In pure metals or homogeneous alloys, the number of electrons per atom as well as the pressure are constant in a temperature gradient, and the electrochemical potential of the electrons is a unique function of the temperature. That is why it is possible to obtain the thermopower of these materials not only in the conventional evaluation of the Onsager equations, which involves the calculation of two transport coefficients, but also with an alternative approach, which involves the calculation of the temperature dependence of the electrochemical potential. The method is illustrated with the calculation of the thermopower of Cr, Mo, and W from the density of states of these metals.