What is the total magnetic energy in joules that the Earth produces?

Answer 1

I can't tell u Total Magnetic energy of earth.But there is a apparatus known as EARTH COIL which is able to calculate the Earth magnetic field i.e B= Bv + Bh --- {B= Total magnetic field of Earth, Bv= Vertical component of Earths Magnetic Field,
Bh=Horizontal component of Earths magnetic field}
You ask a student studying bachelor in physics or completed, they perform practical on this instrument to calculate the Earth magnetic field.
It may or may not be constant.