Aerovator, Angel fleet, Polywell

Ideas that are currently entertaining me:

• The Aerovator: a spinning wing 2,000km long whose tips rise 100km up and travel at 8 km/s which unlike the Space Elevator can be built (just) with today's materials.
• The Angel fleet: Counteracting global warming with a fleet of 16 trillon solar shades in space between the Earth and the Sun (we can use the Aerovator to put them up)
• Polywell fusion which if it turned out to be possible would save the world - plus we can power the Aerovator with it.