I just came up with a theory:  I think the solution to every problem in the world is to invent and employ personal electric generators.  The basic idea would be to utilize the energy humans normally spend to freely generate electricity that could be used to power homes, cars, and devices, and maybe even sell back to electric companies at a profit.  Think about it:  We humans go to extreme lengths to expend energy.  We each spend hundreds and thousands of dollars per year for gym memberships and workout equipment that enable us to spend our energy with the benefit of making our muscles strong and/or last longer.  What if, instead of spending money on these things (and also money to electrically power these things), we used the energy we would normally spend in a workout to power some sort of energy collecting device?  Think "giant hamster wheel".  What's a treadmill, stair-climber, or elliptical machine except a simple belt and pulley system?  But instead of having an electric motor provide power to make the belt move and in turn force the human to move, the human could provide the power to make the belt move and in turn power the motor.  Or what about a punching bag?  [Warning:  Science content follows]  It seems like a relatively simple idea to make a device that would generate heat by compressing a gas when a certain force is applied.  That's how every internal combustion engine in every car on earth works (except the engine produces work instead of heat when the gas is compressed; similar idea though).  If a human provides the force (punch or kick), the device could easily compress the gas and provide heat output, which could be used to heat a house or refrigerate food (same process, opposite direction). 

Partial list of problems this would solve or at least slightly diminish:  High energy prices, depletion of fossil fuels, problems in/with the Middle East, most current wars and conflicts, global warming (including but not limited to ice cap melting, water level rising, destruction of arctic habitats, increased frequency and strength of natural disasters, eventual annihilation of all mankind). #science