Some advocate sourcing all the world's energy with space-based solar power, on the order of 30 Terawatts. They suggest power satellite masses on the order of 4 kg / kW, or 0.004 kg per watt. That works out to 4e-3 kg/W * 3e13 W or 120e9 kg of power satellite mass delivered to Geostationary Orbit ( GEO, 42164 km radius, 3075 m/s ). This does not include construction equipment or longitudinal station-keeping fuel.
Modern comsats use noble-gas electric thrusters to climb to GEO. This is propellant-thrifty; however, this has driven up the price of Xenon and is shifting to Krypton. There is not enough available high-Z noble gas (xenon, krypton) to raise the orbits of 120 million of tonnes of power satellite. There is plenty of argon, but that must be chilled below 27 Kelvin to store densely for the long trip to GEO.
The transfer orbit, and GEO injection velocity
So, consider liquid hydrogen/liquid oxygen ( LH/LOX) chemical rockets, with typical 1:6 mass ratio (slightly fuel rich), producing a propellant plume of and H₂ and H. The mass ratio of water to total hydrogen ( H₂ plus H ), assuming complete combustion and no hydroxyl ( OH or HO ) or hydronium ( H₃O ).
Assuming a high expansion vacuum nozzle, the exhaust velocity of a liquid hydrogen engine might be as high as 4460 m/s.
Spacecraft typically launch to GEO from low earth orbit (LEO) via a geostationary transfer orbit (GTO). Presume that the GTO perigee starts from a 7000 kilometer radius LEO orbit (622 km equatorial altitude, 7546 m/s orbital velocity) so that GTO is an ellipse with perigee = 7000 km, apogee = 42164 km, semi-major axis 24582 km. The perigee velocity of the GTO ellipse is 9883 m/s and the apogee velocity is 1641 m/s. GTO injection delta V is (9883-7546) = 2337 m/s, and GEO circularization delta V is (3075-1641) = 1434 m/s .
- For a direct launch from the Earth's surface, the GTO transfer orbit may start at a lower altitude, and the GEO circularization delta V will be higher.