Oh, sorry. With a hand-crank you could get about 63.108 poundal-furlongs per lunar year, so... given all six billion humans you could generate that much energy

Oh, sorry. With a hand-crank you could get about 63.108 poundal-furlongs per lunar year, so... given all six billion humans you could generate that much energy in... uhh, 5.2 * 10^27 fortnights.