You mean to feed the alpha/Hakkon?, When you beat the fight of the sub-guh’nir alpha and recruit him on your crew (A.K.A Hakkon), You can buy 10 pure energy crystals in the core, for 1,000 galaxy crédits (i think, I’m not sure). If you killed ‘Hakkon’ after beating him then you can’t access this option. Hope this helps! ^^