Aug 6 2012: For the bulk of our energy resources, a 44 year old idea, power satellites, might become the dominate power source.
It can scale to tens of TW, the energy payback time is less then 2 months.
The reason it has not been taken seriously is the high cost of lifting parts to GEO. Rocket performance is limited by the energy in chemical fuels, barely enough to get 2% of takeoff mass to GEO.
If you can sidestep the limitation of chemical fuels, then the payload fraction goes way up. Solid state lasers, grown up versions of the tiny ones in CD players, will do that. I.e., unrelated developments in electronics are about to cause a "Black Swan" effect on space transportation.
Burning hydrogen in air is even better than lasers—till you run out of air. The current concept is an air breathing rocket plane such as Reaction Engines' Skylon for the first 2 km/s velocity gain and hydrogen heated to 2700 deg K by a multi GW laser in GEO for the rest of the velocity to LEO. That gets about 25% of the starting mass on the runway to LEO as payload. From there up, lasers deliver around two thirds of the mass in LEO to GEO, about 18 tons out of 120 or 15%. Three times an hour.
That gets the cost down to under $100/kg, the cost of power plants to $1.6 B per GW, the cost of power to 2 cents per kWh or less and the cost of synthetic gasoline made with electric power to a dollar a gallon.
Further bootstrapping (10% of new power sat construction) allows lift capacity to grow by a factor of 3 every year (based on laser capacity). Goal is energy at such low cost that humanity can painlessly get off fossil fuels in two decades. Cost is about 1/3 of the $500 B for a Mars mission *and* you get a Mars mission virtually for free by sending the 100th power sat (all 25,000 tons of if) to Mars for local propulsion. (The high cost is due to having to haul up the first power sat with conventional rockets.)
The previous iteration of the concept is here: http://www.theoildrum.com/node/7898
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It can scale to tens of TW, the energy payback time is less then 2 months.
The reason it has not been taken seriously is the high cost of lifting parts to GEO. Rocket performance is limited by the energy in chemical fuels, barely enough to get 2% of takeoff mass to GEO.
If you can sidestep the limitation of chemical fuels, then the payload fraction goes way up. Solid state lasers, grown up versions of the tiny ones in CD players, will do that. I.e., unrelated developments in electronics are about to cause a "Black Swan" effect on space transportation.
Burning hydrogen in air is even better than lasers—till you run out of air. The current concept is an air breathing rocket plane such as Reaction Engines' Skylon for the first 2 km/s velocity gain and hydrogen heated to 2700 deg K by a multi GW laser in GEO for the rest of the velocity to LEO. That gets about 25% of the starting mass on the runway to LEO as payload. From there up, lasers deliver around two thirds of the mass in LEO to GEO, about 18 tons out of 120 or 15%. Three times an hour.
That gets the cost down to under $100/kg, the cost of power plants to $1.6 B per GW, the cost of power to 2 cents per kWh or less and the cost of synthetic gasoline made with electric power to a dollar a gallon.
Further bootstrapping (10% of new power sat construction) allows lift capacity to grow by a factor of 3 every year (based on laser capacity). Goal is energy at such low cost that humanity can painlessly get off fossil fuels in two decades. Cost is about 1/3 of the $500 B for a Mars mission *and* you get a Mars mission virtually for free by sending the 100th power sat (all 25,000 tons of if) to Mars for local propulsion. (The high cost is due to having to haul up the first power sat with conventional rockets.)
The previous iteration of the concept is here: http://www.theoildrum.com/node/7898