We consider the Ginzburg–Landau equation in dimension two. We introduce a key notion
of the vortex (interaction) energy. It is defined by minimizing the renormalized Ginzburg–Landau
(free) energy functional over functions with a given set of zeros of given local indices.
We find the asymptotic behaviour of the vortex energy as the inter-vortex distances grow.
The leading term of the asymptotic expansion is the vortex self-energy while the next term is
the classical Kirchhoff–Onsager Hamiltonian. To derive this expansion we use several novel