Super idea, attach the "merry-go-round" to a generator and develop DC current to charge the gel batteries in the basement, most of your energy for night-time reading would be supplied with a 0% carbon footprint!!!

A 0% carbon footprint? Are you suggesting to not feed the child? ;-)

Anytime a human (or animal) performs labour, he/she/it uses muscles. And just like a combustion engine, muscles need to burn a fuel to get their energy. The fuel comes from reducing sugars, carbohydrates and fats; producing CO₂. And in the digestive system, CH₄ (methane) is produced.