How do I collect the energy from chemical reactions?

A. Hi Samuel. One low technology and conventional way is to burn the hydrogen, heat water to steam, and use the steam for heating, or for driving a steam turbine connected to a generator to create electricity. Another low-tech way is to burn the hydrogen in an internal combustion engine (like an automobile motor) to harvest mechanical energy or power an electrical generator. Between them then, you can get heat, electricity, or mechanical energy as desired.

For higher technology, look into hydrogen fuel cells as a way to more directly convert the chemical potential into electricity.

But where are you going to get the hydrogen? You need an energy efficient way to pull it out of the atmosphere, or the earth or something. One obvious source of hydrogen would be to electrolyze water into hydrogen and oxygen but, as you'll learn in thermodynamics class, there is no such thing as perpetual motion machines and it will always cost you more energy to separate water into hydrogen and oxygen than you will get from recombining them. Good luck.

Regards,