some decent thrusters to counteract the solar wind.

The solar panels would last only about 20 years on the ground; in space they will be bathed in ionizing radiation and experience large, repetitive temperature swings.

You'll need to invert the low-voltage DC from the panels to low voltage AC, step up to high voltage AC, transmit it to the antenna, step down to low voltage AC, invert to DC, transmit microwaves to rectenna on Earth, invert to AC and finally step up to grid voltage(if you're far from consumers you may have to put in two additional steps and use HVDC).

Then they will start SERIOUSLY reducing those costs and shazaam, it MAY actually become commercially viable. A most exciting proposition, no?

No. I don't think it could ever be commercially viable even if launch costs are effectively free.

Well, I guess we will have to agree to disagree, but my recollection of the results of many a Space Development Conference was that this could almost be cost effective even with $500/kg to orbit if lunar resources were used for the main masses. Many of the issues you raised have been reviewed and solutions proposed decades ago.

$500 a kg? Well that is encouraging. They could break even with a 20X reduction in launch costs. Now how about a profit?

[KitemanSA]

$500 a kg? Well that is encouraging. They could break even with a 20X reduction in launch costs. Now how about a profit?

20 years of new thought and development, who knows. The company in question may have a grand idea I am not familiar with. As I said, its an exciting thought.